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MBCHB - PRINCIPLES 1 Summary > Genetics Summary > Flashcards

Genetics Summary Flashcards

1
Q

What contributes to disease?

A

Genes and environment

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2
Q

In what fashion do DNA strands pair up?

A

Antiparallel

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3
Q

What direction is DNA replicated and read?

A

5’ to 3’ direction

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4
Q

What type of backbone does DNA have?

A

Sugar-phosphate backbone

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5
Q

How are DNA strands wound?

A

By associating with proteins including Histones

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6
Q

What is the wound DNA structure called?

A

Chromosome

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7
Q

When does disease occur in relation to DNA replication?

A

DNA can be damaged during replication, disease occurs when repair mechanisms are defective

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8
Q

What joins Okazaki fragments together?

A

DNA ligase

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9
Q

What unzips DNA?

A

DNA helicase

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10
Q

What does Mitosis produce?

A

One diploid parent cell becomes two identical diploid daughter cells

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11
Q

What does Meiosis produce?

A

One diploid parent cell becomes 4 varying haploid daughter cells

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12
Q

What process produces genetic variation between cells produced via meiosis?

A

Crossing over

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13
Q

When is meiosis used?

A

Formation of gametes

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14
Q

What type of back bone does RNA have?

A

Ribose sugar backbone

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15
Q

What is central dogma?

A

DNA is transcribed into preRNA
PreRNA is spliced into mRNA
mRNA is translated into protein

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16
Q

How many bases encode 1 amino acid or stop codon?

A

3 bases

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17
Q

What are the possible sequence variations within a gene?

A

Changes in promoter sequence (marks where gene begins)
Changes in exon sequence

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18
Q

What are the possible sequence changes possible in DNA between genes?

A

SNPs (Single Nucleotide Polymorphisms)
Larger deletions or duplications

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19
Q

What are polymorphisms?

A

Any variation in human genome which has a population frequency of greater than 1%

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20
Q

Do polymorphisms cause disease?

A

Not in their own right but can predispose to common disease

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21
Q

What is a mutation?

A

Any heritable change in the human genome
Gene change that causes a genetic disorder

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22
Q

What is classical genetic disease?

A

One mutation sufficient to cause disease

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23
Q

What is multifactorial disease?

A

Multiple polymorphisms cause risk of disease

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24
Q

What is the chromosomal nomenclature of a normal female?

A

46 XX

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25
Q

What is the chromosomal nomenclature of a normal male?

A

46 XY

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26
Q

What is a balanced chromosomal rearrangement?

A

All chromosomal material is present

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27
Q

What is unbalanced chromosomal arrangement?

A

Extra or missing chromosomal material

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28
Q

What is aneuploidy?

A

Whole extra or whole missing chromosome

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29
Q

What is translocation?

A

Rearrangement of chromosomes

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30
Q

What condition is 47 XY +21?

A

Down’s syndrome
Trisomy 21

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31
Q

What condition is 47 XY +14?

A

Miscarriage
Trisomy 14

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32
Q

What condition is 47 XY +18?

A

Edward syndrome
Trisomy 18

33
Q

What condition is 45 X?

A

Turner syndrome

34
Q

What condition is 47 XXY?

A

Klinefelter syndrome

35
Q

What is Robertsonian translocation?

A

Long ends of two acrocentric chromosomes are stuck together end to end
Short ends are lost

36
Q

What does Microarray CGH detect?

A

Missing or duplicated chromosome

37
Q

What is PCR?

A

A small piece of human genome is amplified and sequenced to find mutations

38
Q

What is FISH?

A

Used to light up a specific sequence of chromosome

39
Q

Mutation
Promotor and splice site sequence changes causes

A

Stopping of transcription
Abnormal splicing

40
Q

Mutation
Base changing causing amino acid change causes

A

Change in protein sequence
May or may not reduce protein function

41
Q

Mutation
Premature stop codon causes

A

Shortened protein
May or may not reduce protein function

42
Q

Mutation
Insertion or deletion of bases

A

May or may not change protein produced

43
Q

What is a Mendelian disorder?

