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A-level Biology > 8- Mutations And Genes > Flashcards

8- Mutations And Genes Flashcards

1
Q

What is a mutation

A

Any change to the base sequence of dna

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2
Q

When can mutations occur

A

Error during DNA replication

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3
Q

What can increase rate of mutations

A

Mutagenic agents

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4
Q

What are the 6 types of mutations

A

Substitution
Deletion
Addition
Duplication
Inversion
Translocation

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5
Q

Substitution mutation

A

One of more bases are swapped for another

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6
Q

Deletion mutation

A

One or more bases are removed

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7
Q

Addition mutation

A

One of more bases are added

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8
Q

Duplication mutation

A

One or more base are repeated

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9
Q

Inversion mutation

A

A sequence of bases is revers3d

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10
Q

Translocation mutation

A

A sequence of bases is moved form one location in. The genome to another
This could be movement within the same chromosome or movement to a differnt chromosome

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11
Q

What determines the polypeptide

A

The order of dna bases in a gene
Determined the sequence of amino acids

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12
Q

How does mutation in a gene. Effect a polypeptide

A

Sequence of amino acids change so polypeptide changes

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13
Q

Why might a mutation in an enzyme stop it working

A

A change in amino acid sequence may change the final 3D shape of the protein . The active site may change so substrates are no longer complementary so can’t bind

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14
Q

Explain how some mutations can cause genetic disorders

A

Inherited disorders caused by abnormal genes or chromosomes
Some mutations can increase the likelihood of developing certain cancers

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15
Q

What is a hereditary mutation

A

If a gamete containing a mutation for a genetic disorder or a type of cancer is fertilised it will be present in the new fetus formed

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16
Q

Why do not all mutation affect the order of amino acids

A

The degenerate nature of genetic code means that some amino acid are coded for by more than one dna triplet .
This means that not all types of mutation will always result in a change of amino acid sequences of the polypeptide
Eg. Some substitution will still code for the same amino acid and some inversion

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17
Q

If a mutation doesn’t cause a change in amino acid order what is it called

A

A silent mutation

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18
Q

What mutations cause a frame shift

A

Addition , deletion , duplication

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19
Q

Why do Addition duplicated and deletions almost always change amino acid sequence

A

they change the number of bases present
This causes a frame shift

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20
Q

Base triplets that follow on from the mutation are said to be …….. of the mutation

A

Downstream

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21
Q

When do mutations occur

A

Spontaneously
Eg. When dna is misread during replication

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22
Q

Examples of mutagenic agents

A

Ultra violet radiation
Ionising radiation
Some chemicals
Some viruses

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23
Q

What 3 ways can mutagenic agents increase rate of mutations

A

Acting as a base
Altering vases
Changing the structure of dna

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24
Q

What 3 ways can mutagenic agents increase rate of mutations
Acting as a base
Eg,

A

Chemicals called base analogs can substitute for a base during dna replication . Changing the base sequence in the new DNA

5-bromouracil is a base analog that can substitute for thymine. It can pair with guanine causing a substitution mutation in the new dna

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25
Q

What 3 ways can mutagenic agents increase rate of mutations
Altering bases
Eg,

A

Some chemicals can delete or alter bases
Eg, Alkylating agents can add an alkyl group to guanine which changes the structure so that is pairs with thymine

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26
Q

What 3 ways can mutagenic agents increase rate of mutations
Changing the structure of dna
Eg

A

Some types of radiation can change the structure of dna which.
Causes problems during dna replication

Eg, uv radiation can cause adjacent thymine bases to pair up togetehr

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27
Q

Mutations that occur in individual cells after fertilisation are called….

A

Acquired mutations

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28
Q

If an acquired mutation occurs in genes that control rate of cell division ( by mitosis) what can happen

A

Uncontrolled cell division

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29
Q

If a cell divides uncontrollably the results is a ….

A

Tumour

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30
Q

What is a tumour

A

A mass of abnormal cells

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31
Q

When are tumours cancer

A

Theme they invade and destroy surrounding tissue

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32
Q

What are the two types of gene that control cell division

A

Tumour suppressor genes
Proto-oncogenes

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33
Q

Mutations in tumour suppressor genes and proto-oncogenes cause ….

