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Phase 1 > IMMS: Week 1 > Flashcards

IMMS: Week 1 Flashcards

1
Q

Describe the structure of DNA

A

Double helix which complementary base pairing (A-T + G-C) -> nucleosomes -> supercoils -> chromosomes

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2
Q

How many chromosomes are there in an individual

A

46

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3
Q

What is an autosomal chromosome

A

One that is not sex-determining

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4
Q

What are the sex chromosomes in males and females

A

Males - XY and Females - XX

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5
Q

What is a karyotype

A

The number and appearance of a chromosome in a cell, arranged in order of size

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6
Q

How are chromosomes arranged in a karyotype

A

Pair 1 is the LARGEST, pair 22 is the SMALLEST, sex pair is 23

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7
Q

How many base pairs does each DNA duplex have

A

10^7 base pairs

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8
Q

How many genes do we have

A

22,000

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9
Q

Describe the arms of a chromosome

A

Each has a p (small) and a q (long) arm

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10
Q

What is mitosis

A

The division of a parent cell into two identical diploid daughter cells

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11
Q

What is DNA not in replication called

A

chromatin

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12
Q

What is DNA during replication called

A

Chromosomes

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13
Q

What is DNA following replication called

A

Chromatids

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14
Q

What stage of the cell cycle do we have to be in so mitosis can occur

A

Interphase

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15
Q

What is the longest phase of the cell cycle

A

Interphase

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16
Q

What happens in G1

A 
No visible activity:
Rapid Growth
Normal Metabolic Function
New Organelles produced
Protein synthesis of those involved in spindle formation
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17
Q

What happens in synthesis

A

DNA doubles through DNA replication
Histone proteins double through protein synthesis
Centrosome replication

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18
Q

What happens in G2

A

Chromosomes condense
Energy stores accumulate
Mitochondria and centrioles double

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19
Q

What happens in prophase

A

Chromatin condenses into chromosomes

Centrosomes nucleate microtubules and move to opposite poles of the nucleus

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20
Q

What happens in metaphase

A

Chromosomes line up along the equatorial plane

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21
Q

What happens in anaphase

A

Sister chromatids separate and are pushed to opposite poles of the cells, centromere first as spindle fibres contract

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22
Q

What happens in telophase

A

Nuclear membrane forms
Chromosomes unfold into chromatin
Cytokinesis begins

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23
Q

What happens in cytokinesis

A

Cell organelles are distributes evenly across the two daughter cells

Cytoplasm divides

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24
Q

What is Down Syndrome

A

An extra chromosome at 21 (trisomy 21)

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25
Q

How can we tell on histological slides if a cell is undergoing mitosis

A

Dark nuclei and if the nuclei are not all the same size

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26
Q

Is meiosis a cycle?

A

No

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27
Q

What is the product of meiosis

A

4 haploid daughter cells which are distinct from each other and the parent cell

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28
Q

Where does crossing over of sister chromatids occur

A

meiosis 1 when chromosomes pair up into homologous pairs

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29
Q

Where does random assortment of chromosomes occur

A

In metaphase 1

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30
Q

What is the product of oogenesis

A

One egg cell and two polar bodies

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31
Q

Define non-disjunction

A

Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division

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32
Q

Name the two types of non-disjunction

A

Failure of separation of homologous chromosomes - meiosis I

Failure of sister chromatids to separate - meiosis II

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33
Q

What condition can this result in

A

Down Syndrome

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34
Q

Define Gonadal mosaicism

A

When precursor germline cells are a mixture of two or more genetically identical cell lines

One cell line is normal, the other is mutated

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35
Q

How can incidence of gonadal mosaicism increase

A

Increasing paternal age

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36
Q

Is gonadal mosaicism more common in males or females

A

Males

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37
Q

Is the parent also affected with gonadal mosaicism. Explain your answer

A

No because it results from mutation of the germline and not via inheritance

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38
Q

What inheritance pattern is usually seen with gonadal mosaicism

A

Autosomal dominant or X-linked

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39
Q

How common are genetic diseases

A

Not very rare but enough for us to make services which tailor to these conditions

