1
Q
The process of stabilizing the structure of an enzyme in it’s active form by the binding of a molecule is an example of
A
Allostatic regulation
2
Q
A chemical reaction is designated as exergonic rather than endergonic when
A
The potential energy of the products is less than the potential energy of the reactants
3
Q
Describe the electron transport chain of cellular respiration
A
Electrons are passed from one carrier to another, releasing a little energy at each step. Includes four major protein complexes.
4
Q
Where do the reactions of glycolysis occur in a eukaryotic cell?
A
In the cytosol
5
Q
The electron transport chain involved in cellular respiration is locates in/on the
A
Inner membrane of the mitochondrion
6
Q
Why is the citric acid cycle called a cycle?
A
The four-carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the pathway
7
Q
Where do the reactions of the citric acid cycle take place in eukaryotic cells?
A
The matrix of the mitochondrion
8
Q
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
A
H+ concentration across the membrane holding ATP synthase
9
Q
Most of the ATP produced in aerobic cellular respiration comes from which process?
A
Oxidative phosphorylation
10
Q
What role does O2 have in aerobic cellular respiration?
A
It is the final electron acceptor at the end of the electron transport chain
11
Q
Most of the NADH that delivers electrons to the electron transport chain come from which process?
A
The citric acid cycle
12
Q
What is the sequence of events in cellular respiration?
A
Oxidation of glucose to pyruvate (glycolysis), oxidation of pyruvate, oxidation of Acetyl-CoA (citric-acid cycle), oxidative phosphorylation
13
Q
The Calvin cycle occurs in the
A
Stroma
14
Q
Chlorophyll molecules are in which part of the chloroplast?
A
Thylakoid membranes
15
Q
How does carbon dioxide enter the leaf?
A
Through the stomata
16
Q
Describe the relationship between the light reactions and the Calvin cycle
A
The light reactions produce ATP and NADPH, both of which are used in the Calvin cycle
17
Q
What is the difference between anabolic and catabolic pathways?
A
Anabolic pathways consume energy to build complex molecules. Catabolic pathways release energy by breaking down complex molecules
18
Q
What is the first law of thermodynamics?
A
The energy of the universe is constant. Energy can be transferred and transformed but not created or destroyed
19
Q
What is the second law of thermodynamics?
A
Every energy transfer or transformation increases the entropy of the universe
20
Q
What is Gibbs free energy?
A
The amount of energy available to do work in a system
21
Q
What is the active site
A
The region of an enzyme that binds to the substrate
22
Q
What happens when an enzyme is saturated?
A
All active sites are occupied, adding more substrate won’t increase rate
23
Q
What is a competitive inhibitor?
A
A molecule that binds to the active site, blocking the substrate
24
Q
What is a noncompetitive inhibitor?
A
A molecule that binds elsewhere on the enzyme, changing enzyme shape and function
25
What are the three steps of cellular respiration?
Glycolysis, pyruvate oxidation & citric acid cycle, and oxidative phosphorylation
26
What is substrate level phosphorylation?
An enzyme transfers a phosphate group to ADP to form ATP. Occurs during glycolysis and the citric acid cycle
27
Is glycolysis oxygen dependent?
No
28
What are the two major phases of glycolysis?
Energy investment phase, energy payoff phase
29
What is the net yield of glycolysis per glucose molecule?
2 ATP and 2 NADH
30
What is the first step of the glycolysis energy investment phase?
Phosphorylation of glucose into glucose-6-phosphate by hexokinase. This step uses ATP, creating ADP. The phosphorylation of glucose traps it in the cell
31
What is the second step of the glycolysis energy investment phase? (Not in slide)
An isomerization reaction catalyzed by phosphoglucoisomerase which converts glucose-6-phosphate into fructose-6-phosphate
32
What is the third step of the glycolysis energy investment phase?
Additional phosphorylation of glucose by phosphofructokinase. This destabilizes the molecule making it possible to split into two. This uses ATP and produces ADP. Converts fructose-6-phosphate into fructose-1,6-bisphosphate
33
What is the fourth and fifth step of the glycolysis energy investment phase?
