Gene Regulation in Eukaryotes part 2

Question 1

Insulators

Answer 1

Are cis DNA elements (bounded by proteins, are barriers for remodeling, & can block enhancer effect)

Question 2

Methylation yield ________

Answer 2

Epigenetics

Question 3

Epigenetics

Answer 3

Changes gene expression but not DNA sequences or not mutations & it is heritable & reversible

Question 4

Epigenetics involved ____________

Answer 4

methylation (DNA)

Question 5

What are factors that promote epigenetics?

Answer 5

1. X-inactivation in females where 1 X-chromosome is inactive
2. Genomic imprinting where an allele in 1 parent is off but allele in other parent on

Question 6

Genomic Imprinting

Answer 6

Involves Igf2

Question 7

In genomic imprinting what occurs?

Answer 7

1. If the mom’s allele off then its imprinted•
2. If the dad’s allele on then its not imprinted
3. monoallelic 2 alleles present only 1 expessed

Question 8

Imprinting of Igf2

Answer 8

1. When no methylation occurs then a loop forms and the H19 enhancer can’t turn on the Igf2 gene (Igf2 is off)
2. When methylation occurs then no loop forms and the H19 enhancer can turn on the Igf2 gene

Question 9

What is the Igf2 gene in mice

Answer 9

In mice the Igf2 gene controls growth hormone where it will yield a normal body size

Question 10

When the maternal allele imprinted is off then the _______ allele is expressed

Answer 10

Paternal

Question 11

Igf2^- mutant allele

Answer 11

Causes dwarfism only when the paternal allele is mutated

Question 12

When the mom is (-) & the dad is (+) then the F1 is what?

Answer 12

Normal het. that is (-/+)

Question 13

Het. F1 Normal (-/+)

Answer 13

The dad allele is expressed(wild type allele) & the mom is imprinted (off) (mutant allele)

Question 14

Dwarf Het. F1 (+/-)

Answer 14

Dads allele is the mutant allele & is expressed & mom allele is the wild type allele that is imprinted (off)

Question 15

How is epigenetics regulated by the environment?

Answer 15

Through toxins, diet, & temperature

Question 16

Smokers

Answer 16

1. Have 7000 genes that are methylated differently & leads to cancer & heart disease
2. 2. After 5 yrs of quitting methylation is reversible but 19 genes don’t get reverse & it leads to lymphoma

Question 17

Gene regulation mostly occur at transcription but it can occur mainly after transcription by _______

Answer 17

Alternative splicing

Question 18

Alternative splicing

Answer 18

Used for pre-mRNA where it uses the alpha-tropomyosin protein

Question 19

alpha-tropomyosin protein is used for _______ & _______

Answer 19

smooth & striated muscles

Question 20

mRNA Stability

Answer 20

Can occur in minutes or days & regulate to increase or decrease expression

Question 21

PolyA tail on mRNA

Answer 21

1. The 3’ UTR bounded by proteins to increase stability where if it shortens overtime its cut by nucleases & if its too short then protein can’t bind to it & the mRNA is degraded

Question 22

The 5’ UTR (at the 5’ end) & the 3’ UTR (from the stop codon to the 3’ end)

Answer 22

Untranslated region

Question 23

The translated region contains the _______ condon

Answer 23

AUG

Question 24

Destabilizing elements

Answer 24

ARE protein that binds to the AU rich region at the 3’ UTR to decrease stability

Question 25

Translation regulation

Answer 25

Iron is used where its essential for enzymes & toxic if its high

Question 26

Transferrin receptor

Answer 26

Increases cellular iron

Question 27

Ferritin

Answer 27

Stores excess iron & prevents the build up of iron

Question 28

Can control transcription of transferrin & ferritin to _______ the build of toxic iron build up

Answer 28

Prevent

Question 29

IRP

Answer 29

Iron regulatory protein (trans factors) that binds to the IRE

Question 30

IRE

Answer 30

Iron response element (cis factor) that is on the mRNA

Question 31

If iron is _______ then IRP binds to IRE & if iron is ______ then IRP falls off IRE

Answer 31

Low, High

Question 32

When iron is low its results in a ________ translation

Answer 32

Decrease, when iron is low the ferritin can’t storage excess iron

Question 33

When iron is high then iron inhibits IRP & _________ translation

Answer 33

Increase, the ferritin can storage excess iron & prevent toxicity

Question 34

Regulation of transferrin receptor mRNA when iron is high

Answer 34

If iron is low then IRP bind to the IRE to increase stability & increase translation (receptor that imports iron)

Question 35

Regulation of transferrin receptor mRNA when iron is low

Answer 35

When iron is high it binds to the IRP & the IRP is release from the IRE & mRNA is degraded (the receptor doesn’t import iron when iron is hgih)

Question 36

dsRNA (found by accident by introducing cloned genes to plants)

Answer 36

Regulates gene expression by gene splicing (endogenous gene sliced)

Question 37

C. elegans

Answer 37

Injects dsRNA

Question 38

Inject ssRNA & dsRNA to detect ____________

Answer 38

Gene expression

Question 39

Coding ssRNA injected it can’t bind mRNA since its on the same sequence so the mRNA is ________ degraded

Answer 39

Not

Question 40

Template ssRNA injected can bind to mRNA since its a complementary sequence so mRNA is ________ degraded

Answer 40

Mildly

Question 41

When dsRNA is injected mRNA is ___________ degraded

Answer 41

Completely

Question 42

RNAi is caused by __________ (microRNA) which is a nonstructural gene that functions as RNA & not protein

Answer 42

miRNAs (21-23 bp)