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Cytogenetics > AII. Introduction to Cytology > Flashcards

AII. Introduction to Cytology Flashcards

1
Q

is the science that deals with DNA

A

Genetics

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2
Q

Each of us is composed of trillion of (?), and each of those cells contains very thin (?), a few centimeters long that play a major role in who we are, as human beings and persons. These all-important intracellular fibers are made of

A

cells
fibers
DNA

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3
Q

Every time a (?) divides, its (?) is replicated and apportioned equally to two (?).

A

cell
DNA
daughter cells

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4
Q

The DNA content of these cells – called the (?) – is thereby conserved.

A

genome

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5
Q

This (?) is a master set of instructions, like a whole library of information, that cells use to maintain the living state.

A

genome

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6
Q

Ultimately, all the activities of the cell depend on it.

A

genome

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7
Q

To know the DNA is therefore to know the cell, and, in a larger sense, to know the (?) to which that cell belongs.

A

organism

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8
Q

− A three-base sequence in mRNA that causes the insertion of a specific amino acid into protein, or causes termination or translation

A

Codon

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9
Q

Codon Example:

A

TAG-AAA-UAUGGA

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10
Q

− The basic unit of heredity

A

Genes

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11
Q

− Contains the information for making one RNA and, in most cases, one polypeptide

A

Genes

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12
Q

− Deoxyribonucleic acid

A

DNA

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13
Q

− A polymer composed of deoxyribonucleotides linked together by phosphodiester bonds

A

DNA

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14
Q

− The material of which most genes are made

A

DNA

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15
Q

− Ribonucleic acid

A

RNA

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16
Q

− A polymer composed of ribonucleotides linked together by phosphodiester bonds

A

RNA

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17
Q

− The physical structure, composed largely of DNA and protein, that contains the genes of an organism

A

Chromosomes

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18
Q

− One complete set of genetic information from a genetic system

A

o Genome

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19
Q

− Example: the single, circular chromosome of a bacterium is its

A

genome

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20
Q

Sum of all chromosomal characteristics of a cell

A

Karyotype

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21
Q

− The process of determining karyotype

A

Karyotyping

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22
Q

− Diagrammatic representation of karyotype

A

Idiogram

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23
Q

− Shows alternating dark and light band patterns

A

Idiogram

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24
Q

− Where genes are located

A

Chromosome

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25
Q

− Contains nucleoproteins

A

Chromosome

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26
Q

− Serves to maneuver DNA during cell division

A

Chromosome

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27
Q

− Consists of two sister chromatids with contracted and compacted double helix of DNA

A

Chromosomes

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28
Q

Chromosomes in human

A

23 pairs

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29
Q

• Autosomes pairs
➢ Non-sex chromosome

A

➢ 1-22 pairs

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30
Q

• Sex chromosomes

A

➢ 1 pair

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31
Q

Areas of the chromosome:

A

Centromere
Telomere
Nucleolar organizing regions

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32
Q

▪ A constriction visible on metaphase chromosomes where two sister chromatids are joined together

A

Centromere

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33
Q

▪ Essential to the survival of the chromosome during cell division

A

Centromere

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34
Q

▪ It is where interaction with the mitotic spindle during cell division occurs

A

Centromere

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35
Q

– functional elements that separate the sister chromatids during cell division

A

− Mitotic spindle

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36
Q

– attach chromosomes to the spindle fibers during cell division

A

− Kinetochore apparatus

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37
Q

− Classification of Centromere based on its position:

A

❖ Metacentric
❖ Acrocentric
❖ Submetacentric

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38
Q

❖ – middle
❖ – end
❖ – between middle and end

A

Metacentric
Acrocentric
Submetacentric

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39
Q

▪ The physical end of chromosomes

A

Telomere

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40
Q

▪ Acts as protective caps of chromosome ends

A

Telomere

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41
Q

▪ Prevents end-to-end fusion of chromosomes

A

Telomere

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42
Q

▪ Prevents DNA degradation resulting after chromosome breakage

A

Telomere

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43
Q

▪ Plays a role in synapsis during meiosis

A

Telomere

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44
Q

▪ Chromosome pairing appears to be initiated in the

A

subtelomeric regions

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45
Q

▪ (?) complex with telomeric DNA to protect the ends of chromosomes nucleases located within the cell

A

Nonhistone proteins

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46
Q

The maintenance of (?) permits the binding of (?) that form the (?) at chromosome ends and regulate (?)

A

telomeric DNA
telomeric proteins
protective cap
telomere length

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47
Q

Cells that have defective or unstable telomerase will exhibit (?) leading to chromosome instability and cell death.

