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genetics exam 2 > chapter 10 > Flashcards

chapter 10 Flashcards

(52 cards)

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1
Q

What are chromosome numbers?

A

Different species have different diploid chromosome numbers (e.g., humans have 46, fruit flies have 8)

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2
Q

What are chromosome territories?

A

Chromosomes are confined to specific regions (territories) in the nucleus during interphase but can move, twist, and turn during transcription and DNA replication.

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3
Q

Chromosomes are categorized based on what?

A

the position of their centromeres

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4
Q

What is Metacentric?

A

Centromere in the middle

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5
Q

What is Submetacentric?

A

Centromere between middle and tip

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6
Q

What is Acrocentric?

A

Centromere close to one end.

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7
Q

What is Telocentric?

A

Centromere at the tip.

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8
Q

What are Karyotypes?

A

Visual displays of chromosomes, useful for identifying abnormalities in chromosome number or structure.

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9
Q

What are banding patterns?

A

Chromosomes can be identified based on size, shape, and banding patterns using techniques like G-banding.

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10
Q

What is euchromatin?

A

Less condensed, gene-rich, and actively expressed chromatin

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11
Q

What is heterochromatin?

A

Tightly condensed, gene-poor, and less expressed chromatin

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12
Q

What is nondisjunction?

A

Failure of chromosomes to separate properly during meiosis, leading to aneuploidy (abnormal chromosome number)

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13
Q

What is meiotic Nondisjunction?

A

Can occur in meiosis I (homologs fail to separate) or meiosis II (sister chromatids fail to separate).

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14
Q

What is Aneuploidy? give an example

A

Leads to monosomy (missing a chromosome) or trisomy (extra chromosome), which alters gene dosage and affects phenotype.
ex: trisomy 21 results in Down syndrome.

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15
Q

What is Polyploidy?

A

Presence of three or more sets of chromosomes (common in plants).

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16
Q

What is Autopolyploidy?

A

Chromosome duplication within the same species.

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17
Q

What is Allopolyploidy?

A

Combining chromosome sets from different species.

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18
Q

What causes polyploidy?

A

Meiotic and mitotic nondisjunction

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19
Q

What is Meiotic Nondisjunction?

A

Leads to diploid gametes (e.g., 2n + n = 3n plants)

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20
Q

What is mitotic nondisjunction?

A

Chromosome number doubles in somatic cell

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21
Q

What are the consequences of Polyploidy?

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A

Increased size of fruits and flowers, decreased fertility (especially in odd-numbered polyploids), and hybrid vigor (more robust growth and disease resistance).

22
Q

Polyploidy can lead to what?

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A

the formation of new species in a single generation by reproductive isolation.

23
Q

Centromeres divide chromosomes into what?

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A

chromosome arms of unequal length

24
Q

what is the short and long chromosome arms?

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A

the short arm is the p arm and the ling arm is the q arm

25
What is the Fluorescent in situ hybridization (FISH) staining for?
Uses molecular probes to detect a target sequence
26
What is the standard for human banding?
The G (Giemsa) banding; the patterns are distinct and reproducible
27
What is hybrid vigor?
more rapid growth, increased fruit and flower production, and improved resistance to disease that occurs in heterozygous progeny of inbred lines
28
What is the euploid number of chromosomes?
the number of complete sets (e.g., n, 2n, 3n)
29
What is mosaicism?
can develop as a result of mitotic nondisjunction early in embryogenesis
30
look more at gene dosage
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31
What is uniparental disomy?
when both copies of a homologous chromosome pair arise from the same parent. A rare abnormality in humans
32
What is trisomy rescue?
one copy of the trisomy chromosome is randomly ejected in one of the first mitotic divisions after fertilization
33
Chromosome breakage can cause mutations through what?
the loss, gain, or rearrangement of chromosomes, resulting in gene dosage imbalances
34
The process of chromosome breakage and mutation can lead to what?
partial deletions or duplications, affecting gene function and potentially causing disorders
35
Chromosome breaks result in what?
partial deletions where fragments can be lost if they lack a centromere.
36
Terminal deletions occur where?
at the end of the chromosome, while interstitial deletions involve loss within the chromosome.
37
What is Cri-du-Chat Syndrome?
It is caused by a terminal deletion on chromosome 5, leading to characteristic symptoms like the "cat-cry" sound. it is caused by partial deletion heterozygotes
38
What is unequal crossover?
Occurs rarely when homologous chromosomes misalign, leading to duplications in one and deletions in another. ex: williams-beuren syndrome (on the PMS gene, chromosome 7)
39
What are detection methods?
Large deletions or duplications can be detected microscopically via altered chromosome banding patterns, while smaller changes require techniques like FISH (fluorescent in situ hybridization)
40
What are chromosomal rearrangements?
Inversions and translocations occur when chromosome fragments reattach incorrectly, potentially leading to fertility issues due to abnormal chromosome segregation.
41
What are the 2 types of inversions?
paracentric (centromere outside inverted region) and pericentric (centromere within the inverted region).
42
What is reciprocal translocations?
involve switching fragments between nonhomologous chromosomes
43
What is Robertsonian translocations?
Lead to chromosome fusion and changes in chromosome number.
44
What is a chromosome break point?
When a chromosome breaks, both DNA strands are severed at a location
45
What are interstitial deletion?
Its the loss of an internal portion of a chromosome, and results from two chromosome breaks
46
What is an unpaired loop?
A normal genetic material if one chromosome carries a deletion or is duplicated genetic material if one homolog has a duplication
47
What is Pseudodominance?
It occurs when a recessive allele is “unmasked” by a deletion that removes the dominant allele on the homologous chromosome
48
What is crossover suppression?
Inversion suppresses the production of recombinant chromosomes
49
About half of the proteins are what?
histone proteins, small basic proteins that tightly bind DNA
50
Position effect variegation (PEV) in Drosophila illustrates what?
the effect of chromatin compaction on gene expression
51
What is M A Rs (matrix attachment regions?
Chromatin loops of 20 to 100 k b are anchored to the chromosome scaffold by nonhistone proteins at sites
52
read more about high order chromatin and solenoid structure
okk

genetics exam 2 (3 decks)

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