Chapters 10-14 Flashcards
(102 cards)
1
Q
Catabolic Pathways yeild energy by oxidizing organic fuels
A
-Catabolic pathways release stored energy by breaking down complex molecules
2
Q
Fermentation
A
- Partial degradation of sugars that occurs without O2
- Alcohol fermentation by yeast: pyruvate–> Ethanol + CO2
- Lactic Acid fermentation: pyruvate–> lactase
- Used by human muscle cells to generate ATP when O2 is scarce
- Produces 2 ATP per glucose
3
Q
Aerobic respiration
A
-Consumes organic molecules and O2, yeilds ATP
4
Q
Anaerobic Respiration
A
-Similar to aerobic respiration but consumes compounds other than O2
5
Q
Cellular Respiration
A
-Both aerobic and anaerobic respiration
-Glucose + Oxygen –> CO2 + water + energy (atp + heat)
Steps:
1. Glycolysis
2. Citric Acid Cycle
3. Oxidative Phosphorylation
-Total ATP: 32
6
Q
Redox Reactions
A
- Used to synthesize ATP
- Oxidation: loses electrons
- Reduction: gains electrons
7
Q
Redox Reactions of Cellular Respiration
A
-Glucose is oxidized, O2 is reduced
8
Q
Substrate Level Phosphorylation
A
- The small amount of ATP formed in glycolysis and the citric acid cycle
- 4 ATP in total (2 from each)
9
Q
Glycolysis
A
- Oxidizes glucose into 2 molecules pyruvate
- Major phases: energy investment phase, energy payoff phase
- Occurs whether or not O2 is present, in the cytosol
10
Q
Cytric Acid Cycle
A
- W/ presence of O2, pyruvate enters mitochondria, where oxidation of glucose is completed
- To start cycle, pyruvate converted to acetyl CoA
1. Oxidation of pyruvate and release of Co2
2. Reduction of NAD+ to NADH
3. Combinaiton of remaining 2-C fragment and coenzyme A to form acetyl CoA - 2 pyruvates–> 2 ATP, 6 NADH, 2 FADH2
11
Q
Oxidative Phosphorylation
A
- NADH and FADH2 donate electrons to electron transport chain, powers ATP synthesis
- Occur in inner membrane of mitochondria
- Chain’s components= proteins
- Electrons pass to O2, forming water
- Electron carriers alternate btwn reduced and oxidized states
12
Q
Chemiosmosis in Cellular Respiration
A
- Energy-coupling mechanism
- Energy released as electrons are passed down ETC used to pump H+ through ATP synthase
- Causes ATP synthase to spin, creating ATP
- Uses H+ gradient to drive cell work
13
Q
Producing ATP w/o oxygen
A
- Electron transport chain doesn’t work w/o oxygen
- Glycolysis couples w/ anaerobic respiration or fermentation to produce ATP
14
Q
Chloroplasts
A
- Organelle in photosynthetic organisms
- Convert solar energy to chemical energy using photosynthesis
- Found in the mesophyll (interior tissue of lead)
- CO2 enters and O2 exits through stomata
- Enveloped by stroma
- Thylakoid= sacs in chloroplast, stacked in grana
- Chlorophyll= green pigment
15
Q
Photosynthesis
A
- Converts light energy into food
- H2O+ light energy+ CO2–> O2 + glucose
16
Q
Pathway of water
A
- Absorbed through roots and enters leaf through veins
- Veins export sugars to roots and other parts of the plant
17
Q
Photosynthesis as a redox process
A
- CO2 reduced to glucose
- H2O oxidized to o2
- Endergonic
18
Q
The splitting of water in photosynthesis
A
- O2 given off by plants is derived from H2O
- Chloroplasts split H2O into H and O, release into atmosphere
19
Q
Light Reactions
A
- Solar energy–> chemical energy
- Water split to create O2
- Location: tylakoid
20
Q
Calvin Cycle
A
- CO2+ organic moleculed (NADPH and ATP) –> glucose
- Location: Stroma
- Anabolic (uses energy)
- Phases: 1. Carbon fixation (catalized by rubisco), 2. reduction, 3. regeneratin of CO2 acceptor (RuBP)
- Must occur 3 times to create 1 G3P
- 9 ATP used, 6 NADPH
21
Q
Light Reactions process
A
- Photon (light) hits chlorophyll pigments in photosystem II, excited chain reaction
- Electron transfered to primary electron acceptor
- Water splits–> 2 e-, 2 H+ (in thylakoid space), 1 O (combined w/ another to make O2)
- Excited electrons pass from PEA of PSII to PSI via electron transport chain
- Potential energy of proton gradient is used to make ATP in chemiosmosis
- Light energy transfered to PSI reaction-center complex
- Photoexcited electron transfered to PSI’s PEA, can now accept e- at bottom of PSII PEA
- Excited e- passed from PI’s PEA down 2nd ETC
- Enzyme NADP+ transfers e- –> NADPH, removes H+ from stroma
22
Q
Linear Electron Flow in Light Reactions
A