A

shortening of chromosomes,

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48
Q

(enzyme that synth esize telomeres)

A

telomerase

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49
Q

Found in the satellite stalks of human acrocentric chromosomes

A

Nucleolar organizing regions

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50
Q

Where nucleoli form in the interphase of cells

A

Nucleolar organizing regions

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51
Q

Site of rRNA genes and its production

A

Nucleolar organizing regions

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52
Q

There are (?) NORs in human chromosomes

A

10

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53
Q

Two types of chromatin:

A

Euchromatin
Heterochromatin

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54
Q

Loosely organized, extended and uncoiled

A

Euchromatin

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55
Q

Contains active early replicating genes

A

Euchromatin

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56
Q

Highly contracted, geneticall mitosis

A

Heterochromatin

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57
Q

Two types of Heterochromatin:

A

Facultative heterochromatin
Constitutive heterochromatin

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58
Q

➢ The condensed inactivated X chromosome of female cells

A

Facultative heterochromatin

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59
Q

➢ Consists of simple repeats of nitrogenous bases

A

Constitutive heterochromatin

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60
Q

➢ Location: around centromeres of all chromosomes; distal end of the Y chromosome

A

Constitutive heterochromatin

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61
Q

➢ Function: Regulation of crossing over – the exchange of genes from one sister chromatid to the other during cell division

A

Constitutive heterochromatin

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62
Q

o One X chromosome of every female cell is randomly inactivated

A

Facultative heterochromatin

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63
Q

Condensation occurs during interphase

A

Facultative heterochromatin

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64
Q

− An ordered set of events

A

Cell cycle

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65
Q

− Results in cell growth and division into two daughter cells

A

Cell cycle

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66
Q

Cell cycle

− Two alternating process:

A

Doubling of its genome (S phase) and halving of the genome (M phase)

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67
Q

− Growth and preparation of the chromosomes for replication

A

G1 – “Gap 1”

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68
Q

− Stage when DNA replication occurs

A

S – Synthesis

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69
Q

− Duplication of the centrosome

A

S – Synthesis

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70
Q

− Preparation of mitosis

A

G2 – “Gap 2”

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71
Q

− Nuclear division

A

M – mitosis

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72
Q

– chromosome separates

A

Nuclear division

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73
Q

− Cytoplasmic division (cytokinesis)

A

M – mitosis

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74
Q

− causes the cells to move from G1 to S and G2 to M

A

o Proteins that control the cell cycle

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75
Q

− levels remain fairly stable but each must bind with the appropriate cyclin in order to be activated

A

CdK

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76
Q

− they add phosphate groups to a variety of protein substrates that control processes in the cell cycle

A

CdK

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77
Q

• CdK 4 –

A

G1 CdK

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78
Q

• CdK 2 –

A

S phase CdK

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79
Q

• CdK 1 –

A

M phase CdK

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80
Q

− Levels rise and fall with the stages of the cell cycle

A

Cyclins

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81
Q

• G1 cyclins

A

(D cyclins)

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82
Q

• S phase cyclins

A

(cyclins E and A)

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83
Q

• Mitotic cyclins

A

(B cyclins)

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84
Q

− Also known as the cyclosome

A

Anaphase Promoting Complex (APC)

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85
Q

− The complex is often designated as APC/C

A

Anaphase Promoting Complex (APC)

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86
Q

Anaphase Promoting Complex (APC)

− Functions include:

A

• Destroys cohesin allowing sister chromatids to separate
• Degrades mitotic cyclins

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87
Q

− Functions to block the cell cycle if the DNA is damaged

A

p53

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88
Q

− It can also lead to apoptosis when the DNA damage is severe

A

p53

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89
Q

are increased in damaged cells to allow time to repair the DNA

A

• p53 levels

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90
Q

is the most frequent mutation leading to cancer

A

p53 mutation

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91
Q

extreme case of p53 mutation and leads to a high frequency of cancer in affected individuals

A
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92
Q

− a disease that results when the regulation of the cell cycle is not controlled and normal cell growth and behavior is lost

A

Cancer

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93
Q

− it blocks the entry into the S phase by binding to cyclins and CdK

A

p27

94
Q

− Reduced levels predict a poor outcome for breast cancer patients

A

p27

95
Q

– signals the cell to prepare the chromosomes for replication

A
  1. G1 cyclins bind to their CdK’s
96
Q

– includes A cyclin bound to CdK2

A
  1. S-phase promoting factor (SPF)
97
Q

➢ Enters the nucleus

A
  1. S-phase promoting factor (SPF)
98
Q

➢ Prepares the cell to duplicate its DNA and centrosome

A
  1. S-phase promoting factor (SPF)
99
Q

➢ As DNA replication continues, cyclin E is destroyed, and the level of mitotic cyclins begins to rise (in G2)