A

Cancer

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34
Q

What happens if a mutation occurs in a tumour suppressor gene

A

The gene can be inactivated

When functioning normally, tumour suppressor genes slow cell division by product of proteins that stop cell dividing or cause them to self distruct( apoptosis ;

If a mutation occurs in a tumour suppressor gene, the protein isn’t produced. The cells divide uncontrollably , resulting in a tumour

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35
Q

What happens if a mutation occurs in a proto-oncogene

A

The effect of the gene can be increased if a mutation occurs in the dna sequence
When functioning normally , proto-oncogenes stimulate cell division by producing proteins that make cells divide
If a mutation occurs in a proto-oncogene , the gene can become overactive. This stimulated the cells to divide uncontrollably resulting in a tumour

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36
Q

What is a mutated proto-oncogene called

A

Oncogene

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37
Q

What are the two types of tumours

A

Malignant
Benign

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38
Q

What is a malignant tumour

A

Cancers
They usually grow rapidly and invade and destroy surrounding tissues. Cells can break off the rumours and spread to other parts of the body in the blood stream or lymphatic system

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39
Q

What is a benign tumour

A

Non cancerous . They usually grow slower than malignant tumours, and a tee oftern cover in fibourous tissues that stop cells invading other tissues. Benign tumour are oftern harmless , but they can cause bloackages and put pressure on organs

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40
Q

Can benign tumours become malignant

A

Yes

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41
Q

How might tumour cells differ to normal cells

A

1) irregular shape
2)nucleus larger an darker, sometimes the cells have more than one nucleus
3) they don’t produce all proteins needed ot function correctly
4) they have differnt antigens on their surface
5: they don’t respond to growth regulating processes
6) they divide more frequently than normal cells

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42
Q

What is methylation

A

Adding a methyl (CH3) group onto something

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43
Q

What is methylating of DNA an important method of

A

Regulating gene expression - it can control whether or not a gene is transcribed and translated

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44
Q

When methylation is happening normally, what does it play a key role in

A

Many processes in the body

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45
Q

WhT is it called if methylation occurs to much

A

Hypermethylation

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46
Q

What is it called when methylation occurs to little

A

Hypomethylation

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47
Q

How can tumour growth be caused by hypermethylation

A

When tumour suppressor genes are hypermethylated, the genes are not transcribed - so the proteins they produce to slow down cell divison arnt made. Thus means that cells are able to divide uncontrollably by mitosis and tumours can develope

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48
Q

How can tumour growth be caused by hypomethylation

A

Hypomethylation of proto-oncogene chauses them to act as oncogenes - increasing the production of the proteins that encourages cell divison , this stimulated cells to divide uncontrollably which causes the formation of tumours

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49
Q

What can increased exposure to oestrogen over an extended period of time cause

A

Increase risk of developing breast cancer

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50
Q

What can u creased exposure to oestrogen be due to

A

starting menstruation earlier then usual t or menopause later

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51
Q

What are the 3 theory’s of how oestrogen can contribute to the development of some breast cancers

A

1) oestrogen can stimulate certain breast cells to divide and replicate. The facts that more cell divison are taking place naturally increase the chances of mutations occurring m and so increases the chance of cells becoming cancerous
2) This ability to stimulate division could also mean that if cells do become cancerous, their rapid replication could be further assisted by ostrogen, helping tumours to form quickly.
3) Other research suggests that ostrogen is actually able to introduce mutations directly into the DNA of certain breast cells, again increasing the chance of these cells becoming cancerous.

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52
Q

Where do all specialised cell come form

A

Stem cells

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53
Q

What are stem cells

A

Unspecialised cells that can develop into other types of cell
They divide to become new cells which then become specialised

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54
Q

T or f
All multicellular organism have some form of stem cells

A

T

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55
Q

Where are stem cells found

A

Embryo
Some adult tissue

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56
Q

What are stem cells found in the embryos for

A

Become all the specialised cells needed to form the fetus

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57
Q

What are stem cells found in some adult tissue for

A

they become specialised cells that need to be replaced

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58
Q

what is a totipotent cell

A

stem cells that can mature into any time of body cell in an organism

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59
Q

when are totipotent stem cells present in mammals

A

In the first few cell divisions of an embryo

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60
Q

After totipotent stem cells, the embryonic stem cells become …..

A

Pluripotent

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61
Q

What are pluripotent cells

A

They can still specialise into any cell in the body, but lose the ability to become the cells that make up the placenta

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62
Q

What 2 types of stem cells are present in adult mammals

A

Multi potent
Unipotent

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63
Q

What are multipotent stem cells

A

These are able to differentiate into a few differnt types of cells
Eg, red and white blood cells can be formed form them found in bone marrow

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64
Q

What are unipotent stem cells

A

these can only differentiate into one type of cell.

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65
Q

How do stem cells specialise

A

1) stem cells all contain the same genes - but during development not all of them are transcribed and translated
2) under the right conditions, come genes are expressed and other are switched of
3) mRNA is only transcribed form specific genes
4) the mRNA form these genes is then translated into proteins
5) these proteins modify the cell- they determine the cell structure and control cell processes ( including the expression of more genes , which produce more proteins )
6) changes to the cell produced by these proteins cause the cell to become specialised. These changes are difficult to reverse, so once a cell has specialised it stays specialised

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66
Q

Explain how stem cells specialise into red blood cells

A

Red blood cells are produce from a type of stem cells in the bone marrow
They contain lots of heamoglobin and no nucleolus
The stem cells produce a new cell in which th genes for haemoglobin production are expressed, other genes, such as those involved in removing the nucleus , are expressed too.
Many other genes are not exporessed, resulting in specialised RBc

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67
Q

What are the heart muscle cells that are up a lot of the tissue in out heart

A

Cardiomyocytes

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68
Q

What was the previous ideas about cardiomyoctes and why is this a problem

A

That they can’t divide to replicate themselves in mature mamamles
If heart becomes damaged, eg, by heart attack of cell worn out by age.

