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Molecular Medicine and Forensics. Flashcards

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1
Q

Define anaemia?

A

A condition caused by a lack of oxygen in the blood, either due to a lack of haemoglobin red blood cells.

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2
Q

Define a disease carrier?

A

A person who carries genes that code for disease, but does not suffer from the disease.

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3
Q

Define DNA profiling?

A

A technique used by scientists to distinguish between individuals of the same species using only DNA samples.

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4
Q

Define a monogenic recessive disorder?

A

Another name for genetic disorders that are caused by a recessive gene.

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5
Q

Define monosomy?

A

When only one member of a pair of chromosomes is present.

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6
Q

How many chromosomes will people who suffer from monosomy have?

A

45 chromosomes.

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7
Q

Define trisomy?

A

This occurs when an extra chromosome is added to a pair.

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8
Q

How many chromosomes will people who suffer from trisomy have?

A

46 chromosomes.

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9
Q

What does molecular medicine examine?

A

The disease process at the cellular or molecular level.

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10
Q

What is the goal of molecular medicine?

A

To find new methods of treating various diseases.

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11
Q

Molecular medicine can be used to treat what kind of diseases?

A

Both genetic diseases and acquired diseases.

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12
Q

How many factors are usually involved in the disease process?

A

3 different factors.

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13
Q

Can any of the 3 factors of the disease process cause disease on their own?

A

Yes.

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14
Q

Can more than one of the 3 factors of the disease process cause disease?

A

Any 2 or all f of the 3 factors can overlap.

The degree of overlap can vary depending on the disease or the person who is affected by the disease.

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15
Q

What are the 3 factors that contribute to a disease?

A

Genetic factors.

Environmental factors.

Behavioural factors.

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16
Q

What causes genetic diseases?

A

An inherited failure in one or more genes that code for normal body functions.

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17
Q

Are genetic factors that cause disease unique to the person or are they universal?

A

They are usually unique to the host, or to the person who has the disease.

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18
Q

What are the the behavioural factors that contribute to disease?

A

The various ways that people behave can lead to disease.

E.g. habits such as smoking and drinking are huge contributors to many different diseases.

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19
Q

What are the genetic factors that lead to disease?

A

Malfunctioning genes.

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20
Q

The behavioural factors that contribute to disease can be considered as what?

A

As agents that contribute to disease.

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21
Q

How does the environment contribute to disease?

A

The immediate environment that surrounds people can heavily contribute to the onset of disease.

E.g. if people live near a nuclear reactor or have huge exposure to toxic chemicals.

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22
Q

What are the 4 different categories that genetic diseases can be divided into?

A

Single gene disorders.

Multifactorial or complex disorders.

Chromosomal imbalances.

Mitochondrial disorders.

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23
Q

What are the 3 categories that single gene disorders can be divided into?

A

Autosomal recessive.

Autosomal dominant.

Sex linked.

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24
Q

When are autosomal recessive diseases expressed in a person?

A

When a person inherits 2 recessive alleles that code for a disease.

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25
Q

Where will a person who has an autosomal recessive disease inherit the disease causing alleles from?

A

They will inherit one recessive allele from their mother and one recessive allele from their father.

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26
Q

Why do recessive disorders tend to be quite rare?

A

As they can be masked by the presence of a dominant allele.

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27
Q

What kind of people can pass a recessive allele onto their children?

A

Anyone who is heterozygous.

Anyone who is homozygous recessive.

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28
Q

What kind of person will be a carrier of an autosomal recessive disease?

A

They will be a carrier of the disease.

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29
Q

What kind of person has absolutely no chance of passing on an allele that leads to a recessive disorder to their children?

A

A person who has 2 dominant alleles.

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30
Q

What are 6 common autosomal recessive disorders?

A

Cystic fibrosis.

Phenylketonuria.

Tay Sachs disease.

Thalassaemia.

Sickle cell anaemia.

Galactosaemia.

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31
Q

What are the symptoms of cystic fibrosis?

A

Recurrent lung infections.

Pancreatic deficiencies.

Male sterility.

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32
Q

What are the symptoms of phenyletonuria?

A

Mental retardation.

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33
Q

What are the symptoms of Tay Sachs disease?

A

Neurological degeneration, blindness and paralysis.

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34
Q

What are the symptoms of thalassemia?

A

Anaemia.

