2 Differential gene expression Every somatic cell in an individual organism contains the same genetic information and replicated from the same original fertilized zygote. Why then, do we have differences such as tissues and organs that develop? At different points in time and in different parts of the body, gene expression varies. The amount of transcription and translation occurring for each is regulated and controlled. In bacterial cells, regulation of gene expression occurs as well, but it is controlled differently.
3 Concept 18.1 Bacteria often respond to environmental change by regulating transcription Bacteria have operons which can coordinately control groups of functionally related genes Gene expression can be controlled through the binding or unbinding of proteins to the operator The operator acts as a switch that can turn gene expression on or off for the operon
4 Bacterial regulation The processes of transcription and translation use energy and resources. Expressing unnecessary genes results in wasted energy and resources. For example, if a nutrient is freely available from the environment, there is no need for the bacteria to synthesize it. The energy and resources can then be diverted to another more useful task. Regulation of metabolism can occur in two ways: Control of enzymatic activity through feedback inhibition Control of gene expression through repression
5 Precursor Feedback inhibition trpe gene Enzyme 1 Enzyme 2 trpd gene trpc gene Regulation of gene expression Enzyme 3 trpb gene trpa gene Tryptophan (a) Regulation of enzyme activity (b) Regulation of enzyme production
6 Operons The synthesis of certain molecules consists of a multistep pathway that requires specific enzymes at each step. An operon is a stretch of DNA that includes an operator, a promoter, and a group of functionally related genes. The operator acts as an on-off switch for the operon, controlling transcription of the group of genes. This means the genes are under coordinate control, as they are all controlled together.
7 The trp operon E. coli synthesizes tryptophan through a series of reactions catalyzed by different enzymes. The subunits for these enzymes are under the control of the same operator and are part of the trp operon. The operon produces one long transcript that codes for all five subunits. During translation, five separate polypeptides are produced. Production of these enzymes can be turned off by a protein known as the trp repressor. If the repressor binds to the operator, it prevents the attachment of the RNA polymerase and therefore prevents transcription.
8 The trp repressor The trp repressor is produced from a regulatory gene and is continuously expressed in low amounts. However, it is an allosteric protein. This means that there are two conformations of the protein: active and inactive. In its inactive form, it cannot bind to the operator. To become active, it must be bound to a tryptophan molecule which acts as a corepressor. Therefore, when tryptophan is abundant, it activates the trp repressor, which in turn can now bind to the operator to repress synthesis of enzymes that catalyze tryptophan synthesis.
9 trp operon Promoter Promoter Genes of operon DNA trpr trpe trpd trpc trpb Regulatory Operator gene Start codon Stop codon 3 mrna 5 mrna RNA 5 polymerase E D C B trpa A Protein Inactive repressor Polypeptide subunits that make up enzymes for tryptophan synthesis (a) Tryptophan absent, repressor inactive, operon on
10 DNA No RNA made mrna Protein Active repressor Tryptophan (corepressor) (b) Tryptophan present, repressor active, operon off
11 The lac operon Through the enzyme β-galactosidase, E. coli are able to breakdown the disaccharide lactose into its component monosaccharides. In environments with little lactose, very little β- galactosidase is present. However, if lactose increases, so does the amount of β-galactosidase. The lac operon is responsible for controlling the expression of β-galactosidase, along with two other genes involved in lactose regulation.
12 The lac repressor The lac repressor is an allosteric protein that can bind to the lac operator In its regular state, it is active and can bind to the lac operon. For it to be inactivated, it has to be bound to an inducer which inactivates the repressor but induces the operon. For the lac operon, the inducer is allolactose. Allolactose is an isomer of lactose that is formed in the presence of lactose. Hence, more lactose means more allolactose which induces the operon by repressing the lac repressor.
13 Regulatory gene Promoter Operator DNA laci lacz mrna 5 3 RNA polymerase No RNA made Protein Active repressor (a) Lactose absent, repressor active, operon off
14 lac operon DNA laci lacz lacy laca mrna 5 3 RNA polymerase mrna 5 Protein -Galactosidase Permease Transacetylase Allolactose (inducer) Inactive repressor (b) Lactose present, repressor inactive, operon on
15 Inducible and Repressible Enzymes Inducible enzymes enzymes whose synthesis can be induced by the presence of a substance. Usually part of catabolic pathways which break down a nutrient. E.g. lac operon induced by presence of allolactose. Repressible enzymes enzymes whose synthesis can be repressed by the presence of a substance. Usually part of anabolic pathways which synthesize essential products. E.g. trp operon repressed by presence of tryptophan.
