Chapter 4: Cell Structure

Transcription

1 This study guide is intended to provide you with a basic outline of exam content, help you organize the material, and direct you to the most important concepts. Take your time to fill out this guide referring to your textbook, handouts, classmates and myself as necessary. You will do very well on the exam if you successfully complete this study guide and can apply the concepts it outlines. Best of luck! Chapter 4: Cell Structure Cell Theory 1. All organisms are composed of cells. 2. Cells are the smallest living things. 3. Cells arise only from pre-existing cells. Limitations to cell size a. SA/V ratio decreases as cell size increases b. How a shrinking SA/V affect cell size? Two Cell Types Cell Structures Prokaryote Eukaryote Genetic material DNA in nucleiod DNA in nucleus Cytoplasm Yes Yes Plasma Membrane Yes Yes Organelles No Yes Ribosomes Yes Yes Surface Structures: Cilia Yes Yes Flagella Yes Yes Pili Yes No Cell Wall Yes Yes 1

2 Three Domains determined cell type: Domains 1. Eukarya Kingdoms Eukaryotic a. Plantae b. Fungi c. Animalia d. Protista Prokaryotic 2. Bacteria 3. Archaea Cell Structures and Functions 1. Nucleus: a. Cell DNA is organized with proteins to form chromatin b. Chromosomes are tightly packed (condensed) with proteins inside the nucleus into nucleosomes c. DNA is wound around histone proteins to resembles beads on a string 2. Nucleolus: a. location: b. structures: c. functions: 2

3 3. Nuclear envelope a. location: b. structures: c. functions: 4. Ribosomes a. location: b. structures: c. functions: 5. Endomembrane System: A. Endoplasmic Reticulum Smooth ER a. location: b. structures: c. functions: Rough ER a. location: b. structures: c. functions: 3

4 B. Golgi Apparatus a. location: b. structures: Cis face: Trans face: c. functions: C.Lysosomes a. location: b. structures: c. functions: D.Vacuoles a. location: b. structures: c. functions: E. Vesicles a. Transport vesicles: b. Secretory vesicles: 6. Peroxisomes a. location: b. structures: c. functions: 4

5 7. Plastids Define plastid: A. Mitochondria a. location: b. structures: intermembranous space: matrix: cisternal space: cristae: c. functions: B. Chloroplasts a. location: b. structures: thylakoids: grana: stroma: c. functions: C.Endosymbiosis Theory: 5

6 8. Cytoskeleton a. location: b. structures: c. functions: Actin Filaments responsible for cellular contractions, crawling, pinching 1. Composed of actin protein subunits Microtubules provide organization and move materials within the cell 1. Composed of tubulin protein subunits Intermediate Filaments provide structural stability 1. Composed of vimentin protein subunits 9. Centrosomes a. Centrioles location: structures: functions: 10. Cell Wall The domains and kingdoms contain organisms with cell walls: location: structure: function: 11. Extracellular Matrix location: structure: function: 6

7 Chapter 5: Membranes 1. The fluid mosaic model of membrane structure has two components: a. Phospholipids arranged in a bilayer b. Globular Proteins inserted in the lipid bilayer 2. Arrangement of Phospholipid Bilayer a. Hydrophobic/philic interactions of phospholipids b. Cholesterol structure and functions in membrane 3. Membrane Proteins a. Peripheral vs. Intergal b. Integral Transmembrane domain structure Beta barrels structure and function 4. Membrane Transport A. Selective Permeability: B. Concentration Gradient: C.Passive transport: 1. Diffusion: a. Simple Diffusion a. nonspecific b. passive c. not saturated d. plot a graph of simple diffusion vs. concentration gradient b. Facilitated Diffusion a. specific b. passive c. saturated d. plot a graph of facilitated diffusion vs. concentration gradient 7

