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Spring Sophomore Year > Genetics Chapter 8 > Flashcards

Genetics Chapter 8 Flashcards

1
Q

Deletion (aka deficiency)

A

phenotypic consequences of deletions depend on its size and genome content

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2
Q

Terminal deletion

A

single break, usually at the end

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3
Q

Interstitial deletion

A

2 breaks and reattachment of the outer pieces
Example: cri-du-chat syndrome in humans
Caused by a deletion in the short arm of chromosome 5
(CTNND2/delta-catenin is deleted), affected individuals have more severe intellectual disability

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4
Q

Duplication

A

tend to have less harmful effects than deletions
Usually caused by abnormal events during recombination

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5
Q

Inversion

A

is a segment that has been flipped to the opposite orientation
Total amount of genetic information stays the same

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6
Q

Pericentric inversion(left)

A

the centromere within the inverted region
During meiosis I, homologous chromosomes synapse with each other in an inversion loop

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7
Q

Paracentric inversion(right)

A

the centromere is outside of the inverted region

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8
Q

In rare cases, inversion can alter the phenotype of an individual
Consequences of inversion

A

Breakpoints
Position effect: a gene that is repositioned in a way that alters its gene expression

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9
Q

Simple translocations

A

single piece of chromosome is attached to another chromosome

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10
Q

Reciprocal translocations

A

2 non-homologous chromosomes exchange genetic material
Leads to a rearrangement of the genetic material, not a change in the total amount, thus it is also called balanced translocation
Mechanism 1: chromosomal breakage and DNA repair
Mechanism 2: nonhomologous recombination
Just like inversions, they are usually WITHOUT PHENOTYPIC CONSEQUENCES!!

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11
Q

Unbalanced Translocations

A

significant positions of genetic material are duplicated and/or deleted
Usually WITH phenotypic abnormalities or even lethality

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12
Q

Robertsonian translocation

A

most common type of chromosomal rearrangement in humans
Majority of chromosome 21 is attached to chromosome 14

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13
Q

Individuals with reciprocal translocation may produce

A

abnormal gametes

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14
Q

Balanced translocation have a greater risk of producing gametes with

A

UNBALANCED COMBINATIONS OF CHROMOSOMES

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15
Q

What must happen for a chromosome to synapse properly?

A

TRANSLOCATION CROSS MUST FORM

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16
Q

Mitotic segregation of chromosomes with reciprocal translocation

A

Alternate segregation: viable-balance
Chromosomes on opposite sides of the translocation cross segregate into the same cell

Adjacent-1 segregation: inviable-unbalanced:
Adjacent non-homologous chromosomes segregate into the same cell-both have duplications/deletions

Adjacent-2 segregation: inviaible-unbalanced
Adjacent homologous chromosomes segregate into the same cell-both have duplications and deletions
RARE

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17
Q

When is it likely for alternate and adjacent-1 segregation outcomes?

A

When an individual carries a RECIPROCAL TRANSLOCATION
With reciprocal translocation, it usually produces 4 types of gamete
2 are viable & 2 nonviable
This condition is called SEMISTERILITY

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18
Q

Explain what a karyotype is and what it can be used for

A

Karyotype: using a light microscope, it checks the chromosomes in our cells
Can observe if we have the full set of 46 chromosomes
Checks for diseases such as down syndrome, turner syndrome etc

19
Q

Metacentric

A

centromere is at the middle, equal p & q length

20
Q

Acrocentric

A

centromere located at the end of the chromosome

21
Q

Telocentric

A

centromere is in a terminal position

22
Q

Submetacentric

A

centromere is NEAR the middle, p and q are slightly uneven
p=short arm
q=long arm

23
Q

Explain what chromosome banding patterns are and what they can be used to study

A

Staining revealing bands
Example: Giemsa stan-G band
Stains of bright and dark transverse bands
Bands identify where the genes are located on a chromosome

24
Q

Aneuploidy

A

variation in the number of particular chromosomes within a set

25
Q

Trisomy (2n+1)

A

down syndrome (47 chromosomes)

26
Q

monosomy (2n-1)

A

turner’s syndrome (45 chromosomes)

27
Q

Autosomal aneuploidies are most compatible with

A

survival: 13, 18, 21

28
Q

Sex chromosome aneuploidies generally have less severe effects
Some human aneuploidies are influenced by what?

A

Parental age

29
Q

Euploidy

A

variations in the number of complete sets of chromosomes
Most species of animals are diploid
Some euploidy variations are naturally occurring
Example: bees are haplodiploid
In many animals, certain body tissues display normal variations in the number of sets chromosomes—> endopolyploidy

30
Q

Polyploidy

A

common in plants
Fruits and grains
Large in size and more robust

31
Q

Alloploidy

A

more common mechanism for changes in the number of sets of chromosomes
Results of interspecies cross
Example: horse x donkey, tiger x lion

32
Q

Nondisjunction

A

is the improper segregation of chromosome pairs during anaphase
It produces daughter cells with an incorrect number of chromosomes

33
Q

Meiosis I

A

homologous chromosomes
46 chromosomes in a diploid parent cell→ 24,24,22,22 chromosomes in haploid daughter cells

34
Q

Meiosis II

A

sister chromatids
diploid parent cell→ 24,22,23,23 chromosomes in haploid daughter cells

35
Q

Mitosis

A

sister chromatids: sister chromatids
46 chromosomes in diploid parent cell→ 47, 45 chromosomes in diploid daughter cells

36
Q

Complete Nondisjunction

A

in rare cases, all the chromosomes can undergo nondisjunction and migrate to one daughter cell
It results in 1 diploid cell and 1 without chromosome

37
Q

Homologs

A

one pair of chromosomes that segregate from one another during meiosis

38
Q

Paralogs

A

are homologous genes present in the genome of the same species that arise by DUPLICATION EVENTS and code for proteins with similar but not identical functions

39
Q

Copy number variation

A

structural variations in which a DNA segment 1000bp or larger has copy number differences in members of the same species

40
Q

gene families

A

Duplication can provide additional genes, forming gene families
Two or more genes that are similar to each other

41
Q

Chromosome breakage

A

deletion occurs when a chromosome breaks and some genetic materials will be lost
Translocation can occur

42
Q

Repetitive DNA

A

DNA fragments that are present in multiple copies in the genome

43
Q

Nonallelic homologous recombination

A

a mechanism for repairing broken chromosomes which results in genome rearrangement

44
Q

Nonhomologous recombination

A

a major pathway for the repair of chromosomal double-stranded breaks in the DNA of somatic cells

Spring Sophomore Year (11 decks)

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