- Light drives the synthesis of ATP and NADPH by energizing the two photosystems embedded in thylakoid membranes of chloroplasts
- Flow of electrons through the photosystems and other molecular components built into thylakoid membrane
23
Q
Chemiosmosis in Photosynthesis
A
- Electron transport chain, pumps H+ across membrane, powers ATP-synthase’s creation of ATP
- Electron from water
- Light–> glucose energy
- Stroma holds H+
24
Q
Carbon Fixation
A
- Incorportation of CO2 molecules, attached to RuBP (5 carbon sugar)
- Catalyzed by rubisco
- Forms 2 molecules of 3-phosphoglycerate
25
Reduction (Calvin Cycle)
- 3-phosphoglycerate + Phosphate group from ATP--> 1,3-bisphosphoglycerate--> reduced by NADPH--> Glyceraldehyde 3-phosphate
- 6 G3P formed, 5 used to regenerate RuBp
- Net: 1 G3P
26
Regeneration of RuBP
- CO2 acceptor
| - 5 G3P recycled into 3 RuBp using 3 ATP, continued cycle
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Alternative mechanisms of carbon fixation
- On hot, dry days, plants close stomata, which conserves H2O but limits photosynthesis
- Reduces access to CO2, O2 builds up
- Lead to photorespiration
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Photorespiration
- Rubisco adds O2 instead of CO2 to Calvin cycle, producing 2-carbon compound
- Consumes O2 and organic fuel and releases CO2 w/o producing ATP or sugar
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C3 Plants
-Initial fixation of CO2, via rubisco, forms 3-carbon compound (3-phosphoglycerate)
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C4 Plants
- Minimize the cost of photorespiration by incorporating Co2 into 4-C compounds
- Types of cells in leaves that store 4-C
1. Bundle-sheath cells are arranged tightly in packed sheaths around veins of leag
2. Mesophyll cells packed loosely betwen bundle sheaths and leaf surface
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CAM Plants
- Open stomata at night, incorporating CO2 into organic acids that are stored via vacuoles
- Stomata close during day, CO2 is released from organic acids and used in Calvin cycle
* Separates initial steps of carbon fixation from calvin cycle
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Reception
- Target cell detects a signaling molecule that binds to receptor protein on cell surface
- Binding btwn signal molecule (ligand) and receptor is highly specific
- Receptors found in plasma membrane of proteins
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Transduction
- Change in receptor's shape after binding is initial transduction of signal
- Multistep process
1. Binding of signaling molecule to receptor
2. activation of another protein, another protein, etc. until the protein producing the response is activated
- At each step signal is transduced into different form (phosphorylation/dephosphorylation)
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Response
- Transduced signal triggers a specific response in target cell
- Nuclear and Cytoplasmic
- Regulate the synthesis of enzymes and proteins
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G protein-coupled receptors (GCPRs)
- Cell-surface transmembrane receptors
- Work w/ help of G protein
- Binds to energy-rich GTP
1. Receptor receives signaling molecule, GDP leaves
2. GTP is released and attaches to inactive enzyme (now active)
3. Cellular response
4. GTP loses phosphate group, goes back to G-protein coupled receptor via G protein as GDP
36
Receptor Tyrosine Kinases (RTKs)
- Membrane receptors that transfer phosphate groups from ATP to another protein
- Can trigger multiple signal transduction pathways at once
1. Signaling molecules attach to inactive monomer, becomes phosphorylated dimer
2. ATP--> ADP (uses phosphates)
3. Cellular responses
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Ligand-gated ion channel
- Acts as a gate that opens and closes when the receptor changes shape
- When signal molecule binds as a ligand to the receptor, gate allows specific ions through a channel in the receptor
1. Ligand binds to receptor
2. Channel opens and ions pass through (cellular response)
3. Ligand is removed
4. Channel closes
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Protein phosphorylation
- Widespread cellular mechanism for regulating protein activity
- Protein kinases transfer phosphates from ATP to protein
