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Genetics PCB 3063 > Ch 2 - Chromosomes & Cellular Reproduction > Flashcards

Ch 2 - Chromosomes & Cellular Reproduction Flashcards

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1
Q

____ cells are compartmentalized by intracellular membranes.

A

Eukaryotic

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2
Q

_______ are unicellular; _____ are unicellular or multicellular.

A

Prokaryotes; eukaryotes

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3
Q

_____ are true bacteria; _____ are ancient bacteria.

A

Eubacteria; archaea

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4
Q

T or F: archaea are more closely related to eubacteria than to eukaryotic organisms.

A

False; they aren’t more closely related to either.

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5
Q

Eukaryotes are distinguished from prokaryotes in that _______ (RNA synthesis) is physically separated from ______ (protein synthesis).

A

Transcription; translation

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6
Q

In ______ organisms, transcription and translation occur in the same compartment.

A

prokaryotes

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7
Q

The difference in transcription and translation for prokaryotes and eukaryotes affects how genes are regulated, meaning that _________ dictates ________.

A

Structure dictates function.

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8
Q

50% of the protein in DNA is a special class of proteins called _________ which facilitate packing huge amounts of DNA into small spaces.

A

Histones

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9
Q

______ is made of DNA and proteins (about 50/50).

A

Chromatin

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10
Q

During ________, DNA is wrapped around a core of 8 _____ proteins to form a nucleosome.

A

Interphase; histone

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11
Q

A _____ is a basic repeating unit of chromatin consisting of a core of 8 histone proteins and ~146 bp of DNA that wraps around the core just under 2x.

A

nucleosome

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12
Q

Bacteria usually have _______ chromosome(s) that is ______ in shape/form.

A

one; circular

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13
Q

Eukaryotes have multiple _______ that each have a single DNA molecule that is _______ in shape/form.

A

chromosomes; linear

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14
Q

T or F: viruses are a living cell.

A

False; they are a cellular parasite.

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15
Q

Viral genes are most closely related to their cellular ______.

A

cellular hosts

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16
Q

Viruses have either _____ or _____, but not both; and their genetic material is either ______-stranded or _______- stranded.

A

DNA or RNA; single- or double-stranded.

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17
Q

Typical error rate of DNA replication is?

A

~10^-9, or about 1 error per billion nucleotides

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18
Q

The 3 critical steps to cell replication are _____ replication of DNA; completed copies of the genome must be ________ to different regions of the cell; and the cell must divide.

A

faithful (accurate); separated

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19
Q

Human cells contain ~_____B nucleotides

A

4B

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20
Q

DNA synthesis in prokaryotes is ~____ to ____ bp/min in prokaryotes usually results in < 1 error per ______ Mbp.

A

600 - 700 bp (nucleotides); per 3M base pairs

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21
Q

DNA replication in prokaryotes is __-_______ with specific _____ of replication.

A

bi-directional; origins of replication

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22
Q

_____ are circular, self- replicating DNA molecules (much smaller than the genome) found in prokaryotes that are completely autonomous and can be lost without consequence to the organism.

A

Plasmids

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23
Q

Many plasmids carry genes for _______ ______ which is especially consequential in human medicine.

A

antibiotic resistance.

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24
Q

Plasmids can be _____ between different species of prokaryotes.

A

transferred

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25
Q

F-factor in E. coli is a plasmid that is required for _______ (genetic exchange) between organisms.

A

conjugation

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26
Q

DNA is distributed along multiple _____ in eukaryotic organisms.

A

chromosomes

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27
Q

Chromosomes are separated from the cytoplasm by a _____ _____.

A

Nuclear envelope

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28
Q

The nucleus has an extensive protein network crisscrossing all around called the nuclear _______.

A

Matrix.

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29
Q

T or F: the complexity of an organism can be predicted by the number of chromosomes.

A

False

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30
Q

Cells with two sets of chromosomes are ______, aka _____ cells.

A

diploid; somatic

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31
Q

_____ cells are cells that are designed to be gametes and have ____ member of each homologous pair.

A

germline; one

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32
Q

A karyotype is typically made from a cell in ______; this is when the chromosomes are most ________.

A

Metaphase; condensed

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33
Q

In humans, 3 pairs of chromosome 21 yields?

A

Down syndrome

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34
Q

Nearly ______ chromosomes form a _________ pair.

A

identical; homologous

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35
Q

Variants of the same genetic locus due to different DNA sequences are said to be _____.

A

Alleles

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36
Q

During most of the cell cycle, the chromosomes are diffuse state known as ________.

A

chromatin

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37
Q

Name the 3 essential elements of chromosomal anatomy.

A

Centromere, telomere, and origin of replication

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38
Q

The _____ is the DNA sequence that specifies where the kinetochore forms, and there is exactly _____ per chromosome.

