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Biochemistry > Lecture 14, Regulation (Ford) > Flashcards

Lecture 14, Regulation (Ford) Flashcards

1
Q

How are metabolic enzymes regulated?

A

Compartmentalization, enzyme concentration, enzyme activity, hormone signals

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2
Q

How can reactions be affected?

A

Substrate-level control or feedback control

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3
Q

What kind of reaction does substrate-level control act on?

A

Single reaction

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4
Q

What kind of reaction does feedback control act on?

A

Targets a different step in the pathway

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5
Q

How is product formation affected by feedback?

A

Activators promote more product; inhibitors prevent more products

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6
Q

What are isozymes?

A

Catalyze the same reaction but with different efficiencies

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7
Q

T or F: Isozymes are compartmentalized based on tissue specificity.

A

True.

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8
Q

During development, what kind of expression do isozymes utilize?

A

Temporal

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9
Q

What can be added via reversible covalent modification?

A

Functional groups

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10
Q

How would the addition of functional groups affect an enzyme?

A

Activate or deactivate the enzyme

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11
Q

What are some common functional group additions?

A

Myristic acid, farnesyl, nucleic acids, ubiquitin, carbohydrates, small molecules

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12
Q

What is the greatest source of diversity to the proteome?

A

Addition of carbohydrates

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13
Q

What are the sources of diversity when carbohydrates are added via covalent modifications?

A

O- vs. N- linkages, composition of sugars, branched vs. unbranched, length of oligosaccharide

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14
Q

What are some common small molecule additions?

A

Gamma-carboxylation, sulfation, acetylation, methylation, phosphorylation

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15
Q

T or F: Acetylation tends to be deactivating.

A

False. Acetylation tends to be activating.

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16
Q

What types of covalent modification can histones experience?

A

Acetylate, methylate, phosphorylate

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17
Q

Why is phosphorylation activating regarding thermodynamics?

A

ATP hydrolysis can drive unfavorable reactions (-deltaG)

18
Q

Why is phosphorylation activating regarding kinetics?

A

Physiological processes dictate reaction rate

19
Q

Why is phosphorylation activating regarding cell processes?

A

ATP amounts dictated by metabolism (energy charge); Signal transduction amplification (catalytic turnover)

20
Q

Why is phosphorylation activating regarding shape and charge complementarity?

A

Each phosphate adds -2 charge and 3+ H bonds

21
Q

T or F: Phosphatases remove phosphates, while kinases add phosphates.

A

True.

22
Q

What does the name of a kinase indicate?

A

On which amino acid the phosphate will be added

23
Q

T or F: A tyrosine kinase will add a phosphate to a serine.

A

False. A tyrosine kinase will add a phosphate to a tyrosine.

24
Q

Where is covalent modification happening?

A

Allosteric site

25
Q

What is heteroallostery?

A

Effector binds at allosteric site

26
Q

What is homoallostery?

A

Cooperativity

27
Q

What is ATCase inhibited by?

A

CTP

28
Q

The binding of CTP prefers which state?

A

T (inactive) state

29
Q

The binding of ATP prefers which state?

A

R (active) state

30
Q

How is it determined when covalent modification happens?

A

Enzyme amount (protein synthesis regulation = on/off switch)

31
Q

What are the 2 levels of control that are possible during protein synthesis regulation?

A

Transcription regulation at the promoters; Translation regulation at the UTRs

32
Q

Histone phosphorylation ___ transcription.

A

Prevents

33
Q

Histone methylation can ___ or ___ transcription.

A

Prevent or promote

34
Q

T or F: mRNA levels correlate to protein levels.

A

False. mRNA levels do not correlate to protein levels.

35
Q

Why are enzymes regulated?

A

Irreversible covalent modifications (proteolytic activation)

36
Q

What is the inactive form of an enzyme called?

A

Zymogens (take something away) or apoenzymes (add something)

37
Q

What are some examples of enzymes that begin their lives as zymogens?

A

Proteases, collagen, blood clotting factors, insulin/hormones

38
Q

Chymotrypsin is an example of what kind of protease?

A

Serine protease

39
Q

How many times must chymotrypsin be cleaved to be activated?

A

Twice

40
Q

What type of reaction makes a disulfide bond?

A

Oxidation

41
Q

What amino acid must be present in order to have a disulfide bond?

A

Cysteine

Biochemistry (10 decks)

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