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biology > paper 2: Gene Expression > Flashcards

paper 2: Gene Expression Flashcards

1
Q

describe a deletion mutation

A

one or more DNA bases are removed from the DNA base sequence

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2
Q

describe a substitution mutation

A

when one base is changed for a different base

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3
Q

describe an addition mutation

A

when one or more bases are inserted into a DNA base sequence, causing a frameshift

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4
Q

describe an inversion mutation

A

a group of bases becomes separated from the DNA base sequence and re-join at the same position but in the inverse order

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5
Q

describe a translocation mutation

A

a group of bases become separated from the DNA base sequence on one chromosome and becomes inserted into the DNA sequence of a different chromosome which causes a frameshift

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6
Q

describe a duplication mutation

A

one or more bases are repeated so a frameshift is caused

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7
Q

describe the two features in a stem cell

A

stem cells are undifferentiated and can keep dividing and can differentiate into specialised cells.

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8
Q

define the term totipotent stem cells and name at what point in life are they present.

A

cells which divide and differentiate into any cell type and are present during early life in mammalian embryos

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9
Q

define the term pluripotent stem cells nd name at which point in life they are present

A

cells which divide and differentiate into most cell types and are found later in mammalian embryos

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10
Q

define the term multipotent stem cells and name at what point in life they are present

A

cells which divide and differentiate into a limited number of different cell types and are found in mature mammals

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11
Q

define the term unipotent stem cells and name at which point in life are thye present and give an example in humans

A

cells which divide and differentiate into only one cell type and is found in mature mammals
e.g. cardiomyocytes in the heart muscle

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12
Q

explain how stem cell transplants can be used in treatment of diseases.

A

stem cells are transplanted into the body so they can divide and differentiate to produce healthy cells to replace the damaged cells.

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13
Q

describe how leukemia can be treated with stem cells

A
  • bone marrow is used from a close relative to reduce the chance of rejection
  • the stem cells continuously divide and differetiate to produce healthy white blood cells, giving a long term treatment
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14
Q

describe adult stem cells

A

from same individual/close relative and are multipotent

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15
Q

describe embryonic stem cells

A

pluripotent

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16
Q

what are the advantages of using adult stem cells in medicine

A
  • no ethical issues
  • less chnace of rejection (similar/same DNA)
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17
Q

what are the disadvantages of using adult stem cells in medicine

A
  • multipotent so can only differentiate into a limited number of cell types
  • difficult to isolate
18
Q

what are the advantages of using embryonic stem cells in medicine

A
  • pluripotent so can divide and diferentiate into almost all cell types
  • easy to isolate as yoiu use embryos from IVF
19
Q

what are the disadvantages of using embryonic stem cells in medicine

A
  • ethical issues
  • high chance of rejection
20
Q

describe what induced pluripotent stem cells are

A
  • normal cells which are removed from a patient and factors are added to make a cell pluripotent
  • they can then divide and differentiate into the desired cell type
  • specialised cells are transplanted back into the patient
21
Q

what are the advantages of induced pluripotent stem cells

A
  • no ethical issues as using own cells
  • can differentiate into almost all cell types
  • less chance of rejection
22
Q

explain how transcription factors control transcription

A
  • transcription factors are prtoeins
  • in eukaryotes, transcription factrs move from the cytoplasm to the nucleus
  • they bind a promoter of a gene
  • this stimulates/ inhibits RNA polymerase to transcribe the gene and produce mRNA
23
Q

what are the 2 types of transcription factors and what do they do

A
  • activators: activate transcription by causing RNA polymerase to bind
  • inhibitors: inhibit transcription by binding the promoter and preventing RNA polymerase binding
24
Q

describe how oestrogen (or testosterone) acts as a transcription factor

A
  • oestrogen is a lipid so is lipid soluble so crosses the phospholipid bilayer by diffusion
  • oestrogen binds to a protein receptor in the cytoplasm
  • receptor - oestorogen complex is a transcription factor so binds a promoter
  • this stimulates RNA polymerase to transcribe the gene and produce mRNA
25
Q

how can increased oestrogen conc.s lead to an increased risk of breast cancer

A
  • oestrogen can cause breast cells to divide more
  • more likely that mutations occur when DNA replicates
  • faster division of cancerious cells will produce tumours more quickly
26
Q

why are all cells not affected by oestorgen

A

not all cells have a complimentary oestrogen receptor in the cytoplasm

27
Q

describe the steps of RNAi

A
  1. small interfering RNA (siRNA) has a specific complimentary base sequence to the target mRNA
  2. the siRNA binds to a protein (RISC) which acts as an enzyme
  3. one of the siRNA strands is removed to make it single stranded
  4. the siRNA now binds to mRNA molecules by complimentary base pairing
  5. the mRNA is destroyed
  6. the mRNA can no longer be used in translation and is broken down by enzymes
28
Q

describe the difference between miRNA and siRNA

A
  • miRNA is not fully complimentary and not specific to one mRNA and therefore targets more than one type of mRNA unlike siRNA which can only target one type.
29
Q

how is cancer caused

A
  • mutations in the genes which control mitosis
  • this leads to uncontrolled xell division formng a mass of cells called a tumour
30
Q

what are the 2 types of tumours

A

benign and melignant

31
Q

describe a melignant tumour

A

cells can break off and spread to other parts of the body, forming a tumour elsewhere (metastasis)

32
Q

describe a benign tumour

A

cells do not spread to other parts of the body ( no metastasis)

33
Q

what is a tumour supressor gene

A

they produce protiens which inhibit cell division

34
Q

happens when there is a mutation in a tumour supressor gene

A
  • inhibit the formation of proteins which prevents mitosis or makes them non-functional
  • this leads to uncontrolled cell division
35
Q

what are proto-oncogenes

A

produce proteins which stimulate cell division

36
Q

what happens when there is a mutation nin a proto-oncogene

A
  • mutations of of proto-oncogenes to oncogenes forms more proteins which cause cell division
  • leads to uncontrolld cell division
37
Q

define epigenetics

A
  • hertable chnages in gene function
  • caused by changes in the environment
  • without changes in the DNA base sequence
38
Q

describe methylation

A
  • methyl groups are added to DNA
  • transcrition factors cannot bind the promoter
  • gene is not transcribed
39
Q

describe acetylation of histone proteins

A
  • the addition of histone proteins makes chromatin less eondensed
  • transcriptions factors can bind the promoter
  • transcription does occur
40
Q

what would happen if acetyl groups were removed from the histone proteins

A
  • chromatin would become more condensed
  • transcription factors cannot bind the promoter
  • transcription does not occur

biology (30 decks)

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