Adolase cleaves glucose into two 3-carbon molecules. DHAP converted into G3P catalyzed by isomerase
34
What is the end result of the glycolysis energy investment phase?
2 G3P molecules
35
What is the first step of the glycolysis energy payoff phase?
G3P is oxidized by transfer of electrons to NAD+, producing NADH. A phosphate group is attached to the oxidized substrate making it a high energy product. G3P converted to 1,3-bisphosphoglycerate. Catalyzed by triose phosphate dehydrogenase
36
What is the second step of the glycolysis energy payoff phase?
The phosphate group in 1,3-bisphosphoglycerate is transferred to ADP via substrate level phosphorylation. Catalyzed by phosphoglycerokinase
37
What is the last step of the glycolysis energy payoff phase?
A second phosphate group is transferred from PEP to ADP via substrate level phosphorylation, forming pyruvate. Catalyzed by pyruvate kinase
38
Which glycolytic enzyme uses ATP to phosphorylate glucose?
Hexokinase
39
What is the end product of glycolysis?
4 - 2 ATP = 2 ATP net gain. 2 NADH. 2 pyruvate
40
What process will cells undergo in the absence of oxygen?
Fermentation
41
What happens during pyruvate oxidation?
Pyruvate is converted to acetyl-CoA, and CO2 is released. This process yields 1 NADH per pyruvate
42
What products does the citric acid cycle generate for each glucose molecule?
2 ATP, 6 NADH, and 2FADH2 per glucose molecule
43
What is the first step of the citric acid cycle?
In the first reaction, CAC-1, the two carbon acetate group is transferred from acetyl-CoA to oxaloacetate (4C) to form citrate (6C). This reaction is catalyzed by citrate synthase and drived by the free energy of hydrolysis of the acetyl-CoA thioester bond
44
What is the second step of the citric acid cycle, CAC-2?
Citrate is converted to isocitrate. The enzyme aconitase catalyzes the reaction. Isocitrate has a hydroxyl group that is easily oxidized in the next step
45
What is the third step of the citric acid cycle, CAC-3?
Isocitrate is oxidized by isocitrate dehydrogenase to oxalosuccinate, with NAD+ as the electron acceptor. Oxalosuccinate immediately undergoes decarboxylation to form a-ketoglutarate (5C)
46
What is the fourth step of the citric acid cycle, CAC-4?
a-ketoglutarate is oxidized to succinyl-CoA by a-ketoglutarate dehydrogenase with NAD+ as the electron acceptor
47
What is the fifth step of the citric acid cycle, CAC-5?
Succinyl-CoA is converted to succinate catalyzed by succinyl-CoA synthetase. The energy from hydrolysis of the high energy thioester bond is used to generate one ATP in plants or GTP in animals
48
What is the sixth step of the citric acid cycle, CAC-6?
Succinate is oxidized fumarate by succinate dehydrogenase. This transfers electrons to FAD, a lower energy coenzyme than NAD+
49
What is the seventh step of the citric acid cycle, CAC-7?
Fumarate is hydrated to produce malate by fumarate hydratase
50
What is the eight step of the citric acid cycle, CAC-8?
The newly formed hydroxyl group is the target of the final oxidation catalyzed by malate dehydrogenase. NAD+ serves as the final electron acceptor producing NADH. Oxaloacetate is regenerated
51
Where is the electron transport chain located in eukaryotes?
In the inner mitochondrial membrane
52
What does complex 1 of oxidative phosphorylation do?
Complex 1 harvests electrons from NADH
53
What does complex 2 of oxidative phosphorylation do?
Complex 2 harvests electrons from FADH2
54
How is the energy released by the electron transport chain used?
The energy released is used to pump protons across the inner membrane
55
What is chemiosmosis?
