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Genetics > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

What is genetic variation

A

The difference between members of the same species or different species

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2
Q

How can chromosomes vary in structure and number

A

Very in structure by segments of the chromosome being deleted, duplicated, or rearranged
They vary in number of individual chromosomes or number of chromosome sets

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3
Q

What is cytogenetics

A

Involves microscopic examination of chromosomes

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4
Q

What does cytogenetics allow for

A

Examining of chromosomal composition of a particular cell
Detection of individual with abnormal chromosomes
Allows a way to distinguish species

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5
Q

What three ways is cytogenetics used to classify chromosomes

A

Location of centromere
Size
Banding patterns

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6
Q

What is a karyotype

A

Micrograph that shows all chromosomes within a single cell arranged in standard fashion

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7
Q

What is G banding and what does it means when you have light or dark bands

A

When chromosomes are exposed to the giemsa stain
Dark bands are regions that heavily bind to dye
Light bands are regions that don’t bind to dye heavily

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8
Q

What is a deletion

A

Removes dna
Loss of chromosomal segment

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9
Q

What is a duplication

A

Adds dna
Repetition of chromosomal segment

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10
Q

What is an inversion

A

Flipped dna segments or change in direction

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11
Q

What is Translocation

A

Movement of DNA
Segment of one chromosome becomes attached to another chromosome

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12
Q

What is a simple translocation

A

Piece of chromosome attached to another chromosome

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13
Q

What is Reciprocal translocation

A

Two different types of Chromosomes exchange pieces and produce two abnormal chromosomes

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14
Q

When a chromosome is broken into pieces what happens

A

The part without the centromere is eventually lost
The remaining chromosome has a terminal deletion

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15
Q

What happens when a chromosome breaks in two places

A

The central fragment is lost and the two outer pieces reattach
This chromosome has an interstitial deletion

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16
Q

What do phenotypes depend on when it comes to deletions

A

The size of the deletion and the material deleted

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17
Q

What can repetitive sequences often cause

A

Misalignment between homologous chromosomes
If crossover occurs a nonallelic homo,goys recombination results

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18
Q

If you have a segment of dna with equal sizing, does a deletion of this segment or a duplication cause a more harmful affect

A

Deletion

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19
Q

What do small chromosomal duplications lead to

A

Formation of gene families

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20
Q

What is a gene family

A

Two or more genes in a single species derived from the same ancestral gene

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21
Q

What is a paralog

A

Homologous genes within a single species

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22
Q

What are globin genes

A

Encode subunits of proteins that bind oxygen
Different globulins are expressed in red blood cells during different developmental stages

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23
Q

What is copy number variation

A

Segment of dna that varies in copy number among members of the same species
Could be missing a gene of it could be a duplication

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24
Q

What are three possible reasons for copy number variations

A

Nonallelic homologous recombinations
Proliferation of transposable elements
Errors in dna replication

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25
Q

What is break points affect

A

Occurs within vital gene which separates it into two nonfunctional parts

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26
Q

What is position affect

A

Gene is repositioned in a way that alters gene expression

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27
Q

What are inversion heterozygotes

A

Individuals with one copy of a Normal chromosome and one inverted chromosome

28
Q

In regards to inversion heterozygotes what happens during meiosis I

A

Normal and inversion chromosomes synapse and form an inversion loop

29
Q

What happens if crossing over occurs in the inversion loop

A

Highly abnormal chromosomes are produced

30
Q

What happens if crossing over occurs in the inversion loop of a pericentric inversion chromosome

A

You create two parental types but both pairs have a deletion and a duplication

31
Q

What happens if crossing over occurs in the inversion loop of a paracentric inversion chromosome

A

One chromosome is missing a centromere and one has two centromeres

32
Q

What is reciprocal translocation

A

Two non homologous chromosomes exchange genetic material
Occur because of chromosomal breakage or dna repair and abnormal crossovers

33
Q

What is a balanced translocation

A

Rearrangement of genetic material
No change in amount of material

34
Q

What are unbalanced translocations

A

Genetic material is duplicated or deleted

35
Q

What is robertsonian translocation

A

When breaks occur near the centromeres of two non homologous Acrocentric chromosomes
Small acentric fragments lost
Larger fragments fuse at centromeric regions to form single chromosome which is metacentric or submetacentric

