1
Q
Metabolism:
2
A
- sum total of an organism’s chemical reactions
- arises from interactions between molecules within the cell
2
Q
Metabolic Pathways:
2
A
- begin with specific reactants and end with specific products
- for each step, multiple specific enzymes are needed
3
Q
Catabolic Pathway:
(2)
ex (2)
A
- breaks down complex molecules into similar smaller components
- releases energy
- proteins to amino acids; cellular respiration
4
Q
Anabolic Pathway:
(2)
ex (2)
A
- build complex molecules from simpler components
- absorb energy
- amino acids to proteins and photosynthesis
5
Q
Energy (definition)
A
the capacity to cause change (do work)
6
Q
3 Forms of Energy:
A
- kinetic
- potential
- chemical
7
Q
Definitions:
- kinetic energy
- potential energy
- chemical energy
A
- kinetic: energy of motion (atoms molecules; heat/thermal)
- potential: energy based on position/gravity/structure
- chemical: potential energy available for release in a chemical reaction
8
Q
Thermodynamics definition
A
- study of transformations of energy
9
Q
Isolated vs Open Systems
which are living things?
A
- isolated: energetically isolated from the surrounding environment (thermos)
- impossible to be absolute*
- open: allow transfer of energy to and from surrounding environment
10
Q
1st Law of Thermodynamics
A
the energy of the universe is constant; can be transferred or transformed but cannot be created or destroyed
11
Q
2nd Law of Thermodynamics
A
energy transfer increases the entropy of the universe
entropy: measure of disorder/randomness
12
Q
- spontaneous
ex
A
- can occur without input (doesn’t have to happen fast); release energy and increase entropy
- iron rusting
13
Q
- nonspontaneous
ex: 2
A
- cannot occur without an input of energy
- energetically unfavorable
- locally decrease entropy (increase universal; lose some heat energy)
- making glucose, forming polymers
14
Q
Cells create order from disorder by
A
- making energy more ordered/usable
- organisms replacing ordered forms of energy with less ordered forms
15
Q
Free energy determines:
definition of free energy
spontaneous or non-spontaneous
A
- whether a reaction will be spontaneous
- energy that can be used to do work when temperature/pressure are uniform (living cells)
- negative ^G is spontaneous
16
Q
Spontaneous processes can be used to?
A
- perform work based by energy coupling
17
Q
Equilibrium: (2)
diffusion
A
- products and reactants have equal concentrations
- molecules move from a high concentration to a low concentration
- bad for living things (means they aren’t metabolizing)
18
Q
exergonic reaction (exothermic) - 4
A
- releases energy
- more complex to simpler
- spontaneous; catabolic
19
Q
endergonic reaction (endothermic) - 4
A
- absorbs energy
- simple to complex
- non-spontaneous; anabolic
20
Q
Respiration of glucose
A
6CO2+6H2O —-> C6H12O6+6O2
21
Q
Equilibrium and Metabolism:
closed systems?
open systems?
metabolism?
A
- reactions will reach equilibrium and do no work in a closed system (non-living)
- cells are open systems that are not in equilibrium (must transfer energy)
- metabolism is never at equilibrium
22
Q
Catabolic Processes:
A
release energy in a series of steps
23
Q
Cellular Work:
3
A
chemical
transport
mechanical
24
Q
Cellular Work:
chemical
transport
mechanical
A
- chemical - synthesis of polymers from monomers
- transport - pumping ions against concentration gradient
- mechanical - beating of cilia
25
Cells manage energy by?
- energy coupling (exothermic drives endothermic)
26
Glucose is highly exergonic.
| Why doesn't it combust at room temperature?
- lacks the initial energy to start the reaction
27
```
ATP functions as
composed of (3)
```
- the energy shuttle of cells
| - ribose, adenine, 3 phosphate groups (neg charge of phosphates causes it to coil like a spring)
28
ATP ADP + P
| phosphorylated intermediate
- exothermic
| - molecule that receives a phosphate group (unstable)
29
ATP needed by
- neurons and muscles as energy
30
ATP
| ADP to ATP
- renewable process in the cell
| - comes from catabolic reactions in the cell
31
Catalyst:
Enzyme:
- speeds up reaction rates without being consumed or changed
- enzyme: catalytic protein
32
Pectin:
Pectinase:
- holds together plant cell walls (glue of walls)
| - ase: digests/breaks down pectin
33
Activation Energy (2)
- initial eery needed to start a reaction
- outside body, this is supplied by thermal energy absorbed from the environment
- enzymes lower activation energy
34
Catabolic Reactions:
| Why are enzymes necessary?
- release potential chemical energy and are spontaneous and high in free energy
- normal cellular temperatures are not high enough which is good because they aren't specific to needed reactions and temperature denatures proteins
- enzymes don't change ^G, just make the reaction faster
35
Substrate
Enzyme-substrate complex
Active site
- specific reactants that an enzyme acts on
- enzyme + substrate
- one or more pockets on the surface of the protein (complementary to substrate)
36
Induced fit model
- active site isn't rigid (like plastic gloves vs a lock and key)
37
Function of Active Sites:
| 3
- 2 substrates - orients them in a particular way to break bonds
- strains bonds
- favorable environment for bond breaking (polar or non polar; pH)
38
Denaturation:
destruction of bonds that cause protein structures to form and be stable
39
Factors that effect enzyme activity:
| because?
- temperature
- pH (H+ can interfere with bonds)
- salt concentration (ions/charges)
- substrate concentration (solute vs solvent)
changes shape of active site
40
Enzymes and pH:
- most enzymes are active over a narrow pH range (have optimal pH)
41
Enzymes and Temperature:
| optimum temperature
- fastest conversion from reactants to products
| - higher temperatures cause collisions between active sites and substrates to increase rate (usually)
42
Substrate Concentration:
vmax
high substrate
- vmax: maximum rate at which enzymes catalyze a reaction (all enzymes are busy because they're bound to substrate)
- [high substrate] leads to engagement of all active sites which means reaction rate will not continue to be increased (to increase rate more, increase [enzyme])
43
Non-Protein Catalytic Helpers:
- cofactors (inorganic; iron, copper, manganese, or zink; catalase)
- coenzymes (organic; usually vitamins; electron carriers; NAD+, NADP, FAD+, Coenzyme A)
44
Enzyme Inhibitors - Decrease Activity
Importance?
competitive and noncompetitive inhibitors
- negative feedback mechanisms (prevent chaos)
- competitive: mimics shape of substrate to take up enzyme active sites
- noncompetitive: bind to non-active site surface of protein (cause change in shape of active site)
- competitive inhibitor: more substrate reduces inhibitor
45
Feedback Inhibition:
- noncompetitive inhibitors
| - prevents cells from wasting resources and lowers chaos
46
Enzymes for Cellular Respiration:
- live in mitochondria
| - break down many things (not just glucose)
47
Aerobic Respiration:
| Anaerobic Respiration:
- aerobic: requires oxygen; most efficient; polymers to monomers
- anaerobic: doesn't require oxygen; least efficient; partial but not complete
48
Catabolism is Versatile:
- glycolysis and the citric acid cycle funnels electrons from organic molecules
- breaks down carbohydrates, proteins (removes amino groups - deamination), fatty acids (beta oxidation), and glycerol
- gets 2x as much energy from lipids as carbs
49
Aerobic Respiration: (steps)
1. glycolysis - oxidation of pyruvate
2. citric acid cycle
3. oxidative phosphorylation - electron transport chain and chemiosmosis
Honors Biology
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