Chapter 14

Front 1

transcriptional-level control

Back 1

the most efficient mechanism of gene regulation in bacteria

Front 2

(IGF2) insulin-like growth factor 2

Back 2

codes for a protein produced by both muscle and liver tissue, ie pigs that have more muscle and less fat

Front 3

Prokaryotic vs Eukaryotic
(gene regulation)

Back 3

prokaryots -> only transcriptional level

eukaryots -> transcriptional level dominates but other levels as well b/c they live longer and respond to many dif stimuli, also a single gene may be reglated in dif ways in dif types of cells

Front 4

operon

Back 4

gene complex consisting of a group of structural genes with related functions plus the closely linked DNA sequences responsible for controlling them

Front 5

promoter

Back 5

where RNA polymerase first binds to DNA before transcription begins, located the operon

Front 6

operator

Back 6

located on the operon, serves as the regulatory switch for transcriptional-level control of the operon

Front 7

repressor protein

Back 7

binds to the operator to prevent the RNA polymerase from attaching which keeps transcription from occuring

Front 8

inducible operon

Back 8

- normally turned off (ie lac operon)
- repressor protein is made in an active form hat bindsto the operator
- if lactose is present it i converted to allolactose the INDUCER which binds to the repressor protein and changes the repressor's shape
- the altered repressor cannot bind to the operator an the operon is transcribed

Front 9

repressible operon

Back 9

- normally turned on (ie trp operon)
- repressor protein made in an inactive form that cannot bind to the operator
- a metabolite (usually the end product of a metabolic pathway) acts as a COREPRESSOR
- when an intracellular corepressor levels are high, a corepressor molecule binds to the repressor, changing the repressor's shape so that it binds to the operato and thereby turns off transcription of the operon

Front 10

Constitutive genes

Back 10

neither inducible or repressible but active at all times

Front 11

catabolite activator protein (CAP)

Back 11

a regulatory protein that is produced constitutively, repressor proteins are too
- the activty of constitutive genes is controlled by how efficiently RNA polymerase binds to their promoter regions

Front 12

negative control

Back 12

- what repressible and inducible operons are under
- when the repressor protein binds to the operator, transcription of the operon is turned off

Front 13

positive control

Back 13

- what some inducible operons are also under
- an activator protein binds to the DNA and stimulates transcription of the gene
- CAP activates the lac operon, CAP binds to the promoter region which stimulates transcription by binding RNA polymerase tightly

Front 14

cyclic AMP (cAMP)

Back 14

- what CAP requires to bind to the lac operon
- levels of cAMP increase as levels of glucose decrease

Front 15

posttranscriptional controls

Back 15

- TRANSLATIONAL CONTROL: regulates the rate of translation of a particular mRNA
- includes FEEDBACK INHIBITION of key enzymes i some metabolic pathways

Front 16

Regulation of Eukaryotic genes

Back 16

-not normally organized into operons
- occurs at the levels of transcription, mRNA processing, translation, and modifications of the protein product

Front 17

transcription initiation site

Back 17

- needed for the transcription of a gene
- where transcription begins
- needs a promoter to which RNA polymerase binds
- in multicellular eukaryotes RNA polymerase binds to a promoter called a TATA BOX

Front 18

upstream promote elements (UPEs) aka proximal control element

Back 18

- the promoter of a regulated eukaryotic gene consists of an RNA polymerase-binding site and short DNA sequences known as UPEs
- the number and type of UPEs within the promoter region determine the efficiency of the promoter

Front 19

enhancers

Back 19

- located thousands of bases from the promoter
- control some eukaryotic genes
- help form an active transcription initiation complex
- specific regulatory proteins binds to enhancers and activate transcription by interacting with the proteins bound to the promoter

Front 20

transcription factors

Back 20

- DNA-binding protein regulators which control eukaryotic genes
- many are transcriptional activators, others are transcriptional repressors
- some have a helix-turn-helix arrangement and insert one of the helices into the DNA
- others have loops of amino acids held together by zinc ions
- some are LEUCINE ZIPPER PROTEINS that associate as dimers that insert into the DNA

Front 21

domain

Back 21

- each transcription factor has a DNA-binding domain

Front 22

heterochromatin

Back 22

densely packed regions of chromosomes which contain inactive genes

Front 23

how are genes inactivate or activated?

Back 23

- by changes in chromosome structure
- cells change chromatin structure from hetero' to eu' by modifying HISTONES (proteins that associate with DNA to from nucleosomes)

Front 24

euchromatin

Back 24

- loosely packed chromosome structure assaciated with active genes

Front 25

DNA methylation

Back 25

mechanism that perpetuates gene inactivation

Front 26

Epigenetic inheritance

Back 26

involves changes in how a gene is expressed

Front 27

gene amplification

Back 27

- some cells selectively amplify genes by DNA replication
- some genes whose products are required in large amounts exist as multiple copies in the chromosome

Front 28

differential mRNA processing

Back 28

- as a result, a single gene produces different forms of protein in different tissues
- such a gene contains a segment that can be either an intron or an exon
- intron --> sequence removed
- exon --> sequence retained

Front 29

What do regulatory mechanisms do after mRNA is formed?

Back 29

- increase the stability of mRNA
- allows more protein molecules to be synthesized before mRNA degredation

Front 30

How does posttranslational control of eukaryotic genes occur?

Back 30

- by feedback inhibition or by modification of the protein structure

Front 31

How is a function of a protein changed?

Back 31

- by KINASES adding phosphate groups
- by PHOSPHATASES removing phosphates

Front 32

protein degradation

Back 32

- proteins targeted for destruction are covalently bonded to UBIQUITIN
- a protein tagged by ubiquitin is targeted for degradation in a PROTEASOME (a large macromolecular structure that recognizes the ubiquitin tags)
- PROTEASES (protein-degrading enzymes) associated with proteasomes degrade the protein into short peptide fragments