A

centromere; one

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39
Q

The ______ serves as the attachment site for spindle microtubules (forms over the centromere).

A

kinetochore

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40
Q

The ____ _______ are responsible for pulling chromosomes to the edges of the cell during division.

A

spindle microtubules

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41
Q

What happens when a chromosome lacks a centromere?

A

The chromosome cannot take part in cell division and is lost.

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42
Q

Homologous chromosomes joined at the centromere are called _____ _____.

A

Sister chromatids.

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43
Q

Centromere positions: ____ is centrally located; _____ is slightly skewed from center; _____ is close to the end; and _____ is terminally located.

A

metacentric; submetacentric; acrocentric; and telocentric

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44
Q

T or F: centromere position is absolute.

A

False - it is relative and different people may disagree whether it is acrocentric or submetacentric

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45
Q

______ are special structures on the ends of chromosomes required for chromosomal stability.

A

Telomeres

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46
Q

_____ shorten over time and may play a role in controlling cell division, and / or possibly aging, and cancer.

A

Telomeres

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47
Q

As cells age, telomeres begin to shorten due to reduced ______.

A

Telomerase

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48
Q

Once telomerase is all gone and telomeres have shrunk to nothing, the cells initiate _______, or programmed death.

A

apoptosis

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49
Q

It’s common in cancer to find that ____ have been reactivated due to increased ____ activity.

A

telomeres; telomerase

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50
Q

Following DNA replication, each sister chromatid contains a single ______ molecule.

A

DNA

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51
Q

The process that passes an exact copy of the genetic information from a parent to two daughter cells is _____.

A

mitosis

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52
Q

The two major phases of mitosis are _____ and ______.

A

interphase and mitotic (M) phase

53
Q

Interphase begins with _____ where cell growth and synthesis of proteins needed for cellular devision are made.

A

G1

54
Q

T or F: interphase lasts for several minutes

A

False: several hours

55
Q

______ are regulated key transition points during mitosis that allow or prohibit cellular division to proceed to the next stage.

A

Checkpoints.

56
Q

Interphase is divided into what 3 stages?

A

G1 (gap 1); S (DNA synthesis); and G2 (gap 2)

57
Q

T or F: after passing G1/S checkpoint, cells may go on to S phase or G0.

A

False: once the G1/S checkpoint has passed, the cell is committed.

58
Q

T or F: Cells in G0 are unstable

A

False

59
Q

T or F: cells in G0 are recycled and resubmitted to G1

A

False; they can remain in G0 indefinitely, cycle round and round through G1/G0, or just chill in G0.

60
Q

In S phase, _____ synthesis must take place before the cell can proceed.

A

DNA

61
Q

After S phase, each chromosome is composed of ____ _____ ______.

A

2 sister chromatids

62
Q

In S phase, un-replicated or damaged DNA can inhibit the activation of certain _______ that are necessary for mitosis to take place.

A

proteins

63
Q

After the ____/_____ checkpoint has passed, the cell is ready to divide and enters ____ phase.

A

G2/M checkpoint; M phase

64
Q

Cells undergoing mitosis spend ___ hours in G1, ___ hours in S, and ____ in G2.

A

10; 9; 4

65
Q

T or F: throughout interphase, chromosomes are in a relaxed and uncoiled state.

A

False: they are relaxed, but they are not uncoiled.

66
Q

Sister chromatids separate and the cell divides under _____ phase.

A

M (mitotic)

67
Q

M phase is divided into 6 stages (from the end of interphase): Peter Pan Masturbates And Tinkerbell Cums.

A

Prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis

68
Q

A cell in G2 has twice the _____ molecules, but the same number of _______ as the parent cell.

A

DNA; chromosomes

69
Q

In prophase, a group of proteins called ______ bind to DNA and bring about condensation of chromatin.

A

Condensins

70
Q

In prophase, the ____ ____ (an organized array of microtubules) forms.

A

mitotic spindle

71
Q

In animal cells, the mitotic spindle grows from a pair of _________ (during prophase) that migrate to opposite sides of the cell. Within each centrosome is an organelle called a _______ which is also composed of microtubules.

A

centrosomes; centriole

72
Q

Some plant cells don’t have ______ or ______, but they do have mitotic spindles.

A

centrosomes or centrioles.

73
Q

During ______ of M phase, chromosome structure becomes visible using light microscopy.

A

prophase.

74
Q

Using FISH visualization techniques, ____ filaments appear orange while _____ appears blue.

A

actin; DNA

75
Q

In a diploid cell that has undergone S phase, what is the ratio of chromosomes to chromatids?

A

There are twice as many chromatids as there are chromosomes (bound at the centromere.

76
Q

______ ______ is the process by which prokaryotic cells divide.

A

binary fission

77
Q

During _______ in mitosis, the nuclear envelope/membrane ______, and spindle microtubules enter the _______.

