Exam 2

Question 1

Define metabolism, catabolism, and anabolism. Describe their relationship to each other and with energy.

Answer 1

metabolism - all chemical processes carried out by living organisms
catabolism - complex molecules broken down into smaller molecules and energy
anabolism (biosynthesis) - small molecules and energy are used to build complex molecules (skin, muscle, etc)
catabolism and anabolism are opposites. they are both metabolic processes

Question 2

What is the currency of energy? Where does the energy come from?

Answer 2

ATP. Comes from phosphate bonds.

Used in metabolic processes that require energy

Question 3

What are the three ways to make ATP?

Answer 3

1. substrate level phosphorylation - transferring of P from another organic molecule to make ATP
2. Oxidative phosphorylation - energy released by electrons transfer to make ATP (red ox reactions)
3. Photophosphorylation - light energy used to make ATP and O2

Question 4

Describe oxidation reduction reactions.

Answer 4

Oxidation - removal of electrons from molecule (or dehydrogenation), releases energy
Reduction - addition of electrons (or H) to a molecule (stores energy)
They are coupled reactions

Question 5

What are enzymes? How do they affect organic reactions?

Answer 5

Enzymes - protein catalysts - lowers activation energy (energy required for a reaction)
Catalysts - substances that speed up reactions while remaining unchanged by the reaction

Question 6

What is the active site?

Answer 6

Binding site for specific substrate for enzyme. The substrate the enzyme binds to is determined by the AA sequence in of the enzyme
ex. enzyme that breaks PCN structure has an active site on PCN that breaks and makes it ineffective

Question 7

Explain the process of what happens when an enzyme binds to a substrate

Answer 7

1. substrate and enzyme bind
2. complex induces enzyme to change in shape more closely to substrate - induced fit model
3. bonds break the substrate in catabolic rxns
4. dissociation between the enzyme and the product
5. enzyme resumes original form and can bind original substrate again

Question 8

Why do we need enzymes for reactions?

Answer 8

the activation energy for many reactions are naturally high. this would require an enzyme because if we increased the temperature to get the energy high enough to perform the run, it would be too high for survival

Question 9

What are cofactors? What are coenzymes?

Answer 9

Cofactors - inorganic ion/coenzyme that associated with an enzyme to increase its activity - required for active enzyme
Coenzyme - type of cofactor that is vitamin derived
Apoenzyme - inactive form of enzyme that lacks cofactors
holoenzyme - apoenzyme + cofactors

Question 10

What are the basic steps of cellular respiration?

Answer 10

Glucose goes through glycolysis to make pyruvic acid - gets CoA, becomes acetyl CoA, goes through Krebs/Citric acid cycle to make NADH, FADH2 - electron donors go through ETC to make ATP

Question 11

What happens in glycolysis?

Answer 11

Glucose is phosphorylated using 2 ATP (raises energy of molecule), split in half into G3P, G3P gets oxidized, loses 2 P’s and converted into pyruvic acid
Releases 4 ATP (2 net per glucose) and 2 NADH
THIS IS AN EX FOR SUBSTRATE LEVEL PHOSPHORYLATION

Question 12

What happens in the Krebs cycle?

Answer 12

pyruvic acid connected into acetyl CoA - releases NADH and CO2
oxaloacetic acid gets 2 C’s from acetyl CoA - goes through cycle - series of red ox reactions - generated a GTP that makes an ATP, 2 CO2, 3 NADH, and 1 FADH2
oxaloacetic acid loses 2 C’s and can use another Acetyl CoA

Question 13

What are some of the electron carriers in the ETC

Answer 13

integral membrane structures that go through red-ox reactions until the last electron acceptor O2
flavoproteins - protein derived from riboflavin
metal-containing proteins - Fes
ubiquinones - non-proline carrier derived from Vit K, found in all cells
cytochromes - associated with heme
- H donated by NADH and FADH2, NADH gives more energy

Question 14

Describe fermentation

Answer 14

• partial oxidation of NADH to NAD+ making it available to become an e- acceptor again
• reduces organic molecules - no need for e- acceptor from environment
• generates low amounts of ATP
• does not use Krebs or ETC
• products depend on organism

Question 15

Describe a protease and what it does

Answer 15

• enzyme that breaks down proteins into AA’s
• AA are deaminated (amino groups removed), hydrolyzed, and enter the Krebs cycle
• too much protein catabolism can increase ammonia levels in blood

Question 16

Describe a lipase and what is does.

Answer 16

• enzyme that breaks down fats into fatty acid and glycerol components
• requires 3 H2O molecules to hydrolyze bonds
• glycerol uses ATP to be converted into GP3 and can go into glycolysis

Question 17

Describe beta oxidation

Answer 17

after a fat molecule had been broken down by lipase, fatty acids get broken down into 2 C segments that get an acetyl CoA attached and can go into Krebs cycle

• generates an NADH and FADH2 for each 2 C’s removed
• occurs in cytosol

Question 18

What is the pentose phosphate pathway and what is it play a role in?

Answer 18

phosphorylated 5C sugar intermediate formed from glucose
formation of products used for anabolic/biosynthesis rxns:
- NADPH for photosynthesis
- important for making nucleotides, AA’s
- part of the Calvin Benson cycle
- G3P