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35
Q

What are the symptoms of sickle cell anaemia?

A

Anaemia.

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36
Q

What are the symptoms of galactosaemia?

A

Kidney failure.

Hepatomegaly.

Cataracts.

Poor growth.

Mental retardation.

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37
Q

What is the term sickle cell disease used to describe?

A

A group of disorders which are individually known as sickle cell anaemia and β thalassaemia.

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38
Q

What kind of genetic disorder is sickle cell disease?

A

An autosomal recessive.

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39
Q

What gene is affecteed in sickle cell disease?

A

The beta globin gene.

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40
Q

What is the beta globin gene used for?

A

It helps to code for the synthesis of haemoglobin.

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41
Q

Where is the haemoglobin protein found?

A

Exclusively in red blood cells.

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42
Q

What is the function of haemoglobin?

A

It is responsible for binding to oxygen and transporting it around the body.

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43
Q

What kind of molecule is haemoglobin?

A

A tetramer.

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44
Q

How is the haemoglobin tetramer constructed?

A

It is made of 4 identical subunits.

2 alpha subunits and 2 beta subunits.

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45
Q

People who have sickle cell anaemia will have mutant alles in which gene?

A

They will have 2 mutant alleles for the beta-globin gene.

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46
Q

What chromosome is the beta globin gene found on?

A

On chromosome 11.

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47
Q

What is product of the mutant alleles of the beta globin gene?

A

A defective haemoglobin protein.

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48
Q

What kind of mutation causes the mutant alleles in the beta globin gene?

A

A point mutation.

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49
Q

What amino acid does the G-A-G sequence of a normal beta gene result in?

A

Glutamic acid.

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50
Q

What amino acid does the G-T-G sequence of a normal beta gene result in?

A

Valine.

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51
Q

The amino acid that is affected by the mutation in the beta globin gene is which amino acid in the beta globin polypeptide?

A

The 6th amino acid.

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52
Q

How can the sickle cell induced change to the beta globin peptide be described in shorthand?

A

As GLU-6-VAL.

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53
Q

The beta globin gene codes for the strucutre of what part of haemoglobin?

A

The beta subunit.

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54
Q

How does the inclusion of valine instead of glutamic acid affect the beta globin protein in people with sickle cell?

A

It leads to massive conformational changes within the beta subunit when haemoglobin is not bound to oxygen.

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55
Q

What is the haemoglobin protein that is formed by sickle cell disease known as?

A

As haemoglobin S.

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56
Q

What does the shape of the haemoglobin S protein resemble?

A

A sickle.

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57
Q

When will the haemoglobin S protein resemble a sickle?

A

When it is in the de-oxygenated form.

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58
Q

The major effects of sickle cell anaemia are due to what?

A

The changes that arise in the structure of haemoglobin.

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59
Q

What is the usual shape of the haemoglobin protein?

A

A bi-concave disc.

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60
Q

Will haemoglobin S ever retain its usual bi-concave disc shape?

A

Only in the oxygenated state.

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61
Q

What causes the change in shape when haemoglobin S is de-oxygenated?

A

Because valine the protein chain to stiffen and distort.

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62
Q

How does sickle-shaped haemoglobin differ from regular haemoglobin?

A

Sickle shaped haemoglobin is much less flexible than regular haemoglobin.

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63
Q

How can the inflexibilities of haemoglobin S affect the body?

A

They lead to blocked capillaries which causes the patient to suffer from pain and potential organ damage.

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64
Q

Do sickle-shaped haemoglobin cells tend to live longer than regular haemoglobin molecules?

A

Sickle-shaped haemoglobin cells die prematurely and this leads to a shortage of red blood cells and anaemia.

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65
Q

What is a common molecular technique that can be used to determine whether a person has sickle cell?

A

Allele specific oligonucleotides (ASO).

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66
Q

How do allele specific nucleotides help to detect sickle cell anaemia in a person?

A

It uses short sequences of DNA that are complimentary to the mutant allele that codes for sickle cell anaemia.

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67
Q

How can RFLP’s be used to detect for sickle cell anaemia?

A

Restriction enzymes are used to cleave restriction sites on DNA.

The size of the cleaved fragments will determine whether a person has sickle cell or not.

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68
Q

What are the 2 restriction enzymes that are used in RFLP when detecting sickle cell anaemia?

