Brainscape's Knowledge GenomeTM

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


See full index

Biochemistry I > Chapter 8: Enzyme Control Mechanisms > Flashcards

Chapter 8: Enzyme Control Mechanisms Flashcards

1
Q

Enzyme time frames

A
  • Short (allosteric control)
  • Medium (covalent modification)
  • Long (induction and repression)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Enzyme control mechanisms

A
  • Feedback and feedforward inhibition
  • Phosphorylation/dephosphorylation
  • Calcium binding proteins
  • Proteolytic activation
  • Allosteric control
  • Induction/repression
  • Substrate availability
  • Compartmentalization
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Characteristics of biochemical reactions in pathways

A
  • Highly ordered enzyme sequence
  • Tightly controlled
  • Often by factors other than substrate
  • Environmental changes influence flux
  • Non equilibrium enzymes are key
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Long time frame activity

A
  • Gene expression
  • Alters the amount of enzyme made
  • Days or weeks
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Action of cortisol

A
  • Slow to turn on enzymes
  • Makes more enzymes
  • We don’t want epi and norepi on all the time
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Medium time frame activity

A
  • Covalent modification

- Reversible phosphorylation/adenylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Phosphate group is negative and will impact/change enzyme activity

A
  • Doesn’t always increase activity, always changes though
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Short time frame activity

A
  • Allosteric effectors

- Noncovalent interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Long time scale changes

A
  • Induction and repression
  • Changes in the AMOUNT of enzyme synthesized
  • Lac operon is good example (large dynamic range)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Enzyme activity if lactose is present

A
  • Bact make the enzymes to break down the lactose

- If it is not present we turn the gene off

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

Medium time scale changes

A
  • Covalent modification of enzyme structure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Reversible phosphorylation (medium) occurs at

A
  • Serine and threonine residues

- Enzymes cycle between active and inactive forms

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

Changes in medium time frame scale mediated by

A
  • Hormone-receptor cell interactions at the cell surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Covalent modification of amino acid residues on enzymes coordinates

A
  • Control of muscle glycogen metabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Phosphorylation in medium time frame reactions activates/inhibits

A
  • Activates glycogen phosphorylase

- Inhibits glycogen synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Allosteric activators/inhibitors in short time frames bind to

A
  • Bind reversibly (noncovalently) to the allosteric site on allosteric enzymes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

GMP and AMP feedback inhibition regulates and inhibits

A
  • Regulates purine biosynthesis

- Inhibits glutamine PRPP amidotransferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Control mechanism of the irreversible steps of glycolysis

A
  • Feedback inhibition and feedforward inhibition
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Phosphorylation/dephosphorylation (type of modification)

A
  • Reversible covalent modification
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Residues that can be phosphorylated

A
  • Serine
  • Threonine
  • Tyrosine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Glycogen phosphorylase activity enhanced by

A
  • Covalent reversible phosphorylation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Glycogen phosphorylase kinase is controlled by

A
  • Reversible phosphorylation
23
Q

Examples of reversible phosphorylation/dephosphorylation

A
  • Glycogen phosphorylase
  • Adenylation
  • Methylation
24
Q

Calmodulin (calcium binding protein) found in

A
  • Ubiquitous
  • Found in the cytoplasm
  • Component of several enzymes
25
Calcium binding to calmodulin activates
- Calcium-calmodulin dependent kinases
26
Importance of calcium binding proteins
- Signal transduction mechanisms for hormones: - Vasopressin - Oxytocin - Angiotensin II
27
Limited proteolysis modification
- Permanent modification of inactive proenzymes (zymogenic precursors) - Not reversible - Can be extracellular - Digestive enzymes and coagulation cascade
28
Digestive enzymes and coagulation cascade enzymes
- Pepsinogen | - Trypsinogen
29
Limited proteolysis is not a control mechanism
- It is an activation mechanism
30
Limited proteolysis activates
- Digestive enzymes | - Clotting factors
31
Induction/repression regulated by
- Controlling enzyme synthesis
32
Induction ( + ) or repression ( - ) of gene transcription works at level of
- Mechanism working at level of gene expression
33
Selective proteolytic degradation
- Done by proteosomes with ubiquitin system | - Reduces enzyme levels
34
Slow mechanisms for regulating enzyme concentration (induction/repression)
- Changes occur over hours, days, or even weeks | - Long time frame
35
Main site of control for eukaryotic gene expression
- First step | - Transcription of DNA sequence into RNA
36
Cortisol
- Steroid hormone than can induce gluconeogenic enzymes
37
Steroid hormones
- Interact with nuclear or cytoplasmic receptors | - Alter enzyme synthesis
38
Cortisol mechanism
- Diffuses through membrane - Binds to intracellular receptors or in nucleus - Turns on gene expression
39
Cortisol increases synthesis of
- Transcription and translation (making new proteins)
40
Compartmentalization is aided by
- Subcellular specialization | - Selectively permeable membranes
41
Fatty acid oxidation occurs in
- The mitochondria
42
Fatty acid synthesis occurs in
- The cytosol
43
Glycolysis occurs in
- The cytosol
44
Citric acid cycle occurs in
- The mitochondria
45
Availability of substrates is critical
- Crucial in compartmental control
46
Endoplasmic reticulum
- Delivery of proteins | - Synthesis of lipids for membranes
47
Nucleus
- Nucleic acid synthesis
48
Mitochondria
- Citric acid cycle - Oxidative phosphorylation - Fatty acid breakdown
49
Cytosol
- Fatty acid synthesis - Glycolysis - Gluconeogenesis - Pentose phosphate pathway
50
Golgi apparatus
- Sorting and secretion of proteins
51
Control
- The ability to alter metabolic flux in a pathway as needed
52
Irreversible and non-equilibrium enzymes
- Achieves metabolic control
53
Purpose for control of enzyme activity
- Avoids unnecessary metabolic activity/utilization of resources - Prevents accumulation of excess product
54
Most common control mechanisms
- Altering concentration - Covalent/allosteric modification - Proteolysis - Compartmentalization

Biochemistry I (34 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions