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MCM Week 2 > B2-014 - Genomic DNA and Nucleic Acids > Flashcards

B2-014 - Genomic DNA and Nucleic Acids Flashcards

1
Q

Describe human DNA structure

A

Anti-parallel strands with major and minor grooves

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2
Q

Whats the size of the human genome

A

3 million bases

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3
Q

how many genes are coding

A

20,296

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4
Q

how many non coding genes are there

A

25,173

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5
Q

what is a pseudogene

A

non expressed “broken” genes

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6
Q

how big is the mitochondrial genome

A

17000, 14 - protein coding, 23 rRNA/tRNA

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7
Q

What is the inter-individual variation in the genome

A

3-3.5 million nucleotide differences

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8
Q

how many copy number variations are there

A

1000

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9
Q

how many chromosomes are there

A

22 autosomes and 2 sex chromosomes

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10
Q

Most human cells are…

A

diploid, 46 chromosomes per cell

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11
Q

how long is the human genome

A

2 meters long

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12
Q

what is chromatin

A

a protein DNA complex that packages DNA and regulates transcription

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13
Q

what is euchromatin

A

light staining, gene rich, actively transcribes genes, structurallly open

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14
Q

what is heterochromatin

A

dark staining, repetitive and gene free, structurally compact

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15
Q

what is constitutive heterochromatin

A

repeats, telomeres, centromeres

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16
Q

what is facultative chromatin

A

developmentally silenced genes

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17
Q

Where is DNA methylation most common

A

on cytosine bases in 5’ CpG pairs (CG-GC)

70% of cytosine bases are demethylated

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18
Q

What happens when DNA gets methylated

A

irreversible packaging of DNA into transcriptionally silent chromatin
It can be reversed but its cumberson and this makes it LONG TERM MODIFICATION

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19
Q

DNA-CH3 spreads along DNA molecule unless

A

specific mechanisms stop it

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20
Q

DNA methylation is important in regulation

A

constitutive heterochromatin, silencing of tissue specific genes,

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21
Q

in cancer what role does methylation play

A

silencing (methylation) of tumor suppressor genes

22
Q

what is special about female X chromosomes

A

one is always hypermethylated to silence it

23
Q

Histone proteins are rich in what

A

basic residues (Arg, Lys)

24
Q

How is phosphate backbone charged

A

negatively

25
Q

What are the histone n terminal tails exposed to do

A

site of modifications that alter chromatin structure

26
Q

what do histone modifications do

A

regulate gene transcription and open and close chromatin structure

27
Q

what does acettylation do to chromatin

A

makes it looser, raises potential for transcription

28
Q

what does methylation do to chromatin

A

adds a ch3, Lysin and arginine, depends

29
Q

histone modifications differ from DNA methylation how

A

its dynamic and fast

30
Q

what does acetylation do to lysine

A

makes it neutrally charges as opposed to positively

31
Q

what enzyme acetylates lysine

A

HAT - acetyl coa acetyltransferase

32
Q

what are epigenetics

A

information in DNA not based on nucleotide sequence but is still inherited, such as imprinting

33
Q

epigenetic silencing

A

a gene being methylated and shut down

34
Q

chromatin

A

what DNA is packaged into

35
Q

when is chromatin most compact

A

prophase and metaphase (least during interphase)

36
Q

types of repeats

A

interspersed and tandem

37
Q

LINEs are

A

Long interspersed Nuclear elements - 20% of human genome

38
Q

LINes transpose how

A

via RNA intermediate

39
Q

SINEs are

A

Short Interspered Nuclear Elements also known as Alu repeats

40
Q

how are SINEs moved

A

theyre inactive but can be moved by active transposons

41
Q

what are HERVs

A

human endogenous retroviruses

42
Q

can HERVs be transposed

A

no, theyre inactive

43
Q

what is the 4th type of intersperesed repeats

A

DNA transposon fossils, cant transpose

44
Q

Types of tandem repeats

A

satelline, minisatellite DNA, microsatellite DNA

45
Q

what is special about microsatellites and minisatellites DNA

A

used for DNA fingerprinting

46
Q

whats the third type of duplications

A

segmental

47
Q

are repetitive elements “junk” DNA?

A

no

48
Q

what are repetitive elements uses

A

transposons (SINE/LINE) contribute to molecular evolution

49
Q

what is chromatin status of repetitive DNA?

A

most is methylated, heterochromatin silent and unexpressed

50
Q

how much of the human genome is repetitive?

A

about half

MCM Week 2 (3 decks)

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