16 Repressible and Inducible Operons Repressible operon usually on but transcription can be turned off (repressed) E.g. trp operon Inducible operon usually off but transcription can be turned on (inducible) E.g. lac operon These are both examples of negative gene regulation because the operons can be switched off by the active form of a repressor protein.
17 Positive Gene Regulation The lac operon can also provide an example of positive gene regulation. When glucose is lacking, lactose can be broken down as an energy source. Cyclic AMP (camp) accumulates when glucose is low and can bind to catabolite activator protein (CAP) which activates it. An activator is a protein that can bind to DNA and stimulate transcription (increasing rate of transcription). Once active, it binds upstream of the lac promoter and increases affinity of RNA polymerase for the promoter, thereby increasing transcription.
18 Promoter Operator DNA laci lacz CAP-binding site camp Active CAP RNA polymerase binds and transcribes Inactive CAP Inactive lac repressor Allolactose (a) Lactose present, glucose scarce (camp level high): abundant lac mrna synthesized
19 Promoter Operator DNA laci lacz CAP-binding site RNA polymerase less likely to bind Inactive CAP Inactive lac repressor (b) Lactose present, glucose present (camp level low): little lac mrna synthesized
20 Concept 18.2 Eukaryotic gene expression is regulated at any stage Different cell types in the same organism will express a different combination of genes There are many steps to gene expression in eukaryotic cells Control of gene expression in eukaryotic cells can be controlled at many of these steps
21 Differential Gene Expression Differential gene expression is the expression of different genes by cells with the same genome. In each cell, only a fraction of the genes are expressed and the subset of genes expressed depends on the cell type. Control of gene expression can occur at different stages of the process
22 Signal Chromatin NUCLEUS Chromatin modification DNA Gene available for transcription Gene Transcription RNA Exon Intron Primary transcript RNA processing Tail Cap mrna in nucleus Transport to cytoplasm CYTOPLASM
23 mrna in cytoplasm CYTOPLASM Degradation of mrna Translation Polypeptide Protein processing Degradation of protein Active protein Transport to cellular destination Cellular function
24 Regulation of Chromatin Structure Heterochromatin Highly condensed areas of chromatin where genes are not usually expressed Histone Modifications Histone acetylation (addition of acetyl groups) to histone tails Prevents folding of chromatin into more compact structure Easier access for transcription Other modifications such as methylation and phosphorylation can also occur. The histone code hypothesis proposes that specific combinations of modifications influence transcription
25 Histone tails DNA double helix Amino acids available for chemical modification (a) Histone tails protrude outward from a nucleosome Unacetylated histones Acetylated histones (b) Acetylation of histone tails promotes loose chromatin structure that permits transcription
26 Regulation of Chromatin Structure DNA Methylation Methylation (addition of a methyl group) to nitrogen bases in DNA. Genes are usually more heavily methylated in cells in which they are not expressed. Methylated DNA can promote histone deacetylation Demethylation of DNA can switch on expression of certain genes. Methylation patterns are passed on to replicated daughter cells. Also a factor in genomic imprinting.
27 Regulation of Chromatin Structure Epigenetic Inheritance Modifications to chromatin structure do not alter DNA sequences. However, these modification can be passed on to future generations. This is known as epigenetic inheritance
28 Regulation of Transcription Initiation Recall: Transcription is initiated in a eukaryotic cell through assembly of the transcription initiation complex at the promoter sequence that is upstream of the gene. Control elements, which are segments of noncoding DNA, help to regulate transcription through binding of proteins. General transcription factors are essential for the transcription of all protein-coding genes. However, general transcription factors initiate a low rate of transcription. For increased transcription, specific transcription factors are needed.
29 Specific Transcription Factors Proximal control elements are sequences located close to the promoter Distal control elements, groups of which are called enhancers, are sequences located more distantly upstream or downstream of a gene, or within an intron. Activator proteins can bind to the enhancer elements. A DNA-bending protein can bend the DNA to bring the activator proteins into contact with mediator proteins which interact with protein at the promoter.