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69
Q

What does recent reasearch about cardiomyocytes show

A

They do have some regenerative capability
Soem scientists not think that old or damaged cardiomyocytes can be replaced by new cardiomyocytes derived form a small supply of unipotent stem cells in the heart.
Some research think that this process coal be occurring constantly

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70
Q

What are the 2 views on how quickly cardiomyocytes regenerate

A

1- some believe that it’s really slow process and that it’s possible that some cardiomyocytes are never replaces throughout a persons lifetime.
2- others think that it’s occurring more quickly so that every cardiomyocytes in the heart is replaced several times in a lifetime

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71
Q

Soem stem cell therapies already exist for some disease affecting,,…

A

Blood and immune system

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72
Q

Explain stem cell therapies for abnormal blood cells

A

Bone marrow contains stem cells that can become specialised to form any type of blood cell. Blood marrow transplant can be used to replace faulty bone marrow in patients that produce abnormal blood cell. The stem cells in the transplanted bone marrow divide and specialise to produce healthy blood cells

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73
Q

What have bone marrow transplants been used to treat

A

leukaemia
Lumphoma
Genetic disorders such as sickle cell anaemia and severe comined immunodeficiency (SCID)

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74
Q

what other diseases COULD stem cells treat

A

1) spinal cord injuries - stem cells could be used to replace demaage nerve tissue
2) heart disease and damage caused by heart attacks - stem cells could be used to replace damage heart tissue
3) bladder conditions. - stem cells cloud be used to grow while bladders, which are then implanted in patients to replace disease ones
4) respiratory diseases - donated windpipes can be stripped down to their simple collagen structure and then converted with tissues generated by stem cells. This can then be transplanted into patients
5) organ transplants - organs could be grown form stem cells to provide new organs for people on donor wiaiting lists

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75
Q

Potential benifits of stem cell therapies

A

1) save many lives - eg. People waiting for organ transplants die before. Donor organ becomes available. Stem cells could be used to grow organs for those people awaiting transplants
2) they could improve QOL for many people- eg, stem cells could be used to replace damaged cells in the eyes of people who are blind

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76
Q

What are the 3 main potential sources of human stem cells

A

adult stem cells
Embryonic stem cells
Induced pluripotent stem cells(IPS)

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77
Q

Where are adult stem cells obtained

A

From the body tissues of an adult
Eg. Adult tem cells are found in bone marrow

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78
Q

How are adult stem cells obtained

A

Relatively simple operation
With very little risk involved , but quite a lot of dicomfort

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79
Q

Negative of adult stem cells

A

Aren’t as flexible as embryonic stem cells - they can only specialise into a limited range of cells, not all body cell types ( they’re multi potent )

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80
Q

Where are embryonic stem cells obtained

A

From embryos at an early stage of development

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81
Q

How are embryonic stem cells obtained

A

Embryos Created in the lab using IVF
Once the embryos are approximately 4 to 5 days old, stem cells are removed form the, and rest of the embryo are destroyed

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82
Q

Positive of embryonic stem cells and what type of cell are they

A

Divide an unlimited number of times and develope into all types of body cells - pluripotent

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83
Q

How are iPS cell created

A

By scientists in the lab
The process involves ‘reprogramming’ specialised adult body cells so that they become pluripotent

The adult cells are made to express a series of transcription factors that are normally associated with pluripotent cells . The transcription factors cause adult body cells to express genes that are associated with pluripotency

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84
Q

What is a way of making transcription factors that cause adult body cell to express genes associated with pluripotency

A

Infecting them with specifically modified virus.
The virus has the genes coding for fhe transcription factors within its DNA
When the virus infects rhe adult cell, these genes are passed into the adult cells DNA ,, meaning the cell is able to produce the transcription factors

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85
Q

Ethical issues surrounding embryonic stem cells

A

1) obtaining stem cells from embryos created by IVF rashes ethical issues as the procedure results in the destruction of an embryo that could become a fetus if placed in the womb

2) Some people believe that at the moment of fertilisation an individual is formed that has the right to life — so they believe that it’s wrong to destroy embryos.

3( Some people have fewer objections to stem cells being obtained from egg cells that haven’t been fertilised by sperm, but have been artificially activated to start dividing. This is because the cells couldn’t survive past a few days and wouldn’t produce a fetus if placed in a womb.

