1
Q
What does ATP allow to occur by adding energy?
A
Energetically unfavorable reactions
2
Q
Which molecules are more stable and energetically favored than ATP?
A
ADP and inorganic phosphate
3
Q
What does ATP provide energy for and how?
A
Reactions by adding a high-energy phosphate group to other molecules
4
Q
Is ATP transported between cells?
A
No
5
Q
Is ATP stored in cells?
A
No, must be used quickly
6
Q
What are the major pathways for the synthesis of ATP?
A
- Glycolysis
- Oxidative phosphorylation
7
Q
Is glycolysis oxygen dependent?
A
No
8
Q
Is oxidative phosphorylation oxygen dependent?
A
Yes
9
Q
What features do all branches of the tree of life share?
A
- The genetic code
- Ribosomes
- Cell membranes
- Glycolysis
10
Q
What was the composition of the atmosphere in the Hadean?
A
Mostly hydrogen and helium
11
Q
What characterized the second atmosphere of Earth?
A
Composed mostly of water vapor and volcanic activity (CO2 and ammonia)
12
Q
Who are the earliest known photosynthesizers?
A
Cyanobacteria
13
Q
What is a waste product of cyanobacteria during photosynthesis?
A
Oxygen
14
Q
What are banded iron formations composed of?
A
- Iron oxide (rust)
- Chert
15
Q
What did the Great Oxygenation Event lead to?
A
The first major glaciation (Huronian Glaciation)
*b/c it removed the methane in the atmosphere which lead to a cooling…
16
Q
What are reactive oxygen species (ROS)?
A
Byproducts formed when dioxygen steals electrons = natural byproducts from cellular metabolism
17
Q
Who survived the Huronian Glaciation?
A
- Those who could tolerate oxygen (who were using aerobic oxygen for metabolism)
- Those in extreme environments
18
Q
What is associated with the Cryogenian period?
A
Another surge in dioxygen levels
19
Q
What role do sponges play in the atmosphere?
A
They feed on cyanobacteria, benefiting larger eukaryotic photosynthesizers
20
Q
What was the Cambrian Explosion characterized by?
A
Huge diversification of life
21
Q
What are the causes of the Cambrian explosion according to the oxygen model?
A
- Increasing oxygen levels
- Increase in activity levels
- Origin of predation
- Evolutionary arms race
22
Q
What led to a huge spike in oxygen levels during the Carboniferous?
A
- Huge increase in plant growth
- Diversification of seed plants
23
Q
What is the tracheal system in insects used for?
A
Respiration, making it diffusion dependent
24
Q
What does Fick’s law of Diffusion explain?
A
the movement of particles is proportional to the concentration gradient… particles move from a high concentration to low concentration
25
What type of lung do archosaurs have?
Flow-through foveolar lung
26
What does the mammalian alveolar lung have that is a limitation?
Anatomical dead space which reduces the efficency of gas exchange
27
When oxygen levels started to rise again, what adaptation did organisms use to survive?
Foveolar lung
28
What is the greatest source of energy use for most animals?
Locomotion
## Footnote
In mammals, this energy budget is significant, and ectotherms have an even larger proportion devoted to locomotion.
29
What determines how animals obtain energy for locomotion?
The suddenness, intensity, and duration of the activity
30
What happens to a molecule when it is oxidized?
It loses an electron
31
What are the oxidized forms of reducing equivalents?
* NAD+
* NADP+
32
What are the challenges in breaking down sugars to get ATP?
-ATP is both invested and gained
- oxidation of G3P requires NAD+ reduction to NADH2
33
What do reducing equivalents feed into?
The electron transport system (ETS)
34
Where do electrons go after being delivered by cytochrome c?
To cytochrome c oxidase
35
What is the final electron acceptor in the electron transport system?
Dioxygen
36
What is the consequence of univalent reduction of O2?
Production of reactive oxygen species (ROS)
37
How does cytochrome c oxidase facilitate the reduction of oxygen?
By storing four electrons to perform a tetravalent reduction
38
What occurs in cells when oxygen levels are low?
Reductive stress
39
What happens to the electron transport system when there is low oxygen? Why
The electron transport system (ETS) slows down beacuse there are too many free electrons => NADH/NAD+ ratio increases.... can lead to reductive stress
40
What must happen to NADH for glycolysis to continue during reductive stress?
It must be oxidized
NADH => NAD+
41
What are some consequences of reductive stress?
* Mitochondrial dysfunction
* Impairment of cell signaling
* Tissue acidosis (buildup of lactic acid leading to tissue damage)
42
What type of fermentation occurs when cells cannot get enough oxygen?
Lactic acid fermentation
43
What products are formed from lactic acid fermentation?
* Lactate
* NAD+
44
What can lactate be converted back to as muscle cells receive more oxygen?
Pyruvate
45
What is unique about lanternfish?
* Most abundant vertebrate on earth
* Can live in hypoxic water in the oxygen minimum zone (OMZ)
46
What are phosphagens in metabolism?
