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cell biology > epigenetics > Flashcards

epigenetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define epigenetics

A

all the processes that lead to heritable changes in gene expression as cells divide

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2
Q

is the genome static or flexible?

A

static

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3
Q

is the epigenome static or flexible?

A

flexible

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4
Q

what is the barker hypothesis?

A

the environment that a fetus faces in utero affects their risk of developing disorders in later life

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5
Q

what are the 4 types of epigenetic mechanisms?

A

DNA methylation
micro and small RNAs
chromatin architecture
histone modification

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6
Q

does DNA methylation activate or inactive a gene?

A

inactivates it

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7
Q

explain the process of DNA methylation

A

methyl group adds to cytosines immediately adjacent to guanines (e.g. CpG islands in promoter regions) using DNA methyltransferase

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8
Q

how does DNA methylation cause gene silencing?

A

methyl group stops RNA polymerase II from binding

stops transcription factors from binding to the promoter region

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9
Q

what are CpG islands?

A

areas rich in C and G in the promoter region

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10
Q

how do micro and small RNAs cause gene silencing?

A

miRNA binds to complementary regions on the DNA so ribosomes cant attach and translate
can induce degradation of mRNA

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11
Q

what changes in the shape of the histone can take place?

A

sliding
ejection
H2A-H2B dimer ejection or replacement

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12
Q

what are the main types of post-transcriptional histone modifications?

A

acetylation
methylation
phosphorylation
ubiquitination

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13
Q

what amino acid does modifications of histones occur on?

A

lysine

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14
Q

what does histone acetylase do?

A

catalyses the transfer of acetyl group onto lysine

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15
Q

how does acetylation affect a histone?

A

makes the promoter more accessible for transcription

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16
Q

what does histone deactylase do?

A

reverses the process of adding an acetyl group on

17
Q

how does hypomethylation play a role in the development of cancer?

A

less methylation
less silencing
more room for tumours to form

18
Q

what is imprinting?

A

the preferential expression of either the paternal or maternal allele

19
Q

name imprinting related disorders and how they’re caused

A

part of chromosome 15 deleted
Prader-Willi - allele from father
Angelman - allele from mother

20
Q

define genome

A

The complete set of genes / genetic material present in a cell or organism

21
Q

define epigenome

A

the parts of the genome that are actually used

22
Q

what does low availability of nutrients in prenatal stage followed by improvement in nutritional availability in childhood cause?

A

metabolic disorders e.g. diabetes type 2, obesity, coronary heart disease

23
Q

what is a nucleosome?

A

DNA wrapped around a histone

24
Q

how does DNA packing prevent gene expression?

A

prevents transcription proteins from accessing DNA

25
Q

how does chromatin architecture affect DNA expression?

A
  • Alter the contact between DNA and histones
  • Alter the path of the DNA as it winds around the histones
  • Alter the structure of the nucleosome core itself
26
Q

what does histone acetylation do?

A

opens chromatin
DNA accessible
transcription activated

27
Q

what does histone deactylation do?

A

closed chromatin
DNA inaccessible
transcription repressed

28
Q

what are HDAC inhibitors?

A

used to increase gene transcription for some genetic conditions

29
Q

what does genome wide hypomethylation occur with?

A

ageing and tumourgenesis

30
Q

what is non-coding RNAs?

A

functional RNA but not translated into proteins

31
Q

what causes Prader Willi syndrome? how does it present?

A

deletion of PATERNAL copy of chromosome 15q11 q13

leads to language, motor and developmental delays, excessive weight gain

32
Q

what causes Angelman syndrome? how does it present?

A

deletion of MATERNAL copy of chromosome 15q11q13

severe mental retardation, happy demeanor, non-verbal

33
Q

what are epigenetic therapies?

A

HDAC inhibitors
DNMT inhibitors
Non-coding RNA
Osteopathic manipulation

34
Q

how does reducing calorie lead to increased lifespan?

A

works by maintaining degree of methylation

cell biology (17 decks)

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