Chapter 4: Cell Structure and Function

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. Note that chapters 6 and 7 are not included in this study guide. Take time to fill out this guide referring to your textbook, handouts, classmates and myself as necessary. You will do very well on the midterm if you successfully complete this study guide and understand the concepts it outlines. Best of luck! 4,5,6,7,9 Chapter 4: Cell Structure and Function 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? Cell Structures and Functions A.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 B. Three Domains determined cell type: Domains 1. Eukarya Kingdoms Eukaryotic a. Plantae b. Fungi c. Animalia d. Protista Prokaryotic 2. Bacteria 3. Archaea C.All cells have certain structures in common: 1. Genetic Material in a nucleoid or nucleus 2. Cytoplasm a semifluid matrix 3. Plasma Membrane a phospholipid bilayer 4. Ribosomes 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: 2

3 3. Nuclear envelope 4. Ribosomes 5. Cytoskeleton Actin Filaments responsible for cellular contractions, crawling, pinching - Composed of actin protein subunits Microtubules provide organization and move materials within the cell - Composed of tubulin protein subunits Intermediate Filaments provide structural stability - Composed of vimentin protein subunits 6. Centrosomes/Centrioles 3

4 7. Endomembrane System (Organelles composed of plasma membrane): A. Endoplasmic Reticulum Smooth ER Rough ER B. Golgi Apparatus Cis face: Trans face: C.Lysosomes 4

5 D.Vacuoles E. Vesicles a. Transport vesicles: b. Secretory vesicles: 6. Peroxisomes 7.Mitochondria intermembranous space: matrix: cisternal space: cristae: 5

6 G.Chloroplasts thylakoids: grana: stroma: 8.Plasma Membrane A.The fluid mosaic model of membrane structure has two components: 1.Phospholipid Bilayer a.hydrophobic/philic interactions of lipids b.cholesterol 2.Membrane Proteins a. Surface vs. embedded proteins b.functions: B.Membrane Transport Define: Selective Permeability: Concentration Gradient: C.Passive transport: 1. Diffusion: a. Simple Diffusion: nonspecific passive not saturated 6

7 b. Facilitated Diffusion: specific passive saturated c. Be prepared to describe how facilitated diffusion allows the cell to regulate what passes in/out and regulate the rate of diffusion d. Be prepared to graph rate of simple or facilitated diffusion vs. concentration gradient. 5. 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 D.Active Transport Carrier proteins used in active transport: Endocytosis a. phagocytosis b. pinocytosis c. receptor mediated endocytosis Exocytosis 7

8 Chapter 5: Enzymes, Coenzymes, and Energy A. Enzymes: molecules that catalyze reactions in living cells 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 specific substrate Binding of an enzyme to a substrate causes the enzyme to change shape, producing a better induced fit between the molecules. Allosteric site: Cofactors/Coenzymes: B. Enzymes and their environment Three factors that can denature - change an enzyme s 3-dimensional shape - and affect its function 1. Temperature 2. ph 3.Substrate concentration Be prepared to graph turnover rate vs. temperature, ph, and [substrate] C. How enzymes work Lower the activation energy of reactions D. Metabolic/Biochemical Pathways Series of chemical reactions carried out by separate enzymes Series of chemical reactions carried out by separate enzymes Metabolism: a. Anabolism: + b. Catabolism: 8

9 Regulation of Metabolism: 1. Enzymatic Competition for substrate: E. ATP Functions: 2. Gene Regulation: 3. Enzyme Inhibition: a. Feedback Inhibition: b. Allosteric Inhibition: Competitive: Structure: a.amp, ADP, ATP ATP regeneration Noncompetitive: 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. F. Other Sources of Cellular Energy a. Redox reactions provide electrons for energy NAD and FAD are molecules that carry electrons b.proton pumps establish a proton gradient, a flow of protons provides energy to build ATP 9

10 Chapter 6: Cellular Respiration 1. Organisms are Classified According to How They Obtain Energy Autotroph vs. Heterotroph: 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? 10

11 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) 11

12 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) 12

13 B. Krebs (Citric Acid) Cycle Reactants (what goes in) a. pyruvate converted to Acetly-CoA b. Products (what comes out, i.e. what is produced) a. b. c. d. Location (where this step occurs in the cell) Steps to know: a. Step 1: Reactants: a. b. Products (Intermediates): a. Citrate Enzymes involved (name, category, and function of enzyme) 13