8 2. Osmosis a. Hypertonic solutions: have a higher relative solute concentration b. Hypotonic solutions: have a lower relative solute concentration c. Isotonic Solutions: have equal relative solute concentrations d. Osmotic Balance e. Be able to determine if cells will lyse or create in given solutions D.Active Transport Carrier proteins used in active transport include: 1. uniporters move one molecule at a time 2. symporters move two molecules in the same direction coupled transport provide an example of coupled transport 3. antiporters move two molecules in opposite directions Sodium-potassium pumps 4. Bulk Transport a. Endocytosis: 1. Phagocytosis 2. Pinocytosis 3. Receptor mediated endocytosis b. Exocytosis: E. Ion Channels transport ions: establish membrane potentials: F. Gated Channels open/close in response to a stimulus 8

9 Chapter 6: Energy and Metabolism A. Energy: the capacity to do work kinetic energy: the energy of motion potential energy: stored energy B. Laws of Thermodynamics 1. First Law: 2. Second Law - Entropy: 3. Enthalpy: a. Free energy b. Activation energy c. Relationship of G=H-TS When products of chemical reactions contain more free energy than reactants ΔG is positive When reactants contain more free energy than products ΔG is negative Endergonic reactions vs. Exergonic reactions C. Oxidation/ Reductio Reactions 1. Oxidation: loss of electrons 2. Reduction: gain of electrons 3. Redox reactions are coupled to each other D. ATP What does ATP stand for: Functions: a. energy currency b. provide phosphate groups ATP regeneration The energy released when ATP is broken down to ADP can be used to fuel endergonic reactions. The energy released from an exergonic reaction can be used to fuel the production of ATP from ADP + Pi 9

10 E. Enzymes Three rules to be considered an enzyme 1. Most are proteins (some RNA enzymes) 2. Lower the activation energy required for a reaction to occur 3. Are not changed or consumed by the reaction Substrate: molecule that will undergo a reaction Active site: region of the enzyme that binds to the substrate lock and key hypothesis induced fit hypothesis Allosteric site: Factors that can change an enzyme s 3-dimensional shape can change its function plot a chart of enzyme activity vs. ph, temperature, or substrate concentration Metabolism: 1. Anabolism: + 2. Catabolism: G. Metabolic Pathways Series of chemical reactions carried out by separate enzymes Regulation of Metabolism: 1. Enzymatic Competition for substrate: 2. Gene Regulation: 3. Phosphorylation: Kinases add phosphate groups to destabilize substrates 4. Enzyme Inhibition: a. Feedback Inhibition: b. Allosteric Inhibition: Competitive: Noncompetitive: 10

11 Chapter 7: Cellular Respiration 1. Organisms are Classified According to How They Obtain Energy Autotroph vs. Heterotroph: Two types of autotrophs a. Chemoautotrophs: b. Photoautotrophs: Three types of respiration 1. Aerobic: final electron acceptor? products? relative efficiency for ATP production as compared to anaerobic respiration? be prepared to describe several reasons why aerobic respiration in more efficient than anaerobic respiration. 2. Anaerobic: final electron acceptors: methanogens: sulfur bacteria: 3. Fermentation: final electron acceptor? products? 11

12 2. Aerobic Respiration Balanced chemical formula for cellular respiration: Reactants: Which is oxidized? Which is reduced? Products: Three stages of cellular respiration A. B. C. A. Glycolysis Glucose-splitting Reactants (what goes in) a. Products (what comes out, i.e. what is produced) a. b. c. Location (where this step occurs in the cell - eukaryote vs. prokaryote) 12

13 Steps to know: a. Step 1: Reactants: Products (Intermediates): Enzymes involved (name, category, and function of enzyme) Step 2: Reactants: Products (Intermediates): Enzymes involved (name, category, and function of enzyme) Step 3: Reactants: Products (Intermediates): Enzymes involved (name, category, and function of enzyme) Steps 4/5: Reactants: Products (Intermediates): 2 G-3-Pʼs Steps 6-10 occur twice for every glucose Step 10: Reactants: Products (Intermediates): Enzymes involved (name, category, and function of enzyme) 13

14 1. Pyruvate Oxidation (Prep Step) Reactants (what goes in) a. b. Products (what comes out, i.e. what is produced) " a. b. c. Location (where this step occurs in the cell) B. Krebs (Citric Acid) Cycle Reactants (what goes in) a. b. Products (what comes out, i.e. what is produced) a. b. c. d. e. Location (where this step occurs in the cell) 14