A
  1. S-phase promoting factor (SPF)
100
Q

M-phase promoting factor (the complex of mitotic [B] cyclins with the M-phase CdK [CdK1]) initiates the following:

A

➢ Assembly of the mitotic spindle
➢ Breakdown of the nuclear envelope
➢ Cessation of all gene transcription
➢ Condensation of the chromosomes

101
Q

▪ These events take the cell to the metaphase stage of mitosis

A

Condensation of the chromosomes

102
Q

▪ At this point, the M-phase promoting factor activates the

A

Condensation of the chromosomes

103
Q

Steps in the Cell cycle

A
  1. G1 cyclins bind to their CdK’s
  2. S-phase promoting factor (SPF)
  3. M-phase promoting factor
104
Q

− allows the sister chromatids at the metaphase plate to separate and move to the poles (anaphase), thereby completing the mitosis

A

The Anaphase-Promoting Complex

105
Q

− Destroys B cyclins. This is also done by attaching them to ubiquitin which targets them for destruction by proteasomes

A

The Anaphase-Promoting Complex

106
Q

− Turns on synthesis of G1 cyclins (D) for the next turn of the cycle

A

The Anaphase-Promoting Complex

107
Q

− Degrades geminin, a protein that keeps the freshly-synthesized DNA in S phase from being re-replicated before mitosis

A

The Anaphase-Promoting Complex

108
Q

Division of chromosomes

A

MITOSIS

109
Q

division of the cytoplasm to form two cells (occurs at the last part of mitosis)

A

Cytokinesis

110
Q

− General body cells

A

Somatic cells

111
Q

− Same number of chromosomes as each other within the body of an organism

A

Somatic cells

112
Q

− Chromosomes comes in pairs
o One from the father
o One from the mother

A

Somatic cells

113
Q

− There are 46 chromosomes arranged in 23 pairs

A

Somatic cells

114
Q

Degrades geminin, a protein that keeps the freshly-synthesized DNA in S phase from being re-replicated before mitosis

A

o This is another mechanism by which the cell ensures that every portion of its genome is copied once – and only once – during S phase.

115
Q

− Sex cells
o Eggs in females
o Sperm in males

A

Gametes

116
Q

− Have only one set of chromosomes consisting of one chromosome from each pair

A

Gametes

117
Q

− There are 23 individual chromosomes

A

Gametes

118
Q

− Cells are not dividing

A

Interphase

119
Q

− Chromosomes are decondensed (called chromatin) and their information is available to the cell for synthesizing products

A

Interphase

120
Q

− Cells spend most of their time in this intermediate non-mitotic state

A

Interphase

121
Q

− During interphase (in S phase), all the cells’ DNA is duplicated

A

Interphase

122
Q

All resulting DNA is duplicated – resulting in 4 copies of each gene instead of the normal 2 in a diploid cell

A

Interphase in S phase

123
Q

− Chromatin begins to coil and condense to form chromosomes

A

Prophase

124
Q

− Each chromosome appears to have two strands (each containing a single molecule of DNA)

A

Prophase

125
Q

− Each strand is called a chromatid

A

Prophase

126
Q

− Each chromatid is attached to its sister chromatid at the centromere

A

Prophase

127
Q

− At this stage, the number of chromosomes (containing a pair of chromatids) is considered to be equal to the number of centromeres

A

Prophase

128
Q

− The two chromatids are the result of DNA replication that takes place just before mitosis starts

A

Prophase

129
Q

− The nuclear envelope disappears

A

Prophase

130
Q

− The nucleolus disappears

A

Prophase

131
Q

− In cytoplasm, the spindle apparatus forms

A

Prophase

132
Q

− Eventually the spindle guides the separation of sister chromatids into two daughter cells

A

Prophase

133
Q

− Spindle grows and forms attachments to the chromosomes at the centromeres

A

Metaphase

134
Q

− Chromosomes move to an equatorial plate which is formed along the midline of the cell between poles

A

Metaphase

135
Q

− Chromosomes are at their most condensed state now

A

Metaphase

136
Q

− the chromosomes can be stained and will show distinctive banding patterns

A

Metaphase

137
Q

− Centromeres divide to create two chromosomes instead of a pair of attached chromatids

A

Anaphase

138
Q

− Spindle fibers shorten and the sister chromosomes are drawn to the opposite poles of the cell

A

Anaphase

139
Q

− Poles of the spindle apparatus are pushed apart as the cell elongates

A

Anaphase

140
Q

− Anaphase results in the exact division of chromosome, distributing one complete diploid complement of genetic information to each daughter cell