The use of the H+ gradient generated by the ETC to drive cellular work, ATP synthesis. ATP synthase uses the exergonic flow of H+ down the concentration gradient to drive the phosphorylation of ADP
56
Approximately how much of the energy in a glucose molecule is transferred to ATP?
34% making about 30 to 32 ATP
57
In what cells does anaerobic respiration take place?
Anaerobic respiration takes place in prokaryotes that use SO4^2- as the final electron acceptor in the ETC as opposed to oxygen
58
What is fermentation?
Fermentation is a way for a cell to regenerate NAD+ so ATP can be synthesized via glycolysis. NAD+ is regenerated via electron transfers from NADH to pyruvate
59
What are the two types of fermentation?
Alcohol fermentation, and lactate fermentation
60
What is alcohol fermentation?
In alcohol fermentation, pyruvate is converted to ethanol in two steps. CO2 is released from pyruvate, forming acetaldehyde. Acetaldehyde is reduced by NADH to ethanol
61
What is lactic acid fermentation?
In lactic acid fermentation, pyruvate is converted directly to lactate, an ionized form of lactic acid, without producing CO2. NADH is oxidized to produce NAD+
62
What are autotrophs?
Autotrophs are self-feeders, they get energy and carbon entirely from nonliving sources
63
What are heterotrophs
Heterotrophs obtain energy and carbon from the organic materials derived from other organisms
64
How are thylakoids grouped?
Thylakoids are grouped into grana
65
What is the area surrounding the grana?
The area surrounding the grana is the stroma
66
What is a photosystem?
A photosystem consists of a reaction center complex surrounded by light-harvesting complexes
67
What is the reaction center complex of a photosystem?
The reaction center complex is an association of proteins holding a pair of chlorophyll-a molecules and a primary electron acceptor. Chlorophyll-a transfers an excited electron to the primary electron acceptor, the reaction center is oxidized
68
How are electrons taken from water in photosynthesis?
The energy supplied by the first photosystem allows electrons to be pulled from water. Energy supplied by the second photosystem allows electrons to be transferred from NADP+ to form NADPH
69
What is the Z scheme?
The trajectory of energy in the two photosystems. As electrons travel through the ETC of photosystem 2, it's energy decreases. Second input of energy comes from photosystem 1
70
What are the three main steps of the Calvin cycle?
Carbon fixation, reduction, regeneration
71
How many times must each reaction of the calvin cycle take place in order to complete the net synthesis of one G3P molecule?
Three times
72
What is the first step of the Calvin cycle?
Carbon fixation. CO2 is absorbed from the air and added to a 5-carbon molecule, RuBP. Catalyzed by rubisco. Product is a 6-carbon compound that is broken down into 2 molecules of 3-PGA
73
What is the second step of the Calvin cycle?
Reduction. NADPH is the reducing agent used in the Calvin cycle. ATP is used to phosphorylate 3-PGA. NADPH transfers two high energy electrons to the phosphorylated compound. 6 ATP and 6 NADPH are required to produce 6 G3P, only one G3P exits cycle for use by the cell.
74
What is the third step of the Calvin cycle?
Regeneration. Initial molecule of RuBP must be regenerated. Triose phosphate molecules are used to regenerate RuBP. For every 6 triose phosphate molecules, only one can be withdrawn from the Calvin cycle
75
What are the three phases of interphase?
G1 phase, S phase, G2 phase
76
What is the G1 phase of interphase?
First gap. The size and protein content of the cell increase in preparation for the S phase. Many regulatory proteins are made and activated
77
What is the S phase of interphase?
Synthesis. The entire DNA content in the nucleus of the cell is replicated
78
What is the G2 phase of interphase?
Second gap. Cell checks replicated DNA for errors and prepares for cell division
79
When a cell in not dividing, how are chromosomes stored?
Each chromosome is a long, thin chromatin fiber
80
What are sister chromatids, and how are they attached?
Sister chromatids are joined duplicates of the original chromosome. The centromere is where the two chromatids are attached
81
What are the phases of the mitotic (M) phase?
Prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis
82
What is the prophase of mitosis?
First step. Characterized by chromosome condensation. Each duplicated chromosome appears as two identical sister chromatids. Mitotic spindles begin to form from centrosomes. Centrosomes move away from each other
83
What is the prometaphase of mitosis?
Second step. The nuclear envelope fragments. The kinetochore has now formed at the centromere of each chromatid, 2 per chromosome. Microtubules attach to kinetochore
84
What are kinetochores?
Protein complexes located on either side of the centromere.
85
What is the metaphase of mitosis?
Third step. Aligning of chromosomes at the center of the cell, metaphase plate. Movement of microtubules pull the chromosomes
86
What is the anaphase of mitosis?
Fourth step. Begins when cohesin proteins breakdown. Separation of sister chromatids, each chromatid becomes an independent chromosome. Microtubules pull newly seperated chromosomes to opposite sides of the cell
87
What is the telophase of mitosis?
Fifth step. Starts when chromosomes arrive at a spindle pole. Microtubules of the mitotic spindle break down and dissapear. Nuclear envelope begins to re-form around each set of chromosomes, creating two new nuclei. Chromosomes decondense and become less visible
88
What is the cytokinesis phase?
Actual division of a parent cell into 2 daughter cells. Actin filament contractile ring in animals. Cell plate via vesicles in plants
89
What are the checkpoints of the cell cycle control system?
G1 checkpoint, G2 checkpoint, M checkpoint
90
What is the G1 checkpoint of the cell cycle control system?
First check. Functions as the restriction point in mammalian cells. If a cell receives go ahead signal at G1 check, it will usually complete cycle. If it doesn't, it will exit the cycle and switch to G0 phase
91
What is the G2 checkpoint of the cell cycle control system?
Second check. Preparation for cell division. Checks for mistakes during S phase DNA replication. Large number of mistakes will result in apoptosis, cell death
92
What is the M checkpoint of the cell cycle control system?
Third check. Tension at kinetochore. Anaphase does not start if any kinetochores remain unattached to spindle microtubules. Complete attachment results in the activation of the enzyme, separase, which breaks down cohesin
93
What are growth factors?
Growth factors are protein signals released by certain cells that stimulate cells to divide
94
What is chemotherapy treatment for cancer?
Chemicals that selectively kill dividing cells. Used for cancers difficult to remove surgically or spreading to new locations. Injected into bloodstream
95
What is radiation therapy treatment for cancer?
Use of high-energy particles to destroy cancer cells. Used after surgical removal or if surgery not possible. Usually for cancers close to the surface
96
What is immunotherapy treatment for cancer?
Immune system selectively destroys cancer cells. Target cancer cells with specific surface marker proteins. Healthy cells without protein marker are spared
97
What is meiosis?
A process that results in four haploid daughter cells
98
What is fertilization?
The union of haploid gametes resulting in a new diploid cell called a zygote
99
What are gametes?
The only types of human cells produced by meiosis, they are haploid
100
What is the meiosis 1 phase of meiosis?
Separation of homologous chromosome pairs
101
What is the meiosis 2 phase of meiosis?
Separation of sister chromatids
102
What happens during prophase 1 of meiosis?
Synapsis, homologous chromosomes come together and pair with each other. Chiasmata, specialized chromatin structure linking non-sister chromatids
103
What is crossing over in meiosis?
Homologous chromosomes of maternal and paternal origin exchange DNA segments, increasing genetic diversity
104
What is independent assortment?
Random orientation of homologous pairs at metaphase I, leading to different chromosome combinations
105
What is the formula for the number of chromosome combinations that are possible?
2^n, where n is the haploid number. For humans, 2^23.
106
What happens during anaphase 1 of meisosis?
Homologous chromosomes separate and move toward opposite poles
107
What happens in telophase 1?
Nuclear envelopes reform, and cytokinesis produces two haploid cells
108
What allows sister chromatids to separate in meiosis?
Release of cohesin at centromeres in anaphase 2
Biology 2107
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