15 Steps to know: a. Step 1: Reactants: a. b. Products (Intermediates): a. b. Enzymes involved (name, category, and function of enzyme) b. Step 9: Reactants: a. b. Products (Intermediates): a. b. Enzymes involved (name, category, and function of enzyme) C. Electron Transport Chain (Oxidative Phosphorylation) Cytochromes: Location: Functions in ATP production 15

16 ATP Synthase: Location: Functions in ATP production NAD: Functions in ATP production How are electrons used for ATP production? How are protons used for ATP production? Define: Chemiosmosis: Theoretical yield: Actual yield: Why ATP actual yield always less than theoretical yield? Be prepared to describe why aerobic respiration so much more efficient than anaerobic respiration: 1. Other Nutrients as Energy Sources Deamination: Amino acids amino group removed amino acids metabolized and enter cellular respiration at different locations produces urea Beta-Oxidation: fats triglycerides hydrolyzed to fatty acids and glycerol fatty acids metabolized to acetyl groups and enter Krebs cycle 16

17 Chapter 8: Photosynthesis 1. Photosynthesis converts sun energy to carbohydrates Carbon fixation: Define: Autotroph: Photoautotroph: Chemoautotroph: Heterotroph: Pigment: Accessory pigment: Photon: Absorption spectrum: 2. Chemical formula for photosynthesis: Reactants: Which is oxidized? Which is reduced? Products: 3. Compare/ Contrast Photosynthesis and Cellular Respiration Location (organelle) Order of events (ETC, Calvin, Krebs) 17

18 4. Structure of a Chloroplast Thylakoid membrane Photosystems Grana Stroma 5. Photosynthesis A. Light-Dependent Reactions a. Photosystem II antenna complex reaction center (680 nm) source of electrons: destination of electrons: b.b6-f complex quinone produces ATP c. Photosystem I antenna complex reaction center (700 nm) source of electrons: destination of electrons: produces NADPH 18

19 B. Carbon-Fixation Reactions (Light-Independent Reactions) a. Calvin Cycle Uses energy to fixe and reduce CO2 to produce carbohydrates Source of energy: Source of electrons: Three phases: 1. Carbon Fixation: Reactants: Products: Required enzyme: 2. Reduction: Reactants: Products: G3P 3. Regeneration of RuBP: C. Review Z-Diagram 19

20 Chapter 10: How Cells Divide 1. The Prokaryotic Chromosome Describe location, number, structure of the typical prokaryotic chromosome. Compare and contrast prokaryotic and eukaryotic DNA in terms of location, chromosome number, structural complexity. Define/ Describe: a. Haploid: " b. Diploid: c. Nucleoid: d. Nucleus: 2. DNA Replication Describe the structure of a nucleotide: the functional groups and where they bind to the ribose the 5 nitrogenous bases " base pairing 3ʼ-5ʼ-phosphodiester linkages to form macromolecule Describe the structure of the DNA molecule: double helical what forms the ʻsides of the ladderʼ what forms the ʻrungs of the ladderʼ 20

21 Define/ Describe the following properties of the DNA molecule a. Complementary: b. Parent strand: c. Template strand: Describe the Semi-Conservative model for DNA replication 3. Bacterial Cell Division The process of Binary Fission where it begins along the chromosome where is ends along the chromosome formation of the septum Define/ Describe: a. Bidirectional replication: b. Daughter cells: 4. The Eukaryotic Chromosome Compare and contrast the eukaryotic and prokaryotic chromosome Define/ Describe: a. Chromosome: a single DNA molecule b. Chromosome number: average human has how many chromosomes? average human has how many homologous chromosome pairs: c. Chromatin: what is it composed of: heterochromatin vs euchromatin in structure and function d. Karyotype: array of chromosomes of an organism 21