A

Anaphase

141
Q

− Nuclear envelopes reassemble and surround each set of daughter chromosomes

A

Telophase

142
Q

− Nucleoli reappear inside the newly formed nuclei

A

Telophase

143
Q

− In animal cell, a furrow appears around the cell that eventually pinches the cell into two new cells

A

Telophase

144
Q

− Chromosome decondense in the daughter cells to become chromatin and the cells are once again in Interphase

A

Telophase

145
Q

o Takes place only in the ovaries and testes

A

MEIOSIS

146
Q

o Involves one duplication of the DNA and two cell divisions (Meiosis I and Meiosis II)

A

MEIOSIS

147
Q

o Reduces the number of chromosomes from the diploid number (2n=46) to the haploid number (n=23)

A

MEIOSIS

148
Q

o Each gamete produced contains only one copy of each chromosome

A

MEIOSIS

149
Q

o Fertilization restores the diploid number in the zygote

A

MEIOSIS

150
Q

o

A
151
Q

a single cell divides into two

A

Meiosis I

152
Q

the two cells from meiosis I divides again

A

Meiosis II

153
Q

Prophase I important processes

A

Synapsis
Crossing over

154
Q

➢ The coming together of two homologous chromosomes

A

Synapsis

155
Q

➢ Homologous chromosomes consist of two chromatids thus, 4 chromatids (tetrads) are actually aligned next to one another

A

Synapsis

156
Q

➢ Segments of DNA from one chromatid in the tetrad pass to another chromatid in the tetrad

A

Crossing over

157
Q

➢ Results in a genetically new chromatid

A

Crossing over

158
Q

➢ Important driving force in evolution

A

Crossing over

159
Q

➢ After this process, the four chromatid of the tetrad are genetically different from the original tetrad

A

Crossing over

160
Q

The Four Subdivisions of Prophase I

A

Leptotene
Zygotene
Pachytene
Diplotene
Diakinesis

161
Q

− There are 46 chromosomes, each comprised of two chromatids

A

Leptotene

162
Q

− The chromosomes begin to condense but are not yet visible by light microscopy

A

Leptotene

163
Q

− Once it takes place, the cell is committed to meiosis

A

Leptotene

164
Q

− follows leptotene

A

Zygotene

165
Q

− Chromosomes appear threadlike

A

Zygotene

166
Q

− Homologous chromosomes pair locus for locus

A

Zygotene

167
Q

o This is when synapsis occurs

A

− Homologous chromosomes pair locus for locus

168
Q

o A tripartite structure

A

Synaptonemal complex

169
Q

o Necessary for the phenomenon of crossing-over that will take place later in Prophase I

A

Synaptonemal complex

170
Q

o Synapsis of the X and Y chromosomes in males occurs only at the pseudoautosomal regions.

A

Synaptonemal complex

171
Q

o These regions are located at the distal short arms and are the only segments of the X and Y chromosomes containing homologous loci.

A

Synaptonemal complex

172
Q

o The nonhomologous portions of these chromosomes condense to form the sex vesicle

A

Synaptonemal complex

173
Q

− Synapsis is complete during

A

Pachytene

174
Q

− Chromosomes continue to condense

A

Pachytene

175
Q

− Chromosomes appear as thicker threads

A

Pachytene

176
Q

− They now form tetrads (aka bivalents)

A

Pachytene

177
Q

− The phenomenon of crossing-over takes place during

A

pachytene

178
Q

− Chromosomes continue to shorten and thicken

A

Diplotene

179
Q

− Homologous chromosomes begin to repel each other

A

Diplotene

180
Q

points at which crossing-over took place

A

Chiasmata

181
Q

Chromosomes reach their greatest contraction during this last stage of prophase

A

Diakinesis

182
Q

− Characterized by disappearance of the nuclear membrane and formation of the meiotic spindle

A

Metaphase I

183
Q

− The tetrads line up on the equatorial plate with their centromeres randomly oriented toward opposite poles

A

Metaphase I

184
Q

− The centromeres attach to spindle fibers (one centromere per spindle fiber)

A

Metaphase I

185
Q

− centromeres of each tetrad separate and migrate to opposite poles

A

Anaphase I

186
Q

− homologous chromosomes separate

A

Anaphase I

187
Q

o One homologous chromosome (consisting of two chromatids) moves to one side of the cell

A

homologous chromosomes separatehomologous chromosomes separate

188
Q

o The other homologous chromosome (consisting of two chromatids) moves to the other side of the cell.