A

A disease that is caused by a change in a single gene

44
Q

Autosomal Dominant
How many generations are affected?

A

All generations

45
Q

Autosomal Dominant
What is the risk of affected child if parent affected?

A

50%

46
Q

Autosomal Dominant
How severe is disease?

A

Variable severity

47
Q

Autosomal Dominant
Is a particular sex more affected?

A

Both males and females are equally likely to be affected

48
Q

Autosomal Dominant
How many copies of gene are required to cause disease?

A

Only 1 copy of faulty required to cause disease

49
Q

Autosomal Recessive
How many copies of gene required to cause disease?

A

2 copies faulty gene are required to cause disease

50
Q

Autosomal Recessive
How many generations are affected?

A

Often only one generation is affected

51
Q

Autosomal Recessive
How likely is it that a child is affected if parents are carriers?

A

25%

52
Q

Autosomal Recessive
What increases likelihood of being affected by this disorder?

A

Consanguineous (incestuous) families

53
Q

Autosomal Recessive
What does this type of disorder cause?

A

Usually loss of function

54
Q

X-linked
Is this type of disorder dominant or recessive?

A

Recessive

55
Q

X-linked
What role does the Y chromosome play in this type of disorder?

A

Almost irrelevant

56
Q

X-linked
If a mother is a carrier, what is the chance of daughter being a carrier or son being affected?

A

50% chance of daughter being a carrier
50% chance of son being affected

57
Q

X-linked
If a father is affected, what is the chance of daughter being a carrier or son being affected?

A

50% chance daughter is affected
0% chance son is affected

58
Q

What is X-inactivation?

A

In females one of X chromosomes within each cell is randomly inactivated

59
Q

Why does X-inactivation occur?

A

Cell only required one working copy of the X chromosome

60
Q

Mitochondrial Disorders
Where is mitochondrial DNA inherited from?

A

Almost exclusively maternally

61
Q

Mitochondrial Disorders
What does mitochondrial DNA contain?

A

Genes for mitochondrial metabolic pathways and ribosomal RNAs

62
Q

Mitochondrial Disorders
Symptoms of this type of disorder

A

Myopathy - disease of muscle tissue
Diabetes
Deafness
Optic atrophy - damage to optic nerve
Stroke like episodes
Encephalitis - inflammation of brain

63
Q

What is haploinsufficiency?

A

Having only one copy of working gene is not enough

64
Q

What is a dominant negative?

A

Abnormal protein interferes with normal protein

65
Q

What is a Gain of function mutation?

A

A mutation activated gene

66
Q

Mendelian Disorders
What extent does environment contribute to disease?

A

Small environmental contribution

67
Q

Mendelian Disorders
What level is penetrance of this type of disorder?

A

High penetrance

68
Q

Multifactorial Disease
What role does genetic change play in risk of disease?

A

Just another risk factor

69
Q

Multifactorial Disease
What is the penetrance of one mutation in this type of disorder?

A

Low for any one mutation

70
Q

What does DNA methylation cause?

A

Modification of histones which represses transcription

71
Q

What does imprinting cause?

A

Differences in gene expression depending on whether the gene was maternally or paternally inherited

72
Q

What is Heteroplasmy?

A

Different daughter cells contain different proportions of mutant mitochondrial

73
Q

What characteristics are gained by cells on progression to cancer?

A

Proliferation
Evasion of immune system
Aquire vascular supply
Avoid apoptosis
Metastasis - development of secondary growths

74
Q

What genes are involved in cancer?

A

Oncogenes
Tumour suppressors
DNA repair genes
Drug metabolism

75
Q

Cancer
What is oncogenes role?

A

Switch on for cell division

76
Q

Cancer
What are tumour suppressors role?

A

Switch on to stop cell division

77
Q

Cancer
What is the role of Drug metabolism?

A

Genes that metabolise carcinogens

78
Q

What are mechanisms of gene activation?

A

Duplication of gene
Activation of gene promotor
Change in amino acid sequence

MBCHB - PRINCIPLES 1 Summary (5 decks)

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