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BIOL 311 > Chapter 17 > Flashcards

Chapter 17 Flashcards

1
Q

What is a euploid?

A

This is an organismt that possesses the normal number of sets of chromosomes it is the base line.

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2
Q

What is an aberrant euploid?

A

This is a mutation where there are more or fewer sets of chromosomes that the organism possesses.

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3
Q

What are polyploids?

A

These are organisms that possess 2 or more sets of chromosomes than a euploid.

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4
Q

What is the haploid chromosome number?

A

This is the number of sets of chromosomes that a haploid possesses.

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5
Q

What is a monoploid?

A

This is a mutation where a traditional diploid organism has half of the number of sets of chromosomes that it usually would have.

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6
Q

What is the difference between monoploid and haploid?

A

Haploids exist with half the number of sets of chromosomes compared to a diploid but a monoploid is a mutation that forces the diploid to have less.

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7
Q

What is parthenogenesis?

A

This is the process in which the monoploid organisms develop whereby there is an unfertilized specialized egg that develops to form the organism.

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8
Q

Why is it that monoploids often do not survive?

A

This is because the genetic load is no longer masked by the wild type phenotype thus causing the mutation to have a larger effect.

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9
Q

What is the genetic load?

A

This is the build up of deleterious mutations in the genome.

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10
Q

How do monoploids produce gametes?

A

Through mitosis

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11
Q

What are autopolyploids?

A

These are organisms whose single genome doubled.

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12
Q

What are allopolyploids?

A

These are organisms that are a result of the union of the gametes and then it doubles. Also the union of the gametes is between related species and the result is homolegous chromosome pairs.

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13
Q

What is the difference between the autopolyploids and the allopolyploids?

A

The difference is that for autopolyploids their entire genome is doubled however the allopolyploids are a result of related species first mating and then producing a zygote which is then doubled.

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14
Q

What are homoleogous chromosomes?

A

These are chromosomes which are are parially homologous.

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15
Q

Why do these ploidy problems occur?

A

It is a result of homologous chromosomes that fail to separate correctly or pair up correctly during Anaphase I or Prophase I of meiosis respectively.

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16
Q

What is another cause of polyploidy (spindle)?

A

The failed connection of the spindle fibres to the kinetochores therefore the failed division of the chromosomes into the gametes.

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17
Q

What is an aneuploid?

A

This is an organism that has an alteration made to part of the genome a couple of chromosome sets from the wild type differ not the entire genome like abberant euploids.

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18
Q

What is nondisjunction?

A

This is the process of chromosomes or chromatids failing to separate during anaphase of meiosis or mitosis. However, when it occurs in meiosis it impacts the entire organism where as if it occurs in mitosis then it is only impacting whatever that chromosome encodes due to the spindles not connecting to the kinetochores.

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19
Q

What are the 2 procedures that help to form a normal disjunction process?

A

1.) Crossing over
2.) The chiasma crossing over

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20
Q

What is monosomy?

A

This is when a chromosome is lost and an example of this would be Turner Syndrom XO where females lack certain feminine traits.

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21
Q

What is trisomy?

A

This is when there is an additional chromosome such as Klinefelter Syndrome where men lack masculinity.

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22
Q

Why is aneuploidy sever is certain cases and less in others?

A

This is due to gene balance.

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23
Q

What is gene balance?

A

The 1:1 relative proportion of genes in the genome.

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24
Q

What is the gene dosage effect?

A

This is the result of relationship between the number of genes and the amount of product the more genes there are to transcribe the more products will be produced.

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25
Q

Why are monosomic more detrimental than trisomic?

A

Similar to monoploids there is only one gene copy left so the deleterious recessive mutation is stronger than it would be since it can’t be masked by the wild-type.

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26
Q

What are rearrangements?

A

These are changes in the chromosome structure.

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27
Q

How can rearrangements occur?

A

Through crossing over or changes made to the chromosome structure.

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28
Q

What is a deletion?

A

Removal of DNA segment.

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29
Q

What is an inversion?

A

Change in the DNA segment’s orientation.

30
Q

What is a translocation?

A

Moving a DNA segment to another location on the chromosome.

31
Q

What is a duplication?

A

Addition of a DNA segment.

32
Q

How can double stranded breaks be artificially induced?

A

Through high energy radiation such as X-rays or gamma rays.

33
Q

When rejoining the double stranded breaks is it possible for there to be no rearrangement?

A

Yes, if the broken ends of the same breaks are joined then the original is restored if different breaks are joined then the rearrangement occurs.

34
Q

How can repetitive DNA sequences and crossing over lead to rearrangement?

A

There is ambiguity when there are repetitive DNA sequences and if they are on different loci of the homologs when crossing over occurs then there would be deletions, inversions, and translocations.

35
Q

What is unequal crossing over?

A

Non-allelic homologous recombination

36
Q

What are acentric chromosomes?

A

These are chromosomes that lack a centromere therefore they do not get inherited.

37
Q

What is a deletion loop?

A

This is the result of pairing a normal chromosome with a chromosome that has a deleterious mutation.

38
Q

What can often happen to the recessive phenotype in deletions?

A

They become unmasked and are therefore more dominant.

39
Q

What are the 3 steps to inverted genes?

