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genetics > Lecture 16 > Flashcards

Lecture 16 Flashcards

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Biology 101 flashcards
1
Q

What does streptomycin interact with?

A

16S RNA and S12 protein
-both are encoded by the rpsL gene

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2
Q

What can we do with this rpsL gene?

A

insert it into the pet 21 genome of bacteria

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3
Q

which cells with be ampicillin antibiotic resistant?

A

cells that contain the plasmid

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4
Q

what regulates protein in pet 21?

A

lac repressor

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5
Q

how can we put that gene into ecoli?

A

gibson assembly after we PCR the rpsl-strR gene

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6
Q

epigenetics

A

changes in genes that are not the result of changes to the DNA sequence
-may let parents send info abt the world to their kids
-all about chromatin structure and DNA methylation
-like putting a word in bold but not changing the letters

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7
Q

How does DNA fit into the nucleus?

A

it wraps around the histone

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8
Q

each chromosome has it own?

A

domain/ place in the nucleus
-the domains are dynamic and can change
-chromosomal repositioning/ domain rearrangement

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9
Q

chromosomal DNA hierarchy

A

-lamina (LAD) where the chromosomes are under the nuclear membrane
-inside the nucleus
-dna loop
-fiber
-chromatin
-dna (smallest)

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10
Q

what are eukaryotic chromosomes?

A

nucleoprotein complexes
-146 bp of DNA wrapped around histone that has 8 subunits

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11
Q

is the wrapping of histones highly regulates

A

-yes and so is the spacing between beads

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12
Q

what is a nucleosome bead

A

8 histone molecules (4 highly conserved) and 146 bp of DNA wrapped around it
-they coil into chromatin fibers that are then coiled into chromosomes

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13
Q

what forms chromatin?

A

beads on a string,
that chromatin will later be packed by nucleosomes, then the fibers folded into loops

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14
Q

basic nucleosome structure

A

beads on a string
-seen in interphase

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15
Q

when are the beads on a string visible

A

when they compact during meitosis
-but then it is harder to find sequences

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16
Q

what do histones have that regulate compaction?

A

amino acid tails
-they can be covalently modified
-they are also available for chemical modification
-tail modification do not come into contact with DNA

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17
Q

What loosens the chromatin?

A

-acetylation of the histone tail lysines
-it is also reversible
-the lysine side chain will open when it is acetylated
-remove it= deacetylation (compact again bc the DNA can now wrap around tightly again)

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18
Q

what makes the chromatin more compact?

A

methylation of the histone tail lysine
-chromatin will be less active bc it is compacted

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19
Q

what can the chromatin state be used for

A

gene regulation/ expression
-when the gene is wrapped tight around nucleosome the polymerase can express
-wrapped tight= less expression

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20
Q

what recruites histone acetylases to acetylate the histone?

A

transcriptional activators
-open up the chromosome

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21
Q

what reverses the opening up of the chromosome?

A

histone deacetylases

22
Q

chromatin remodeling complexes

A

move nucleosome aside to reveal TATA/ expose the promoter so transctiption factors and RNA pol 2 can bind tot he DNA

23
Q

what recruits chromatin remodeling complexes?

A

transcription activators

24
Q

what happens when the tails get modified?

A

they are recognizable by other proteins which will promote assembly or disassembly of histone

25
Q

can histone modifications effect transcription?

A

yes, depending on the number of methyl groups present

26
Q

encode project

A

use ChIP to map DNA binding proteins in humans
-lets us pinpoint regions of the DNA where the modification is and what type it is (methylated or acetylated)

27
Q

euchromatin

A

less packed transcriptionally active DNA

28
Q

heterochromatin

A

highly compact and transcriptionally silent
-all methylated

29
Q

what do mammals do with their X chromosome?

A

there can only be one active X chromosome so females will put one in “storage”

30
Q

how does heterochromain stain?

A

dark bc it is tightly packed

31
Q

barr body

A

-transcriptionally inactive bc methylated
-what females do with other X

32
Q
A
33
Q

lyonization

A

x inactive

34
Q

what is mosaic and why are females mosaic

A

-expressing maternal and paternal X genes throughout the body
-females are this bc they have 2 x chromosomes and they each develop independently and activate a different X chromosome
-the choice can not be changed not even by the daughter cells of somatic cells
-everything is euchromatic until the cell decides which genes to keep on

35
Q

are twins truly identical?

A

no bc they will have different mosaics which is why they can have different phenotypes

36
Q

x inactivation

A

the process of turning off one x chromosome

37
Q

where does CpG methylation happen?

A

5 prime CG 3 prime
3 prime GC 5 prime
-prevents transcription factors from binding so this can silence genes
-this is NOT DNA methylation in bacteria when they repair damage

38
Q

what does methylation interfere with?

A

DNA binding proteins interacting with DNA bases
-the DNA protein will not recognize the bases so it wont bind

39
Q

why is folic acid important for pregnancy?

A

folate is a co factor for methyltransferases

40
Q

what happens when CpG hypermethylates cells?

A

-cells dont get the stop dividing signal leading to cancer
-methylation enzymes are over active and demethylases are inactive
-results in the CpG island sequence getting silenced therefore no stop codon/ gene inactivation

41
Q

imprinting

A

small deletions of chromosome 15
-can cause prader willi and angelman syndromes
-normal 15 is silences which leads to a homozygous deletion of some genes
-the different outcomes/ illnesses depend on weather the maternal or paternal gene was deleted

42
Q

paternal 15 deleted

A

prader willi
-cant stop eating

43
Q

maternal 15 deleted

A

angelman
-always happy and jerky movement

44
Q

methylation is removed where

A

-in embryonic germ cells that are going to form gametes, all imprints are erased and all genes are active
-the methylations that will be sex specific (maternal or paternal) are later in germ cell development and then transfered to gametes
-the egg will look like mommy somatic cell origianlly looked with each gene active or silenced and sperm will look like daddy cell oriningal did

45
Q

what happens when there is a deletion on paternal chromosome?

A

anything active on the maternal chromosome gets expressed like angelman

46
Q

hunger winter fetuses

A

higher rate of obesity later in life but they were in utero during the hunger winter
-as adults they had more ares of CpG methyalation and this hypermethylation was near metabolic genes

47
Q

kids of sick worms from PA14

A

avoid PA14 even though they have never been exposed to it
-transgeneration memory of PA14 lasts four generation until worms stop avoiding it

48
Q

training c elegans to avoid pa14

A

-only need short under 200 nt bacterial RNA to train them
-just exposing them to this RNA and they know to stay away even though they ahve never seen it before

49
Q

P11 RNA

A

can train animals to stay away from P14 wihtout ever meeting P14
-give P11 to parents and the kids will avoid it
-parents never met the actual bacteria just the RNA
-has a stem loop complementary to sensory neuron maco-1 in c elegans gene (odor)
-maybe RNAi or miRNA mechanism

50
Q

RNA dependent RNA polymerase

A

(RdRP) can amplify RNAi response
-that RNAi response can be passed down

51
Q

RNAi dicer dcr-1

A

needed for P11 learning
-transgene will express the dicer in the intestine and suggest intestinal processing of ingested bacterial RNA

genetics (16 decks)

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