- Many relay molecules in signal transduction are protein kinases, creating phosphorylation cascade
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Protein Dephosphorylation
-Protein phosphatases rapidly remove the phosphates from proteins
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Second Messengers
- Small, nonprotein, water-soluble molecules or ions that spread throughout a cell by diffusion
- Participate in pathways initiated by GPCRs and RTKs
- Ex: Cyclic AMP and calcium ions
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Cyclic AMP
- Widely used second messanger
- cAMP
- Adenylyl cyclase (enzyme) converts ATP to cAMP in response to extracellular signal
42
Transduction w/ cAMP as 2nd messenger
- Signal molecules trigger formation of cAMP
- other components of cAMP pathways are G proteins, G protein-coupled receptors, and protein kinases
- cAMP activates protein kinase A, phosphorylates various proteins
- Further regulation of cell metabolism is provided by G protein systems that inhibit adenylyl cyclase
43
Calcium ions as second messenger
- Its concentration in the cytosol is normally much lower than the concentration outside the cell
- Smaller change in # of Ca+ thus represents a relatively large percentage change in C+ concentration
44
Transduction w/ Ca+
-A signal relayed by a signal transduction pathway may trigger an increase in calcium in the cytosol
45
Nuclear and Cytoplasmic Responses
- Signalling pathways regulate synthesis of enzymes or proteins by turning genes on or off in the nucleus
- Final activated molecule in signaling pathway functions as transcription factor
- Other pathways may regulate the activity of enzymes rather than synthesis
46
Regulation of the Response
- Four aspects of signal regulation
1. Pathway leads to single response
2. Pathway branches, leading to two responses
3. Cross-talk btwn 2 pathways
4. Different receptor leads to a diff response
- Enzyme cascades amplify the cell's response to signal
47
Termination of the Signal
- Inactivation of mecchanisms= essential aspect of cell signaling
- If the ceoncentration of external signaling molecules fall, fewer receptors will be bound
- Unbound receptors revert to inactive state
48
Apoptosis
- Cells that are infected, damaged, or at end of life undergo programmed cell death
- Components of cell are chopped up and packaged into vesicles that are digested by scavenger cells
- Prevents enzymes from leaking out of dying cells and damaging neighbor cells
49
Apoptosis examples
- Normal part of development of hands and feet in humans
- Diseases such as parkinsons and alzheimers
- Cancers occur when apoptosis is inhibited, doesn't kill cells that later divide
50
Mitosis
- The division of genetic material in the nucleus
- Results in two daughter cells with identical genetic information
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase
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Somatic Cells
- Nonreproductive cells
| - Have 2 sets of chromosomes (2N), 46 total chromosomes (23 pairs)
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Gametes
- Reproductive cells (sperm and egg)
| - 1 set of chromosomes
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Distribution of Chromosomes during Eukaryotic Cell Division
- DNA is replicated, chromosomes condense
- Each duplicated chromosome has 2 sister chromatids (joined copies of the original chromosome)
- Centromere= narrow waist where chromosomes attach
- Two sister chromatids of each duplicated chromosome separate and move into 2 nuclei (now called chromosomes)
54
Cytokinesis
- The division of the cytoplasm
- Cells separate
- Process known as cleavage, forms cleavage furrow
- In plants, cell plate forms
55
Interphase
- Growth and copying of chromosomes in prep for cell division
- Overlaps w/ mitosis
- 3 phases: G1 (growing), S (DNA synthesis, chromosome duplication), G2 (growing, getting ready for mitosis)
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Prophase (Mitosis)
- Preparation
- Centrosomes move to opposite sides of cell
- Form mitotic spindles
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Metaphase
-Sister chromatids align in the middle, pair up
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Anaphase
