Review 13

Question 1

Structure of threonine

Answer 1

Same as serine except OH and CH3 both come off CH2

Question 2

How can you break a peptide bond?

Answer 2

Add strong base

Question 3

Conjugated protein

Answer 3

Proteins w/ covalently attached molecules

• Attached molecule = prosthetic group (metal ion, vitamin, lipid, carbohydrate, nucleic acid)

Question 4

Mixed inhibition = inhibitor binds to E and ES w/ (equal/unequal) affinity

Answer 4

Unequal

Question 5

Enzyme devoid of necessary cofactor = ______

Answer 5

Apoenzyme

• Catalytically inactive

Question 6

Lyase

Answer 6

Breakdown of single molecule into two molecules

• Often forms cyclic compounds or double bonds
• Does not add water and does not transfer electrons

Question 7

Ligase

Answer 7

Joins two large biomolecules together

Question 8

Epimer

Anomer

Answer 8

Epimer = subtype of diastereomers that differ at exactly 1 chiral carbon

Anomer = subtype of epimer that differ at anomeric carbon

Question 9

Number of glucose chiral centers

Answer 9

4 => 16 stereoisomers

Aldohexose

Question 10

React ethanol w/ glucose => ?

Answer 10

Glycoside

• Replace hemiacetal w/ acetal

Question 11

Beta-amylase

Alpha-amylase

Answer 11

Beta-amylase = cleaves maltose at non-reducing end => maltose exclusively

Alpha-amylase = cleaves maltose anywhere => maltose, glucose, and polysaccharides

Question 12

Reducing sugar

Answer 12

Any sugar w/ hemiacetal ring

• Has free aldehyde group or ketone group (that can tautomerize)
• One anomeric carbon in molecule is NOT involved in anomeric bond and is free to be oxidized under H2O/Br => forms acetal/ketal
• Ex. all monosaccharides b/c all have aldehyde group, maltose, lactose, cellobiose

Question 13

Amylose

Amylopectin

Answer 13

Amylose = linear, all alpha 1-4

Amylopectin = has branches, alpha 1,6

Question 14

Hemiacetal vs. Acetal

Answer 14

Hemiacetal has OR, H, R, and OH group (like monosaccharides)

Acetal has no OH group but OR, H, R and OR group (polysaccharides)

Question 15

One terpene = ____ isoprenes

Answer 15

One terpene = 2 isoprenes

Question 16

Prostaglandin

Answer 16

Autocrine + paracrine hormones that regulate cAMP

Question 17

Saponification = ______ hydrolysis of triacylglycerol using strong ______

Answer 17

Ester hydrolysis using strong bases

Question 18

Triacylglycerols

Answer 18

Highly hydrophobic

Does not get hydrated => does not have extra weight on it (which would take away energy density)

Highly reduced => can produce more energy

Question 19

More saturated fatty acids => (more/less) fluid solution

Answer 19

Less fluid b/c can pack more tightly and form more noncovalent bonds

• Higher melting point for saturated than unsaturated

Question 20

How do you hydrolyze an amide?

Answer 20

Add H2O and heat to form COOH from amide

Question 21

Fructose structure

Answer 21

6 carbons => forms 5 carbon ring (furanose)

• Ketohexose

Question 22

Is longer DNA more/less stable?

Answer 22

More stable b/c more H bonds throughout

Question 23

Unfolding of proteins = (cooperative/noncooperative) => shape of curve is ________

Answer 23

Cooperative => sigmoidal

Question 24

Non-reducing sugar

Answer 24

Cannot be oxidized b/c no hemiacetal/hemiketal present

• Both anomeric carbons are involved in anomeric bond
• Ex. sucrose (glucose + fructose)

Question 25

Peptidyl transferase

Answer 25

Catalyzes formation of peptide bond b/w incoming AA and growing polypeptide chain

Question 26

What does RNA Pol I do and where is it?

Answer 26

Located in nucleolus

Transcribes rRNA

Question 27

Compounds that contribute to membrane fluidity do what?

Answer 27

Lower melting point or disrupt crystal structure

• Ex. cholesterol, unsaturated lipids

Question 28

Which glycolysis enzymes catalyze irreversible reactions?

What enzymes are used instead in gluconeogenesis and what are they activated by?

Answer 28

Glucokinase (liver) and hexokinase (muscle), PFK-1, and pyruvate kinase

Gluconeogenesis:

• Pyruvate carboxylase - converts pyruvate to OAA => PEP
  
  • Activated by acetyl CoA
• Fructose 1,6 bisphosphatase - converts F16BP to F6P
  
  • Activated by ATP and glucagon
• Glucose 6 phosphatase - converts G6P to glucose
  
  • Only found in ER of liver

Question 29

Pyruvate dehydrogenase is stimulated by _____ and inhibited by _______

Answer 29

Stimulated by insulin

Inhibited by Acetyl Co-A

Question 30

What does glycogen synthase do?

Answer 30

Creates alpha 1-4 glycosidic linkages b/w glucose molecules

• Activated by insulin in liver and muscle

Question 31

Glycogen phosphorylase

Answer 31

Breaks alpha 1-4 links b/w glucose in glycogen => catalyzes glycogen breakdown

• Activated by glucagon when glucose is gone

Question 32

Pentose-phosphate pathway rate-limiting enzyme

Answer 32

Glucose-6-phosphate dehydrogenase

• Activated by NADP+ and inhibited by NADPH and insulin

Question 33

Pyruvate can form what three molecules?

Answer 33

Lactate (fermentation)

OAA (gluconeogenesis via pyruvate carboxylase)

Acetyl-CoA (TCA via pyruvate DH)

Question 34

What does citrate regulate?

Answer 34

Negative allosteric regulator of PFK1 (which catalyzes rate-limiting step of glycolysis)

Question 35

What does pentose phosphate pathway do?

Answer 35

Generates NADPH using G6PDH => reduces glutathione (antioxidant)

• PPP mitigates oxidative stress
• NADPH also synthesizes lipids/cholesterol, produces bleach in lysosomes in addition to mitigating oxidative stress

Question 36

Name the rate-determining enzymes for:

• Glycolysis
• Gluconeogenesis
• PPP
• Glycogenesis

Answer 36

Glycolysis = PFK1

Gluconeogenesis = F16BP

PPP = G6P dehydrogenase

Glycogenesis = glycogen synthase