22 e. Sister chromatids: 2 copies of the chromosome within the replicated chromosome connected at kinetochore Eukaryotic chromosome condensation: Describe how the eukaryotic chromosome is condensed to fit into the nucleus: Define/ Describe: a. Nucleosome: what is the nucleosome composed of? b. Histone proteins: function in chromosome condensation: c. Condensin: 5. The Eukaryotic Cell Cycle What is function of the cell cycle? List the five phases of the cell cycle: Interphase: 1. function in chromosome condensation: " Mitosis: a. b. c. d. 5. Cytokinesis: 22

23 Where in the cell cycle does the cell spend most of its time? Describe what occurs within the cell during each stage of the cell cycle: Describe what happens to/calculate each of the following during stages of cell cycle: For practice, calculate the chromosome number, number of chromatids, and number of copies of each gene for a diploid cell with 6 chromosomes as it progresses through interphase. 1. Gap 1 (G1): Cell growth 2. Synthesis (S): DNA synthesis 3. Gap 2 (G2): Chromosome condensation 23

24 6. Mitosis What is the function of mitosis? What is the end result of mitosis? Describe what occurs within the cell during each stage of mitosis: For practice, calculate the chromosome number, number of chromatids, and number of copies of each gene for a diploid cell with 6 chromosomes as it progresses through mitosis. 1. Prophase: 2. Prometaphase: 3. Metaphase: 4. Anaphase: 5. Telophase: Compare and contrast cytokinesis in animal cells and cell with cell walls cleavage furrow: cell plate: Recognize the stage of mitosis by the appearance of the cell nucleus as done in lab 24

25 7. Control of the Cell Cycle The three checkpoints of the cell cycle: G1/S checkpoint when does this occur during the cell cycle? what aspect of cell division is being checked? Cyclins active enzymes for DNA replication G2/M checkpoint when does this occur during the cell cycle? what aspect of cell division is being checked? Cell commits to mitosis Late Metaphase (spindle) checkpoint when does this occur during the cell cycle? what aspect of cell division is being checked? Anaphase promoting complex activates proteins to remove cohesin and allow sister chromatids to separate Growth factors encourage cell division Cancer is failure to regulate cell cycle and cell division Tumor-suppressor genes vs. proto-oncogenes 25

26 Chapter 11: Sexual Reproduction and Meiosis 1. Meiosis What is the function of meiosis? What is the end result of meiosis? How do the cells produced during meiosis differ from the cells produced by mitosis? Define/ Describe: a. Gamete: what cell is the male gamete what cell is the female gamete 2. Sexual Reproduction b. Haploid (n): c. Diploid (2n): d. Chromosome number of somatic cells vs. gametes Sexual reproduction restores chromosome number to diploid number (2n) Define/ Describe: a. Fertilization: b. Zygote: 3. Features of Meiosis One round of replication, two divisions - results in reduction of chromosome number. Define/ Describe: a. Synapsis of homologous chromosomes b. Crossing over " c. Chiasmata 26

27 4. The Process of Meiosis Describe what occurs within the cell during each stage of meiosis: Describe what happens to/ calculate each of the following during stages of meiosis: For practice, calculate the chromosome number, number of chromatids, and number of copies of each gene for a diploid cell with 6 chromosomes as it progresses through meiosis. Meiosis I Prophase I chromosome condensation homologous pairs synapsis crossing over haploid or diploid: Metaphase I homologues are aligned at metaphase plate independent assortment haploid or diploid: Anaphase I chromosomes separate haploid or diploid: Telophase I sister chromatids no longer identical because of crossing over haploid or diploid: 27

28 Meiosis II Meiosis II resembles a mitotic division: Prophase II nuclear envelopes dissolve and spindle apparatus forms haploid or diploid: Metaphase II chromosomes align on metaphase plate haploid or diploid: Anaphase II sister chromatids are separated from each other haploid or diploid: Telophase II nuclear envelope re-forms; cytokinesis follows Define/ Describe: haploid or diploid: a. Four key features of meiosis: b. The key differences between mitosis and meiosis: c. Three reasons for genetic variation: 1. Crossing over (during meiosis) 2. Independent assortment (during meiosis) 3. Sexual reproduction for genetic variation: 28