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40
Q

Four examples of genetic diseases

A

Huntingtons
Cystic Fibrosis
Downs Syndrome
Haemophilia

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41
Q

What are multifactorial diseases

A

A combination of genetic and environmental factors

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42
Q

What is the main type of disease affecting developed countries

A

Multifactorial

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43
Q

Four examples of multifactorial diseases

A

Diabetes
Spina Bifida
Cleft Lip
Schizophrenia

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44
Q

What is the main cause of disease in third world and A&E

A

Environmental

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45
Q

What chromosomes are autosomal

A

1-22 (No sex chromosome)

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46
Q

What is a locus

A

The position of a gene/DNA on the genetic map

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47
Q

What is a genotype

A

Genetic constitution of an individual

48
Q

What is a phenotype

A

Appearance of an individual which results from the interaction with the environment and genotype

49
Q

What is an allele

A

One of several alternative forms of a gene at a specific locus

50
Q

What is polymorphism

A

Frequent hereditary variations at a locus that do not cause problems.

51
Q

How can polymorphisms affect you

A

Makes you more/less efficient or make you more/less susceptible to disease

52
Q

Define consanguinity

A

Reproductive union between two relatives

53
Q

Define autozygosity

A

Homozygous by descent (inheritance of the same mutant allele through two branches of a family tree)

54
Q

Define homozygous

A

Both alleles at a specific locus are the same

55
Q

Define heterozygous

A

Alleles at a locus are different

56
Q

Define hemizygous

A

Describe that are carried on an unpaired chromosome (refers to X chromosome on a male)

57
Q

Define penetrance

A

Proportion of people with a gene/genotype who show the expected phenotype

58
Q

Define complete penetrance

A

Gene or genes for the trait are expressed in all the population

59
Q

Define incomplete penetrance

A

Gene or genes for the trait are expressed only in parts of the population

60
Q

Define variable expression

A

Variation in clinical features (type and severity) of a genetic disorder between individuals with the same gene alteration

61
Q

Define sex limitation

A

Expression of a particular characteristic limited to one of the sexes

62
Q

Define a multifactorial condition

A

Due to a combination of genetic and environmental factors

63
Q

Define late-onset

A

Condition that hadn’t manifested itself at birth

64
Q

Define autosomal dominant

A

A disease that only manifests itself in the heterozygous state

65
Q

Why can both parents be unaffected by a disease even if the son has it (3 reasons)

A
  1. Gonadal mosaicism
  2. Variable (incomplete) penetrance
  3. Only way to pass it is from male to male

These are all seen with autosomal dominant conditions

66
Q

Define autosomal recessive

A

A disease that manifests itself in the homozygous state only.

67
Q

What is the chance of an offspring getting the disease if its autosomal recessive

A

25%

68
Q

What is the chance of offspring being a carrier if its an autosomal recessive disease

A

50%

69
Q

What is the chance of a healthy sibling being a carrier

A

2/3

70
Q

What is the most common autosomal recessive disease in whites

A

Cystic Fibrosis

71
Q

Does cystic fibrosis have complete or variable penetrance

A

Variable

72
Q

Incidence of cystic fibrosis in the UK

A

1 in 25,000

73
Q

Define X-Linked inheritance

A

Caused by a mutation in genes on the X-chromosome

74
Q

Can an X-linked disease be passed on from father-to-son? and why?

A

No, never not even carriers

Because sons always get their X chromosomes from their mother

75
Q

What are all daughters from an affected male (X-Linked disease)?