30 Enhancer (distal control elements) DNA Upstream Proximal control elements Promoter Exon Intron Exon Intron Transcription Poly-A signal sequence Exon Termination region Downstream Primary RNA transcript 5 Exon Intron Exon Intron Exon RNA processing Cleaved 3 end of primary transcript Intron RNA Poly-A signal Coding segment mrna 5 Cap 5 UTR Start codon Stop codon 3 UTR Poly-A tail 3
31 DNA Enhancer Activators Distal control element DNA-bending protein Promoter TATA box General transcription factors Gene Group of mediator proteins RNA polymerase II RNA polymerase II Transcription initiation complex RNA synthesis
32 Specific Transcription Factors Specific transcription factors can also function as repressors that inhibit gene expression. Repressors can bind directly to control elements which can in turn block activator binding. Along with directly binding to DNA, other activators and repressors can indirectly influence gene expression by altering chromatin structure through recruitment of proteins to acetylate or deacetylate histones
33 Combinatorial Control of Gene Activation Though there are many genes that must be regulated, only a few sequences appear in control elements. Each enhancer is composed of around ten control elements which can each bind one or two specific transcription factors. A particular combination of control elements can activate transcription only when the appropriate activator proteins are present.
34 Enhancer Promoter Control elements Albumin gene Crystallin gene Available activators LIVER CELL NUCLEUS LENS CELL NUCLEUS Available activators Albumin gene expressed Albumin gene not expressed (a) Liver cell Crystallin gene not expressed (b) Lens cell Crystallin gene expressed
35 Coordinately Controlled Genes in Eukaryotes Unlike functionally related genes in bacteria, functionally related genes in eukaryotic cells are usually each controlled by their own promoter. To coordinate expression, changes in chromatin structure occurs that renders the group of genes available or unavailable for transcription. The association of a specific combination of control elements can also coordinate expression of a widely dispersed group of genes. For example, molecules binding to receptors on the cell surface and trigger a signal transduction pathway that leads to activation of transcription activators or repressors based on a certain combination of control elements.
36 Mechanisms of Post-Transcriptional Regulation Production of a transcript does not equate with gene expression. Gene expression is measured in the amount of functional product. Therefore, post-transcription, there are still mechanisms that can control gene expression through regulation of RNA processing and translation.
37 Regulation of RNA Processing In alternative RNA splicing, different mrna molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns For example, the tropoin T gene produces one primary transcript. However, this primary transcript can produce two possible proteins, based on alternative RNA splicing.
38 Exons DNA Troponin T gene Primary RNA transcript RNA splicing mrna or
39 mrna Degradation Eukaryotic mrna is more long-lived than bacterial mrna. Research shows that removal of the poly-a tail can result in the beginning of enzymatic mrna breakdown. Sequences that are found in the untranslated region (UTR) of the 3 end of the mrna can affect the life-span of that mrna.
40 Regulation of Initiation of Translation The initiation of translation of selected mrnas can be blocked by regulatory proteins that bind to sequences or structures of the mrna Alternatively, translation of all mrnas in a cell may be regulated simultaneously For example, translation initiation factors are simultaneously activated in an egg following fertilization
41 Protein Processing and Degradation After translation, various types of protein processing can occur. Cleavage of the initial polypeptide can activate many proteins. As well, the addition of chemical groups (such as phosphate groups by phosphorylation) can be used to regulate activity of certain regulatory proteins. Ubiquitination (addition of the protein ubiquitin) can often signal a protein for degradation. Proteasomes are giant protein complexes that bind protein molecules and degrade them once they have been tagged with ubiquitin.
42 Ubiquitin Proteasome Proteasome and ubiquitin to be recycled Protein to be degraded Ubiquitinated protein Protein entering a proteasome Protein fragments (peptides)
43 Concept 18.3 Noncoding RNAs play multiple roles in controlling gene expression micrornas (mirnas) and small interfering RNAs (sirnas) are small noncoding RNAs They are able to bind to complementary sequences of mrna to inhibit gene expression through RNA interference (RNAi) These small RNAs also play a role in heterochromatin formation and transcription
44 Effects on mrnas by MicroRNAs and Small Interfering RNAs Some non-coding regions of DNA can produce small RNA molecules known as noncoding RNAs. MicroRNAs (mirnas) are small single-stranded RNA molecules that can bind to mrna They are formed from longer mrna molecules that fold to form double-stranded hair pin structures that are held together by hydrogen bonds. Once it is trimmed by the dicer enzyme, one of the strands is degraded and the other strand forms the mirna. These mirnas can then bind to target mrnas of a complementary sequence and either degrade them or block translation.
