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AP Bio > Chapter 18: Gene Regulation > Flashcards

Chapter 18: Gene Regulation Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What does bacteria must do in the environment?

A

they must respond quickly to changes in the environment

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2
Q

Why must bacteria need to stop production if they have enough of a product,

A

Waste of energy to produce more

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3
Q

How must bacteria need to stop production if they have enough of a product?

A

stop production of enzymes for synthesis

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4
Q

Why must bacteria need to utilize the new food/energy source, quickly if they find it?

A

metabolism, growth, reproduction

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5
Q

How must bacteria need to utilize the new food/energy source, quickly if they find it?

A

start production of enzymes for digestion

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6
Q

Feedback Inhibition

A

products acts as an allosteric inhibitor of 1st enzyme of in tryptophan pathway

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7
Q

What is the drawback of feedback inhibition?

A

Its a wasteful production of enzymes

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8
Q

Gene Regulation

A

blocks the transcription of genes for all enzymes in tryptophan pathways

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9
Q

What is the benefit of gene regulation?

A

Saves energy by not wasting it on unnecessary protein synthesis

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10
Q

How do cells vary the amount of specific enzymes ?

A

regulating gene transcription

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11
Q

Operon

A

genes grouped together w/ related functions
ex: all enzymes in a metabolic pathway

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12
Q

Promoter

A

RNA polymerase binding site, single promoter controls transcription of all genes in operon

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13
Q

Operator

A

DNA binding site of repressor proteins

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14
Q

How can genes be turned off?

A

the repressor protein can bind to DNA at operator site, blocking RNA polymerase, blocks transcription

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15
Q

Repressible Operon: Tryptophan

A

Synthesis pathway model
When excess tryptophan is present, it binds to tryp repressor protein & triggers repressor protein & triggers repressor to bind DNA
- blocks (represses) transcription

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16
Q

What happens when excess tryptophan is present

A

an active repressor protein will bind with the operator to stop the transcription of trytophan.

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17
Q

Inducible Operon: lactose

A

Digestive pathway model when lactose is present, binds to lac repressor protein & triggers repressor to release DNA
- induces transcription

18
Q

What happens when lactose is present?

A

The inhibitor that blocks the lactase enzyme from being produced is unblocked allowing the production of lactase

19
Q

Jacob & Monod

A

1st to describe operon system coined the phrase “operon”

20
Q

How does E coli sense the glucose concentration is low?

A

Cyclic AMP (cAMP) concentration is high.

If glucose is low and lactose is present then lac operon is turned on

21
Q

Repressible operon

A

usually functions in anabolic pathways
-synthesizing end products
when end product is present in excess,
cell allocates resources to other uses

22
Q

Inducible operon

A

usually functions in catabolic pathways
-digesting nutrients to simpler molecules
produce enzymes only when nutrient is available
- cell avoids making proteins that have nothing to do, cell allocates resources to other uses

23
Q

points of control

A

The control of gene expression can occur at any step in the pathway from gene to functional protein

24
Q

What are the points of control?

A
  1. packing/unpacking DNA
  2. transcription
  3. mRNA processing
  4. mRNA transport
  5. translation
  6. protein processing
  7. protein degradation
25
Q

How do you fit all that DNA into nucleus?

A

DNA coiling & folding
-double helix
-nucleosomes
-chromatin fiber
-looped domains
-chromosome

26
Q

Nucleosome

A

“Beads on String”
1st level of DNA packing
histone proteins
- 8 protein molecules
- positively charged amino acid
-bind tightly to negatively charged DNA

27
Q

What happens when DNA is tightly wrapped the histone?

A

no transcription, genes are turned off

28
Q

Missense Mutation

A

a point mutation, switch between bases, that causes the wrong protein to be

29
Q

Nonsense Mutation

A

a point mutation because it codes for a stop codon in the middle of the sequence causing the rest of the amino acids to not be coded

30
Q

Silent Mutation

A

point mutation that has no effect on the amino acid sequence.

31
Q

Methylation of DNA blocks transcription factors

A

no transcription
→ genes turned off
attachment of methyl groups (–CH3) to cytosine
C = cytosine
nearly permanent inactivation of genes
ex. inactivated mammalian X chromosome = Barr body

32
Q

DNA Phosphorylation

A

addition of a phosphate group to an amino acid (phosphorylation) will prevent the chromatin from condensing

33
Q

Acetylation of histones

A

unwinds the DNA
-loosely wrapped around histones, which enables transcription and turns on genes

attachment of acetyl groups (–COCH3) to histones
conformational change in histone proteins
transcription factors have easier access to genes

34
Q

Epigenetics Inheritance

A

Mutations in the DNA are permanent changes….but modifications to the chromatin CAN BE reversed.

35
Q

What is the 1st control of gene expression?

A

chromatin modifying enzymes by just making the area of DNA more or less accessible to the process of transcription

36
Q

Promoter

A

nearby control sequence on DNA
binding of RNA polymerase & transcription factors
“base” rate of transcription

binds transcription factors that controls the initiation of transcription

37
Q

Enhancer

A

distant control sequences on DNA
binding of activator proteins…brings it closer to promoter
“enhanced” (high level

38
Q

Activator proteins

A

bind to enhancer sequence & stimulates transcription

39
Q

Silencer proteins

A

bind to enhancer sequence & block gene transcription

40
Q

Post Transactional Control

A

Alternative RNA splicing
-variable processing of exons creates a family of proteins

AP Bio (19 decks)

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