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2nd Year 2nd Term > MT6315 L4 CHROMOSOMES > Flashcards

MT6315 L4 CHROMOSOMES Flashcards

1
Q

carried traits from one generation to the next

A

Mendelian “factors”

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2
Q

Who recognized and explored the fibrous network within the nucleus? And what are these networks?

A

Walther Flemming and it is chromatin or “stainable material”

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3
Q

center of the cell where genetic material is formed

A

nucleus

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4
Q

What did Walther Flemming observe in cell division stages?

A

observed cells in various stages of division and recognized that chromosomal movement during mitosis offered a mechanism for the precise distribution of nuclear material during cell division

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5
Q

What did Theodor Boveri discover?

A

first evidence that germ cell chromosomes imparted continuity between generations

observed cells during meiosis

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6
Q

What was Boveri’s profession?

A

Embryologist

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7
Q

What did Boveri focus on?

A

cytoplasmic changes to see possible changes in the offspring

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8
Q

What kind of embryos did Boveri work with?

A

Ascaris embryos that first depicted meiosis

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9
Q

What did Walter Sutton discover?

A

described the configurations of individual chromosomes in cells at various stages of meiosis (testes of Brachystola magna) on grasshoppers

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10
Q

Who confirmed and expanded upon Boveri’s observations?

A

Walter Sutton

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11
Q

Sutton and Boveri’s experiments provided physical basis for?

A

physical basis of the Mendelian law of heredity – developed the “Chromosomal Theory of Inheritance

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12
Q

Boveri hoped that his experiments would also help to distinguish the roles of the______ and ________ in _______.

A

nucleus and the cytoplasm; embryogenesis.

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13
Q

T or F: Boveri was particularly interested in how offspring are shaped by the attributes of their parents.

A

T

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14
Q

Who experimentally demonstrated Chromosomal Theory of Inheritance using Drosophila melanogaster and pioneered “Fly Room” experiments?

A

Thomas Hunt Morgan

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15
Q

Who helped establish the chromosomal basis of heredity and sex?

A

Calvin Bridges

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16
Q

What else did Calvin Bridges discover?

A

nondisjunction caused chromosomes, under some circumstances, to fail to separate when forming sperm and egg cells.

nondisjunction caused sperm or egg cells to contain abnormal amounts of chromosomes, and the offspring produced by the sperm or eggs would display traits that they would typically not have.

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17
Q

Chromosomes are also called?

A

“colored bodies” or thread-like structures

Chroma=color
Soma=body

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18
Q

Chromosomes are made of?

A

a protein and a single molecule of has DNA, and some minute RNA

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19
Q

What do chromosomes do?

A

Enable transmission of genetic information from one generation to the next

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20
Q

What do chromosomes do in the context of mitosis?

A

Ensure daughter cell retains complete genetic complement

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21
Q

What do chromosomes do in the context of meiosis?

A

Enable each mature ovum and sperm to contain a unique single set of parental genes

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22
Q

Why is having a unique set of genes important in meiosis?

A

genetic recombination protects us from diseases and create new genetically different species from parents

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23
Q

How many chromosomes in the human?

A

44 autosomes
2 sex chromosomes
Extra-chromosomal DNA
̶ Other DNA materials found in the mitochondria

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24
Q

How many meters of DNA in a chromosome?

A

about 2m

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25
Q

How many base pairs per set of chromosomes?

A

about 3 billion

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26
Q

How many genes code for proteins that perform most life structures?

A

20,000-25,000

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27
Q

Replicated chromatids condensed chromosome with sister chromatid

A

Metaphase chromosome

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28
Q

What is the protein that links DNA together?

A

H1 Histones

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29
Q

What composes the nucleosome?

A

8 histone globus and 147 nucleotide pairs, 1 peripheral protein (H1 Histone)

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30
Q

Telomeres resemble?

A

aglets of shoelace

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31
Q

What is the technique that cytogeneticists employ in order to produce a banding pattern in individual chromosome?

A

G-banding

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32
Q

Cytogeneticists make use of diagrams referred to as __________ to determine the ______ and ______ of chromosomes.

A

chromosome ideograms
relative sizes and the banding patterns

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33
Q

What are the other types of banding techniques?

A
  1. Reverse (R-) banding,
  2. Constitutive heterochromatin (C-) banding,
  3. Quinacrine (Q-) banding,
  4. Nucleolar Organizer Region (NOR-) banding, and telomeric R (T-) banding.
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34
Q

Giemsa stain is a compound of? And utilizes what?

A

methylene blue-eosin and methylene blue

utilizes acetic acid fixation, air drying, denaturing chromosomes mildly with proteolytic enzymes, salts, heat, detergents, or urea, and finally giemsa stain.