45 Effects on mrnas by MicroRNAs and Small Interfering RNAs When researchers injected double stranded RNA into a cell, it would turn off the gene expression of genes with that sequence. The phenomenon of inhibition of gene expression by RNA molecules is called RNA interference (RNAi) RNAi is caused by small interfering RNAs (sirnas) sirnas and mirnas are similar but form from different RNA precursors
46 Hairpin mirna Hydrogen bond Dicer 5 3 (a) Primary mirna transcript mirna mirnaprotein complex mrna degraded Translation blocked (b) Generation and function of mirnas
47 Chromatin Remodeling and Silencing of Transcription As well as interfering with mrnas, sirnas can play a role in heterochromatin formation Small RNAs may also block transcription of specific genes This means that these small non-coding RNAs are involved with regulating multiple steps of gene expression. Many of the mirnas that have been characterized thus far have been shown to play a role in embryonic development.
48 Concept 18.4 A program of differential gene expression leads to the different cell types in a multicellular organism During embryonic development, a fertilized egg gives rise to many different cell types Cytoplasmic determinants and regulation of gene expression can control differentiation of cells
49 Biological organization and heirarchy A zygote and the organism is becomes are very different. The genetic information is the same but differential gene expression leads to formation of different cells. Cell differentiation leads to the formation of many cell types. These specialized cells are organized into tissues, which are organized into organs. Multiple organs together can form organ systems, which work together to form the whole organism.
50 A Genetic Program for Embryonic Development The transformation from zygote to an adult organisms results from cell division, cell differentiation, and morphogenesis. Cell differentiation is the process by which cells become specialized in structure and function. The physical processes that give an organism its shape constitute morphogenesis Differential gene expression results from genes being regulated differently in each cell type Materials in the egg can set up gene regulation that is carried out as cells divide
51 (a) Fertilized eggs of a frog (b) Newly hatched tadpole
52 Cytoplasmic Determinants and Inductive Signals An egg s cytoplasm contains RNA, proteins, and other substances that are distributed unevenly in the unfertilized egg Cytoplasmic determinants are maternal substances in the egg that influence early development As the zygote divides by mitosis, cells contain different cytoplasmic determinants, which lead to different gene expression Along with this, environmental factors can also influence cell differentiation through signaling molecules in a process called induction.
53 Unfertilized egg cell Sperm Nucleus Fertilization Two different cytoplasmic determinants Early embryo (32 cells) NUCLEUS Zygote Mitotic cell division Signal transduction pathway Signal receptor Two-celled embryo Signal molecule (inducer) (a) Cytoplasmic determinants in the egg (b) Induction by nearby cells
54 Sequential regulation of gene expression during cellular differentiation Determination refers to the events that lead to the observable differentiation of a cell. Once determination has occurred, it is irreversible. With observations of molecular changes, it can be seen that determination is directed through gene expression of tissue-specific proteins. Sets of genes are sequentially expressed as cells arise from division of precursor cells.
55 Sequential regulation of gene expression during cellular differentiation For example, the precursor cell for muscle cells can be has the potential to develop into a number of cell types. Researchers examined the effect of isolating different genes to be expressed and identified master regulatory genes which are responsible for determination. The master regulatory gene myod encodes for the MyoD protein which is a transcription factor that can stimulate expression when bound to control elements.
56 Nucleus Master regulatory gene myod Other muscle-specific genes Embryonic precursor cell DNA OFF OFF mrna OFF Myoblast (determined) MyoD protein (transcription factor) mrna mrna mrna mrna Part of a muscle fiber (fully differentiated cell) MyoD Another transcription factor Myosin, other muscle proteins, and cell cycle blocking proteins
57 Pattern Formation: Setting Up the Body Plan Pattern formation is the development of a spatial organization of tissues and organs in characteristic places. In animals, pattern formation begins with the establishment of the major axes (anterior-posterior, rightleft, dorsal-ventral). Positional information are molecular cues that control pattern formation and are provided by cytoplasmic determinants and inductive signals. The genetics of pattern formation has been studied in Drosophila melanogaster. Combining anatomical, genetic, and biochemical approaches, researchers have discovered developmental principles common to many other species, including humans.
58 The Life Cycle of Drosophila Fruit flies have segmented bodies which make up the head, thorax, and abdomen. The body can be divided by three major axes. In Drosophila, cytoplasmic determinants in the unfertilized egg determine the axes before fertilization. After fertilization, the embryo develops into a segmented larva with three larval stages. BODY AXES (a) Adult Head Anterior Left Thorax Dorsal Ventral Abdomen Right 0.5 mm Posterior
59 Genetic Analysis of Early Development Edward B. Lewis was a biologist that studies developmental defects in Drosophila to link developmental abnormalities to specific genes. He discovered genes, called homeotic genes, which control pattern formation in the late embryo, larva, and adult. Eye Antenna Leg Wild type Mutant
60 Genetic Analysis of Early Development Another 30 years later, Christiane Nüsslein-Volhard, and Eric Wieschaus were able to determine genes involved with pattern formation during early embryonic development. They created mutants, conducted breeding experiments, and looked for corresponding genes. Breeding experiments were complicated by embryonic lethals, embryos with lethal mutations. These mutants could not be bred for study. They found 120 genes essential for normal segmentation and were able to map and clone them for further study.
61 Axis Establishment Cytoplasmic determinants in the egg are the substances that initially establish the axes of the Drosophila body. These cytoplasmic determinants are coded for by maternal effect genes. When these are mutated in the mother, it results in a mutant phenotype in the offspring. This is regardless of the offspring s own genotype. These maternal effect genes are also called eggpolarity genes because they control orientation of the egg and help set up the axes.
62 Bicoid: A Morphogen Determining Head Structures Bicoid is a maternal effect gene. When mutated in the mother, the embryo doesn t develop an anterior end and instead has two posterior ends. This phenotype suggests that the product of the mother s bicoid gene is concentrated at the future anterior end. This hypothesis is an example of the morphogen gradient hypothesis, in which gradients of substances called morphogens establish an embryo s axes and other features. It was then shown that mrna for bicoid is more concentrated at the anterior end. If injected into early embryos, anterior structures formed at the site of injection.
63 EXPERIMENT Tail Head T1 T2 T3 A1 A2 A3 A4 A5 A6 A7 A8 Wild-type larva Tail Tail A8 A7 A6 A7 A8 Mutant larva (bicoid) RESULTS CONCLUSION 100 µm Bicoid mrna in mature unfertilized egg Fertilization, translation of bicoid mrna Anterior end Bicoid protein in early embryo Nurse cells Egg bicoid mrna Developing egg Bicoid mrna in mature unfertilized egg Bicoid protein in early embryo
64 Importance of bicoid research o It identified a specific protein required for some early steps in pattern formation o It increased understanding of the mother s role in embryo development o It demonstrated a key developmental principle that a gradient of molecules can determine polarity and position in the embryo
Chapter 18: Control of Gene Expression 海洋生物研究所 曾令銘 海事大樓 426 室分機 : 5326 Differential Expression of Genes Prokaryotes and eukaryotes precisely regulate gene expression in response to environmental conditions
Chapter 18 Regulation of Gene Expression PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from
Prokaryotic Regulation Control of transcription initiation can be: Positive control increases transcription when activators bind DNA Negative control reduces transcription when repressors bind to DNA regulatory
Prokaryotic Gene Expression (Learning Objectives) 1. Learn how bacteria respond to changes of metabolites in their environment: short-term and longer-term. 2. Compare and contrast transcriptional control
Name: AP Biology Mr. Croft Chapter 15 Active Reading Guide Regulation of Gene Expression The overview for Chapter 15 introduces the idea that while all cells of an organism have all genes in the genome,
Prokaryotic Gene Expression (Learning Objectives) 1. Learn how bacteria respond to changes of metabolites in their environment: short-term and longer-term. 2. Compare and contrast transcriptional control
Lecture 18 June 2 nd, 2016 Gene Expression Regulation Mutations From Gene to Protein Central Dogma Replication DNA RNA PROTEIN Transcription Translation RNA Viruses: genome is RNA Reverse Transcriptase
m Eukaryotic mrna processing Newly made RNA is called primary transcript and is modified in three ways before leaving the nucleus: Cap structure a modified guanine base is added to the 5 end. Poly-A tail
PROKARYOTE GENES: E. COLI LAC OPERON CHAPTER 13 CHAPTER 13 PROKARYOTE GENES: E. COLI LAC OPERON Figure 1. Electron micrograph of growing E. coli. Some show the constriction at the location where daughter
3.B.1 Gene Regulation Gene regulation results in differential gene expression, leading to cell specialization. We will focus on gene regulation in prokaryotes first. Gene regulation accounts for some of
