Quiz 5

Question 1

What is meant by metabolism?

Answer 1

Total sum of the chemical reactions within an organism

Question 2

Anabolic reactions
- what they are used for, how do they relate to energy (ender vs exergonic), and whether they involve hydrolysis or dehydration

Answer 2

Anabolic reactions: creation of new macromolecules from building blocks
- endergonic – require energy in the form of ATP
- involve dehydration reactions

Question 3

Catabolic reactions
- what they are used for, how do they relate to energy (ender vs exergonic), and whether they involve hydrolysis or dehydration

Answer 3

Catabolic reactions: breakdown of macromolecules
- exergonic – releases potential energy
- involve hydrolysis reactions

Question 4

ATP – What is it used for? As a nucleotide, what does its structure look like? Where is the potential stored in the molecule?

Answer 4

ATP is used to “store” energy when it is abundant

Question 5

How is ATP created (when energy is in excess) and how is it broken down (when energy is needed)?

Answer 5

Creation of ATP : energy released from catabolic reactions is used to add a third phosphate onto ADP (ADP + P = ATP)

Broken down: when energy is needed, ATP is hydrolyzed and re–released (ATP = ADP + P)

Question 6

What are the different forms of cellular work of which ATP is required?

Answer 6

1) movement
2) cell growth and division
3) active transport
4) anabolic reactions

Question 7

What happens during chemical reactions and what is the role of activation energy in that process?

Answer 7

Chemical reactions occur when particles collide with one another
- bonds are broken and created
- collisions must be in proper orientation and with enough energy
– activation energy is the energy that is required for a reaction

Question 8

Enzymes – know its major properties (how does it speed up chemical reactions, is it used up in the process, etc), know the terms active site, substrate, and product

Answer 8

enzymes are protein or RNA-based catalysts used by all cells
- they speed up chemical reactions by lowering activation energy
- have a binding “pocket” called an active site which attaches to a substrate and helps convert the substrate into a product
- can be reused ; is not completely consumed in the process

Question 9

Know the major factors that affect enzyme rate

Answer 9

1) presence/absence of cofactors
2) temperature
3) pH
4) presence/absence of inhibitors

Question 10

What is an enzyme cofactor, and what are some example cofactors

Answer 10

Enzyme cofactors are extra molecules that will attach to enzymes that cannot bind by themselves
ex. ion, vitamin, or coenzymes

Question 11

What happens to enzymes as temperature gets too hot? What is meant by optimum?

Answer 11

as temperature increases, enzyme rates go up until they reach an optimum (temp they work best at)
– enzymes can denature at too high temps

Question 11

What is the difference between an apoenzyme vs holoenzyme

Answer 11

apoenzyme: an enzyme that this incomplete/inactive by themself

holoenzyme: final active enzyme

Question 12

How does pH impact enzyme activity? In which pH range are most enzymes “happiest”?

Answer 12

most enzymes function best near a neutral pH, although some have acidic/alkaline optima

Question 13

What is meant by osmolarity?

Answer 13

Osmolarity: measure of solute concentration

Question 14

What is the difference between a competitive and allosteric inhibitor? How/where do each attach to enzyme and how do they inhibit?

Answer 14

Competitive inhibitor: inhibitor resembles the substrate
– binds to active site and blocks substrate binding

Allosteric inhibitor: inhibitor binds to other site and causes a shape change so that the active site is altered

Question 15

What is the difference between oxidation and reduction? What is meant by the concept that they are coupled?

Answer 15

Oxidation: loss of electons
Reduction: gaining of electrons

They are coupled, meaning that if one component is oxidized, the other is reduced

Question 16

Why are glucose and other macromolecules often targeted for oxidation during ATP production? What is it about their composition (e.g. electronegativity of its atoms) that make them have lots of potential energy stored in their bonds?

Answer 16

Glucose and other macromolecules are often targeted for oxidation during ATP production bc they contain a lot of potential energy, so oxidation and movement of their electrons releases this energy

Bonds b/t carbon and hydrogen are more susceptible to this bc they have low electronegativity – atoms w/ higher electronegativity will take their electrons
– more carbon-hydrogen bonds means more stored energy

Question 17

Glycolysis – what goes in and what is produced? You need to know how many of each molecule is made. What is the overall function of NADH?

Answer 17

Glucose is oxidized into 2 pyruvate molecules, and it generates 2 net ATP and 2 NADH (electron carrier)

Question 18

How is the ATP made during glycolysis (you need to understand what is meant by substrate-level phosphorylation

Answer 18

The 2 ATP made during glycolysis are generated through substrate-level phosphorylation
– a phosphate is removed from an organic compound and combined with ADP to make ATP

Question 19

Know the two alternatives to glycolysis and what their purpose is

Answer 19

1) Entner-Doudoroff pathway
– used by some bacteria to oxidize glucose to pyruvate (mostly Gram-negative bacteria that lack glycolysis enzyme)
2) Pentose-phosphate cycle
– often occurs alongside glycolysis; converts glucose into other organic compounds

Question 20

Aerobic respiration
- What are all the ways in which pyruvate is modified into acetyl CoA? What is released and what is produced during this process? (Keep in mind that two pyruvates are made from glycolysis and so each goes through this process)

Answer 20

Pyruvate is shuttled into mitochondria (eukaryotic) or stays in the cytosol (prokaryotic)

Each of the two pyruvate are first converted into acetyl CoA
– One carbon is released as CO2
– Pyruvate is oxidized -> e- transferred to form NADH
Ultimately, 2 CO2 and 2 NADH are made

Question 21

Aerobic respiration
- What occurs during the Kreb’s cycle (e.g. what products are made and how many of each)?

Answer 21

For each of the two acetyl CoA:
– 1 ATP, 3 NADH, and 1 FADH2

Question 22

You should know total numbers of ATP, NADH, CO2, FADH2 made during glycolysis, acetyl coA production, and Kreb’s cycle

Answer 22

4 ATP, 10 NADH, and 2 FADH2