Chapter 13

Question 1

Each structural gene has

Answer 1

its own promoter, and is transcribed separately. they dont have polycistronic rna.
so its promoter, gene, promoter, gene.

Question 2

in multicellular organisms

Answer 2

only a small fraction of the genes are expressed.

Question 3

Developmental and homeostasis

Answer 3

maintain same number of cells

Question 4

enhancers are both

Answer 4

positive and negative (repress the gene).

Question 5

enhancers

Answer 5

distance from the gene. dna loop formation brings the sequences together. 50kb from the promoter.

Question 6

cis acting regulatory sequences

Answer 6

regulate transcription located on same chromosome that regulatory sequence is on.

Question 7

trans acting regulatory proteins

Answer 7

proteins able to identify regulatory sequences on any chromosome.

Question 8

enhanceosome

Answer 8

proteins bind other proteins to form large protein complex

Question 9

pioneer factors

Answer 9

they bind first, which allows binding of other transcription factors.

Question 10

mutation in enhancer module

Answer 10

can cause abnormal expression.

Question 11

locus control region LCR

Answer 11

regulates transcription of linked genes at distal chromatin sites. regulates 6 genes. contains 4 regulatory sequences, hs1 to hs4

Question 12

the hs1 to hs4 make small dna loops that serve as

Answer 12

a bridge to the promoters of the b globin complex

Question 13

the making of galactose

Answer 13

requires the action of products of each of four galactose-utilization (GAL) genes

Question 14

upstream activator sequence (UAS) in yeast

Answer 14

transcription activator protein that binds to enhancer element. binding sites for gal4.

Question 15

when galactose is absent

Answer 15

gal80 binds to gal4, blocks gal gene transcription.

Question 16

when galactose is present

Answer 16

gal3 binds gal80, so this way it doesn’t bind to gal4. then gal4 initiates gal gene transcription.

Question 17

mediator

Answer 17

enhancesome that forms after gal4 binds uas. creates dna loop to regulate transcription.

Question 18

transcription repression Mig1

Answer 18

bw uas and Gal1. When there is glucose, Mig1 is produced. Mig1 attracts Tup1, and repress transcription. (prevents uas from starting transcription)

Question 19

insulator

Answer 19

enhancer action on specific gene and away from nearby genes that are not to be regulated by that enhancer.

Question 20

repression dominant over activation

Answer 20

true

Question 21

constitutive heterochromatic

Answer 21

always heterochromatic (tightly compacted)

Question 22

facultative heterochromatin

Answer 22

bw being heterochromatic and euchromatic

Question 23

E(var) mutations

Answer 23

(enhancers of position effect variegation). mutation encourages heterochromatin formation, increase appearance of mutant white eye phenotype.

Question 24

Su(var) mutations

Answer 24

(suppressors of position effect variegation). block heterochromatin formation, increase appearance of normal eyes.

Question 25

length of promoters

Answer 25

1-2 kb long.

Question 26

if you have mutations in the sonic hedgehog (SHH),

Answer 26

you will have multiple fingers.

Question 27

how do activator and repressor bind to regulatory dna if its packed into chromatin

Answer 27

some regulatory sequences are not tightly bound by histones, so more access. 2: chromatin remodelers. 3: chromatin modifiers.

Question 28

open promoters

Answer 28

associated with active genes, like housekeeper genes.

Question 29

nucleosome depleted region (ndr)

Answer 29

100-150 bp region, adenine and thymine rich (poly A/T tract), no TATA box.

Question 30

open chromatin

Answer 30

regulatory sequences access regulatory proteins. DNase I cuts DNA in open chromatin regions, but cant cut in closed chromatin regions. (tells biologists whether a region is open or closed.)

Question 31

chemical modifiers

Answer 31

add or remove chemical groups to modify histone proteins.

Question 32

histone acetyltransferases (HATs)

Answer 32

writers that add acetyl groups

Question 33

histone deacetylases (HDACs)

Answer 33

removes acetyl groups

Question 34

histone methyltransferases (HMTs)

Answer 34

writers that add methyl groups

Question 35

histone demethylases (HDMTs)

Answer 35

remove methyl groups

Question 36

methylation can play a role in

Answer 36

converting open euchromatin to closed heterochromatin, just like deacetylation.

Question 37

if chromatin is in an inaccessible heterochromatic state, how do factors bind to its dna to initiate the transition to euchromatin?

Answer 37

by pioneer factors, which access dna even in heterochromatin.

Question 38

PcG

Answer 38

acting in gene repression

Question 39

Trx

Answer 39

maintain gene expression, opposite to the activity of PcG complex.

Question 40

epigenetic

Answer 40

heritable changes in gene expression but no change in dna sequence. changes by maternal behavior (licking example, more happier dogs).

Question 41

most epigenetic marks are erased during

Answer 41

meiosis, yet it can be passed unto another generation.

Question 42

long noncoding rnas (lncRNAs)

Answer 42

long rnas without an open reading frame.

Question 43

X inactivation

Answer 43

one active euchromatic X chromosome, one inactive heterochromatic X chromosome (mostly silent)

Question 44

Xist gene

Answer 44

active on heterochromatic X, inactive on euchromatic X. it is a lncRNA, and is expressed in cells with at least 2 X's. randomly inactivate 1 of 2 X's to form Barr-bodies

Question 45

genomic imprinting

Answer 45

both copies of genes are functional, just one is expressed. (can be from mother or father.)

Question 46

imprinting control region ICR

Answer 46

bw H19 and IGF2

Question 47

Dicer

Answer 47

cuts dsRNA into 21-25 bp

Question 48

siRNA or miRNA is processed by

Answer 48

RISC (RNA-Induced Silencing Complex). RISC contains Argonaute that produce guide RNA (single stranded). the other is denatured.

Question 49

when good rna goes bad sense rna antisense rna double stranded rna

Answer 49

no effect on offspring no effect twitching

Question 50

When complementarity is perfect: | When complementarity is imperfect:

Answer 50

target mrna is degraded | target mrna is repressed.

Question 51

when bees are injected w rnai

Answer 51

queens pop is lowered. # of dna methylases: lower amounts of dna methylase 3.