A

MST-II and D-DEL

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69
Q

How is pre-natal diagnosis of sickle cell performed?

A

By fluorescent in situ hybridisation (FISH).

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70
Q

How does FISH detect the alleles that code for sickle cell?

A

It uses small oligonucleotides to bind to specific DNA sequences and once bound they give off a signal in the form of radiation or fluorescence.

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71
Q

What are the 4 recommended ways of managing sickle cell anaemia?

A

Prevention of tissue de-oxygenation.

Keep well hydrated.

Avoid sources of infection.

Seek out medical attention when sick.

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72
Q

What are 4 current methods that are used to treat sickle cell anaemia?

A

Gene therapy.

Medication.

Bone marrow transfusion.

Medication.

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73
Q

What is a method of correcting sickle cell disease that has initially proven to be very successful?

A

Via the creation of a therapeutic transgene via RNA interference.

This transgene can produce the normal haemoglobin and suppress the generation of haemoglobin S.

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74
Q

Autosomal dominant disorders are caused by what?

A

The presence of a single dominant allele which codes for the disease.

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75
Q

How many alleles does a person need to recieve if they are to exhbit an autosomal dominant disorder?

A

One dominant allele that can come from either parent.

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76
Q

What is the only genotype that a person can have if they are not to express an autosomal dominant disorder?

A

They must be homozygous recessive for the trait that causes the disease.

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77
Q

Will autosomal dominant disease have any carriers?

A

No.

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78
Q

What are 5 common autosomal dominant diseases?

A

Huntingdons disease.

Myotonic dystrophy.

Familial hypercholesterolaemia.

Familial breast cancer.

Familial Alzheimers disease.

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79
Q

What are the symptoms of Huntingtons disease?

A

Involuntary movements.

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80
Q

What are the symptoms of myotonic dystrophy?

A

Myotonia.

Heart defects.

Cataracts.

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81
Q

What are the symptoms of familial hypercholesterolaemia?

A

Premature heart disease.

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82
Q

What is Huntingtons disease caused by?

A

A genetic mutation that is found on chromosome 4.

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83
Q

What is a normal feature of chromosome 4?

A

The presence a repetition of the triplet code CAG.

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84
Q

Are the number of CAG repeats on chromosome 4 the same in every person?

A

No.

The overall number of repetitions varies from person to person.

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85
Q

What is the usual number of CAG repeats in a person that is not affected by Huntingtons disease?

A

Between 10 and 26 times.

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86
Q

How many CAG repeats do people with Huntingtons disease have?

A

An abnormally high number of CAG repeats, usually 40 or more.

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87
Q

What kind of people are said to be in the pre-mutation range for sickle cell anaemia?

A

People who contain between 27 and 41 CAG repeats are said to be in the pre-mutation range for Huntingdons.

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88
Q

Will people in the pre-mutation range for sickle cell anaemia suffer from the disease?

A

They will not suffer from the disease, but their children have an increased chance of being born with the disease.

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89
Q

Will the amount of CAG repeats change in each generation of a family?

A

The amount of CAG repeats can change in size between generation, but it will commonly increase in size when it is inherited from the father.

90
Q

What does the increased presence of CAG repeats lead to?

A

The production of the huntingtin protein.

91
Q

How is the huntingtin protein that is produced by people with Huntingtons disease abnormal?

A

It contains an abnormal number of glutamines at the N-terminal.

92
Q

How does the presence of an abnormal number of glutamines at the N-terminal of the huntingtin protein affect the overall protein?

A

They are thought to disrupt the normal function of the huntingtin protein.

93
Q

What is the normal function of the huntingtin protein?

A

It will deliver small packages that contain important molecules to extracellular locations.

94
Q

When does the modified huntingtin protein become defective?

A

When cellular enzymes try to remove the glutamine residues.

95
Q

How does the removal of gluatmine residues from a defective huntingtin protein affect the protein?

A

The removal of glutamines leaves sticky ends.

This allows multiple proteins to bind to each other and form large protein clumps.

96
Q

What cells tend to be affected when multiple Huntingtin proteins form protein clumps?

A

Nerve cells and this causes the nerve cells to not function properly.

97
Q

How does Huntingtons disease affect the body?

A

As Huntingtons disease affects more and more nerve cells, it will eventually lead to neural degeneration.

