Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOCH 200 > Metabolism > Flashcards

Metabolism Flashcards

1
Q

State two major purposes of metabolism

A
  1. To obtain usable chemical energy from the environment
  2. To make the specific molecules that cells need to live and grow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Identify the two major ways in which organisms obtain energy from the environment

A
  1. phoyosynthesis
  2. consuming and breaking down nutrient molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

List 3 features that distinguish catabolic and anabolic pathways

A

anabolic: (build)
- use energy
- builds larger molecules
- reductive (something else is getting oxidized, electrons are used to make new bonds)
- NAD+, FAD

catabolic: (break)
- release energy (some of which is stored)
- breaking down of molecules
- oxidative (electrons are removed as bonds are broken)
- NADPH, FADH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

define 1) amphibolic and 2) anapleurotic

A
  1. Operate in both catabolic and anabolic processes, can both break down and build molecules
  2. A reaction that replenishes the intermediates of
    a metabolic pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how are carbohydrates and fatty acids stored?

A
  • as glycogen (a polymer of glucose molecules) in the liver (hepatocytes) and in skeletal muscle (myocytes)
  • fatty acids are stored as fat (triacylglycerols) in adipocytes (fat cells)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Carbon oxidation

A
  • during catabolism, carbon molecules generally become more oxidized

hydoxyls→carbonyls→carboxylates→carbon dioxide

  • fats are more reduced than carbs and will generally need more oxidation steps to be oxidized
  • CO2 is typically the end product for carbon atoms coming in as fuel molecules after catabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

State the relationship between the magnitutde of the free energy change of a reaction and the direction in which that reaction will proceed

A
  • if free energy is negative, rxn is exergonic and occurs spontaneously
  • if free energy is positive, rxn is endergonic and does not occur without the input of energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

explain what the term “spontaneous” means, when describing a biochemical reaction

A
  • thermodynamic process that can occur without the input of energy
  • net decrease in free energy
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Explain why reactions with a ΔG of approx. 0 are reversible

A
  • if free energy = 0, reaction is in equilibrium
  • no change in energy is observed meaning forward and reverse reactions occur simutaneaously
  • a change in concentration of R/P may change the direction of the reaction ~Le Chatelier’s Principle~
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Compare and contrast ΔG, ΔG’ and ΔG° and ΔG°’

A

ΔG - represents FEC under non-standard conditions, indicating whether or not the reaction is spontaneous

ΔG’ - represents the FEC for a reaction under biological standard conditions, providing a reference point for comparing the favourability of biochemical reactions

ΔG° - represents FEC for a reaction under standard conditions, providing a reference point for comparing the favourability of reactions under different conditions

ΔG°’ - represents FEC for a biochemical reaction under standard conditions with all R and P at their standard concentrations, useful for comparing the favourability of biochemical reactions involving proton transfers

FEC - free energy change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Biochemical Standard State

A
  • pH = 7
  • substrate and product concentration = 1M
  • temperature = 25℃
  • pressure = 1 atm
  • concentration of water = 55M
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

equation describing the actual free energy change depending on the concentration of substances in system

A

ΔGreaction = ΔG°’ + RTIn (products/reactants)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Enzyme regulation in metabolism

A
  • irreversible steps are usually regulated
  • reversible steps are not usually regulated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

examples of inhibition and activation

A

inhibition:
1. product inhibition - enzyme is inhibited by the product of it’s reaction (allosteric regulatory process)
2. feedback inhibition - enzyme is inhibited by a metabolite further down the pathway (downstream)

activation:
- feed forward activation: enzyme may be activated by a metabolite upstream (positive homoallostery)

net flux of pathway will increase if irreversible reactions are increased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

State the function of electron carriers

A
  • high energy intermediate that shuttles electrons around during important chemical reactions in cells
  • contain useable chemical energy that can be recovered or used (reaction associated with large FEC)
  • helps generate energy that cells can use
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Identify three electron carriers that function as cofactors in enzymes which catalyze redox reactions

A
  1. NADH
  2. NADPH
  3. FADH₂

the nitrogen base portion of these dinucleotides enables them to undergo a reversible reduction reaction

