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20 gene expression Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

the genetic code is:

A
  • non-overlapping
  • universal
  • degenerate
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2
Q

define non-overlapping

A

each base belongs to one codon/triplet only

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3
Q

define universal

A

the same 3 bases code for the same amino acid in all organisms

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4
Q

define degenerate

A

more than one codon codes for an amino acid

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5
Q

define degenerate

A

more than one codon codes for an amino acid

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6
Q

what is cell differentiation?

A

where cells become specialised

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7
Q

what do stem cells do?

A

differentiate into different specialised cells and divide by mitosis

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8
Q

what are the 4 types of stem cell?

A

totipotent
pluripotent
multipotent
unipotent

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9
Q

what does a totipotent stem cell do?

A

divide by mitosis and produce any type of body cells

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10
Q

why can totipotent stem cells produce any type of body cell?

A

because they only translate part of their DNA, producing specific proteins that lead to cell specialisation

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11
Q

what does a pluripotent stem cell do?

A

divide indefinitely by mitosis and begin to differentiate into the majority of specialised cells

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12
Q

which other stem cell can only translate part of its DNA?

A

pluripotent

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13
Q

what does a multipotent stem cell do?

A

differentiate into some different cell types

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14
Q

give an example of what a multipotent stem cell can differentiate into

A

red and white blood cells

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15
Q

what does a unipotent stem cell do?

A

differentiate into only one type of cell

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16
Q

give an example of a unipotent stem cell

A

unipotent stem cells in the heart differentiate into cardiomyocytes

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17
Q

what are multipotent and unipotent stem cells vital for?

A

growth and repair of damaged tissues

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18
Q

what is the developmental stage for totipotent stem cells?

A

zygote and early embryo

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19
Q

what is the developmental stage for pluripotent stem cells?

A

embryonic and fetal

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20
Q

what is the developmental stage for multipotent stem cells?

A

adult

21
Q

what is the developmental stage for unipotent stem cells?

A

used in the formation of single types of cells

22
Q

give 5 positives of stem cells for medical research

A
  1. research into producing organs for transplant
  2. research into how cells become specialised
  3. research into cancer
  4. producing tissues for skin grafts
  5. to cure diseases like parkinsons disease
23
Q

what is a negative of stem cells in medical research?

A

stem cells may divide out of control leading to the formation of a tumour

24
Q

what are iPS?

A

induced pluripotent stem cells
(lab grown)

25
Q

give 3 ethical concerns about stem cells

A
  1. embryos are seen to have human status to some people
  2. animal testing
  3. consent for donated cell usage
26
Q

what is a promoter region?

A

one or more base sequences found next to a region that controls the expression of that gene

27
Q

what is a transcription factor?

A

proteins that, when activated, bind to the promoter region of a gene stimulating RNA polymerase to begin transcription

28
Q

what is a terminator region?

A

where RNA polymerase detaches

29
Q

how does oestrogen activate transcription?

A
  1. diffuses through phospholipid bilayer (lipid soluble)
  2. diffuses through nuclear envelope
  3. binds to oestrogen receptor
  4. changes 3 structure of receptor
  5. causes the release of transcription factor
  6. TF binds to promoter region of DNA
  7. stimulating RNA polymerase and increases transcription
30
Q

what can control translation?

A

RNAi

31
Q

what are the 2 short regulatory RNA molecules called that reduce the production of a specific polypeptide?

A

micro RNA
small interfering RNA

32
Q

how does RNAi inhibit gene expression

A
  1. single strand of miRNA/siRNA binds to enzyme in cytoplasm to form RISC
  2. miRNA/siRNA has a complementary base sequence to part of specific mRNA
  3. RISC binds to mRNA
  4. either: hydrolyses mRNA or prevents ribosome from attaching to mRNA
33
Q

what has happened if a translation is still being produced in the presence of miRNA or siRNA?

A

not all mRNA destroyed

34
Q

what is epigenetics?

A

inheritable changes in gene expression without changes to DNA base sequence

35
Q

how can inheritable changes inhibit transcription?

A
  • increased methylation of DNA
  • decreased acetylation of histones
36
Q

explain how increased methylation can inhibit transcription

A
  1. attach to C5 cytosine base
  2. prevents TF from binding
37
Q

what is the enzyme that helps with the methylation of DNA?

A

methyltransferase

38
Q

explain how decreased acetylation can inhibit transcription

A
  1. less acetylene groups on histones make histones tightly packed
  2. DNA tightly packed
  3. promoter region hidden so TF can’t bind
39
Q

what are the two types of tumours?

A

benign and malignant

40
Q

what is the difference between benign and malignant tumours?

A

benign- slow growing, capsulated and do not metastasise
malignant- fast growing, not capsulated and do metastisise

41
Q

which genes control gene expression?

A

proto onco genes
tumour suppressor genes

42
Q

how do proto onco genes control gene expression?

A

stimulates cell division
by coding for proteins that increase cell division

43
Q

how do tumour suppressor genes control gene expression?

A

slows cell division
by coding for proteins that decrease cell division

44
Q

what can happen to a proto onco gene that can cause a tumour?

A

mutation/undermethylation

45
Q

what happens if a proto onco gene is mutated or undermethylated?

A

creates ‘onco gene’
that is permanently switched on
leading to an overstimulation of cell division
resulting in a tumour

46
Q

what can happen to a tumour suppressor gene that can cause a tumour?

A

mutation/overmethylation

47
Q

what happens if a tumour suppressor gene is mutated or overmethylated?

A

gene inactivated
so stops inhibiting cell division
which makes the rate of cell division increase
causing a tumour

48
Q

how can breast cancer be hormone stimulated?

A

cancer cells in the breast have ER receptors which oestrogen stimulates them to divide

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