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35
Q

Chromosome bands appear similar to those ________ by _______

A

fluorochromed by Q-banding stain

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36
Q

Regions in the chromosome that stain _____with G-banding tend to be more transcriptionally active, euchromatic, and rich with guanine and cytosine.

A

rather lightly

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37
Q

______ also makes use of Giemsa stain that binds to ______.

A

C-banding ; constitutive heterochromatin.

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38
Q

Two identical strands which are the result of DNA replication

A

Chromatids

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39
Q

What is the centromere?

A

Central region
Primary constriction where sister chromatids are linked
Consists of several hundred kilobases of repetitive DNA
Responsible for chromosome movement at cell division

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40
Q

Centromere divides the chromosome into?

A

▪ Short arm: designated as p (petite)
▪ Long arm: designated as q (queues or “g” = grande)

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41
Q

What are alphoid chromosomes?

A

Centromeric regions of primate chromosomes are dominated by alphoid (alpha satellite) DNA, a family of tandemly repeated nontranscribed sequences

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42
Q

Satellite DNA belongs to which region of genome?

A

the non-coding region

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43
Q

Tandem repeats occur when?

A

a pattern of 2 or more nucleotides are repeated adjacent to one another.

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44
Q

Satellite DNA is concentrated where?

A

near the centromere and telomere regions of chromosomes and forms a large part of heterochromatin.

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45
Q

How many repeating units in alpha satellite?

A

171

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46
Q

How many repeating units in beta satellite?

A

68

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47
Q

How many repeating units in micro satellite?

A

2-10

48
Q

How many repeating units in mini satellite?

A

10-100

49
Q

Organelle located at the centromere region

A

Kinetochore

50
Q

Kinetochore is responsible for?

A

Microtubule Organizing Center
Spindle formation

51
Q

Chromosome types based on number of centromeres?

A

Monocentric
Acentric
Dicentric

52
Q

genetically unstable because they cannot be maneuvered properly during cell division and are usually lost

A

Acentric

53
Q

genetically unstable because it is not transmitted in a predictable fashion

A

Dicentric

54
Q

Types of chromosomes based on centromere position?

A

Metacentric
Sub-metacentric
Acrocentric
Telocentric

55
Q

severely off-set from centre, leading to much shorter p arm

A

Acrocentric

56
Q

centromere off-centre, leading to shorter p arm relative to q arm

A

Submetacentric

57
Q

chromosome is X shape

A

Metacentric

58
Q

centromere found at end of chromosome, meaning no p arm exists

A

Telocentric

59
Q

13 - 15, 21, 22, Y

A

Acrocentric

60
Q

2, 4 - 12, 17, 18, X

A

Submetacentric

61
Q

Not found in humans

A

Telocentric

62
Q

1st, 3rd, 16th, 19th and 20th

A

Metacentric

63
Q

5 pairs in humans

A

Metacentric, Acrocentric

64
Q

Arm ratio - 1.0-1.6/1.7

A

Metacentric

65
Q

Arm ratio - 3.0

A

Submetacentric

66
Q

Arm ratio - 3.1-6.9

A

Subtelomeric

67
Q

Arm ratio - 7.0

A

Acrocentric

68
Q

Telomere contains repeated of what sequence?

A

hexameric sequence ‘TTAGGG’

69
Q

What maintains the structure and form of the telomeres?

A

Lariat model

70
Q

region of repetitive nucleotide sequences associated with specialized proteins

A

Telomeres

71
Q

Telomere Functions in preserving chromosome stability?

A

Preventing abnormal end-to-end fusion
Protecting the ends of chromosomes from degradation
Ensuring complete DNA replication
Having a role in chromosome pairing during meiosis

72
Q

During early meiosis, telomeres play the distinctive function of ?

A

anchoring chromosomes to the inner nuclear membrane.

73
Q

As a consequence of the nuclear membrane polarization, what happens to the telomeres?

A

telomeres cluster together into a bouquet configuration, which facilitates pairing and recombination of the homologous chromosomes

74
Q

Individuals with______ telomeres have been reported to have a longer subsequent lifespan in some studies of vertebrate species

A

longer

75
Q

What is the end of replication problem?

A

the ends of linear DNA cannot be replicated completely during lagging strand DNA synthesis, leading to progressive shortening of the telomeric DNA during each round of DNA synthesis, reducing telomeric protective capacity

accepted for explaining telomere attrition during cell proliferation

progressive shortening of telomeres that lowers if protective capability

76
Q

What is telomerase?

A

ribonucleoprotein enzyme which carries out the task of adding repetitive nucleotide sequences to the ends of the DNA.

77
Q

What does telomerase do?

