Chapter 4: Inheritance Flashcards

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1
Q

What is a gene?

A

A difined section of DNA sequence that encodes a gene product

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2
Q

What are the two different types of sequences found in a gene?

A

Coding sequence - encodes product
Regulatory sequence - Regluates expression of gene

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3
Q

What is a genome?

A

The entirety of an organism/cells genetic material

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4
Q

What is a genotype?

A

The genetic make-up of an individual relative to specific genes carrying.

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5
Q

What do genotypes give rise to?

A

Phenotypes

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6
Q

What is a phenotype?

A

An observable characteristic or trait of an organism produced due to a genotype.

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7
Q

When choosing a model organism for inheritance studies what should be considered?

A
  • Duration of reproductive and life cycle
  • Ease to breed
  • Cost of maintenance and breeding within a lab
  • Genome size
  • Ability to carry our RNA interference
  • Transparency of organism
    -Extent of experimental findings being extrapolated to other species
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8
Q

What does an organisms ‘Karyotype’ describe?

A

The charactertistic number of chromosomes within the nucleus of a species, and their appearance.

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9
Q

What kind of cells produce gametes?

A

Germ cells

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10
Q

What is the scientific name for body cells?

A

Somatic cells

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11
Q

Are somatic cells diploid of haploid?

A

Diploid

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12
Q

Are germ cells diploid or haploid?

A

Haploid

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13
Q

What does it mean if a cell/organism is haploid?

A

One copy of the genetic material

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14
Q

What does it mean if a cell/organism is diploid?

A

Two copies of the genetic material

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15
Q

What are heterosomes?

A

Sex chromosomes (X and Y)

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16
Q

What are non-sex chromosomes called?

A

Autosomes

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17
Q

What is the difference between X and Y chromosomes in terms of genes?

A

The X chromosome has many more genes than the smaller Y chromosome.

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18
Q

Through what process do prokaryotes replicate?

A

Binary fission

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19
Q

Is binary fission an example of sexual or asexual reproduction?

A

Asexual reproduction

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20
Q

Outline the steps of binary fission.

A
  1. Growth and elongation
  2. DNA replication
  3. Segregation of DNA through attachment to membrane and elongation
  4. Constriction of cell membrane
  5. Formation of cell wall
  6. Separation into two identical daughter cells
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21
Q

How would you describe the variation of daughter cells from the parent cells in binary fission?

A

Low variation. Daughter cells are clones of parent cell.

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22
Q

What are the two types of eukaryotic cell division?

A

Mitotic cell division (mitosis)
Meiotic cell division (meiosis)

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23
Q

The process of a diploid cell dividing to form two clone diploid daughter cells is known as what?

A

Mitosis

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24
Q

The process of a diploid germline prevursor cell dividing twice to form 4 haploid gametes is known as what?

A

Meiosis

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25
Q

What are the stages of the eukaryotic cell cycle and what occurs in each stage?

A

G1 Phase | Gap 1
Cell growth, number of organelles increase, preparation for DNA synthesis

S Phase | Synthesis
DNA replication

G2 Phase | Gap 2
Preparation for cell division

M Phase | Mitosis
Chromosomes condense, separate into two separate nuclei

~followed by Cytokinesis
in which the cytoplasm divided into two daughter cells

Cycle then starts again or enters G0 (Resting phase) until stimulated to re-enter G1.

26
Q

In cultured animal cells approximately how long does one complete cell division cycle take?

A

20 hours

27
Q

What are the stages of mitosis?

A

Prophase | Chromosomes condense, breakdown of nuclear membrane, spindle microtubules from poles attach to centromere of each chromosome

Metaphase | Chromosomes line up with centromeres aligned at the cells equator

Anaphase | Each centromere divides and each chromatid is drawn towards opposite poles, separating

Telophae | Spindle disassembles, new nuclear membranes form, chromosomes decondense

28
Q

Describe what happens during cytokinesi in mammilian cells.

A

A contractile ring formed of actin and myosin forms around cell equator, it contracts to form a cleavage furrow, the cell separates into two daughter cells

29
Q

Describe what happens during cytokinesis in plant cells.

A

Secretory vesicles from the golgi take cell wall and cell membrane components to the cells equator where they fuse to form cell plate which expands outwards and matures into two separate cell walls.

30
Q

What is Mitosis?

A

A phase of the eukaryotic cell cycle in which chromosomes separate into two separate nuclei, before the process of cytokinesis occurs.