4)Some people think that scientists should only use adult stem cells because their production doesn’t destroy an embryo. But adult stem cells can’t develop into all the specialised cell types that embryonic stem cells can.

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86
Q

benifits of IPS

A

potential to be as flexible as embryonic stem cells
They’re obtained form adult tissues so arnt the same ethical issues as embryos

Possible to be made form patients own cells, so genetically identical to patients own cells
They could be used to grow some new tissues or and organ that the patients body wouldn’t reject

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87
Q

T or f
all the cells in an organism carry the same genes

A

Yes

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88
Q

If all cells in an organism carry the same genes
How come the structure and functions of differnt cells vary

A

Because not all genes in a cell are expressed
As differnt Genes are expressed, differnt proteins are made and these protien modify the cell
They determine the cell structure and control cell processes

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89
Q

The transcription of genes is controlled by protien molecules called ….

A

Transcription factors

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90
Q

Explain how transcription factors control which genes are expressed in eukaryotes

A
  1. Transcription factors move from the cytoplasm to the nucleolus
  2. In the nucleus they bind to specific DNA sites near the start of their target genes- the genes they control the expression of
    3) they control the expression by controlling rate of transcription
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91
Q

What are the 2 types of transcription factors called

A

Activators
Repressors

92
Q

What do activators (transcription factions) do

A

Stimulate or increase the rate of transcription

93
Q

Give an example of activators ( transcription factors )

A

they help RNA polymerase bind to the strat of the target green and activate transcription

94
Q

What do repressors ( transcription factors ) do

A

Inhibit or decrease the rate if transcription

95
Q

Give an example of repressors ( transcription factors )

A

They bind to the start of the target gene , preventing RNA polymerase from, brining, stopping transcription

96
Q

The expression of genes can also be affected by other molecules in the cell such as …..

A

Oestrogen
RNA interference

97
Q

How does oestrogen affect transcription

A

1) oestrogen is a steroid hormone fhat can affect transcription by binding to a transcription factor called oestrogen receptor, forming an oestrogen-oestrogen receptor complex
2) the complex moved from the cytoplasm into the nucleolus where it binds to specific DNA sites near the start of the target gene
3) the complex can act as an activator of transcription, eg, helping RNA polymerase bind the the start if the target gene

98
Q

What is RNAi (in eukaryotes)

A

Where small , double stranded RNA Molecules stop mRNA from target genes being translated into proteins,

99
Q

What are the molecules involved in RNAi

A

siRNA ( small interfering RNA)
miRNA ( microRNA)

100
Q

How does RNAi work in eukaryotes

A

1) once mRNA has been transcribed p, it leave the ncuelous form the cytoplasm
2) in the cytoplasm, double stranded siRNA associates with several protiens and unwinds. a single strand then bind to target mRNA. The base sequence of the siRNA is complementary to the base sequence in section of the target mRNA.
3) the proteins associated with the siRNA cut the mRNA into fragments - so that is can no longer be translated. The fragments then move into a processing body which contains ‘tools’ to degrade them

101
Q

What is the siRNA equivalent in plants

A

miRNA

102
Q

Explain miRNA in mammals

A

in mammals the MI RNA isn’t usually fully complementary to the target mRNA
. This makes it less specific than SI RNA and so it may target more than one mRNA molecule
like siRNA it associates with proteins and binds to target mRNA in the cytoplasm

instead of the proteins associated with miRNA cutting mRNA into fragments, the miRNA protein complex physically block the translation of the target mRNA

the mRNA is moved into a processing body where it can either be stored or degraded when it stored it can be returned and translated at another time

103
Q

siRNA or miRNA
In mamamls
In which one can the mRNA be stored

A

miRNA

104
Q

In eukaryotes, what can epigenetic control determine

A

Whether a gene is switched on or off

105
Q

How does epigenetic control work

A

Through attachment or removal of chemical groups to or form DNA or histone proteins

106
Q

What are the chemical groups that are attached or removed from DNA or histones called _ through epigenetic control

A

Epigenetic marks

107
Q

Do epigenetic marks alter the base sequence of DNA

A

No

108
Q

What do epigenetic marks alter

A

how easy it is for the enzyme and other proteins needed for transcription to interact with and transcribe the DNA

109
Q

What do epigenetic changes to gene expression plat a role in

A

Lots of normal cellular processes
also can occur in response to change in the environment

110
Q

Organisms inherit their DNA base sequences from their….