Control of Prokaryotic (Bacterial) Gene Expression Figure 18.1 How can this fish s eyes see equally well in both air and water? Aka. Quatro ojas Regulation of Gene Expression: Prokaryotes and eukaryotes
Regulation of Gene Expression at the level of Transcription (examples are mostly bacterial) Diarmaid Hughes ICM/Microbiology VT2009 Regulation of Gene Expression at the level of Transcription (examples
11 Regulation of Gene Expression in Bacteria and Their Viruses WORKING WITH THE FIGURES 1. Compare the structure of IPTG shown in Figure 11-7 with the structure of galactose shown in Figure 11-5. Why is
Ch 10, 11 &14 Preview Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Why did the original one-gene, one-enzyme hypothesis have to be modified? a. Some
Chapter 10, 11, 14: Gene Expression, Regulation, and Development Exam Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Why did the original one-gene, one-enzyme
BIO 5099: Molecular Biology for Computer Scientists (et al) Lecture 18: Eukaryotic genes http://compbio.uchsc.edu/hunter/bio5099 Larry.Hunter@uchsc.edu Eukaryotic vs. Prokaryotic genes Like in prokaryotes,
BIOLOGY 205/SECTION 7 DEVELOPMENT- LILJEGREN Lecture 7 Development of the Fruit Fly Drosophila 1. The fruit fly- a highly successful, specialized organism a. Quick life cycle includes three larval stages
18.4 Embryonic development involves cell division, cell differentiation, and morphogenesis An organism arises from a fertilized egg cell as the result of three interrelated processes: cell division, cell
Name Chapter 10 Reading Guide From DNA to Protein: Gene Expression Concept 10.1 Genetics Shows That Genes Code for Proteins 1. In most cases, genes code for and it is that determine. 2. Describe what Garrod
Developmental Biology Biology 4361 Axis Specification in Drosophila November 6, 2007 Axis Specification in Drosophila Fertilization Superficial cleavage Gastrulation Drosophila body plan Oocyte formation
Multiple Choice Review- Eukaryotic Gene Expression 1. Which of the following is the Central Dogma of cell biology? a. DNA Nucleic Acid Protein Amino Acid b. Prokaryote Bacteria - Eukaryote c. Atom Molecule
Gene regulation II Biochemistry 302 Bob Kelm February 28, 2005 Catabolic operons: Regulation by multiple signals targeting different TFs Catabolite repression: Activity of lac operon is restricted when
Midterm 1 Average score: 74.4 Median score: 77 NAME: TA (circle one) Jody Westbrook or Jessica Piel Section (circle one) Tue Wed Thur MCB 141 First Midterm Feb. 21, 2008 Only answer 4 of these 5 problems.
Be prepared to turn in a completed test review before your test. In addition to the questions below you should be able to make and analyze a plasmid map. Prokaryotic Gene Regulation 1. What is meant by
Chapter 17 From Gene to Protein DNA The information molecule Sequences of bases is a code DNA organized in to chromosomes Chromosomes are organized into genes What do the genes actually say??? Reflecting
Gene regulation II Biochemistry 302 February 27, 2006 Molecular basis of inhibition of RNAP by Lac repressor 35 promoter site 10 promoter site CRP/DNA complex 60 Lewis, M. et al. (1996) Science 271:1247
Developmental Biology Biology 4361 Axis Specification in Drosophila July 9, 2008 Drosophila Development Overview Fertilization Cleavage Gastrulation Drosophila body plan Oocyte formation Genetic control
MOLECULAR CONTROL OF EMBRYONIC PATTERN FORMATION Drosophila is the best understood of all developmental systems, especially at the genetic level, and although it is an invertebrate it has had an enormous
Extranuclear Inheritance Extranuclear Inheritance The past couple of lectures, we ve been exploring exceptions to Mendel s principles of transmission inheritance. Scientists have observed inheritance patterns
Controllo dell espressione genica: procarioti 1. Operon Regolazione dell espressione nei procarioti 2. Regulation mostly on the transcriptional level. POSITIVE: energy saving, regulation of only one mrna
2012 Univ. 1301 Aguilera Lecture Introduction to Molecular and Cell Biology Molecular biology seeks to understand the physical and chemical basis of life. and helps us answer the following? What is the
Chapters 12&13 Notes: DNA, RNA & Protein Synthesis Name Period Words to Know: nucleotides, DNA, complementary base pairing, replication, genes, proteins, mrna, rrna, trna, transcription, translation, codon,
Old FINAL EXAM BIO409/509 NAME Please number your answers and write them on the attached, lined paper. Gene expression can be regulated at several steps. Describe one example for each of the following:
Principles of Cellular Biology آشنایی با مبانی اولیه سلول Biologists are interested in objects ranging in size from small molecules to the tallest trees: Cell Basic building blocks of life Understanding
Regulation of Transcription in Eukaryotes Nelson Saibo firstname.lastname@example.org In eukaryotes gene expression is regulated at different levels 1 - Transcription 2 Post-transcriptional modifications 3 RNA transport