31
Q

What is Meiosis?

A

A reductive form of cell division that results in the production of haploid daughter cells with half the number of chromosomes as the parent cell.

32
Q

How many nuclear divisions occur in meiosis?

A

2

33
Q

What are the stages of Meiosis?

A

Prophase I | Chromosomes condense, homologous chromosomes pair up, nuclear membrane breaks down, assembly of spindle microtubules.

Metaphase I | Chromosome pairs attach to spindle and line up at cell equator

Anaphase I | One homologous chromosome from each pair is drawn to each pole

Telophase I | New nuclear membranes form.

(Cytokinesis)

Prophase II | Nuclear membranes break down, reformation of spindles

Metaphase II | Chromosomes line up at equator

Anaphase II | Centromere divide, chromatins separate to opposite poles

Telophase II | Nuclear membranes form

(cytokinesis)

34
Q

What is synapsis (related to meisos)?

A

The pairing of homologous chromosomes that occurs prophase I of meiosis. Involved the synaptonemal complex (protein complex) which relies on DNA sequence similarity between paired chromosomes which agter lining up allows recombination.

35
Q

What causes the genetic diversity between individuals of a population?

A
  • Independent assortment of chromosomes due to different orientations when lining up during prophase
  • Re combination occuring between homologous chromosomes during prophase I
36
Q

In what phase of meiosis does independent assortment and recombination occur?

A

Prophase I

37
Q

What is independent assortment of chromosomes in meiosis determined by?

A

The lining up furing metaphase I and II

38
Q

How do you calculate the possible gamete genotypes of meiosis?

How do you use this number to calculate the number of zygotic combinations?

A

2^n, where n is the number of homologous chromosome pairs in the diploid parent cell

Square it

39
Q

What is recombination/crossing over?

A

The exchange of genetic material by the switching of sections between homologous chromosome pairs during prophase I of Meiosis I.

40
Q

What does the fusion of 2 gametes form?

A

A zygote

41
Q

If you inherit an allele from each parent, and they are homozygous, what does this mean the alleles are?

A

The same

42
Q

If you inherit an allele from each parent, and they are homozygous, what does this mean the alleles are?

A

Different

43
Q

What is a dominant allele?

A

An allele that determines the phenotype in a heterozygous cell

44
Q

What is a recessive allele?

A

An allele whose phenotype is repressed in a heterozygous cell

45
Q

What is codominance?

A

In which multiple different alleles contribute to the overall phenotype.

46
Q

When writing genotypes, in what situations would you use / and ; ?

A

/ is used when refering to a homologous chromosome pair

; is used when referring to different chromosomes

47
Q

What do the superscripts ‘+’ and ‘1’ imply when writing genotypes?

A

+ refers to a wild allele, or the standard ‘normal’ gene

1 refers to a mutant allele, many may exist

48
Q

What is independent assortment?

A

The random segregation of chromosomes during meiosis.

49
Q

What is linkage?

A

When two genes located on the same chromosome are not able to be independently assorted during genetic crosses.

50
Q

What is a new combination of genes seen in a gamete after meiosis known as?

A

Recombinants

51
Q

Is recombination frequency higher between two distant gene loci or two close gene loci?

A

Two distant loci

52
Q

If only males on a given pedigree have and carry a particular trait, what could be determined about the allele?

A

It is sex-linked and recessive

53
Q

Why is X-linked haemophilia predominantly seen in males?

A

Males only need to inherit one copy of the recessive allele that is present in the X chromosome, whilst females would need to inherit two copies.

54
Q

If a female has X-linked haemophilia, what can be determined about her mother and father?

A

Father has haemophilia and Mother is a heterozygous carrier

55
Q

Mitochondrial mutations are always mutated from which parent?

A

The mother

56
Q

Why are mitochondrial mutations mutated only from the mother?

A

There are no mitochondria in sperm but there are in an ovum.

57
Q

If a female has a mitochondrial DNA mutation what percentage of her children will also recieve that mutation?

A

100%

58
Q

What is dicontinuous variation?

A
  • distinct classes of phenotype (e.g., red or white eyes) with no intermediates
  • Monogenic inheritence (controlled by a single gene)
59
Q

What is continuous variation?

A
  • Non-distinct classes of phenotypes with many intermediates (e.g., intelligence)
  • Polygenic (controlled by many genes)
  • … that interact with environmental factors
60
Q

What do most human variations show: continuous or non-continuous variation?

A

Continuous