98
Q

What part of the brain is often affected by Huntingtons disease?

A

The part of the brain that is responsible for thinking, emotion and movement.

99
Q

What is one of the first symptoms of Huntingtons disease?

A

An inability to recognise disgust in others.

100
Q

What is a common symptom that appears later in Huntingtons disease?

A

An inability to control body movement and this results in random, uncontrollable, rapid movements.

101
Q

What are other notable symptoms of Huntingtons disease?

A

Slurred speech and very slow movements.

102
Q

What will affect the onset of the symtoms of Huntingtons disease?

A

The greater the number of CAG repeats on chromosome 4, the earlier the symptoms of Huntingtons will appear.

103
Q

What molecular techniques are commonly used to diagnose Huntingtons disease?

A

PCR and electrophoresis.

104
Q

What is the first step of using PCR and electrophesis to detect Huntingtons disease?

A

A blood sample is removed from a patient and the genetic region that contains the gene for Huntingtons is amplified via PCR.

105
Q

What is the second step of using PCR and electrophesis to detect Huntingtons disease, after the gene has been amplified by PCR?

A

Restriction enzymes will cleave specific sequences that are then analysed after electrophoresis.

106
Q

What is the second step of using PCR and electrophesis to detect Huntingtons disease, after electrophoresis takes place?

A

The products can be analysed against standard markers that contain a threshold limit for the amount of CAG repeats.

107
Q

How can Huntingtons disease be diagnosed from the analysis of the electrophoresis products of the CAG repeats on chromosome 4?

A

If a sample where the amount of CAG repeats exceeds the threshold then they will have Huntingtons disease.

Those that do not pass the threshold will not suffer from the disease.

108
Q

What is the best method of managing Huntingtons disease?

A

Via medications that help to relive the symptoms of depression and other medications that help to control the involuntary movements.

109
Q

What is a promising technique that might be able to cure Huntingtons disease?

A

Via gene therapy through the use of RNA interference.

110
Q

What do sex linked genetic disorders arise from?

A

From malfunctioning genes that are located on the sex chromosomes.

111
Q

What are the 3 basic subcategories that sex linked genetic disorders can be divided into?

A

X linked recessive disorders.

X linked dominant disorders.

Y linked disorders.

112
Q

What are X linked recessive disorders caused by?

A

By 2 recessive mutated alleles on the X chromosomes.

113
Q

X linked disorders are much more likely to affect what kind of people?

A

They are more likely to affect males than females.

114
Q

Why are X linked recessive disorders much more likely to affect males rather than females?

A

Because males only have a single X chromosome and this means that any X linked disorders will be displayed.

115
Q

Why are X linked recessive disorders less likely to affect females?

A

Females have 2 X chromosomes, meaning that the bad allele can be masked by a good allele on the other X chromosome.

116
Q

Females that have 1 faulty X chromosome are referred to as what?

A

As carriers.

117
Q

What kind of females will be affected by X linked recessive disorders?

A

Females with 2 faulty X chromosomes.

118
Q

What offspring will be created if a male with an X linked recessive disorder mates with a carrier female?

A

All of their female children will be carriers or affected.

The male children will either be affected or unaffected.

119
Q

Why will male children either be affected or unaffected from the mating of a male with an X linked recessive disorder and a carrier female?

A

It depends on which parent they receive their X chromosome from.

120
Q

If a man is affected by X linked dominant disorder, how will this affect his daughters, regardless of the females genotype?

A

All of his daughters will inherit the disease as they have to inherit his X chromosome.

This trait will dominate any recessive traits on the X chromosome that they inherit from their mother.

121
Q

If a man is affected by X linked dominant disorder, how will this affect his sons, regardless of the females genotype?

A

They will only inherit the disease if the mother suffers from the disease.

122
Q

Why can sons only inherit an X linked dominant disorder from their mother?

A

Because males inherit the Y chromosome from their father and the X chromosome from their mother.

123
Q

Why can a heterozygous woman give birth to a normal son, even if she suffers from an X linked dominant disorder?

A

If the mother only has a single dominant allele then it depends on which X chromosome is given to her son.

124
Q

How will a father that is affected by a genetic disorder on the Y chromosome pass on the disease?

A

They will pass this disease on to all of their sons.

125
Q

What is severe combined immune deficiency (X-SCID) disease?