A

Parents

111
Q

What happens to epigenetic marks on DNA between generations

A

Most are removed
But some escape the removal process and are passed on to offspring

112
Q

Some epigenetic marks on dna arnt removed between generations
What does this mean fir the offspring

A

The expression of some genes in the offspring can be affected by environmental changes that affect their parents or grandparents

113
Q

What two ways can genes be switched of in epigenetic control

A

Increased methylation
Decreased acetylation of histones

114
Q

What is methylation of DNA

A

When a methyl group is attached to the dna coding for a gene

115
Q

Where does the methyl group always attach in methylation of DNA

A

The CpG site

116
Q

What is a CpG site

A

Where cytosine and guanine bases are next to each other in the DNA

117
Q

How does methylation effect DNA

A

Changes the structure so that the transcriptional machinery (enzymes, protines ect ) can’t interact with the gene - so the gene is not expressed

118
Q

What makes up chromomes

A

DNA wraps around histones to from chromatin which makes up chromomes

119
Q

Chromatin can be a highly or less condensed. What does this effect

A

How condensed it is affects the accessibility of the DNA and whether or not us can be transcribed

120
Q

How can histones be epigenetically modified

A

By the addition or removal of acetyl groups

121
Q

Give 2 examples of epigenetic marks

A

acetyl groups
Methyl group

122
Q

What happens when histones are acetylated

A

The chromatin is less condensed
This means that the transcriptional machinery can access the DNA allowing genes ot be transcribed

123
Q

What happens when acetyl groups are removed from the histones

A

The chromatin becomes highly condensed and genes in the DNA can’t be transcribed because the transcriptional machinery can’t physically access them

124
Q

What enzymes are responsible for removing the acetyl groups

A

Histone deacetylase (HDAC)

125
Q

What are epigenetics

A

Changes involve inheritable , reverisble changes to DNA that effect whether genes are transcribed or not

126
Q

What do histones do

A

Structural support for dna
Can be modified by acetylation to regulate gene expression

127
Q

Does methylated DNA cause more or less expression amd why

A

Less and more tightly packed

128
Q

What is an acetyl group

A

COCH3

129
Q

What is euchromatin
And what’s it caused by

A

Acetylation
Regions with high transcriptional activity are loosely packed

130
Q

What is heterochromatin caused by

A

Methylation
regions of low or no transcriptional activity are densely packed

131
Q

What feature makes epigenetic changes good targets for new drugs to combat diseases

A

They are reversible

132
Q

Increased methylation can lead to a gene being switched off
How can drugs be used in this scenarios

A

Drugs that stop methylation can sometimes be used to treat disease caused this way
Eg. Azacitidine is used in chemotherapy for types of cancer that are caused by increased methylation of tumour suppressor genes

133
Q

Decreased acetylation of histone can lead to genes being switched off
How can drugs play a part in this

A

HDAC inhivitorcdrugs
Can be used to treat disease that are caused in this way
These work by inhibiting the activity of histone deacetylade ( HDAC) enzyme, which are responsible for removing the acetyl group form histones. Without the activity of HDAC enzymes, the gene remains acetylated and the proteins they code for can be transcribed

134
Q

What is the problem with developing drugs to counteract epigenetic changes

A

these changes take place normally in a lot of cell, so the drugs need to be as specific as possible

135
Q

What is the phenotype of an organism the result of

A

The organisms genotype and the interaction of its genotype with the environment

136
Q

How is overeating an example of beinf effected by genes and environment

A

Environment - increased ability of food
Gene- later discovered food consumption increased dopamine levels , once enough dopanime was released people would stop eating. Reasearch discovered that people with one particals allele has 30% fewer dopamine receptors. People with this more likely to overeat

137
Q

What studies are usefull when tryin g to determine what’s due to environmental factors and what’s due to genetic factors

A

Twin studies

138
Q

How are twin studies useful to determine influenced on phenotype

A

Twins are genetically identical so any differnce in phenotype must be due to environemtnal factors. If a characteristic is very similar in identical twins , genetics probably plays as the most important role, but if a characteristic is differnt between the twins the environemnt must have a larger influence

139
Q

How can cancers be caused genetically

A

Some cancers are linked with specific inherited alleles. If you inherit that allele your more likely o get that type of cancer

140
Q

How can cancer be caused environmentally

A

Exposure to radiation , lifestyle choices such as smoking , increased alcohol consumption and a high fat diet have all been linked to an increase chance of developing some cancers

141
Q

What is cancer a mutation in

A

Proto-oncogenes
tumour suppressor genes

142
Q

Why is it usefull if specific cancer causing mutations are known in terms of prevention
With the example of breast cancer

A

Then it’s possible to screen for the mutation in a persons DNA - can screen for BRCA1 tumour suppressor gene wich increases chance of breast cancer
Knowing. About increases risks means that preventative steps can be taken to reduce it
For example a woman may have a mastectomy or be screened for breast cancer more often to increase chances of an early diagnosis

knwoung about specific mutations also means more sensitive tests can be developed which can
Lead to earlier and more accurate diagnosis

143
Q

Why is it usefull if specific cancer causing mutations are known in terms of treatment

A

Useful in developing drugs that effectively target them .
Some cancer causing mutations require more aggressive treatment than others so understanding how the mutation that causes them works can help produce the best treatment plant.
Gene therapy may also be able to retreat cancer caused by some mutations.