14 C. Electron Transport Chain (Oxidative Phosphorylation) Cytochromes: Location: Functions in ATP production 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: Be prepared to describe why aerobic respiration so much more efficient than anaerobic respiration: 4. 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 14

15 Chapter 7: Photosynthesis 1. Photosynthesis converts sun energy to carbohydrates Carbon fixation: Define: a. Autotroph: b. Photoautotroph: c. Chemoautotroph: d. Heterotroph: e. Pigment: chlorophyll accessory pigments, carotenoids: f. Photon: g. Absorption spectrum: 2. Chemical formula for photosynthesis: Reactants: Which is oxidized? Which is reduced? Products: 3. Compare/ Contrast Photosynthesis and Cellular Respiration Location (organelle where process takes place) Order of events (ETC, Calvin, Krebs) 15

16 4. Structure of a Chloroplast Thylakoid Grana Stroma 5. Photosynthesis Photosystems A.Light-Capturing Events The pigment chlorophyll absorbs certain wavelengths of light to excite electrons Use the energy in the excited electrons to make ATP and NADPH. light-capturing events take place in Photosystems B.Light-Dependent Reactions a. Photosystem II occurs first a. Antenna complex: b. Reaction center: antenna complex: captures light energy, excites electrons reaction center: passes electrons to ETC source of electrons: H2O destination of electrons: ETC b.electron Transport Chain receives electrons from PSI powers ATP synthases, produces ATP quinone 16

17 c. Photosystem I occurs second antenna complex: captures light energy, excites electrons reaction center: passes electrons, reduces NADP + to NADPH source of electrons: ETC destination of electrons: NADP + produces NADPH to be used to make carbohydrates C. Carbon-Fixation Reactions (Light-Independent Reactions) Occur in stroma of chloroplast a. Calvin Cycle Uses energy to fix and reduce CO2 to produce carbohydrates Source of energy: Source of electrons: Three phases: 1. Carbon Fixation Sugar Formation: Reactants: CO2, Ribulose Required enzyme: RuBisCO 2. Sugar Formation: Reactants: CO2, Ribulose, ATP, NADPH Products: 2 G3Pʼs 1 G3P is used to make carbohydrates 3. Regeneration of RuBP: 1 G-3-P is returned to the Calvin Cycle to make another Ribulose. D. Review Z-Diagram 17

18 Chapter 9: Cell Division - Proliferation and Reproduction 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 Review the structure of a nucleotide: a. the functional groups and where they bind to the ribose: b.the 5 nitrogenous bases c.base pairing d.3ʼ-5ʼ-phosphodiester linkages to form macromolecule Review the structure of the DNA molecule: a. double helical b.what forms the ʻsides of the ladderʼ c.what forms the ʻrungs of the ladderʼ Review the following properties of the DNA molecule a. Complementary: b. Parent strand: c. Template strand: Describe the Semi-Conservative model for DNA replication 18

19 3. Bacterial Cell Division Binary Fission 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 e. Sister chromatids: 2 copies of the chromosome within the replicated chromosome connected at kinetochore Eukaryotic chromosome condensation: a. Describe how the eukaryotic chromosome is condensed to fit into the nucleus: b. Nucleosome: what is the nucleosome composed of? c. Histone proteins: function in chromosome condensation: 19

20 5. The Eukaryotic Cell Cycle What is function of the cell cycle? List the five phases of the cell cycle: Interphase: 1. # Mitosis: a. b. # c. d. 5. Cytokinesis: 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 20

21 3. Gap 2 (G2): Chromosome condensation 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. Metaphase: 3. Anaphase: 4. Telophase: Compare and contrast cytokinesis in animal cells and cell with cell walls cleavage furrow: cell plate: 21

22 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? 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? Growth factors encourage cell division Cancer is failure to regulate cell cycle and cell division Tumor-suppressor genes vs. proto-oncogenes 8. Sexual Reproduction Sexual reproduction restores chromosome number to diploid number (2n) Define/ Describe: a. Fertilization: b. Zygote: 9. 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 22

23 10.The Functions of 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 b. Haploid (n): c. Diploid (2n): d. Chromosome number of somatic cells vs. gametes 11.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: 23

24 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: 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: 24

25 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: 25