A

Telomerase “replenishes” the telomere “cap” and requires no ATP

78
Q

Where is telomerase active in eukaryotes?

A

germ cells, some types of stem cells such as embryonic stem cells, and certain white blood cells.

79
Q

T or F: Telomerase cannot be reactivated.

A

F; it can be, reverting the telomere back into the embryonic state by somatic cell nuclear transfer

80
Q

The steady shortening of telomeres with each replication in somatic (body) cells may have a role in?

A

senescence and in the prevention of cancer

81
Q

In vitro studies have shown that telomeres accumulate damage due to _____ .

A

oxidative stress

82
Q

In Telomere damage, oxidative stress-mediated DNA damage has a major influence on_____.

A

telomere shortening in vivo.

83
Q

The phenomenon of limited cellular division was first observed by? Which is now called?

A

Leonard Hayflick, and is now referred to as the Hayflick limit.

84
Q

Additional to the Hayflick model, significant discoveries were subsequently made by?

A

a group of scientists organized at Geron Corporation by Geron’s founder Michael D. West, that tied telomere shortening with the Hayflick limit.

85
Q

Theodor Boveri developed the chromosomal theory of inheritance and the idea of?

A

Chromosomal individuality

86
Q

Who are the pioneers for the discovery of sex chromosomes and association between specific genes and specific chromosomes?

A

Thomas Hunt Morgan
Calvin Bridges

87
Q

T or F: Calvin Bridges also used Drosophila to prove his experiments in nondisjunction

A

T

88
Q

What is an example of a mitochondrial sickness?

A

MELAS (Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like episodes)

89
Q

What protects the end of the chromosomes?

A

Telomeres

90
Q

What wraps around the histone octamer?

A

DNA double helix

91
Q

When nucleosomes bind together, what forms?

A

A 3-D zigzag structure with histone H1 and other DNA-binding proteins

92
Q

Condensed nucleosomes form what structure? What binds these together?

A

Solenoid structure, bound together by bent Linker DNA

93
Q

Cytogeneticists employ staining techniques to determine the pattern of?

A

Characteristic pattern of light and dark bands

94
Q

Chromosomal shorthand for DiGeorge Syndrome?

A

del22q 11.2

95
Q

Chromosomal shorthand for Cystic fibrosis transmembrane conductance regulator (CF)?

A

7q 31.2

96
Q

5-300 base pairs long and are part of the high evolving eukaryotic genome

A

Satellite DNA

97
Q

Location of beta-satellites?

A

In the pericentric region

98
Q

What kind of satellite DNA is dispersed all throughout the chromosome?

A

Microsatellite

99
Q

What Satellite DNA is found in the telomeric region?

A

Minisatellite

100
Q

The kinetochore contains how many regions? What are these regions and their functions?

A

Inner kinetochore - tightly associated with the centromere
Outer kinetochore - interacts with microtubules

101
Q

Chromosome type that is a broken fragment left after breaking off from a chromosomal fragile site

A

Acentric

102
Q

Chromosomal type that is left in the metaphase plate because of the lack of kinetochores

A

Acentric

103
Q

Chromosome type that fused chromosomes in cases precipitated by conditions like Robertsonian translocation

A

Dicentric

104
Q

What are the metacentric chromosomes?

A

1,3,16,19,20

105
Q

What are the submetacentric chromosomes?

A

2,4-12,17,18,X

106
Q

What are the Acrocentric chromosomes?

A

13-15,21,22,Y

107
Q

In Acrocentric chromosomes, the p arm is very short, thus they are considered as?

A

satellite regions

108
Q

T or F: Loss of the satellite regions in the acrocentric chromosomes will still lead to genetic aberrations

A

T

109
Q

During anaphase, what is the shape of metacentric chromosomes?

A

V shaped

110
Q

During anaphase, what is the shape of submetacentric chromosomes?

A

J shaped

111
Q

During anaphase, what is the shape of acrocentric chromosomes?

A

I shaped

112
Q

Where are telocentric chromosomes usually found?

A

In Oxalis (Shamrock)

113
Q

Who created the chromosome type based on arms ratio?

A

Levan et al

114
Q

What is another name for arm ratio in chromosomes? Hint: It’s an equation

A

L/S

115
Q

What protein is responsible for the packaging of DNA in the cell nucleus? Why is this necessary?

A

Histones (H1 histones, histone octamers)
This is important to make DNA be able to fit into the nucleus, needs to be tightly packed

116
Q

What is the role of telomeres in cancer development?

A

As a cell begins to become cancerous, it divides more often, and its telomeres become very short. If its telomeres get too short, the cell may die. Often times, these cells escape death by making more telomerase enzyme, which prevents the telomeres from getting even shorter.

2nd Year 2nd Term (38 decks)

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