144
Q

What is a genome

A

The entire set of DNA, including all the gene in an organism

145
Q

what allowed us to sequence the genomes of a variety of organisms form bacteria to humans

A

Improvements in technology

146
Q

Gene sequencing methods only work on …..

A

Fragments of dna

147
Q

What do you need to do if you want to sequence the entire genome of an organism

A

Chop into smaller pieces first
the smaller pieces are sequences and then put back in order to give the sequence of the whole
genome

148
Q

When was the human genome project competed and what do they do

A

2003
Mappend the entire sequence of the human genome for the first time

149
Q

What is a proteome

A

all the proteins that are made by an organism

150
Q

How much non coding dna do simple organisms like bacteria have

A

Not much

151
Q

why is it easy to determine proteome from dna sequence of simple organisms genome

A

They don’t have much non coding dna

152
Q

Why would it be useful to know the proteome of a bacteria

A

Identifying protien antigens on the surface of disease causing bacteria can help develop vaccines to prevent these diseases

153
Q

Why is it harder to translate the genome of complex organisms

A

They have large sections of non coding DNA
contain complex regulatory genes which determine when the genes that sore for particular proteins should be switch3d on and off
This makes it difficult to translate their genome unit their proteome Because it’s harder to find the buts that code for proteins among the non coding and regulatory dna

154
Q

Exmplaim how sequencing methods have been updated

A

In thepast, many sequencing methods were labour intensive, expensive and could only be done on a small scale. Not they are oftern automated, more cost effective and can be done on a very large scale

155
Q

What is an example of an updated sequencing technique

A

Pyrosequecning is recently developed technique that can sequence around 400 million bases in a10 hour period

156
Q

What is a proteome

A

All the proteins that are expressed

157
Q

cant we transfer knowledge of the genome to the proteome in more complex organisms?

A

WhyContain introns so we don’t know which parts are coding and which arnt

158
Q

How could knowing the genome help under a stand evolutionary relationships

A

Q sequence genomes and cross compare, the more separated on the evolutionary tree the less similar the ge

159
Q

How could knowing the genome help with personalised medicine

A

identify disease before they start showing, Taylor medical care to specific patients, sequence genome allows us to identify where a mutation occurs in a gene in order to target with specific drugs ( this will be different from patients to patients), finding severe immune problems in a baby

160
Q

how could understanding the genome improve agriculture

A

understanding genome means altering for the benefit of crops

161
Q

Ethical conservations of the genome project

A

Having Someone’s genome opens up options of exploiting someone’s genome. Such as cloning, designing babies , would be only available to the rich , playing ‘god ‘ in religious arguments
However, positively could scan for genetic diseases which could be removed before birth

162
Q

Gene definition

A

Section of DNA that codes for a specific protein / characteristic

163
Q

What 3 ways can fragments of can be produced

A

Reverse transcriptase
Restriction enzymes
Gene machine

164
Q

Where are restriction enzymes from

A

Bactria
Most likely evolved as a defence against viruses that infect bacteria

165
Q

What 2 ways do restriction enzymes cut dna

A

Blunt ends
Sticky ends

166
Q

How could a restriction enzyme cut DNA in a sticky end

A

an end with a bit of DNA that is single stranded.
in order to do this the restriction site must be palindromic , ie the sequence of bases must be the same forward on one strand and backwards on the complimentary strand

167
Q

What feature of DNA allows gene technology to work

A

DNA sequences are universal so allows gene technology to work
( all organisms are coded for by the same 4 base Paris )

168
Q

b. Why might producing a DNA fragment using reverse transcriptase be advantageous compared to using restriction enzymes?

A

in general fragments from a eukaryotic. Cell and is made by cutting NDA with restriction enzymes it will contain introns and exons. If it is places into prokaryotic cells to transform them they cannot splice the RNA to removed the introns. If the gene fragment is made using reverse transcriptase there will not be any introns

169
Q

A Gene machine can produce small lengths of DNA called….

A

Oligonucleptides

170
Q

What does recombinant DNA technology involve

A

transferring a fragment of DNA from one organism to another

171
Q

Why can transferred DNA fragment from one organism to another work

A

Genetic code is universal, and because transcription and translation mechanisms are pretty similar too. So the transferred DNA can be used to produce a protein in the cell of the recipient organism.