- Sister chromatids separate, becoming chromatids
| - Pull back to outsides of cell
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Telophase
- Termination
| - 2 identical daughter cells that have almost split
60
Mitotic Spindle
- Structure made of microtubules
| - Controls chromosome movement during mitosis
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Centrosome
- Microtubule-organizing center
- Replicates during interphase
- Forms two centrosomes that migrate to opposite ends during prophase and prometaphase
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Metaphase Plate
- Where the chromosomes light up in the middle
| - Plane midway between the spindle's two poleds
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Genes
- Units of heredity
- Made up of segments of DNA
- Passed to next generation via gametes (sperm or egg)
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Karyotype
- Ordered display of pairs of chromosomes from a cell
| - Staining, looking at shape and size to determine # of chromosomes
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Homologous Chromosomes
- Two chromosomes in each pair
- Same length and shape
- Carry genes w/ same inherited characteristics
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Sex Chromosomes
- Determine the sex of the individual (pair 23)
- Female: XX
- Male: XY
- Remaining 22: autosomes
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Haploid Cell
- A gamete w/ a single set of chromosomes (23)
- Egg: X
- Sperm: either X or Y
68
Fertilization
- Union of gametes (sperm and egg)
- Fertilized egg= zygote, 1 set of chromosomes from each parent
- Develops into an adult
69
Meiosis
- Results in one set of chromosomes from each gamete
- Only produces gametes (sperm and eggs)
- Results in 4 haploid daughter cells
- Meiosis I and II
- Chromosomes duplicate before meiosis (sister chromatids)
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Meiosis I
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I
- Cytokinesis
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Meiosis II
- Similar to Mitosis
- Prophase II
- Metaphase II
- Anaphase II
- Telophase II
- Cytokinesis
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Prophase I
- Chromosome pairs w/ homolog and crossing over occurs
| - Chiasmata: sites of crossoves
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Metaphase I
- Pairs of homologs line up at metaphase plate (middle)
- Microtubules from one pole are attached to kinetochore of one chromosome of each pair
- Microtubules from 1 pole attach to kinetochore of other chromosome
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Anaphase I
- Pairs of homologous chromosomes separate
- One chromosome of each pair moves to opposite pole
- Sister chromatids remain attached at centromere
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Telophase I and Cytokinesis
Each half of the cell has haploid set of chromosomes, each 2 sister chromatids
- Cytokinesis forms 2 haploid daughter cells
* **No chromosome replication between end of meiosis I and beginning of meiosis II because chromosomes already replicated
76
Prophase II
- Spindle apparatus forms
| - Chromosomes (still composed of two sister chromatids) move toward metaphase plate
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Metaphase II
- Sister chromatids arranged at metaphase plate
- Two sister chromatids no longer identical due to crossover in metaphase I
- Kinetochores of sister chromatids attach to microtubules extending from opposite poles
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Anaphase II
- Sister chromatids separate
| - Sister chromatids from each chromosome now move as two newly individual chromosome towards poles
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Telophase II and Cytokinesis
- The chromosomes arrive at opposite poles
- Nuclei form, chromosomes begin decondensing
- Cytokinesis separates cytoplasm
- 4 haploid daughter cells w/ distinct genetic material
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Events unique to meiosis from meiosis I
- Synapsis and crossing over in prophase I
- Homologous pairs at the metaphase plate
- Separation of homologs during anaphase I
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Genetic Variation
-Contributes to evolution