A

A genetic disorder that affects the X chromosome.

126
Q

What are 4 common X linked disorders?

A

Haemophilia A and haemophilia B.

Duchenne muscular dystrophy.

Fragile X-syndrome.

X linked severe combined immunodeficiency.

127
Q

What are the symptoms of haemophilia A and haemophilia B?

A

Prolonged bleeding following a cut.

128
Q

What are the symptoms of duchenne muscular dystrophy?

A

Muscle wastage in teenage years.

129
Q

What are the symptoms of fragile X syndrome?

A

Mental retardation.

130
Q

What are the symptoms of X linked severe combined immunodeficiency?

A

Recurrent and persistent infections.

131
Q

What causes X-SCID disease?

A

A mutation in the SCID-X1 gene which is located on the X chromosome.

132
Q

What does the SCID-X1 gene usually code for?

A

For a protein that is used to construct a receptor called the interleukin-2 receptor (IL2-RG).

133
Q

Where are IL2-RG receptors usually located?

A

In the plasma membranes of immune cells.

134
Q

What do the IL2-RG receptors usually produce?

A

A protein called cytokine receptor common gamma chain.

135
Q

Where is the cytokine receptor common gamma chain protein that is produced from the IL2-RG receptor usually found?

A

On the surface of various immune cells such as T cells, B cells and natural killer cells.

136
Q

How does the cytokine receptor common gamma chain protein affext the immune cells that it is found on?

A

It allows these cells to communicate with each other.

137
Q

How does X-SCID affect the IL2-RG receptor?

A

It leads to the formation of a faulty IL2-RG and this means that no cytokine receptor common gamma chain proteins are formed.

138
Q

What is the end result of X-SCID?

A

It means that immune cells cannot communicate with each other and this makes infections very difficult to fight.

139
Q

What 4 types of mutations can lead to X-SCID disease?

A

Missense mutations.

Nonsense mutations.

Insertions and deletions.

Splice defects.

140
Q

What is one of the best molecular methods that can be used to diagnose whether someone has X-SCID disease?

A

Via a sequence analysis.

141
Q

How is sequence analysis used to detect whether a person has X-SCID disease?

A

By analysing a persons IL2-RG gene, looking for the unique markers that indicate that the person has X-SCID.

142
Q

Autosomal recessive, autosomal dominant and sex-linked genetic disorders all affect how many genes?

A

1 single gene.

143
Q

What are the 2 subcategories that genetic heterogeneity can be divided into?

A

Allelic heterogeneity.

Locus heterogeneity.

144
Q

What is allelic heterogeneity caused by?

A

By different mutations that occur at the locus of a single gene and result in the same phenotype.

145
Q

How does allelic heterogeneity affect the phenotype?

A

Allelic heterogeneity means that multiple versions of a gene can lead to the same phenotypic outcome.

146
Q

What is genetic heterogeneity?

A

The different ways that genes can be expressed.

147
Q

What is an example of genetic heterogeneity?

A

There are over 1000 mutant alleles of the CFTR gene that can lead to cystic fibrosis.

148
Q

What is locus heterogeneity?

A

A form of heterogeneity that arises due to variations in unrelated genes that lead to a single disorder.

149
Q

How does locus heterogeneity affect a phenotype?

A

This form of heterogeneity leads to the same symptoms, but they are caused by different genes.

150
Q

What is an example of locus heterogeneity?

A

Retinis pigmentosa can arise as an autosomal recessive disorder, an autosomal dominant disorder or as an X-linked recessive disorder.

151
Q

What is penetrance?

A

The percentage of individuals that have a particular genotype which expresses the expected phenotype.

152
Q

How can the degree of penetrance be described?

A

As being complete or incomplete.

153
Q

What is complete penetrance?

A

It means that all individuals within a population carry the allele.

154
Q

What is incolmplete complete penetrance?

A

It means that only some individuals within a population carry the allele.

155
Q

What does the expressivity of a disease revolve around?

A

Around how severely the symptoms of the same disease are expressed.

E.g. 2 different people can have the same disease, but one person is less affected than the other person.

156
Q

What is mosacism?

A

When all of the cells of the body are not genetically identical.

157
Q

What will determine which genes are expressed if a person suffers from mosaicism?

A

Expression depends on the number of cells which contain the mutated DNA or the normal DNA.