A

Carriers

NOTE: All males will be unaffected

76
Q

What gender are X-linked disorders usually transmitted through

A

Females

77
Q

Define lyonisation

A

The process of X chromosome inactivation

78
Q

When is X chromosome inactivated

A

During embryological development

79
Q

Why is the X chromosome inactivated during lyonisation

A

Prevents them from having a double number of X chromosome gene products compared to males

ONLY ONE X chromosome will be functional

80
Q

What is a BARRBODY

A

Inactive X chromosome which is packaged in heterochromatin

81
Q

What is the result of packaging an X-chromosome into heterochromatin

A

Prevents it from being transcripted

82
Q

What is heterochromatin

A

Chromosome material of greater density than normal chromosome. Here the activity of genes are suppressed

83
Q

What is imprinting (non-mendelian)

A

For some genes only 1 out of 2 alleles are active, the other is inactive (could be either that the maternal or paternal allele is inactive)

84
Q

What is Knudson’s 2-hit hypothesis

A

Gene mutations may either be inherited or acquired during a person’’s life

85
Q

What causes a sporadic cancer

A

2 acquired mutations

86
Q

What causes hereditary cancers

A

1 inherited mutation + 1 acquired mutation

87
Q

What is an ‘ideogram’

A

Diagrammatic form of chromosome bands, bands are numbered according to distance to the centromere

88
Q

What is the mendelian classification of genetic disease

A

Autosomal dominant/recessive or X-linked

89
Q

What is a non-traditional genetic disease

A

Mitochondrial (all mitochondria is inherited by the mother), imprinting or mosaicism

90
Q

What is a square in a genetic pedigree

A 
Square = male
Circle = Female
91
Q

What is epithelia needed for

A

Protection, absorption and secretion

92
Q

What are four examples of supporting tissues

A

Blood, tendons, bones and cartilage

93
Q

What are three types of muscle

A

Smooth, skeletal and heart

94
Q

What does haematoxylin stain

A

Acids blue

95
Q

What does eosin stain

A

Alkaline pink

96
Q

What substances does haematoxylin stain

A

Cell nuclei and RNA blue

97
Q

What does eosin stain

A

Cytoplasm and colloidal proteins pink

Keratin - Orange/red

ECF

98
Q

Do water extra-cellular jelly and fat stain

A

No

99
Q

What does Alcian Blue stain

A

GAG rich structures blue

Goblet cells blue

Mast cell granules blue

Stain cartilage matrix blue

100
Q

What does iron haematoxylin stain

A

Nuclei and elastic fibres black

101
Q

What does PAS stain

A

Hexose sugars (e.g. goblet cell mucous cartilage matrix, glycogen, basement membrane and glycocalyx) pink

102
Q

What does touluidine blue stain

A

Nuclei, ribosomes and cytoplasm dark blue

Cartilage matrix and mast cell granules pale blue

GAG bright purple

103
Q

Role of the nucleus

A

Houses DNA as chromatin within the nucleolus

Nucleolus produces RNA

104
Q

Role of the mitochondria

A

Site of oxidative phosphorylation

Double membrane (highly folded inner)

105
Q

What happens in the outer membrane of the mitochondria

A

Lipid synthesis and fatty acid metabolism

106
Q

What happens in the inner membrane of the mitochondria

A

Respiratory chain (electron transport) ATP production

107
Q

What happens in the mitochondrial matrix

A

Krebs’ cycle

108
Q

What take place in the mitochondrial intramembranous space

A

Nucleotide phosphorylation

109
Q

Role of the RER

A

Site of protein synthesis

110
Q

Role of SER

A

Site of membrane lipid synthesis

Processes and stores synthesised proteins

111
Q

Role of the cis golgi

A

Receives SER vesicles and phosphorylates proteins

112
Q

Role of medial golgi

A

Modifies products by adding sugars (to form oligosaccharides) to lipids and peptides

113
Q

Role of the trans golgi network

A

Proteolysis of peptides into active forms and sorting of molecules into vesicles which bud from the surface

114
Q

Where is the golgi apparatus located

A

Close to the cell nucleus

115
Q

Can I see the golgi apparatus in most cells?

A

No, but seen clearly in plasma cells

Phase 1 (30 decks)

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