17
Q

Explain the terms 1) “high-energy” intermediate and 2) “energy currency”

A
  1. molecule possessing an unstable arrangement of atoms or chemical bonds, which makes it capable of releasing a significant amount of energy when it undergoes a specific chemical reaction. Carriers/donors of energy in a pathway
  2. molecule that serves as a universal carrier of chemical energy within a cell. can store energy in a readily accessible form and release it when needed to drive various cellular processes. (eg. ATP)
18
Q

Identify three types of substances which can act as “high-energy” intermediates

A
  1. Electron carriers (NADH, FADH₂)
  2. Nucleoside triphosphates (ATP, GTP - contain phosphoanhydride bonds)
  3. Thioesters
19
Q

Explain why the free energy change of hydrolysis of ATP is large and negative

A

the high-energy phosphate bonds between its phosphate groups are relatively unstable and have a high potential energy because there are 4 negative charges in close proximity due to the phosphate group

the LFEC is due to:
- decreased electrostatic repulsion between phosphate groups
- resonance stabilization and lower energy state of the molecules: terminal phsphoryl has 3 RS, inorganic phosphate has 4
- solvation effects: it becomes easier to from H bonds

ATP hydrolysis - ΔG’° ~32kJ/mol

RS - resonance structures

20
Q

How is ATP generated? (2)

A
  1. directly by catabolism: substrate-level phosphorylation
  2. reoxidation of NADH/FADH₂: oxidative phosphorylation
21
Q

List three energy-requiring processes “driven” by ATP

A
  1. unfavourable reactions (coupling)
  2. cellular movement (muscle, flagella)
  3. primary active transport (ion pumping)
22
Q

State the conditions that must be satisfied for reactions to be coupled

A

free energy changes for reactions are additive
- the combined reactions must have an overall/net ΔG < 0 to be spontaneous
-

23
Q

What is phosphate transfer potential

A

the free energies of hydrolysis for phosphate-containing compounds

24
Q

**Use the formation of glucose-6-phosphate as an example to illustrate “coupling”

A
25
Q

Outline the role of phosphocreatine in muscle and explain how it fulfills this role

A
  • Phosphocreatine (PCr) serves as a reservoir of high-energy phosphate bonds in muscle cells. When ATP is used up during intense muscle contractions, PCr steps in as a rapid source of energy.

phosphocreatine hydrolysis coupled to formation of ATP:
phosphocreatine + ADP ⇋ creatine + ATP
ΔG = -11kJ

hydrolysis of phosphocreatine ΔG = -43kJ/mol

26
Q

Define the terms 1) rate-limiting step and 2) reciprocal regulation, as they apply to metabolic pathways

A
  1. the irreversible, regulated reaction that determines the overall rate of the pathway
  2. when opposing pathways catalyze the “reverse” of another pathway, irreversible reactions must be replaced or bypassed, ensures that both do not operate at the same time
27
Q

identify a phosphoanhydride bond

A

two phosphate groups connected together by a shared oxygen atom

28
Q

state what is meant when nucleoside triphosphates are described as being “high energy” molecules

A

eg. ATP: contains unstable phosphate anhydride bonds containing negative charges that repel each other - hydrolysis = large release in free energy

  • high energy means that these molecules are able to serve readily as a source of energy
29
Q

Explain why the hydrolysis of phosphoanhydride bonds is a highly favourable reaction

A

It leads to a lower energy product - more resonance stabilization, more solvation

phosphoanhydride bonds are very high energy due to low stability

30
Q

recognize NADP+, NAD+ and FAD as dinucleotides

A
  • the nitrogen base portion enables them to undergo a reversible reduction reaction
  • ## NAD+: 2 bases, 2 sugars, 2 phosphates
31
Q

what are the equations to describe the reduction of NAD+, NADP+ and FAD

A

NAD⁺ + 2H⁺ + 2e- ⇌ NADH + H⁺

NADP⁺ + 2H⁺ + 2e- ⇌ NADPH + H⁺

FAD + 2H⁺ + 2e- ⇌ FADH₂

BIOCH 200 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions