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ENSC micro > Notes 1a > Flashcards

Notes 1a Flashcards

1
Q

Do organisms code make copies of every gene they have?

A

No, when e. coli uses glucose it only makes about 800 even though it has enough DNA to code for 2000 to 4000

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2
Q

What is a promoter on a gene sequence

A

sequence of DNA that RNA polymerase binds to “START HERE”

-RNA polymerase’s job is to convert DNA sequence to messenger RNA (mRNA) by Transcription

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3
Q

What is the structural gene on a gene sequence

A

Directions for making protein or RNA

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4
Q

What is the transcriptional stop on a gene sequence?

A
  • Maybe a loop of DNA

- RNA polymerase falls off = stop here

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5
Q

What are the main components of a gene?

A
  1. Promoter
  2. Structural gene
  3. Transcriptional stop
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6
Q

What happens after transcription?

A

The mRNA moves to the ribosome to be translated into a protein.

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7
Q

Why are operons useful

A

It is more efficient to turn on and off entire pathways at once

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8
Q

What are the parts of a operon

A
  1. Promoter

2. Operator

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9
Q

What is the promoter of an operon?

A

The RNA polymerase binding site.

-When repressor is bound, RNA polymerase is bloked from transcribing the genes in the operon

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10
Q

How does the repressor protein bind to the DNA

A

by inserting part of itself into the major groove of the DNA

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11
Q

What is the highly conserved method of binding to DNA do repressors use?

A

Helix-turn-helix motif

-this method of binding to DNA involes inserting one helix into the major groove and the other helix helps maintain the correct geometry for binding

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12
Q

What method do many DNA binding proteins use for binding to specific use sequences of DNA

A

Helix turn Helix

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13
Q

What is an example of the lac operon

A

Coliforms are a group of Gram negative rod shaped bacteria used in water quality testing.

  • They can use glucose or lactose
  • All the genes needed to use lactose are know as the lac operon
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14
Q

What can lactose be broken into?

A

1 unit of glucose and 1 unit of galactose

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15
Q

What has to happen before a cell can use lactose

A

Converted into glucose

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16
Q

What does a cell use if glucose and lactose are present

A

a lac repressor protein binds to the operator sequence and the lac operon shuts off. This stops the production of the mRNA used to made enzymes to break down lactose

17
Q

Are there any copies of the LacZ protein when glucose is present

A

Yes, 3 copies LacZ / cell are always present in the uninduced state due to the repressor protein occasionally falling off just when RNA polymerase arrives.

18
Q

What is the inducer of the lac operon?

A

allolactase. which binds to the repressor protein. It is a converted version of the low level of lactose (minor product)

19
Q

How does allolactose work?

A

Allolactose binds to repressor protein, causing it to change shape and fall off DNA Therefore RNA polymerase can bind

20
Q

Define catabolism

A

breaking things down -> usually to get energy

21
Q

Define Anabolism

A

Building stuff

22
Q

Define metabolism

A

all the reactions in a cell

23
Q

What are global controls used for?

A

for if many genes are needed to respond to a single environmental event.

24
Q

What are two methods for global control

A
  1. CAP - Catabolic activator protein

2. Alternative sigma factors

25
Q

What does catabolite repression do

A

It keeps catabolic pathways turned off if a more efficient substrate is available

26
Q

What is the activator protein for catabolite repression

A

CAP

27
Q

What must CAP bind to to turn on catabolite repressed pathways?

A

Cyclic AMP

CAP-cAMP complex binds to a site upstream of the promoter site for operons that it is involved with.

28
Q

What is the role of the CAP-cAMP complex

A

to help RNA polymerase to bind to the promoters of operons that are under control by catabolite repression

29
Q

What happens if glucose is not present

A
  1. Adenylate cyclase does not make cAMP(Stands for: cyclic AMP) from ATP, and cAMP is exported from the cell.
  2. All catabolite pathways are off except for those that use glucose.
30
Q

What happens if glucose is not present

A
  1. Adenylate cyclase makes cAMP,
  2. cAMP binds to CAP
  3. cAMP-CAP complex binds to promoters of catabolite repressed operons -> helps RNA pol bind
31
Q

What are the two points of regulation for catabolite repressed operons

A
  1. needs glucose gone

2. needs inducer to remove repressor

32
Q

How do you write out genes in reports

A

in italics

33
Q

How do you write out genes in lab books

A

all lower case excepts the last letter and underlined

34
Q

How do you write out proteins in lab books and reports

A

no underlines or italics but the first letter is capitalized

35
Q

what is a dalton

A

1 dalton = mol weight hydrogen

ENSC micro (3 decks)

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