LECTURE 6 - Gene Regulation Flashcards

1
Q

cells contain the ____ ____ for the _____ of different products

A
  • genetic capacity
  • synthesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

WHAT mechanism is present for the control of gene expression

A

regulatory mechanism

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

in ____ organisms, gene regulation occurs at least at _____ levels

+ what are these levels?

A
  • most
  • 2
  1. transcriptional level
  2. post-transcriptional level
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

the 2 regulatory levels operate with some _______ in _____ and ______

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

IN EUKARYOTES,

when can CONTROL be achieved (2)?

CONTROL is achieved at the stage wherein _____ is ____ from the nucleus

and is also achieved ____ the _____ of the polypeptide chain

A
  1. when the mRNA is released from the nucleus
  2. after the synthesis of the polypeptide chain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

WHAT is the primary target of controlling mechanisms?

+ In (WHAT organisms) does this happen?
+ reason for this being the primary target?

A

TRANSCRIPTION

  • prokaryotes and viruses

due to the different ways for enzymes to be synthesized

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

WHAT are the 2 types of enzymes that affect gene regulation in transcription?

A
  1. Constitutive Enzymes
    - mRNA for these enzymes are synthesized continuously
  2. Inducible Enzymes**
    - synthesis of mRNA for these enzymes increases in the presence of substrate

**normally present in small amounts but concentrations increase when substrates are present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

RELATED GENES (specifically in ___)

  • are generally ______?
  • their GENE PRODUCTS / enzymes belong…?
  • consists of a genetic unit called ____?
A
  • prokaryotes
  • clustered together
  • belong to the same metabolic pathway

OPERON

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

OPERON

  • a unit of _____ that is a ____ of ____-related ____?
  • 2 types of operon systems? + definition
A
  • DNA
  • group
  • functionally-related
  • genes
  1. Inducible
    - wherein effector molecules induce weakly transcribed operons
  2. Repressible
    - wherein effector molecules repress the transcription of an operon
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In E coli

  • what type of inducible operon is present?
  • what are its ^^ 4 adjacent parts?
A
  • lactose or lac operon
  1. regulator gene (lacl)
  2. promoter site
  3. operator site
  4. 3 structural genes (z, y, and a)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In E coli, LAC OPERON

  • what regulator protein is present?
  • other term?
  • In ^^, all its subunits are ____
  • each subunit in ^^ is a ___ that is coded by WHAT GENE?
A
  • lac repressor
  • tetramer (protein with 4 subunits)
  • identical
  • polypeptide
  • lacl gene
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

REPRESSOR PROTEIN

  • main function?
  • makes the operon to be “____ ___” or “___”
A
  • binds to operator during TRANSCRIPTION to block the movement of RNA polymerase from promoter to structural genes to hinder the synthesis process
  • turned off or repressed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

IF the lac operon is in repressed state, will there be ENTIRELY no transcription done?

A

no, there will still be a low concentration of proteins coded by the structural genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

LAC OPERON

  • the 3 structural genes present here are involved in the _____ of ______ for ______ release

+ what enzymes do each of the structural genes code for?
+ function of these enzymes (2 ; 1 ; 1)

A
  • metabolism
  • lactose
  • energy
  1. LacY
    - β-galactoside permease
    - a transmembrane transport protein that allows entry of β-galactosides (like lactose) from environment into the bacterial cell
  2. LacZ
    - β-galactosidase
    - breaks down lactose (from environment) into glucose and galactose
    - catalyzes conversion of lactose to allolactose
  3. LacA
    - β-galactoside transacetylase
    - involved in other aspects of β-galactoside metabolism
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ALLOLACTOSE

  • an isomer of ___
  • function?
  • consequence of function ^^?
A
  • lactose
  • binds to the repressor (in the operon) and induces it to change conformations, thereby releasing the repressor protein and TURNING ON the operon
  • transcription then proceeds at a high rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

LAC OPERON

  • basic step-by-step process?
A
  1. β-galactoside permease lets outside lactose to enter bacterial cell
  2. β-galactosidase converts the lactose to glucose, galactose, and allolactose
  3. Allolactose is used to “turn on” the lac operon by affecting the repressor
  4. Transcription occurs at high rate until all the lactose molecules have been used up (wala nang pwede i convert to allolactose)
  5. Lac operon turns off again
17
Q

In E coli

  • what type of repressible operon is present?
  • what are its ^^ 5 adjacent parts?
A
  • tryptophan operon
  1. regulator gene (trpR)
  2. promoter site
  3. operator site
  4. attenuator site (trpL)
  5. 5 structural genes (trpE, trpD, trpC, trpB, trpA)
18
Q

LAC OPERON VS TRYPTOPHAN OPERON

  • type of operon system
  • regulator gene
  • location of regulator gene
  • activity of regulator gene
A

LAC: inducible
- lacl gene
- located upstream near the lac operon
- active by itself (so lac repressor can automatically bind to lac operon)

TRP: repressible
- trpR gene
- located far away from trp operon
- initially inactive (so the trp repressor by itself cannot bind to the trp operon)

19
Q

In E coli, TRP OPERON

  • what regulator protein is present?
  • other term?
  • In ^^, all its subunits are ____
  • each subunit in ^^ is a ___ that is coded by WHAT GENE?
A
  • trp repressor
  • dimer (2 subunits)
  • identical
  • polypeptide
  • trpR gene
20
Q

TRP REPRESSOR

  • since it is initially inactive, what is its other name?
  • what attaches to this protein to become active?
  • for the trp operon, what will the attached protein be?
A
  • aporepressor

to become active, a COREPRESSOR must attach with the aporepressor

  • the corepressor is the tryptophan
21
Q

TRP OPERON

  • the 5 structural genes present here are involved in the _____ of ______ for cell metabolic processes like ______

+ what enzymes do each of the structural genes code for?
+ function of these enzymes

A
  • biosynthesis
  • tryptophan
  • translation
  1. trpE + trp D
    - codes for 2 polypeptides that form the enzyme called anthranilate synthetase
  2. trpC
    - indole glycerol phosphate synthase
  3. trpB + trpA
    - codes for 2 polypeptides that form the enzyme called trytophan synthethase
22
Q

TRP OPERON

  • basic step-by-step process?
A
  1. the 5 structural genes is continuously synthesized by the RNA polymerase into TRYPTOPHAN (since the trp repressor is inactive by itself)
  2. once the concentration of the tryptophan inside the cell becomes too high, a tryptophan molecule (that acts as a corepressor) binds to the aporepressor to activate the trp repressor
  3. turns off the trp operon
23
Q

READ DIFFERENTIATION