Chapter 2: Gene Expression and Epigenetics

Question 1

genetic mutation where a single base pair substitution results in a changed amino acid

Answer 1

missense mutation

Question 2

genetic mutation where a single base pair substitution changes a codon to code for a stop codon resulting in early termination and non functional protein

Answer 2

nonsense mutation

Question 3

deletion or jnsertion of mucleotides that lead to misreading of all nucleotides downstream

Answer 3

frameshift mutation

Question 4

results in changed amino acid but the amino acid has similar chemical characteristics as the original

Answer 4

conservative missense

Question 5

nucleotide sequence is changed but amino acid is similar

Answer 5

silent mutation

Question 6

two types of factors responsible for regulation of mRNA synthesis

Answer 6

cis and trans factors

Question 7

DNA sequences that mark places on the DNA involved in the initiation anf control of RNA synthesis

Answer 7

cis factors

Question 8

proteins that bind to the cis sequences and direct assembly of transcription complexes at the proper gene

Answer 8

trans factors

Question 9

a series of structural genes transcribed together on one mRNA and separated into individual proteins

Answer 9

operon

Question 10

bring about corrdinated expression of proteins required at the same time

Answer 10

operons

Question 11

three structural genes in the lac operon

Answer 11

lac Z
lac Y
lac A

Question 12

gene product of lac Z

Answer 12

Beta-galactosidase (hydrolyzes lactose into glucose and galactose)

Question 13

gene product of lac Y

Answer 13

lactose permease (transports lactose into the cell)

Question 14

lacA gene product

Answer 14

thiogalactoside transacetylase

Question 15

cis factor of lac operon

Answer 15

lac O

Question 16

where RNA polymerase binds in lac operon

Answer 16

lac P

Question 17

encodes the protein repressor that binds to lac O

Answer 17

lac I

Question 18

what happens to the operon if lactose is present

Answer 18

lactose binds to repressor protein, changing conformation and decreasing affinity for lac O

Question 19

mode of regulation of lac operon where a binding protein activates transcription

Answer 19

induction

Question 20

mode of regulation of arg operon where binding protein binds to repressor protein turning off the transcription

Answer 20

repression

Question 21

protein binds with RNA polymerase to turn on transcription like in mal operon

Answer 21

activation

Question 22

formation of stems and loops in RNA transcript by intrastran hybridization of complementary bases such as in trp regulation

Answer 22

attenuation

Question 23

True or False: Eukaryotes have operons

Answer 23

False, synchronous expression is brought about ny combinatorial control

Question 24

examples of distal regulatory elements of eukaryotes

Answer 24

engancers amd silencers

Question 25

a developent phenomenon that allowed cells to differentiate without changes in the genetic structure

Answer 25

epigenetics

Question 26

nuclear DNA and its asscociated proteins

Answer 26

chromatin

Question 27

about 150 bases of DNA wrapped around a complex of 8 histones

Answer 27

nucleosome

Question 28

8 histones that compose a nucleosome

Answer 28

2 H2A 2 H2B 2 H3 2 H4

Question 29

regulate access of trans factors and RNA polymerase to DNA helix

Answer 29

histones

Question 30

lowers the positive charge of histones, decreasing binding strength to DNA , making DNA more available for interaction and transcription factors

Answer 30

histone acetylation

Question 31

causes open chromatin

Answer 31

histone acetylation

Question 32

attracts enzymes that further methylate DNA resulting decreased gene expression

Answer 32

DNA methylation

Question 33

causes closed chromatin

Answer 33

Histone methylation

Question 34

H2A acetylation

Answer 34

activation

Question 35

H2B acetylation

Answer 35

activation

Question 36

H3 methylation

Answer 36

silencing or activation

Question 37

H3 acetylation

Answer 37

activation/histone positioning

Question 38

H4 methylation

Answer 38

silencing or activation

Question 39

H4 acetylation

Answer 39

DNA repair histone positioning

Question 40

occurs in cytosine guanine rich sequences in the DNA (CpG islands)

Answer 40

DNA methylation

Question 41

regions of more than 200 bp length with CpG occurence ratio of greater than 0.6

Answer 41

CpG islands

Question 42

CpG islands are found mostly on

Answer 42

the first exons promoter regions 3' end of genes

Question 43

DNA methylation mechanism of cancer

Answer 43

methylation of cytosine residues in promoter regions of tumor suppresor genes

Question 44

stage and gamete specific silencing of genes

Answer 44

genomic imprinting

Question 45

selective methylation of homologous genes occurs in

Answer 45

gametogenesis

Question 46

maintenance emzyme that mainly methylates cytosines that are methylated on one strand but not the other

Answer 46

DNA methyltransferase 1

Question 47

de novo methylase that methylates ummethylated DNA establishing newly methylated regions

Answer 47

DNA methyltransferase 3

Question 48

nonfucntional beacuse of non exitsent catalytic site but regulates activity of DNMT3A and 3B by occupying binding sites

Answer 48

DNMT3L

Question 49

True or false: Euchromatin has more acetylated histones and less methylated histones than heterochromatin

Answer 49

True, Euchromatins are transcriptionally active and therefore have open chromatin

Question 50

reversal of DNA methylation

Answer 50

DNA demethylation

Question 51

DNA demethylation is catalyzed by

Answer 51

Ten Eleven Transferase

Question 52

histone and nucleic acids modifications are classified into

Answer 52

writers erasers

Question 53

another classification system of epigenetics particularly in cancer cells

Answer 53

modulators modifiers mediators

Question 54

activities that activate epigenetic process

Answer 54

modulators

Question 55

writers and erasers that maintain the chromatin structure

Answer 55

nodifiers

Question 56

carry out their function as RNA and transcribed but not translated to protein

Answer 56

noncoding RNAs

Question 57

17 to 27 nts long regulatory RNAs that control gene expression by hybridizing with the 3' end of imperfectly complementary sequences to inhibit translation

Answer 57

micro RNAs

Question 58

associated with cancer

Answer 58

miRNA dysregulation

Question 59

miRNAs promote the tumor cell phenotype called

Answer 59

oncomirs

Question 60

functional intermediates of RNA interference

Answer 60

small interfering RNAs

Question 61

defense of eukaryotic cells against viral invasion

Answer 61

RNA interference

Question 62

responsible for generation of siRNA and microRNA

Answer 62

ribonuclease III enzyme

Question 63

used in the laboratory to artificially turn off the expression of specific genes

Answer 63

siRNA

Question 64

miRNA and siRNA have similar regulatory mechanisms but differ in

Answer 64

siRNA is foreign miRNA are encoded in the cell DNA

Question 65

uses associated siRNA to bind and degrade mRNA with sequences exactly complementary to the siRNA

Answer 65

RNA-induced silencing complex

Question 66

200 to 100,000 base RNA that regulate chromatin structure affecting gene expression and chromatin structure

Answer 66

lncRNA

Question 67

lncRNA functions

Answer 67

1. bind protein that normally bind to cis sequences 2. hairpin structures scaffold to bring proteins together 3. may connect trans factors to enhancer regions 4. bind small ligands 5. interact with mRNA in RISC 6. form troples structures woth double stranded DNA 7. further processd into small RNA fragments