158
Q

What symptoms will people who suffer from diseases that arise from mosaicism tend to exhibit when compared to the same disease that does not arise from moasicism?

A

People who suffer from mosaicism will experience fewer symptoms as the normal genes can mask some of the effects.

159
Q

What are phenocopy diseases?

A

Disease’s that mimic a genetic mutation but are actually caused by environmental factors.

160
Q

What would be an example of a phenocopy disease?

A

Heart disease.

As it can be caused by diet or lifestyle choices or by bad genes.

161
Q

What element can commonly affect or worsen some genetic disorders?

A

Environmental factors such as diet and exposure to sunlight.

162
Q

How is phenylketonuria affected by the environment?

A

People with this disease can’t metabolise phenylalanine, but if they avoid it in the diet they can live normal lives.

163
Q

How does anticipation affect genetic disorders?

A

By increase the severity of the genetic disorder over successive generations.

164
Q

What is a common example of a genetic disease that is complicated by anticipation?

A

Muscular dystrophy.

165
Q

How does genomic imprinting affect genetic disorders?

A

The severity of the disease is affected by the which parent transmitted the disease causing allele.

166
Q

What is genomic imprinting?

A

The preferential expression or repression of one parental allele.

167
Q

What is an example of how genomic imprinting can affect a disease?

A

A deletion of some genes on chromosome 15 of the father will result in Prader Willi syndrome.

The deletion of the same genes on the mothers chromosome will result in Angelmans syndrome.

168
Q

What can lead to multifactorial diseases?

A

An interaction between genetic factors, lifestyle factors such as smoking and environmental factors.

169
Q

Do multifactorial diseases arise due to a single genetic error?

A

No, they arise due to lifestyle factors which are combined with a genetic predisposition for developing a disease.

170
Q

Does dominance and recessivity have any influence over multifactorial diseases?

A

No.

E.g. If a person if pre-disposed to heart disease then factors such as diet will contribute to disease onset.

171
Q

Do environmental factors affect a single gene or multiple genes?

A

Environmental factors can affect several different genes and these genes each add something to the disease.

172
Q

Is obesity considered to be a multifactorial disease?

A

Yes.

As some people are genetically pre-disposed to be fat, but how fat they are depends on how much they eat.

173
Q

Why are multifactorial disorders likely to affect all members of the same family?

A

Because they all share the same environment and have a similar genome.

174
Q

Can multifactorial disorders can arise in children that are born from parents who do not exhibit the disease?

A

Yes.

175
Q

The recurrance of a multifactorial disorder being transmitted increases with what?

A

The number of family members that are affected by the disease.

176
Q

What kind of parents are more likely to pass on a multifactorial disease to their offspring?

A

A parent who has high penetrance of a multifactorial disorder.

177
Q

What practice increases the risk of breeding children that exhibit a multifactorial disease

A

Inbreeding or consanguinity.

178
Q

What are 4 common congenital complex disorders?

A

Neural tube defects such as spina bifida.

Congenital heart disease.

Cleft palate.

Mental retardation.

179
Q

What are 6 common complex disorders that appear in later life?

A

Rheumatoid arthritis.

Various cancers.

Epilepsy.

Multiple sclerosis.

Diabetes.

Kidney stones.

180
Q

What are 4 common complex psychiatric disorders?

A

Manic depression.

Alcoholism.

Dyslexia.

Alzheimers disease.

181
Q

When will chromosomal imbalances occur?

A

When a person suffers from addition or deletion mutations.

182
Q

What do addition or deletion mutations result in?

A

In genetic information being added to a chromosome, or genetic information being removed from a chromosome.

183
Q

What is a common way that DNA can be added or removed from a chromosome?

A

Translocation.

184
Q

What is translocation?

A

When a chromosome breaks up and the fragment joins another chromosome.

185
Q

What is a major chromosomal imbalance?

A

The addition or removal of an entire chromosome.

186
Q

What is the condition known as when a person has lost an entire chromosome?

A

Monosomy.

187
Q

What is the condition known as when a person has gained an extra chromosome?

A

Trisomy.

188
Q

What cellular process is affected by chromosomal imbalances?

A

Crossing over during meiosis.

189
Q

What are 2 chromosomal abnormalities that affect sex chromosomes?

A

Turners syndrome (45-X).

Kinefelters syndrome (47 XXY).

