Exam 1 Part 4

Question 1

gene silencing

Answer 1

the interplay between DNA methylation and histone acetylation and RNAi to completely shut down expression of genes
More permanent than not

Question 2

Methylation

Answer 2

transcriptional machinery is blocked

Question 3

CpG island

Answer 3

lots of C followed by Gs

Question 4

Methylation can…

Answer 4

sometimes recruit histone deactylases to modify histone tails

Question 5

histone tail modification

Answer 5

In response to signals, histone actyl transferases (HATs) bind to histone tails and pull them away from DNA

Question 6

histone actyl transferases

Answer 6

HATs. bind to histone tails and mask their positive charge to pull them away from DNA

Question 7

histone deactylases

Answer 7

HDACs recruited by DNA methylation to cause the histone tails to cover DNA

Question 8

RNA interference

Answer 8

regulatory RNAs control target mRNA degration

Question 9

Regulatory RNAs

Answer 9

miRNA

siRNA

Question 10

RNAi steps

Answer 10

1. miRNA transcribed
2. miRNA processed to shRNA
3. RISC recognizes shRNA
4. RISC binds to target mRNA
5. RISC cuts mRNA
6. nucleases degrade mRNA

Question 11

Loss of function mutation

Answer 11

results in partially or fully nonfuctional gene product

Question 12

fully nonfunctional gene product

Answer 12

null allele

Question 13

Gain of function mutation

Answer 13

causes the gene product to have more activity

Question 14

Mutagensis

Answer 14

creation of mutations

Question 15

spontaneous mutations

Answer 15

mistakes during replication

Base can exist in 2 forms (isomers) with different base pairing properties

Question 16

Induced mutations

Answer 16

caused by mutagens

Question 17

Mutagens

Answer 17

chemicals, environment (UV, radiation, gamma rays)
base modifying agents
intercalating agents
base analogs

Question 18

Classes of mutations

Answer 18

somatic mutation

germ-line mutation

Question 19

somatic mutation

Answer 19

not passed on to next generation

ex. moles, tumors

Question 20

germ-line mutation

Answer 20

transmitted to future generations

progeny has the mutation in both somatic and germ-line cells

Question 21

Mutation types

Answer 21

base pair substitution

base pair insertions/deletions

Question 22

base pair substitutions

Answer 22

change one base-pair to another base pair

Question 23

base pair insertions /deletions

Answer 23

addition or removal of a base pair

intercalating agents

Question 24

Types of base pair substitutions

Answer 24

transition mutations

transversion mutations

Question 25

transition mutations

Answer 25

changing from purine-pyrimadine to antoher pur-pyr

Question 26

Transversion mutation

Answer 26

change from pur-pyr to pyr-pur and vise versa

Question 27

missense mutation

Answer 27

a change in a codon so that a different amino acid is added to the polypeptide
change in function
phenotype change depends on severity of mutation

Question 28

nonsense mutation

Answer 28

change from a functional codon that codes an amino acid to a stop codon.

Question 29

Silent mutation

Answer 29

change 1 codon for 1 amino acid to a codon that codes for the same amino acid

Question 30

neutral mutation

Answer 30

replacing 1 amino acid with a similar amino acid
ex. Lysine -> arginine
mild or no phenotypic effect

Question 31

frameshift mutation

Answer 31

insertion or deletion that shifts the reading frame so that missense or stop results

Question 32

trinucleotide repeat expansion

Answer 32

areas of the genome hve 3 nucelotides repeated many times in a row
if happens in a coding region, long stretches of an amino acid repeats itself

Question 33

forward mutation

Answer 33

change a wild type allele to a mutant allele

Question 34

reverse mutation

Answer 34

change to promutation state mutation allele so that the phenotype becomes more like wild type

Question 35

suppressor mutations

Answer 35

mutation that masks the phenotype
mutation at a different site than original mutation
2 types

Question 36

suppressor mutation types

Answer 36

intragenic suppressors

intergenic suppressors

Question 37

intragenic suppressors

Answer 37

within the same gene

deletion farther down the line

Question 38

intergenic suppressors

Answer 38

mutation in another gene

mutate tRNA anticodon