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2014 Genetics Topic 1:CM > L2 > Flashcards

L2 Flashcards

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Biology 101 flashcards
1
Q

true or false; the evolutionary complexity of an organism is not related to their chromosome number and chromosome size

A

true

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2
Q

true or false; eukaryotes have much more DNA than they need simply for their genes

A

true

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3
Q

Give examples of a specialized regions in the chromosome that is used for the chromosome’s identification

A

centromere

nucleolar organizers

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4
Q

what is the centromere responsible for

A

for the attachment and movement of the chromosome on the spindle; the primary constriction in the chromosome

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5
Q

what is the position of the centromere relative to

A

relative to the chromosome ends

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6
Q

what is the positioning of the centromere used for

A

used to classify and identify chromosomes

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7
Q

what are the 3 names of the different types of chromosomes based of their centromere location

A

metacentric
acrocentric
telocentric

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8
Q

what are nucleolar organizers

A

sites of the ribosomal RNA genes and like the centromere their position is variable along the chromosome arm so they can be used for identification purposes

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9
Q

what are telomeres

A

are found at the ends of the chromosome, play an important role in DNA replication, and in ‘sealing’ the ends of the chromosomes

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10
Q

what do you call the densely staining regions of the chromosomes

A

heterochromatin

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11
Q

what do you call the less densely staining regions of the chromosome

A

euchromatin

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12
Q

Where can you find polytene chromosomes

A

salivary glands of many flies

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13
Q

what pattern do polytene chromosomes exhibit

A

show transverse bands due to the different staining; useful for chromosome identification

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14
Q

what do you call the proteins that package DNA

A

histones

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15
Q

briefly describe how DNA is packaged

A

packaged with the aid of histones and a complex order of coiling into structures that can readily be moved around the cell

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16
Q

what is nucleosome

A

basic unit of a chromatin

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17
Q

what do you call the linker histone

A

H1

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18
Q

what is n

A

haploid set, single set

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19
Q

true or false, most fungi and algae have only one set of chromosomes

A

true, therefore they are haploid

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20
Q

true or false, most plants and animals have two sets of chromosomes in their body cells

A

true, therefore they are diploid (2n)

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21
Q

what is the lowest haploid number and which species is this from

A

ant species, n=1

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22
Q

what species has the highest amount of haploid number, and what is that haploid number

A

fern, n=728

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23
Q

how many gametes can an organism produce

A

2^n

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24
Q

why can’t the fern sexually reproduce, rather reproduce aesexually

A

due its large number of gametes

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25
Q

true or false, the number of chromosomes a species has is not related to its genome size

A

true

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26
Q

how many chromosomes do humans have

A

46 chromosomes

27
Q

how many autosome pairs do humans have

A

22

28
Q

how many sex chromosome pairs do human have

A

1

29
Q

what is the largest chromosome in humans and what is the smallest, respectively

A

1 and 21

30
Q

define karyotype

A

karyotype is the morphology of ALL the chromosomes at mitotic metaphase

31
Q

how is karyotype organized

A

chromosomes organized in pairs and, from largest to smallest

32
Q

true or false, each functional chromosome has a centromere (where spindle fibres attach) and two telomeres (stablize the chromosome)

A

true

33
Q

what is the most important feature of the chromosome

A

centromere position

34
Q

What does it mean by telocentric

A

centromere at one end; when the chromosome moves towards one pole of the cell during anaphase of cell div., it appears as a simple rod, i shaped

35
Q

Acrocentric

A

centromere off centre; during anaphase it appears as a J

36
Q

metacentric

A

has its centromere in the middle; during anaphase it appears as a V

37
Q

where are telomeres located

A

at the ends of chromosomes

38
Q

true or false, there is no visible structure that distinguishes the telomeres from the rest of the chromosome

A

true

39
Q

What characterizes telomeres

A

tandem repeats

40
Q

what is the tandem repeat in the ciliate Tetrahymena telomeres

A

TTGGGG

41
Q

what is the tandem repeat in human telomeres

A

TTAGGG

42
Q

what is the kinetochore

A

protein which spindle fibres attach

43
Q

What is a nucleoli

A

are organelles within the nucleus that contain ribosomal RNA and components of ribsomes

44
Q

where does the nucleoli reside

A

resides next to a slight constriction in the chromosome called NO (nucleolar organizer)

45
Q

what do NO’s look like

A

contrictions, called secondary constrictions

46
Q

true or false, NO’s are located at different positions on the chromosome

A

true, like the centromeres

47
Q

true or false, ribosomal genes are tandem repeats

A

true

48
Q

how many ribosomal repeats does the human NO have

A

250 copies

49
Q

what do you call a protein and DNA complex

A

chromatin

50
Q

true or false, chromatin is not uniformly distributed along a whole length of the chromosome

A

true

51
Q

What is euchromatin

A

is a loosely packed form of chromatin, that is rich in genes

it has high recombination frequency and stains weakly in interphase

52
Q

what is heterochromatin

A

tightly packed or coiled chromatin
a region with a few genes
lower recombination frequency
stains densely at interphase

53
Q

what are the two things that heterochromatin can be

A

facultative
or
constitutive

54
Q

what is constitutive heterochromatin

A

a permanent feature of a specific chromosome location, gene poor and can inactivate genes

55
Q

what is facultative heterochromatin

A

is sometimes but not always found in a particular chromosome location; normal gene content, can be switched on and off, characteristic of sex chromosomes

56
Q

what are knobs

A

conspicuous heterochromatin regions

57
Q

what is consistent and specific to individual chromosomes

A

position and size of the chromosome bands

58
Q

what is common DNA stain

A

Giemsa; critical factor is chromatin packing density

59
Q

what are polytene chromosomes

A

Giant chromosomes that are found in certain tissues of Drosophila and other organism

60
Q

how do polytene chromosomes arise

A

arise from repeated rounds of DNA replication WITHOUT CELL DIVISION; there are thousands of DNA lying side by side

61
Q

what portion of the genome becomes polytene

A

the euchromatic region

62
Q

true or false, drosophila has four pairs of chromosomes and the euchromatic portion of the genome becomes polytene while the heterochromatin coalesces to form a chromocenter

A

true

63
Q

what is a chromosomal puff

A

regions of relaxed chromatin where active transcription is taking place

64
Q

why is the human genome packed

A

so that it can be moved during cell division, brought about by coiling of the DNA around protein histone cores (nucleosomes) and these are then organized into a further series of coils (solenoids)

2014 Genetics Topic 1:CM (11 decks)

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