190
Q

What are 3 chromosomal abnormalities that affect sex autosomes?

A

Trisomy 21 (Downs syndrome).

Trisomy 18 (Edwards syndrome).

Trisomy 13 (Patau syndrome).

191
Q

What causes mitochondrial genetic disorders?

A

These genetic disease result due to mutations in mitochondrial DNA.

192
Q

What does the number of mitochondria in a cell usually depend on?

A

The energy requirements of that cell.

193
Q

What are common symptoms of mitochondrial disorders?

A

Often these diseases result in a person who cannot synthesise sufficient amounts of energy.

194
Q

What organ can be hugely affected by mitchondrial genetic disorders?

A

The heart.

195
Q

What are 3 common mitochondrial disorders?

A

Chronic progressive external ophthalmoloplegia (CPEO).

Pearsons syndrome.

Neurogenic muscle weakness ataxia and retina pigmentosa (NARP).

196
Q

What are the symptoms of chronic progressive external ophthalmoloplegia (CPEO)

A

Myopathy and paralysis of eye muscles.

197
Q

What are the symptoms of Pearsons syndrome?

A

Muscular disorders.

198
Q

What are the symptoms of Neurogenic muscle weakness ataxia and retina pigmentosa (NARP)?

A

Muscle weakness.

Ataxia.

Blindness.

199
Q

What is DNA profiling?

A

A method that is used differentiate between individuals of the same species through the use of DNA.

200
Q

What was DNA profiling originally called?

A

DNA fingerprinting.

201
Q

What DNA regions are used to identify a person in DNA profiling?

A

Variable nucleotide tandem repeats (VNTRs).

Standard tandem repeats (STRs).

202
Q

Why are VNTR’s and STR’s used for DNA profiling?

A

Because they are unique to a particular person.

203
Q

Who coined the term DNA fingerprinting?

A

Alec Jeffreys.

204
Q

Who are the only people on the planet that will have identical VNTRs and STRs?

A

Identical twins.

205
Q

How do scientists determine whether genetic sample matches to the DNA of a suspect?

A

Therey can see if the VNTRs and STRs in the sample match to those from different individuals.

206
Q

If the VNTRs and STRs of a suspect mataches the VNTRs and STRs of a sample what does this indicate?

A

That the DNA sample came from that individual.

207
Q

What is the first step of DNA fingerprinting?

A

To extract DNA from various cells.

208
Q

What is the second step of DNA fingerprinting, after DNA has been extracted from a cell?

A

The extracted DNA is cut with restriction enzymes and the fragments are separated by gel electrophoresis.

209
Q

What is the third step of DNA fingerprinting, after electrophoresis has taken place?

A

The results from electrophoresis undergo Southern blot.

The double stranded DNA strands are then denatured to form single stranded DNA.

210
Q

What is the fourth step of DNA fingerprinting, after the DNA strands have been denatured to form single stranded DNA?

A

A probe is used to hybridise to specific DNA sequences and this marks the DNA of interest.

These fragments contain a sample of VNTRs and STRs which can be analysed and compared to samples.

211
Q

What can DNA fingerprinting be used for?

A

To identify suspected criminals.

To identify the parents of a child.

To identify long dead human remains.

212
Q

Why is mitochondrial DNA often studied in crimes that have remained unsolved for a long period of time?

A

It allows scientists to make comparisons between the unidentified remains of a person and a suspected maternal relative.

213
Q

Can Y chromosomes be analysed to identify a persons remains?

A

Yes.

214
Q

What are DNA databanks?

A

They store samples of DNA from crime scenes so that they can be used to identify potential suspects of a crime.

215
Q

What DNA databank is used to store crime scene DNA in the UK?

A

The National DNA database.

216
Q

What genetic information is contained in the National DNA database?

A

The DNA profiles of people who are suspected of or charged with a particular crime. T

217
Q

What is the collective name for the 2 DNA databanks that are used to store crime scene DNA in the USA?

A

The Combined DNA Index System (CODIS).

218
Q

What 2 database’s make up CODIS?

A

The Forensic Database and the Convicted Offender Index.

219
Q

What information is stored in the forensic database?

A

DNA profiles that have come from crime scenes.

220
Q

What information is stored in the convicted offender database?

A

The DNA of individuals that have been convicted of violent crimes.

Molecular Biology. (22 decks)

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