Provide istant ATP during the first few seconds of activity ... before glycolysis and oxidative phosophylation kick in
47
How efficient are phosphagens in ATP production?
Less efficient but produce ATP quickly
48
What characterizes oxidative phosphorylation?
Steady state metabolic processes that are efficient in ATP production
49
What are the time course for ATP sources
* ATP present in muscle cells
* Phosphocreatine
* Glycolysis
* Oxidative phosphorylation
50
What factors does metabolic rate depend on?
* Activity
* Digestion
* Temperature
51
What is the basal metabolic rate (BMR)?
The metabolic rate of an endotherm at rest in a comfortable temperature
52
What is the standard metabolic rate (SMR)?
The metabolic rate of an ectotherm at rest at a specific temperature
53
What is aerobic scope?
The difference between maximum metabolic rate and standard metabolic rate
54
What does isometry refer to in biology?
when an organism or stucture grows proportionally in all dimensions= shape does not change as it grows
55
What happens to the surface area to volume ratio as an organism gets isometrically smaller?
It increases
56
How is heat managed in larger animals with smaller surface to volume ratios?
They have a harder time releasing body heat and can overheat
57
What adaptations do smaller animals with larger surface area tend to have?
Adaptations to retain heat
58
Connect the importance of surface area and metabolism...
Metabolism depends on echange of materials (oxygen delivery), a higher surface area: volume = efficient nutrient uptake, gas exchange etc = which supports a higher metabolic rate
** as size increases organisms have to adapt to deal with a lower surface area : volume ratio
59
What is a scaling exponent?
A constant that indicates how size increases for two organisms
60
What is allometry?
The study of how larger animals have different proportions than smaller animals.
61
How do large animals differ from smaller ones in terms of bone and muscle proportions?
Very large animals have larger bone diameters and muscle cross-sectional areas relative to their lengths.
62
How does body size affect metabolic rate?
Larger organisms have a lower mass-specific metabolic rate than smaller organisms, but overall larger animals have a higher metabolic rate than smaller organisms.
63
According to Rubner's surface area to volume hypothesis, how is heat generated in endotherms?
Heat generation is proportional to volume.
64
According to Rubner's hypothesis, what is heat loss proportional too?
Heat loss is proportional to surface area.
65
What factors contribute to oxygen consumption variations?
* Mitochondrial density
* Surface area of inner mitochondrial membrane
* Metabolic rates of individual organs
* Proton leak
66
How do we measure metabolic rate?
By measuring the consumption of oxygen (Vo2).
67
What is oxidative stress?
A condition caused by the accumulation of reactive oxygen species (ROS).
68
How many electrons are in O2?
16 electrons.
69
What is the role of cytochrome c oxidase in the electron transport system?
It is an electron capacitor that reduces oxygen to water.
70
What happens when single electrons are added to oxygen?
Reactive oxygen species (ROS) are formed.
71
What can excessive reactive oxygen species damage?
* DNA
* Lipids
* Proteins
* Joints
72
Do smaller mammals burn more energy per unit of body mass or larger mammals?
smaller mammals.
73
What is the effect of oxidative stress on aging?
The rate of aging is proportional to the flux of oxygen through metabolism.
74
How can ROS damage nucleic acids?
By causing base pairs with adenine instead of cytosine, potentially leading to mutagenesis.
75
How does ROS affect lipids?
Oxidation of polyunsaturated fatty acids can lead to membrane disruption.
76
What structural modifications can hydrogen peroxide cause?
Modifications of cysteine residues, leading to disulfide bonds =helping protein stabilization
77
What do uncoupling proteins do?
Allow protons to move from intermembrane space to matrix, uncoupling the flow of protons from ATP synthesis => slow down the formation of ROS
## Footnote
This process relieves an excess proton gradient and slows the formation of ROS.
78
What is the role of superoxide dismutase (SOD)?
Combines superoxide anions with protons to form peroxide and oxygen, effectively removing superoxide from the cell = degrades ROS
*fast rate of reaction= so SOD needs to be synthesised in areas of se
## Footnote
SOD is 95% effective in removing superoxide, found in all aerobic cells.
79
What are some examples of antioxidants that help keep ROS in balance?
* Glutathione
* Ascorbic acid
* Tocopherol
## Footnote
Antioxidants act as free radical quenchers.
80
Define passive diffusion.
Movement of particles across a membrane without the help of membrane proteins and without ATP, along the concentration gradient.
81
What is facilitated diffusion?
Movement of particles across a membrane using channel proteins without ATP, along the concentration gradient.
82
What is active transport?
Movement of particles across a membrane using ATP and transport proteins, against the concentration gradient.
83
What factors affect passive diffusion through a membrane?
* Size of molecules
* Charge of molecules
* Membrane thickness
* Temperature
84
What is Fick's Law of Diffusion?
Describes the relationship between the difference in partial pressure of a diffusing gas and the concentration gradient.
85
What is the boundary layer effect?