172
Q

Does recipient and donor organisms of DNA fragment, need to be form the same species

A

No

173
Q

What are organisms that contain transferred DNA are known as

A

Transgenic organisms

174
Q

In order to transfer a gene form one organism to another what do you need to do first

A

Get to a DNA fragment containing the gene your interested in

175
Q

Why is mRNA of a gene easier to obtain than DNA of a gene

A

Most cells only contain two copies of each genes making it difficult to obtain a DNA fragment contained th etraget gene . But they contain many mRNA molecules wich are complete art to the gene , so mRNA is easier to obtain

176
Q

How can mRNA be used in the reverse transcriptase method to get a dna fragment

A

1) the mRNA molecule can be used as templates to make lots of dna. Reverse transcriptase enzyme makes dna form an rna template. This is called complimentary DNA
2) mRNA is first isolated, then mixed with free DNA nucleotides and reverse transcriptase. The reverse transcriptase use the mRNA as a template to synthesise a new stand of cDNA , the free dna nueclotides are joined up with DNA polymerase

177
Q

what do some dna have that restriction endonucelase enzymes utilise

A

Some sections of DNAhave palindromic sequecnes of nucleosides, these sequecnes consist of antiparralel base pairs ( base pairs that read the same in opposite directions)

178
Q

What does restriction endonuclease do

A

recognise specific palindromic sequecnes ( known as recognition sequences and cut ( digest( the DNA in these places

179
Q

Why do different restriction endonuclease cut at differnt specific recognition sequence nes

A

Beacuse the shape of the recognition sequences is complementary to the enzyme active site

180
Q

If recognition sequecnes are present at either side of the DNA fragment you want , what can you do

A

Use restriction endonuclease to separate it from the rest of the DNA

181
Q

How is restriction endonuclease enzyme do

A

The DNA sample is incubated with the specific restriction endonuclease wich cuts dna fragments out via a hydrolysis reaction

182
Q

Sometimes the cut of restriction endonuclease enzymes leaves sticky ends, what are sticky ends

A

Small tails of unpaired bases at each end of fragments

183
Q

What can sticky ends be used to do after creating fragments with restriction endonuclease enzymes

A

Sticky ends can be used to bind ( anneal) the DNA fragment to another piece of DNA that had sticky ends with complemaryy sequecnes

184
Q

What does the gene machine do

A

fragments of DNA can be synthesied from scratch , without the need of a pre existing DNA template .
This data has contains the necessary information to produce a DNA fragment

185
Q

When using a gene machine do the DNA sequecnes being made have to exist naturally

A

No

186
Q

How does the gene machine work

A

The sequence that is required is designed ( if one doesn’t already exist (

The first nucleotide un the sequence is fixed to come sort of support ( eg, a bead)

Nucleotides are added step by step in the correct order, in a cycle of processes that include adding protecting groups. Protecting groups make sure that the nucleotides are joined at the right points, to prevent unwanted branching

Short sections of DNA called oligonucleotides roughly 20 nucleotides long are produced . Once these are complete they are broken off from the support and all the protecting groups are removed, the oligonucelotides can then be joined together to make longer DNA fragments

187
Q

Once you have isolated your DNA fragments, what do you need to do

A

Amplify it so you gave sufficient quantity to work with

188
Q

How you amplify dna fragments

A

In vivo cloning

189
Q

What is in vivo cloning

A

Where copies of the DNA fragment are made inside a living organism

190
Q

What are the basic steps of amplifing DNA fragments in vivo cloning

A

1) the dna fragment is inserted into a vector
2) the vector transfers the dna fragments into host cells
3) identifying transformed host cell

191
Q

What is a vector

A

Something that’s used to transfer dna into a cell

192
Q

Examples of vectors that dna fragments can be inserted into

A

Plasmids or bacteriophages

193
Q

What are bacteriophages

A

Viruses that infect bacteria

194
Q

How are dna fragments inserted into a vector

A

1) the vector dna is cut ions using the same restriction endonuclease that was used to isolate the dna fragment. So the sticky ends if the vector are complementary to the sticky ends of the dna fragment containing the gene
2) the vector dna and dna fragment ar mixed together with dna ligase. Joining sticky ends of dna fragment to sticky end of vector dna

195
Q

What does dna ligase do

A

Joins the sticky end of the dna fragment ot the sticky end of the vector dna

196
Q

What is the name of the process of joining dna fragment sticky end to vector dna sticky end using dna ligase

A

Ligation

197
Q

what is the name of dna that is a combination of bases in dna ( vector and fragment dna(

A

Recombinant dna

198
Q

Once the dna fragment is inserted into the vector what does the vector do

A

Transfer the dna fragment into the host cell

199
Q

Vector to host cell ( dna fragment )
What happed if a plasmid vector is used

A

Host cells have to be persuaded to take in the plasmid vector and its dna

200
Q

Vector to host cell ( dna fragment )
What happed if a bacteriophage vector is used

A

The bacteriophages will infect the host bacteria by injecting its DNA into it . The phage dna then integrates into the bacterial dna

201
Q

The host cell that takes up the vectors containing the genes of interest are said to be….

A

Transformed

202
Q

Why do you have to identify which cells have been transformed

A

Only around 5% will take up the vector and it’s dna

203
Q

What can be used to identify transformed cells

A

Marker genes

204
Q

How can marker genes be used to identify transformed cells

A

Marker genes can be inserted into vectors at the same time as the gene to be cloned. So any transformed host cell will contain the gene to be cloned and the marker cell

Host cells grown in agar plate . Each divides and replicates its dna, transformed cells will produce colonies where all the cells contain the cloned gene and marker gene

The marker gene can code for antibiotic resistance - host cells are brown on agar plate containing the specific antibiotic , so only transformed cells that have the marker gene will survive and grow

Identifies transformed cells are allowed to grow more producing lots of copies of cloned gene

205
Q

The marker gene can code for antibiotic resistance - host cells are brown on agar plate containing the specific antibiotic , so only transformed cells that have the marker gene will survive and grow

What else could be used to identify transformed cells

A

Marker gene could code for fluorescence, when the agar plate is placed under vu light only transformed cells with fluoresce

206
Q

What do you need to do if you want the transformed host cell to produce the protein coded for by the dna fragment

A

Make sure the vector contains specific promoter and terminator region

207
Q

What are promotor and terminator regions

A

Promotor regions are DNA sequecnes that tell and enzyme rna polymerase when to start producing mRNA, terminator regions tell it when to stop

208
Q

Why does a transformed host cell need a vector containing the specific promotor and terminator region in order to produce use the protien coded for by the dna fragment

A

Without the promotor region the dna fragment won’t be transcribed by the host cell and a protien won’t be made

209
Q

Promotor and terminator regions might be present in vector dna or…..

A

They may have to be added in along. With the fragment

210
Q

Aside from in vivo how else can dna fragments be amplified

A

In vitro cloning

211
Q

What is in vitro cloning

A

this is where copies of the Dan fragment are made outside the living organism using the polymerase chain reaction

212
Q

What does PCR stand for and what can it be used to do

A

Polymerase chain reaction
Used to make millions of copies of a fragment of dna in just a few hours

213
Q

explain the stages of PCR

A

1) a reaction mixture is set up that contains the dna sample, free nuceleotides, primers and dna polymerase.
2) dna mixture is heated to 95 °c to break the hydrogen bonds between the 2 dna strands
3) the mixture is then cooled to between 50 and 65 °, so that the primers can bind to the strands
4) the reaction mixture is heated to 72° so DNA polymerase can work
5) dna polymerase lines up free dna nucleotides a
Outside each template strand specific base pairing means new complemenary strands are formed
6) two new copies of the fragment of dna are formed and one cycle of PCR is complete
7) cycle stars again , mixture to 95 , this time all 4 strands (2 origional and 2 new) are used as templates

214
Q

What is a primer

A

Short pieces of dna that are complementary to the bases at the start of the fragment you want

215
Q

how many DNA fragments are produced in each PCR cycle

A

Each is doubled
So
1st = 4
2nd = 8
3rd = 16
Ect

216
Q

What type of DNA polymerase is used in PCR

A

Taq DNA polymerase
(Taq is an enzyme extracted from extremophiles)

217
Q

What is the name of the stage in PCR that primers are added

A

Annealing stag e

218
Q

What is the name of the stage in PCR where free nuecloptide are lined up and used to make complementary strands

A

Extension stage

219
Q

Microorganisms plants and animals can all by transformed using recombinant DNA technology. What is the general term for thsi

A

Genetic engineering

220
Q

Transformed organisms are made using …
With the same tech as ….

A

Recombinant DNA technology
In vivo cloning

221
Q

How can transformed plants in produced

A

A gene that codes for a desirable protien is inserted into a plasmid. The plasmid is added to a bacterium and the bacterium is used as a vector to get the gene into the plant cell. If the right promotor region has been added along with the gene the transformed cell will be able to produce the desired protein

222
Q

How can a microorganisms be transformed

A

Eg, foreign DNA can be inserted into microorganisms to produce lots of usefull protins

223
Q

How can an animal be transformed

A

A gene that codes for a particular desirable protein can be inserted into an early animal embryo or into an egg cell of a female. If the gene is inserted into a very early embryo all the body cells of the resulting transformed animal will end to containing the gene

224
Q

What would happen if you insert a gene that codes for a desirable protein into an egg cell

A

When the female reproduces all the cell of her offspring will contain the gene

225
Q

What can the promotor regions that are only activated in specific cell types be used to control

A

Exactly which of an animal body cells the protien is produced It

226
Q

Why might you only want proteins produced in certain cells,

A

Can be harvested more easily
It produced in the wrong cells could cause damage to the organism

A-level Biology (8 decks)

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