A

homologous chromosomes separate

189
Q

homologous chromosomes separate

o Result:

A

23 chromosomes (each consisting of two chromatids) move to one pole and;

190
Q

o 23 chromosomes (each consisting of two chromatids) move to the other pole.

A

homologous chromosomes separate

191
Q

– the chromosome number of the cell is halved

A

o Reduction division

192
Q

− In telophase, the two haploid sets of chromosomes reach opposite poles and the cytoplasm divides.

A

Telophase I

193
Q

− Result: two cells containing 23 chromosomes, each composed of two chromatids.

A

Telophase I

194
Q

− The nucleus reorganizes

A

Telophase I

195
Q

− The chromosomes become chromatin

A

Telophase I

196
Q

− A cytoplasmic division into two cells takes place

A

Telophase I

197
Q

Stages of Meiosis II

A

▪ Interphase II
▪ Prophase II
▪ Metaphase II
▪ Anaphase II
▪ Telophase II

198
Q

− No duplication of the DNA

A

Interphase II

199
Q

− May be brief or very long, depending on the species of organism

A

Interphase II

200
Q

− The chromatin material condenses, and each chromosome contains two chromatids attached by the centromere.

A

Prophase II

201
Q

− The 23 chromosome pairs, a total of 46 chromatids, then move to the equatorial plate.

A

Prophase II

202
Q

− The 23 chromosomes pairs gather at the center of the cell prior to separation

A

Metaphase II

203
Q

− The 23 chromosomes pairs gather at the center of the cell prior to separation

A

Metaphase II

204
Q

− The centromeres divide, and the 23 chromosome pairs (46 chromatids) divides

A

Anaphase II

205
Q

− Spindle fibers move one chromosome from each pair to one pole of the cell and the other member of the pair to the other pole.

A

Anaphase II

206
Q

− In all, 23 chromosomes move to each pole

A

Anaphase II

207
Q

− The chromosomes gather at the poles of the cells and become indistinct

A

Telophase II

208
Q

− Again, they form a mass of chromatin

A

Telophase II

209
Q

− The nuclear envelope develops

A

Telophase II

210
Q

− The nucleoli reappear

A

Telophase II

211
Q

− The cells undergo cytokinesis as in mitosis

A

Telophase II

212
Q

 The 23 chromosomes in the four cells from meiosis are not identical because crossing over has taken place in [?]

A

Prophase I

213
Q

 The crossing over yields variation so that each of the four resulting cells from [?] differs from the other three

A

meiosis

214
Q

 Thus, [?] provides a mechanism for producing variations in the chromosomes

A

meiosis

215
Q

 Also, it accounts for the formation of four haploid cells from a single diploid cell.

A

meiosis

216
Q

Comparison of Mitosis vs. Meiosis:

A

o Chromosome behavior
o Chromosome number
o Genetic identity of progeny

217
Q

o Chromosome behavior
➢ Mitosis:
➢ Meiosis:

A

Mitosis: homologous chromosomes independent
Meiosis: Homologous chromosomes pair forming bivalents until anaphase I

218
Q

o Chromosome number
➢ Mitosis:
➢ Meiosis:

A

Mitosis: identical daughter cells
Meiosis: daughter cells haploid

219
Q

o Genetic identity of progeny
➢ Mitosis:
➢ Meiosis:
➢ Meiosis:

A

➢ Mitosis: identical daughter cells
➢ Meiosis: daughter cells have new assortment of parental chromosomes
➢ Meiosis: chromatids not identical, crossing over

220
Q

– homologues don’t separate in Meiosis I

A

o Nondisjunction

221
Q

➢ Results in aneuploidy

A

o Nondisjunction

222
Q

➢ Can be lethal among embryos

A

o Nondisjunction

223
Q

➢ Can lead to Trisomy 21, leading to Down’s syndrome

A

o Nondisjunction

224
Q

➢ Sex chromosomes

A

o Nondisjunction

225
Q

• Turner syndrome:

A

monosomy X

226
Q

• Klinefelter syndrome:

A

XXY

227
Q

– the transfer of a piece of one chromosome to another or loss of fragment of chromosome

A

Translocation and Deletion

228
Q

(?) is practiced is practiced at different levels.

A

Genetic analysis

229
Q

The oldest type of genetic analysis follows in Mendel’s footsteps by focusing on how traits are inherited when different strains of organisms are (?).

A

hybridized

230
Q

Another type of genetic analysis follows in the footsteps of Watson and Crick and the army of people who have worked on the various genome projects by focusing on the (?) of the genetic material.

A

molecular makeup

231
Q

Still another type of genetic analysis imitates Darwin and Wallace by focusing on (?) of organisms.

A

entire populations

Cytogenetics (11 decks)

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