A phenomenon where fluid viscosity causes molecules to stick to a solid surface, leading to a velocity gradient near the surface.
86
What happens in a hypotonic environment for a freshwater fish?
Water moves into the fish and salts move out along the concentration gradient.
87
What is the role of the sodium-potassium pump?
Maintains greater Na+ outside the cell and greater K+ inside, creating concentration gradients and membrane potential.
88
Why is K+ more favorable inside cells compared to Na+?
K+ has a higher mass to charge ratio, interacts differently with water, and stabilizes protein function better than Na+.
89
What are the three main sources of organic osmolytes?
* Dietary uptake
* Biosynthesis
* Breakdown of micromolecules
90
What is the function of the renal system?
Maintains water/solute balance and excretes metabolic wastes.
91
How do cartilaginous fishes manage their osmotic balance?
Maintain osmolarity close to seawater by converting ammonia to urea and retaining it in tissues to increase solute concentration.
92
What is the urea-TMAO osmolyte system?
A system in cartilaginous fishes that uses urea and TMAO to stabilize proteins and increase buoyancy.
93
Fill in the blank: Organisms need to balance water and solutes because the solute concentration in an environment can _______.
vary
94
True or False: Osmoconformers have the same solute concentration in their intra and extracellular fluids as the environment.
True
95
What distinguishes true osmoregulatory organisms from osmoconformers?
True osmoregulatory organisms expend energy to regulate solute levels while osmoconformers do not.
96
What is the role of organic osmolytes in cells?
Help maintain macromolecule function optimally.
97
What are the two steps osmoconformers use to respond to changes in osmolarity?
* Ensure water balance and volume using inorganic ions from the environment (adjust water in cells/ ion shifts) = short-term response
* Generate compatible osmolytes for protein function to match solute concentration in cells with environment = long-term response
98
What is the role of Urea in protein flexibility?
Urea makes protein more flexible
## Footnote
Urea is a chaotrope that disrupts hydrogen bonds, causing unfolding.
99
How does TMAO affect protein stability?
TMAO makes protein more rigid by stabilizing hydrogen bonds between the water molecules
## Footnote
TMAO is a kosmotrope that creates a stable water shell around proteins.
100
What is the impact of greater instability in proteins?
Greater instability leads to greater interior amino acids exposed.
101
What is the end goal of the loops of Henle?
To have urine with a higher solute concentration than the blood = creating a concentration gradient = allows kidney to reabsorb water more efficently
102
What is the freezing point depression?
Changes in the freezing point due to the concentration of osmotically active solutes.
103
What mechanism do ectotherms use for thermoregulation?
Ectothermic homeothermy = organism maintains realtivley constant body temp (Homeothermy) + but relies mostly on external heat sources (ectothemic) rather than metabolic activity
104
What is freeze avoidance?
Preventing the formation of ice crystals in the body, even below freezing point.
105
What is freeze tolerance?
Ability to survive the formation of ice crystals in extracellular fluids and enter a dormant state.
106
What are colligative mechanisms?
Changes in freezing point due to concentration of osmotically active solutes.
107
What is the role of glycerol in insects?
Glycerol helps prevent nucleation of ice crystals, promoting undercooling.
108
How do Arctic fishes manage freeze avoidance?
Using both colligative and non-colligative mechanisms.
109
What adaptations do endotherms have for cold weather?
Anatomical adaptations (insulation, blood supply) and metabolic adaptations (higher metabolic rate, futile cycles).
110
What is brown adipose tissue (BAT) and its role?
BAT is dense with mitochondria and uses uncoupling proteins to produce heat.
111
What is the Q10 effect?
Reactions run faster at higher temperatures.
112
What is the difference between osmoregulators and osmoconformers?
Osmoregulators maintain a lower osmolarity = activley regulate internal osmolarity; keeping it realativley constant
Osmoconformers adapt to the surrounding osmolarity = do not regulate solute concentrations (their internal fluids fluctuate with environmental changes)
113
Fill in the blank: TMAO is a _______ that causes water to be more ordered.
kosmotrope
114
Fill in the blank: Urea is a _______ that causes water to be less ordered.
chaotrope
115
What is the significance of the counter current heat exchanger?
Mechanism that conserves heat by transferring it between two fluids flowing in opposite directions...= maintains a temperature gradient + reduces energy lost
116
What is the role of ice-binding proteins (IBPs)?
Control the formation of ice crystals and keep them small enough to avoid cell damage.
117
What is the function of regional endotherms?
Maintain key body regions at high, relatively stable temperatures.
118
What are organic osmolytes and their role in hyperthermophilic archaea?
Increase thermal stability of proteins and are all negatively charged ions.
119
What is the adaptation strategy for halophiles regarding protein stability?
Using stabilizing solutes to counteract intrinsically unstable proteins.
120
What does undercooling refer to?
Liquid can be cooled to thermodynamic freezing point without freezing.
121
Do ectotherms or endotherms have a greater metabolic rate (at standard size)
Endotherms
Comparative Physiology Exam 1
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