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Semester 1 > MGD S5 - Inheritance of Genes > Flashcards

MGD S5 - Inheritance of Genes Flashcards

1
Q

List the stages of the cell cycle

A

1) Interphase - G0, G1, S, G2
2) Mitosis
3) Cytokinesis

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2
Q

What happens in the G1 phase of the cell cycle?

A

Metabolic changes prepare the cell for division. At a certain point - the restriction point - the cell is committed to division and moves into the S phase

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3
Q

What happens in the S phase of the cell cycle?

A

DNA synthesis replicates the genetic material. Each chromosome now consists of two sister chromatids

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4
Q

What happens in the G2 phase of the cell cycle?

A

Metabolic changes assemble the cytoplasm materials necessary for mitosis and cytokinesis

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5
Q

What happens in the mitosis phase of the cell cycle?

A

A nuclear division (mitosis) followed by a cell division (cytokinesis)

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6
Q

What are the 5 stages mitosis is conventionally split into?

A

1) Prophase
2) Prometaphase
3) Metaphase
4) Anaphase
5) Telophase

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7
Q

What occurs during Prophase?

A
  • The nuclear membrane breaks down to form a number of small vesicles and the nucleolus disintegrates
  • The centrosome duplicates itself to form two daughter centrosomes that migrate to opposite ends of the cell
  • The centrosomes organise the production of microtubules that form the spindle fibres that constitute the mitotic spindle
  • The chromosomes condense into compact structures
  • Each replicated chromosome can now be seen to consist of two identical chromatids (sister chromatids) held together by a centromere
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8
Q

What occurs during prometaphase?

A
  • The chromosomes , led by their centromeres, migrate to the equatorial plane in the mid-line of the cell, at right angles to the axis formed by the centrosomes
  • The region of the mitotic spindle is known as the metaphase plate
  • The spindle fibre bind to a structure associated with the centromere of each chromosome called a kinetochore
  • Individual spindle fibres bind to a kinetochore structure on each side of the centromere
  • The chromosomes continue to condense
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9
Q

What occurs during metaphase?

A

The chromosomes align themselves along the metaphase plate of the spindle apparatus

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10
Q

What occurs during anaphase?

A

The shortest stage of mitosis

  • The centromeres divide, and the sister chromatids of each chromosomes are pulled apart and move to opposite ends of the cell, pulled by spindle fibres attached to the kinetochores regions
  • The separated sister chromatids now referred to as daughter chromosomes note
  • It is the alignment and separation in metaphase and anaphase that is important in ensuring that each daughter cell receives a copy of every chromosome
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11
Q

What happens during telophase?

A

The final stage of mitosis, and a reversal of many of the processes observed during prophase

  • The nuclear membrane reforms around the chromosomes grouped at either pole of the cell
  • The chromosomes uncoil and become diffuse, and the spindle fibres disappear
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12
Q

What happens during cytokinesis?

A

The final cellular division to form two new cells

  • There is a constriction of the cytoplasm
  • The cell then enters interphase
  • The interval between mitotic division
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13
Q

Define meiosis

A

A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes

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14
Q

What two processes creates genetic diversity during meiosis?

A

1) Crossing-over
2) Independent assortment of chromosomes

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15
Q

Define crossing-over

A

The exchange of genetic material between homologous chromosomes that occurs during meiosis and contributes to genetic variability

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16
Q

Define independent assortment

A

The principle of how different genes independently separate from one another when reproductive cells develop giving different traits an equal opportunity of occurring together

17
Q

When does independent assortment occur?

A

Metaphase I

18
Q

Define genotype

A

The genetic make-up of an individual

19
Q

Define phenotype

A

All observable characteristics of an individual or the expressed trait as a result of the genetic make-up of one (or more) specific genetic locus (loci)

20
Q

What environmental factors have an influence on both genotype and phenotype?

A
  • Radiation
  • Mutagens
  • Chemicals that can affect cell growth
  • Diet
  • Life-style
21
Q

Define gene

A

A unit of hereditary; a length of DNA on a chromosome that contains the code for a protein

22
Q

Define allele

A

An alternative form of a gene; each individual has two alleles for every gene, which can either be the same or different

23
Q

What is autosomal inheritance?

A

When the gene inherited is located on an autosome (not a sex chromosome)

24
Q

What is sex linked inheritance?

A

When the gene in question is located on a sex chromosome

25
Q

An example of an X-linked dominant disease?

A

Hypophosphatemic rickets

26
Q

An example of an X-linked recessive disease?

A

Haemophilia, Duchenne muscular dystrophy

27
Q

What is the inheritance pattern of Y-linked inheritance?

A

Quite rare, when the gene in question is located on the Y-chromosomes and inherited directly from father to son

28
Q

What is dominant trait (genetics)?

A

A phenotypic trait is dominant when it occurs in both homo and heterozygotes

29
Q

What is a recessive trait (genetics)?

A

A phenotypic trait is recessive when it occurs only in the homozygote

30
Q

What is co-dominance?

A

When both alleles are expressed in the phenotype of a heterozygote Eg AB blood type

31
Q

What is complementation?

A

More than one gene is responsible for the phenotype. A general definition is the ability of two mutants in combination to restore normal phenotype Eg - albinism

32
Q

If two genes are on two different chromosomes they show _______ ________ during meiosis. This is not the case if two genes are close together on the same chromosome. Such genes are said to be _____ and _-__________ However the process of ______ _____ and _______ can result in two linked alleles being separated during meiosis

A

Independent assortment

Linked and co-segregate

Crossing over and recombination

33
Q

What are the four most common modes of genetic transfer?

A

1) X-linked dominant
2) X-linked recessive
3) Autosomal dominant
4) Autosomal recessive

34
Q

What is the inheritance pattern of an X-linked dominant trait?

A
  • Men must always be affected
  • Only one X chromosome
  • Daughter of sufferer must also be affected as father only has the affected X gene to pass on
35
Q

What is the inheritance patter of an X-linked recessive trait?

A

Men always affected - only one X chromosome

36
Q

What is a genetic map?

A

The arrangement and distance between genes on a chromosome deduced from studies of recombination. The frequency of recombination between two loci can give information with respect to how close these loci are to each other 1 map unit = 1% recombination

Semester 1 (37 decks)

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