RNA Processing: Eukaryotic mrnas Eukaryotic mrnas have three main parts (Figure 13.8): 5! untranslated region (5! UTR), varies in length. The coding sequence specifies the amino acid sequence of the protein
Life Sciences 1a: Section 3B. The cell division cycle Objectives Understand the challenges to producing genetically identical daughter cells Understand how a simple biochemical oscillator can drive the
Week 10! 10-24-2013! Annotated Bibliography! Sources of papers! 3 papers! Peer-reviewed scientific literature (no review articles)! No more than 2 from:! the same author! the same journal! 2 of the 3 must
The Fly in History 1859 Darwin 1866 Mendel c. 1890 Driesch, Roux (experimental embryology) 1900 rediscovery of Mendel (birth of genetics) 1910 first mutant (white) (Morgan) 1913 first genetic map (Sturtevant
LSM5194 Morphogens in biological development: Drosophila example Lecture 29 The concept of morphogen gradients The concept of morphogens was proposed by L. Wolpert as a part of the positional information
13.2 The Genetic Code The first step in decoding genetic messages is to transcribe a nucleotide base sequence from DNA to mrna. This transcribed information contains a code for making proteins. The Genetic
INTRODUCTION MODELING THE REGULATORY SWITCHES OF THE PITX1 GENE IN STICKLEBACK FISH The types and amounts of proteins produced by a given cell in the body are very important and carefully regulated. Transcribing
Protein Synthesis & Mutations RNA 1. Contains the sugar ribose instead of deoxyribose. 2. Single-stranded instead of double stranded. 3. Contains uracil in place of thymine. RNA Contains: 1. Adenine 2.
Cellular Neuroanatomy I The Prototypical Neuron: Soma Reading: BCP Chapter 2 Functional Unit of the Nervous System The functional unit of the nervous system is the neuron. Neurons are cells specialized
Biofundamentals, Fall 2008 FINAL Name: 1. The following processes are required to produce a transcription factor... A. transcription! B. translation C. transcription and translation D. replication 2. How
CELL CYCLE AND DIFFERENTIATION Dewajani Purnomosari Department of Histology and Cell Biology Faculty of Medicine Universitas Gadjah Mada email@example.com WHAT IS CELL CYCLE? 09/12/14 firstname.lastname@example.org
9 The Nucleus Student Learning Outcomes: Nucleus distinguishes Eukaryotes from Prokaryotes Explain general structures of Nuclear Envelope, Nuclear Lamina, Nuclear Pore Complex Explain movement of proteins
Chem*3560 Lecture 10: Cyclins, cyclin kinases and cell division The eukaryotic cell cycle Actively growing mammalian cells divide roughly every 24 hours, and follow a precise sequence of events know as
CHAPTER 13 MEIOSIS AND SEXUAL LIFE CYCLES Section A: An Introduction to Heredity 1. Offspring acquire genes from parents by inheriting chromosomes 2. Like begets like, more or less: a comparison of asexual
presents Flow of Genetic Information A Montagud E Navarro P Fernández de Córdoba JF Urchueguía Elements Nucleic acid DNA RNA building block structure & organization genome building block types Amino acid
Part III Organization of Cell Populations Chapter Since ancient times, people have wondered how organisms are formed during the developmental process, and many researchers have worked tirelessly in search
The Complete Set Of Genetic Instructions In An Organism's Chromosomes Is Called The What is a genome? A genome is an organism's complete set of genetic instructions. Single strands of DNA are coiled up
Word Definition Word Part Visual/Mnemonic Related Words 1. adenine Nitrogen base, pairs with thymine in DNA and uracil in RNA 2. allele One or more alternate forms of a gene Example: P = Dominant (purple);
AP Biology Summer Reading Guide 2013-2014 The following are questions covering the most important information that you need to be exposed to prior to class starting next year. They are pulled from reading
BIOLOGY STANDARDS BASED RUBRIC STUDENTS WILL UNDERSTAND THAT THE FUNDAMENTAL PROCESSES OF ALL LIVING THINGS DEPEND ON A VARIETY OF SPECIALIZED CELL STRUCTURES AND CHEMICAL PROCESSES. First Semester Benchmarks:
This lecture will discuss the following topics : Definition of Embryology Significance of Embryology Old and New Frontiers Introduction to Molecular Regulation and Signaling Descriptive terms in Embryology
Slide 1 / 54 Gene Expression in Eukaryotic cells Slide 2 / 54 Central Dogma DNA is the the genetic material of the eukaryotic cell. Watson & Crick worked out the structure of DNA as a double helix. According
Chapter 1 Molecules, Cells, and Model Organisms 1.1 The Molecules of Life 1.2 Prokaryotic Cell Structure and Function 1.3 Eukaryotic Cell Structure and Function 1.4 Unicellular Eukaryotic Model Organisms
Big Idea 3: Living systems store, retrieve, transmit and respond to information essential to life processes. 3.a.2- Cell Cycle and Meiosis EU 3.A: Heritable information provides for continuity of life.