-mutations= original source of genetic diversity
-Different versions of genes= alleles
-Shuffling of alleles= genetic variation
Mechanisms that contribute to genetic variation
1. Independent assortment of chromosomes
2. crossing over
3. random fertilization
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Independent Assortment of Chromosomes
- Homologous pairs of chromosomes orient randomly during Metaphase I
- Each pair of chromosomes sort maternal and paternal homologs into daughter cells independently of other pairs
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Crossing Over
- Produces recombinant chromosomes= combined dna of each parent
- Contributes to genetic variation
- 3 crossovers occur per chromosome
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Random Fertilization
- Sperm fuse w/ any ovum
- Each zygote has a unique genetic identity
- Adds to genetic variation
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Alleles
- Alternative versions of genes account for variations in inherited characters
- Ex: pea plants two versions= purple and white
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Locus
-Specific site one chromosomes where gene resides
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Homozygote
-Organism w/ two identical alleles for a character
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Heterozygote
- Organism w/ two different alleles for a gene
| - Not true-breeding
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Phenotype vs. Genotype
- P: trait seen
| - G: genetic composition
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Law of Segregation
- During gamete formation, the alleles for each gene segregate from each other
- Each gamete carries only one allele for each gene
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Law of Independent Assortment
-Genes for different traits can segregate independently during gamete formation
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Mendel's Experiment
- Cross-pollinate purple and white pea plants (p generation)
- Counted offspring in F1 generation= all purple hybrids
- Cross-pollinate purple hybrid w/ purple hybrid
- Counted offspring in F2: 3-1 ratio purple to white
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Meiosis #s
- Interphase 46
- Prophase I- 92
- Metaphase I- 46
- Meiosis II- 23 ( 4 haploid gametes)
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Complete Dominance
- Phenotypes of heterozygote and dominant homozygote= identical
- Ex: Pp or PP
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Incomplete Dominance
- Phenotype of F1 hybrids is somewhere between the two phenotypes of parents
- Ex: Red + white--> pink flower
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Codominance
- Two dominant alleles affect the phenotype in separate, distinguishable ways
- Ex: bloodtype, where IAIB both creates AB bloodtype
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Multiple Alleles
- Most genes exist in more than two allelic forms
| - The four phenotypes of ABO blood are determined by 3 alleles : IA, IB or i
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Pleiotropy
- When genes have multiple phenotypic effects
| - Diseases such as cysitc fibrosis or sickle-cell
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Epistasis
- One gene affects the phenotype of another due to interaction of their gene products
- Ex: Coat color in puppies, where one gene determines coat color, and the other inhibits coat color
* Does not follow mendelian principle
100
Polygenetic Inheritance
- Additive effect of two or more genes on a single phenotype
| - Ex: 180 genes affect height, skin color
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Similarities and Difference between CAM and C4
- Both incorporate CO2 into organic intermediates before it enters the Calvin cycle
- C4: separates the initial steps of carbon fixation from the Calvin cycle
- CAM pathway: steps occur in the same cell, but are separated in time
102
Mendel's Laws
1. Alleles of genes account for variations in inherited characters
2. For each character, an organism inherits two alleles, one from each parent
3. If two alleles at locus differ, dominant determines appearance, recessive has no effect
4. Law of Segregation
