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COB Genetics > Lec 2.1 Specialized chromosome structure/ sequence and DNA packaging > Flashcards

Lec 2.1 Specialized chromosome structure/ sequence and DNA packaging Flashcards

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Biology 101 flashcards
1
Q

What is a telomere?

A

region of repetitive nucleotide sequences at each end of a chromosome.

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2
Q

What is the human telomere sequence?

A

TTAGGG

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3
Q

What does a telomere do?

A

Protects the end of the chromosome

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4
Q

Which telomere is longer? A G-rich strand or C-rich strand?

A

G-rich

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5
Q

How do euk solve the problem of having nucleases around?

A

G-rich strand folds over and pairs with a short stretch of DNA to form a t-loop.

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6
Q

Shortened telomeres are associated with what?

A

Shorter life span and increased incidence of disease

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7
Q

What are two ways that children can have shortened telomeres?

A

Lead exposure, stressed environments

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8
Q

What happens to your telomeres when you age?

A

the shorter they get

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9
Q

Do telomeres contribute to that negative impact of aging or are they just a molecular clock?

A

Conclusion: we dont know

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10
Q

What is a centromere?

A

Region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division.

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11
Q

What is a kinitochore?

A

group of proteins that attach at the centromere, that are responsible for events of chromosome segregation

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12
Q

What is a centriole?

A

Small, cylindrical cell organelle, located near the nucleus in the cytoplasm of most euk cells, that divides in perpendicular fashion during mitosis.

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13
Q

What is the chromosomal locus essential for chromosome inheritance and genome stability?

A

Centromere

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14
Q

What is cohesin?*

A

Wraps around strands around the chromosomes and keeps them together during mit/meiosis. When signla comes in, it melts

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15
Q

What happens if the kinetochore protein is mutated?*

A

Miscarriages.

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16
Q

What happens when a chromosome breaks producing a fragment without a centromere?

A

Loss of a chromosome and a deletion of whatever chromosome was lost, and its genes

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17
Q

What is important to fit the entire genome into such a compact place?

A

Supercoiling

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18
Q

What are topoisomerases responsible for?

A

adding and removing turns in the coil

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19
Q

What does the chromatin structure contain?

A

Euchromatin, heterochromatin, histone proteins

20
Q

If a chromatin structure is hyperacetylated it is?

A

Open active

21
Q

If a chromatin structure is hypoacetylated it is?

A

closed/ inactive

22
Q

Why are lysines important for histones?

A

Keeps DNA highly compacted, less likely for transcription

23
Q

What keeps histones and DNA together?

A

the charge between them. DNA is - and histones are +.

24
Q

What is a nucleosome? *

A

8 proteins, coming together to form this octomere of proteins that makes a ball that DNA can bind around

25
Q

What is chromatin?

A

Nucleosome core, including proteins + DNA that allow wrapping and packaging of DNA

26
Q

What is a chromatosome?

A

basically the nucleosome + linker

27
Q

What are the several levels of organization for DNA packaging?

A
  1. DNA. 2. Coiling happens. 3. Coil wraps around the histone octomere to make the nucleosome. 4. Nucleosomes coil around each other. 5. Chromosome
28
Q

What is the fundamental repeating unit of chromatin?

A

the nucleosome

29
Q

Where is euchromatin location?

A

Chromosome arms

30
Q

Where is heterchromatin location?

A

centromeres, telomeres, and other places

31
Q

What type of sequences does euchromatin have?

A

unique

32
Q

What type of sequences does heterochromatin have?

A

Repeated

33
Q

when is euchromatin replicated?

A

throughout S phase

34
Q

when is heterochromatin replicated?

A

Late S phase

35
Q

How often does transcription occur for euchromatin?

A

Often

36
Q

How often does transcription occur for heterochromatin?

A

Infrequent

37
Q

How common is crossing over for euchromatin?

A

Common

38
Q

How common is crossing over for heterochromatin?

A

Not common

39
Q

What are polytene chromosomes?

A

Strands of chromatin that have been replicated multiple times

40
Q

What does DNase I sensitivity correlate with?

A

transcription or gene activity

41
Q

How can epigenetic changes change chromatin structure?

A

methylation. Can be reversed.

42
Q

What is epigenetics?

A

Heritable alteration of phenotype because of altered chromatin structure or the modification of DNA without changing the DNA sequence.

43
Q

The bigger the genome the more what?

A

More repetitive sequences

44
Q

The majority of repetitive sequences show their origin to be?

A

Retro viral transposons origin

45
Q

What is Microsatellite DNA?

A

Tandemly repeated DNA motifs that range in length from 2 to 5 nucleotides, repeated 5-50 times.

46
Q

What are Microsatellite DNA used for?

A

Mapping locations within the genome. Each person has a unique fingerprint of microsatellites, useful in forensics.

COB Genetics (32 decks)

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