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Biology Paper 2 content > Topic 8 > Flashcards

Topic 8 Flashcards

(54 cards)

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1
Q

In Vitro Cloning

A

when gene copies are made outside of a living organism using PCR

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2
Q

In Vivo cloning

A

when gene copies are made within a living organism

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3
Q

A vector

A

something thats used to transfer DNA into a cell (can be a plasmid or a bacteriophage- a virus that infects bacteria)

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4
Q

What two things stick the DNA fragment and vector DNA together during In Vivo cloning

A

restriction endonucleases and DNA ligase (an enzyme)

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5
Q

3 methods of making DNA fragments

A
  • Gene Machine
  • Reverse transcriptase
  • Restriction endonuclease enzymes
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6
Q

Restriction endonucleases

A

enzymes that recognise palindromic sequences of DNA and cut the DNA at these places

this can be used to seperate a part of DNA if it has palindromic sequences either side of it

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7
Q

sticky ends

A

small tails of unpaired bases at the end of DNA fragments- makes it easier for them to join together because of complimentary base pairing

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8
Q

Reverse transcriptase

A

makes cDNA from an mRNA fragment

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9
Q

How is cDNA made using reverse transcriptase?

A
  • mRNA is isolated from other cells
  • mRNA mixed with free nucleotides and reverse transcriptase
  • reverse transcriptase uses mRNA as a tamplate to create a complimentary cDNA strand
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10
Q

cDNA

A

complementary DNA

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11
Q

mRNA

A

messenger RNA

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12
Q

Palindromic sequence of nucleotides

A

antiparallel base pairs- they read the same in the opposite direction

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13
Q

Recombinant DNA technology

A

transferring a DNA fragment from one organism to another

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14
Q

Why is recombinant DNA technology able to work?

A

genetic code is universal and transcription/translation mechanisms are very simmilar

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15
Q

How does a gene machine create DNA fragments?

A
  • required sequence is designed
  • first nucleotide is attaches to a support eg) bead
  • Nucleotides added one at a time, with addition of protecting groups- to ensure nucleotides join at correct point and avoid unwanted branching
  • Olingonucleotides (20 nucleotides long) are formed, then joined together to make longer DNA strand
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16
Q

6 types of mutation

A
  • Addition
  • Deletion
  • Susbtituton
  • Duplication
  • Inversion
  • Translocation
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17
Q

Degenerate nature of genetic code

A

some amino acids are coded for by more than one DNA triplet - not all mutations will result in a change of amino acid produced

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18
Q

Framshift mutations

A

additions, deletions and duplications

almost always cause a change to the polypeptide produced because all base triplets that follow the mutation are shifted

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19
Q

Mutagenic agents

A

factors that increase the rate of mutations eg) UV rays, ionising radiation, chemicals and viruses

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20
Q

3 ways mutagenic agents can alter rate of mutations

A

1) Acting as a base- changing the sequence
2) Altering bases
3) Changing structure of DNA- causing problems during replication

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21
Q

aquired mutations

A

mutations that occur after fertilisation eg) adulthood

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22
Q

tumour

Study These Flashcards
A

a mass of abnormal calls caused by uncontrolled cell division (by mitosis)

23
Q

two types of gene that control cell division

Study These Flashcards
A
  • tumour supressor genes

- proto-oncogenes

24
Q

tumour supressor genes

Study These Flashcards
A

when working properly, slow cell division by producing protiens that stop cells dividing (or cause them to self-destruct)

