7.2 Flashcards

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1
Q

rna splicing

A

pre-mrna is modified to remove introns and exons
the exons join with spliceosomes to produce mature mrna by the process of rna splicing
many ways of joining so can produce several versions of mrna from the same section of DNA
so can ultimately produce different phenotypes

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2
Q

pre mrna

A

rna produced in nucleus from transcription of all the DNA in a gene including exons and introns

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3
Q

epigenetics

A

changes that affect gene activation
involved in differentiation
involved in changes in proteins synthesised
factors that affect gene control are :
-dna methylation
-histone modification
-non coding rna

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4
Q

dna methylation

A

addition of a methyl group to a base
added by DNA methyltransferase enzyme
can also modify the structure of the histones
changes arrangement of DNA and prevents transcription
switch off genes which cannot be switched on so proteins cannot be transcribed

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5
Q

dna demethylation

A

removal of methyl group
genes become active so can be transcribed

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6
Q

histone modifacation

A

positively charged proteins
dna helices wind around histones to form chromatin
-makes up chromasomes
when densely supercoiled and condensed genes are not available to be copied (heterochromatin)
active chromatin is loose with uncoiled regions opening up more genes for transcription

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7
Q

histone acetylation

A

acetyl group is added to one of the lysines in histone
opens up structure and activates chromatin allowing transcription
removing group produces heterochromatin again

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8
Q

histone methylation

A

methyl group is added to a lysine in histone
depending on the position of lysine methylation may cause inactivation of the DNA or activation of a region
methylation is often linked to silencing of a gene

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9
Q

regulation of gene expression

A

genes can be switched off when not needed preventing resources from being wasted

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10
Q

transcription factors

A

proteins which increase the rate of transcription
bind to specific DNA promoter region at the start of their target gene inviting rna to bind
1- activator
stimulate or increase rate of transcriptions by helping rna polymerase to bind to start of gene and activate transcription
2- repressors
inhibit or decrease the rate of transcription by preventing rna polymerase from binding

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11
Q

enhancer sequences

A

specific regions of dna to which transcription factors bind and regulate the activity of the DNA by changing the structure of the chromatin making it more or less available to rna polymerase and so either stimulating or preventing transcription of gene

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12
Q

gene probe

A

finds the unique sequence of nucleotides on the DNA that make up the gene

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13
Q

pluripotent

A

can differentiate into most cells
-blastocyst

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14
Q

totipotent

A

can differentiate into any cell
-zygote

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15
Q

multipotent

A

can only differentiate into a few cells
-cells in embryo

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16
Q

therapeutic cloning

A

healthy cloned cells from patients
remove nucleus from body cell and transfer to ovum
forming stem cells

17
Q

pros of stem cell therapy

A

revolutionise medicine
save lives
cure diseases
avoid risk of rejection

18
Q

cons of stem cell therapy

A

not enough knowlage
cause the development of cancers

19
Q

ips cells

A

induced pluripotent stem cells
adult cells made into pluripotent cells

20
Q

who can stem cell therapy help

A

parkinson disease
type 1 diabetes
damaged nerves
organs for transplants

21
Q

ethical issues of stem cell therapy

A

using a potential life

22
Q

similarities between ips and embryonic

A

potential to divide indefinitely
potential to differentiate into a number of different cell types

23
Q

differences between ips and embryonic

A

ips were adult but emb were taken from merula
ips have genes added
ips are patient matched but emb are antigenetic
embryonic have ethical issues ips do not