36
Q

Do individuals with balanced or unbalanced translocations have greater risk of producing gametes with unbalanced combinations

A

Balanced

37
Q

What must form for a translocated chromosome to synapse correctly

A

Translocation cross

38
Q

What is alternate segregation

A

Viable gametes
Chromosomes diagonal to each other within the translocation cross segregate into the same cell following meiosis
One cell receives 2 normal chromosomes and the other receives 2 translocated chromosomes

39
Q

What is adjacent 1 segregation

A

4 genetically unbalanced gametes
Adjacent non homologous chromosomes segregated into the same cell after meiosis 1
All four cells have one normal and one translocated chromosome

40
Q

What is adjacent 2 segregation

A

4 genetically unbalanced gametes
Centromeres don’t segregate properly during meiosis 1
One cell receives both copies of the centromere on chromosome 1 and other copies of the centromere in chromosome 2
All 4 cells have one normal and one translocated chromosome

41
Q

What are the two most likely outcomes when an individual carriers a reciprocal translocation

A

Alternate and adjacent 1 segregation

42
Q

What is semisterility

A

An individuals fertility is lowered when they have less viable gametes

43
Q

What is euploidy

A

A variation of complete sets of chromosomes
If you have three or more sets of chromosomes you are considered polyploid

44
Q

What is aneuploidy

A

Variation in the number of particular chromosomes within a set of
Trisomic is having three copies of a chromosome instead of 2
Monosomic is having one copy of a chromosome instead of 2

45
Q

Why can aneuploidy cause abnormal phenotypes

A

It leads to imbalanced amounts of gene products
3 copies of a gene leads to 150 percent production

46
Q

Do trisomic and monosomic individuals have a better chance of survival than euploid individuals

A

No because they are an imbalance of gene products which is detrimental to

47
Q

On what chromosomes does aneuploidy occur (not a number)

A

Autosomal

48
Q

What might cause phenotypic effects in aneuploidy

A

Expression of X linked genes prior to embryonic X linked chromosome inactivation
Imbalance in expression of pseudoautosomal genes

49
Q

What causes Down syndrome

A

Failure of chromosome 21 to segregate properly
Non disjunction

50
Q

Why might Down syndrome be connected to maternal age

A

A females oocytesare arrested in prophase of meiosis 1 so as she ages her primary oocytes have been arrested for a significantly longer time which contributes to increased frequency of nondisjunction

51
Q

What is endopolyploidy

A

Diploid animals produce tissues that are polyploid

52
Q

What are polytene chromosomes

A

When doubling of pairs of chromosomes produce a bundle of chromosomes that lie together in parallel fashion
Also considered repeated chromosome replication

53
Q

What is a chromocenter

A

Where polytene chromosome’s central point aggregate

54
Q

Polyploids with an odd number of chromosomes are usually what

A

Sterile which is a detrimental trait

55
Q

What are three ways chromosome number may vary

A

Meiotic nondisjunction
Mitotic nondisjunction
Interspecies crosses

56
Q

What is nondisjunction

A

Failure of chromosomes to segregate properly during anaphase
Can occur in meiosis I or II

57
Q

What does meiotic nondisjunction produce

A

Haploid cells that have too many or too few chromosomes
If this gamete is fertilized the resulting individual will have abnormal chromosomal composition in all of its cells

58
Q

If non disjunction occurs in meiosis II what is the probability of abnormal and normal gametes

A

50% normal 50% abnormal

59
Q

What is complete nondisjunction

A

When all chromosomes that undergo nondisjunction migrate to one daughter cell which results in one diploid cell and one without chromosomes

60
Q

What is mitotic nondisjunction

A

When sister chromatids separate improperly which leads to trisomic and monosomic daughter cells

61
Q

What is chromosome loss

A

One of the sister Chromatids doesn’t migrate to a pole which leads to normal and monosomic daughter cells

62
Q

What is mosaicism

A

Genetic abnormalities that occur after fertilization lead to this
Size and location of the mosaic region depends on the timing and location of the original abnormality

63
Q

What is autopolyploidy

A

Increase in the number of sets of a single species

64
Q

Alloploidy

A

Combing of chromosome sets from different species

65
Q

Allopolyploidy

A

When the number of chromosome sets increase in an alloploid

66
Q

What is an allotetraploid

A

Contains two complete sets of chromosomes from two different species

Genetics (14 decks)

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