A

Cutting, flipping, and reinserting

40
Q

What are inversion loops?

A

These are twisted loops that form in meiosis when a normal chromosome and an inverted chromosome form a homologous chromosome pair.

41
Q

What is the pericentric inversion?

A

When the inverted segment includes the centromere.

42
Q

What is the paracentric inversion?

A

When the inverted segment does not include the centromere.

43
Q

What is the chance of recombinant frequency in long inversions?

A

The chance of crossing over occurring within the same chromosome is more likely and therefore there is a higher likelihood of producing inviable gametes.

44
Q

What is the result of pericentric and paracentric for the zygote?

A

When crossing over occurs the chromosomes will contain deletions and duplications so, when fertilized the zygote will be inviable.

45
Q

What is the result of the chromatids in viable offspring?

A

This can only occur when there is no crossing over in the organism then the progeny will survive.

46
Q

What else can the inversion loop impact for neighbouring genes?

A

The chance of crossing over.

47
Q

How does the reciprocal translocation occur?

A

This is when there are 2 double stranded cuts that are made in the DNA and then those segments are traded.

48
Q

What is translocation most similar to?

A

Gene linkage and as a result only the parental genotypes can survive the recombinants will die due to the unbalanced genome.

49
Q

What is semisterility?

A

In plants it exists as 50% of the time the gametes will be produced. In animals it exists as the gametes will be produced but the zygote will be lethal so 50% of its life.

50
Q

What are karyotypes?

A

These are visual depictions of the genome of a species.

51
Q

How are speciation and karyotypes related?

A

If the species are closely related there will only be a few differences in the karyotype between them however if the species are not closely related there will be more differences between the karyotypes.

52
Q

What is pseudodominance?

A

This is when the recessive allele becomes dominant since the dominant wild type was deleted.

53
Q

What are the results if a complementation test is used for a heterozygous mutations?

A

Mutant phenotype => The gene is in the deleted region
Wild-type phenotype => The gene is outside the deleted region

54
Q

Can recombination occur in the deletion loop?

A

No, recombination only occurs in homologous regions.

55
Q

What are some of the ways that duplications can occur?

A
  • Tandem
  • Nontandem
    • Normal
    • Same order
    • Reverse order
56
Q

What are the different levels of duplication from most to least severe?

A

1.) The entire genome duplicates
2.) Entire genes duplicate and multigene families are created
3.) Gene families are duplicated and form superfamilies
4.) Exons (DNA coding regions) are duplicated regions are duplicated

57
Q

At what location are inversions or translocations the most impactful on the gene balance?

A

When the inversion or tanslocation is in the middle of the chromosome if its on the ends it can go undetected.

58
Q

When will the results of paracentric and pericentric be viable?

A

If the parental chromsome forms.

59
Q

What is a reciprocal translocation?

A

This is when there is a chromosomal break in 2 different chromosomes and then there is a mutual exchange of broken fragments between the chromosomes similar to crossing over.

60
Q

What is the difference between crossing over and reciprocal translocation?

A

Crossing over is the exchange of genetic material between homologous chromosomes but reciprocal translocation occurs between non-homologous chromosomes.

61
Q

What is a Robertsonian translocation?

A

This is when chromosomal breaks occur near or at the centromeres of 2 acrocentric chromosomes. The result is 1 long metacentric chromosome and 1 small chromosome which is usually lost.

62
Q

What is the difference between the Robertsonian and reciprocal translocation?

A

The Robertsonian and reciprocal translocation both occur due to a break in the chromosome however for the Robertsonian it is at or near an acrocentric chromosome and the reciprocal it is just on a nonhomologous chromosome. The fragments are then exchanged however the result of the reciprocal is just 2 chromsomes with mixed regions while the Robertsonian forms 1 metacentric long chromsome and 1 short chromosome that is lost.

63
Q

Do reciprocal translocations alter the phenotype?

A

No, because the gene balance is not changed.

64
Q

Translocation can lead to oncogene activation what is this?

A

An oncogene is a mutated gene that leads to increased cell division and can lead to cancer formation through a tumor.

65
Q

Can homozygote translocation chromosomes undergo meiosis 1 normally?

A

Yes, so long as the reciprocal translocation breakpoints do not affect the gene.

66
Q

What happens when a translocated heterozygote is crossed with a normal homozygote chromsome?

A

There are 2 viable gametes and 4 inviable options.

67
Q

What is the adjacent -1 segregation?

A

It is a way for the heterozygous (1 wild-type and 1 translocated chromosome) reciprocal translocation chromosomes to be separated to the poles of the cell or undergo anaphase the products however are inviable because each chromosome arm is lacking in something else.

68
Q

What is the alternate segregation?

A

When 2 heterozygous chromosomes are crossed there are 2 wild-type and 2 reciprocally translocated when the 2 wild-type are separated they go to one pole and the translocated go to another pole in which case the products are balanced and viable.

69
Q

Since the alternate segregation and adjacent-1 segregation are even in number what happens to 50% of the population?

A

50% of the gamete population will be semisterile

70
Q

What is pseudolinkage?

A

This is when the genes on translocated chromosomes which are nonhomologous chromosomes appear to be linked.

BIOL 311 (12 decks)

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