Biology 101 2 25 99 1 st lecture for test two/thursday DNA Structure and Replication We have 23 paternal chromosomes and 23 maternal chromosomes from dad and mom. The chromosomes are chosen randomly on
CELL DIVISION AND HEREDITY Student Packet SUMMARY IN EUKARYOTES, HERITABLE INFORMATION IS PASSED TO THE NEXT GENERATION VIA PROCESSES THAT INCLUDE THE CELL CYCLE, MITOSIS /MEIOSIS AND FERTILIZATION Mitosis
Section A. Multiple choice questions 1. Which of the following is not a polymer? a. glucose b. starch 2. Polypeptides are assembled from: a. hexoses b. glycerol c. cellulose d. DNA c. nucleotides d. amino
What is the major functional difference of Theta vs. Rolling-ircle replication, specifically in regards to the tandem linear repeats found in the R- replication. You won t be responsible for this. Rolling-circle
2. Fertilization activates the egg and bring together the nuclei of sperm and egg Sea urchins (what phylum?) are models for the study of the early development of deuterostomes (like us, right?). Sea urchin
SECTION 5.1 THE CELL CYCLE Study Guide KEY CONCEPT Cells have distinct phases of growth, reproduction, and normal functions. VOCABULARY cell cycle mitosis cytokinesis The cell cycle has four main stages.
Bio/Life: Cell Biology 1a The fundamental life processes of plants and animals depend on a variety of chemical reactions that occur in specialized areas of the organism's cells. As a basis for understanding
Heredity Composite Multiple Choice Identify the choice that best completes the statement or answers the question. 1. When a plant breeder crossed two red roses, 78% of the offspring had red flowers and
Genetic Variation: The genetic substrate for natural selection What about organisms that do not have sexual reproduction? Horizontal Gene Transfer Dr. Carol E. Lee, University of Wisconsin In prokaryotes:
AQA Biology A-level Topic 4: Genetic information, variation and relationships between organisms Notes DNA, genes and chromosomes Both DNA and RNA carry information, for instance DNA holds genetic information
BIO 5099: Molecular Biology for Computer Scientists (et al) Lecture 16: Eukaryotes at last! http://compbio.uchsc.edu/hunter/bio5099 Larry.Hunter@uchsc.edu Reminders about Eukaryotes Eukaryotes arose around
CAMPBELL BIOLOGY TENTH EDITION Reece Urry Cain Wasserman Minorsky Jackson 8 An Introduction to Metabolism Lecture Presentation by Nicole Tunbridge and Kathleen Fitzpatrick The Energy of Life The living
Bypass and interaction suppressors; pathway analysis The isolation of extragenic suppressors is a powerful tool for identifying genes that encode proteins that function in the same process as a gene of
Chapters 7 & 8. Weaver, 2/e. Mol Biol X107A. Ch 7. Operons: Fine control of prokaryotic transcription. Ch 8. Major shifts in prokaryotic transcription. A. Introduction... 1 B. Terms... 2 C. Lac operon:
Biology Final Review Packet Directions: Answer the questions below. You may use any notes, worksheets, or your textbook to find the answers. The questions are divided up based on the different units we
Mitosis & Meiosis SC.912.L.16.17 Compare and contrast mitosis and meiosis and relate to the processes of sexual and asexual reproduction and their consequences for genetic variation. 1. Students will describe
Three types of RNA polymerase in eukaryotic nuclei Type Location RNA synthesized Effect of α-amanitin I Nucleolus Pre-rRNA for 18,.8 and 8S rrnas Insensitive II Nucleoplasm Pre-mRNA, some snrnas Sensitive