25
Proto-oncogenes
stimulate cell division by producing protiens that make cells divide
26
oncogene
a mutated proto-oncogene- stimulates cell to divide uncontrollably resulting in a tumour
27
two types of tumour
Maliginant- cancers, grow rapidly, destroy surrounding tissue, spread through bloodstream and lymphatic system Benign- not cancerous, grow slower and covered in fibrous tissue, often harmless but can cause blockages and later become malignant
28
How tumour cells differ from healthy cells
- Nucleus is darker and larger - irregular shape - dont produce protiens needed to function properly - different surface antigens - dont respond to growth regulating processes - mitosis occurs more frequently
29
Methylation
adding a methyl group onto a molecule important in regulating gene expression, can determine when a gene is transcribed and translated
30
hypermethylation
when methylation occurs too much and causes tumours to grown from cancer related genes
31
hypomethylation
when methylation occurs too little so tumours can form due to cancer-related genes
32
what can cause increased exposure to oestrogen
- starting periods earlier - starting menopause later - taking oestrogen containing drugs
33
How could oestrogen contribute to breast cancer?
- stimulates breast cells to divide and replicate- increasing chance of mutation - if cells do become cancerous- they will grow mor quickly - may be able to introcude mutations directly into the cells of certain breast tissue
34
Risk factors for cancer
Genetic: - some cancers are linked with specific inherited alleles Enviromental factors: -radiation, smoking, alcohol, high-fat diet
35
what are stem cells?
undifferentiated body cells that can develop into different types of cell
36
totipotent stem cells
can develop into any type of body cell, present in first divisions of an embryo
37
pluripotent stem cells
after few divisions of embryo can still develop into any body cell, but not placenta
38
multipotent stem cells
can differentiate into a few types of body cell eg) how blood cells can form from bone marrow
39
unipotent stem cells
can only differentiate into one type of cell
40
How do stem cells become specialised?
- certain genes are switched on/off - the mRNA is transcribed and translated into protiens - these proties modify the cell, allowing it to become modified for its specific function
41
cardiomyocytes
heart muscle cells that make up a lot of tissue in the heart. were thought to be unable to divide but now its thought that they can regenerate from a small group of unipotent stem cells in the heart (scientists aren't completly agreed on it)
42
Bone Marrow transplant
bone marrow contains stem cells that can differentiate into any type of blood cell (multipotent) can be used to replace bone marrow in patients that produce faulty blood cells to treat Lukemia, lymphoma and genetic disorders
43
ethical considerations of stem cell treatments
stem cells from embryos involves the descruction of an embryo that some believe has the right to life some people have fewer objections to egg cells before fertilisation as they wouldnt survive much longer anyway some believe only the stem cells of adults should be used, as it doesnt destroy an embryo
44
Benefits of stem cell therapies
- save many lives - possible to make stem cells identical to an induviduals own cells, so organs and tissues can be made that arent rejected from the body - improve quality of life for many people eg) blind people could see
45
Transcription factors
protien molecules that control the transcription of genes
46
activators
transcription factors that stimulate/increase rate of transcription
47
repressors
transcription factors that decrease/ prevent transcription of a gene
48
RNAi
effects gene expression in Eukaryotes | small, double stranded RNA molecule that stops mRNA from target genes being transcribed into a protien
49
epigenetic control
controlles whether a gene is transcribed or not (switched on/off) through the attachment/removal of chemical groups too/from histone protiens or DNA alter how easy it is for enzymes and protiens needed for transcription/translation to reach the DNA and interact with it
50
Two epigenetic mechanisms used to control gene expression
- Increased methylation of DNA- attach to CpG site and changes DNA structure so trancriptional machinery cannot interact - Decreased actylation of Histones- removing acetyl groups and DNA wrapped around histones becomes highly condensed so transcriptional machinery cannot physically access DNA strand
51
transformed cells
host cells that take up the vector containing genes of interest
52
What percentage of host cells take up the vector and its DNA?
approx 5%
53
what type of genes identify transformed cells during in vivo cloning
Marker genes- they are inserted into vectors, so any transformed cells will also contain the marker gene
54
Stages of In Vivo cloning?
1) Making recombinant DNA 2) Transforming cells 3) Identifying transformed cells 4) Producing protiens

Biology Paper 2 content (2 decks)

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