Chapter 11

Question 1

transcription factors

Answer 1

regulatory proteins that control whether or not a gene is active

Question 2

repressor

Answer 2

binds to a specific site to prevent transcription

Question 3

activator

Answer 3

stimulates transcription

Question 4

how do prokaryotes conserve energy and resources

Answer 4

make certain proteins only when they are needed

Question 5

beta-galactoside permease

Answer 5

carrier protein in the bacterial cell membrane that moves the sugar into the cell

Question 6

beta-galactosidase

Answer 6

an enzyme that hydrolyses actose to glucose and galaactose

Question 7

beta-galactoside transacetylase

Answer 7

transfers acetyl groups from acetyl CoA to certain beta-galactosides

Question 8

inducers

Answer 8

stimulate the transcription of specific genes

Question 9

inducible genes

Answer 9

genes that can be activated by inducers

Question 10

constitutive genes

Answer 10

genes expressed most of the time at a constant rate

Question 11

operon

Answer 11

a cluster of genes with a single promoter

Question 12

operator

Answer 12

repressor-binding site that can bind very tightly wiht a repressor protein

Question 13

inducible operon

Answer 13

turned off unless needed

Question 14

repressible operon

Answer 14

turned on unless needed

Question 15

regulatory gene

Answer 15

any gene that encodes a regulatory protein (a transcription factor)

Question 16

structural gene

Answer 16

any gene that encodes a protein not directly involved in gene regulation

Question 17

corepressor

Answer 17

a molecule that binds to the repressor, causing it to change shape and bind to the operator, thereby inhibiting transcription

Question 18

what type of pathways do inducible systems generally control?

Answer 18

catabolic pathways

Question 19

what type of pathways do repressible systems generally control?

Answer 19

anabolic pathways

Question 20

sigma factors

Answer 20

proteins in prokaryotes that can bind to RNA polymerase and direct the polymerase to specific promoters

Question 21

virus

Answer 21

injects genetic material into a host cell

Question 22

lytic

Answer 22

viral genome takes over host cell, host cell begins to produces new viral particles, cell breaks open and releases these virions

Question 23

lysogenic

Answer 23

dormant phase, where viral genome is incorporated into the host cell genome

Question 24

what happens in the early stage of the lytic cycle?

Answer 24

viral genes near the promoter are transcribed, and encode proteins that shut down expression of host genes

Question 25

what happens in the late stage of the lytic cycle?

Answer 25

viral late genes are transcribed to encode enzymes that will lyse the host cell and release the new virions

Question 26

constitutive genes

Answer 26

expressed most of the time

Question 27

inducible genes

Answer 27

expressed only when needed

Question 28

TATA box

Answer 28

a core promoter that is rich in A-T base pairs

Question 29

general transcription factors

Answer 29

bind to most promoters and allow RNA polymerase II to transcribe the protein-coding genes

Question 30

how is transcription initiated?

Answer 30

by a combination of factors

Question 31

NFATs

Answer 31

nuclear factors of activated T cells that control the expression of genes essential for the immune response

Question 32

how are DNA-protein interactions determined?

Answer 32

base sequence of a binding site on DNA

Question 33

what are the two ways for prokaryotes to coordinate the regulation of several genes?

Answer 33

arranging them in an operon, or using sigma factors

Question 34

how can the expression of genes be coordinated?

Answer 34

if they share regulatory sequences that bind the same transcription factors

Question 35

what are some life cycle strategies of viruses?

Answer 35

efficient, faster life cycles than the host cell and can thus release more new virions

Question 36

HIV

Answer 36

infective agent that causes AIDS in humans

Question 37

reverse transcriptase

Answer 37

makes a DNA strand complementary to the RNA, and degrades the RNA

Question 38

provirus

Answer 38

integrated viral DNA

Question 39

Tat

Answer 39

protein that binds to the 5' end of viral RNA, increasing the production of full length viral RNA

Question 40

epigenetic changes

Answer 40

alterations in either DNA or chromosomal proteins that can then be passed on to daughter cells after mitosis or meiosis

Question 41

chromatin remodeling

Answer 41

alteration of chromatin structure

Question 42

histone proteins

Answer 42

positively charged proteins around which DNA is wound

Question 43

histone acetyltransferases

Answer 43

add acetyl groups to positively charged amino acids and neutralise them

Question 44

histone deacetylases

Answer 44

remove the acetyl groups from histones and repress transcription

Question 45

histone methylation

Answer 45

can contribute to activation or repression of gene expression

Question 46

DNA methyltransferase

Answer 46

catalyses the covalent addition of a methyl group to the cytosines in DNA

Question 47

CpG islands

Answer 47

transcriptionally active promoters containing regions of DNA rich in CpG

Question 48

maintenance methyltransferase

Answer 48

catalyses the formation of 5-methylcytosine in the new DNA strands

Question 49

demethylase

Answer 49

enzyme that catalyses the removal of the methyl group

Question 50

euchromatin

Answer 50

contains the DNA that is transcribed into mRNA

Question 51

heterochromatin

Answer 51

contains genes that are generally not transcribed

Question 52

what is an important factor in epigenetic modifications?

Answer 52

environment

Question 53

genomic imprinting

Answer 53

offspring would inherit a maternal gene that is transcriptionally inactive and a paternal gene that is transcriptionally active

Question 54

alternative splicing

Answer 54

generates a family of different proteins with different activities and functions from a single gene

Question 55

miRNA

Answer 55

noncoding regions are transcribed into these tiny RNA molecules, can silence genes

Question 56

how an the translation of mRNA be regulated?

Answer 56

inhibition of translation with miRNAs, modification of the 5' cap, translational repressor proteins

Question 57

ubiquitin

Answer 57

76-amino acid protein that gets attached to a lysine residue

Question 58

proteasome

Answer 58

a huge protein complex

Question 59

how are cyclins broken down at just the right time

Answer 59

by proteasomes