A

prometaphase; disintegrates; nuclear region

78
Q

Disintegration of the nuclear envelope/membrane marks the beginning of _________.

A

prometaphase.

79
Q

By the end of _______ in mitosis, the microtubules anchor each sister chromatid one of two centrosomes. The cell will then go on to ________.

A

prometaphase; metaphase

80
Q

During _______, chromosomes align in a single line called the ________ plate.

A

metaphase; metaphase

81
Q

During metaphase, the _____-______ checkpoint confirms that each chromosome is attached to a spindle fiber, and that the spindle fibers of each sister chromatid are attached to opposite poles of the cell.

A

spindle-assembly

82
Q

During metaphase, chromosomes align such that the metaphase plate runs through the _______ of each chromosome which is aligned vertically/horizontally along each plate?

A

middle; vertically.

83
Q

During ________, tension at the ________ is required before the big “pull” in order to pass the spindle-assembly checkpoint.

A

metaphase; kinetochore

84
Q

What would happen if sister chromatids are not properly attached to microtubules at the spindle-assembly checkpoint?

A

A cell could end up with an abnormal number of chromosomes.

85
Q

After the spindle-assembly checkpoint has passed, the connection between sister chromatids (known as the _______) begins to break down - this marks the end of _______ and the separation of sister chromatids marks the beginning of ________.

A

centromere; metaphase; anaphase

86
Q

During ________, chromosomes begin to move towards opposite spindle poles. The movement is due to the disassembly of _____ molecules at both the + end ( the ______ end) and the – end (the ______ _____ end) via special proteins called molecular ______.

A

anaphase; tubulin; kinetochore; spindle pole; motors.

87
Q

During metaphase, there are ____ chromosomes, during anaphase, there are _____ chromosomes.

A

4; 8

88
Q

Arrival of chromosomes at the spindle poles marks the beginning of ________.

A

telophase

89
Q

During _______, the nuclear envelop re-forms around both sets of chromosomes, and the chromosomes relax.

A

telophase.

90
Q

During telophase, chromosomes are no longer _______ under a light microscope. Why?

A

visible; because they’re no longer condensed (relaxed, diffuse state).

91
Q

The end of ______ is marked by the division of cytoplasm, and the process is known as _____ - the final stage in mitosis. However, in some cells, ______ is simultaneous with ________.

A

telophase; cytokinesis. cytokinesis; telophase.

92
Q

The professor states that a diploid cell undergoing mitosis becomes _______ during S phase, but returns to diploid after _______.

A

tetraploid (4n); cytokinesis

93
Q

T or F: mitosis yields 2 genetically identical cells, including mitochondrial DNA (and chloroplasts for plants).

A

False: DNA is the same, but mitochondrial/chloroplastic DNA is different.

94
Q

The cellular process of _______ reshuffles parental genes amongst progeny.

A

meiosis

95
Q

Mitosis has ____ nuclear division, meiosis has ____.

A

One; two.

96
Q

As in mitosis, DNA replication occurs in ______ in meiosis.

A

S phase

97
Q

Meiosis 1 begins with ________, including all of the same stages as mitosis: ___, _____, and _____.

A

interphase; G1, S, G2

98
Q

____ _____ is often called reduction division because the number of chromosomes is reduced by half; _____ _____ is called equational division because the number of chromosomes have already been halved.

A

Meiosis I; meiosis II

99
Q

In the beginning of prophase I during meiosis 1, the chromosomes ______ and become visible.

A

condense

100
Q

In mid-prophase I of meiosis 1, homologous chromosomes form a close pairing association known as ______; and the two pairs of sister chromatids (four chromatids altogether) are called a ______ or a ______.

A

synapsis; bivalent or tetrad (bi refers to two pairs; tetra refers 4 individuals)

101
Q

Meiosis II is functionally equivalent to _____.

A

mitosis.

102
Q

During late __ 1 of Meiosis 1, homologous chromosomes align nucleotide by nucleotide.

A

prophase

103
Q

Crossing over (aka ________ ________) takes place in ______ ____ during late ______ ____; and the location where chromosomes cross is called ______. Independent assortment (aka random distribution) takes place in ____ ___ during ______ after their random alignment in metaphase 1.

A

genetic recombination; meiosis 1; prophase 1; chiasma (pl. chiasmata). meiosis 1; anaphase 1.

104
Q

Metaphase 1 (meiosis) vs. metaphase (mitosis): in meiosis, homologs line up ____-____-____ along the metaphase _______, and the centromere is/is not split; whereas with mitosis, homologs line up ____ each other with the centromere of sister chromatids _______ by the metaphase plate.

A

side-by-side; plate; is not split; below; split

105
Q

Anaphase 1 (meiosis) vs anaphase (mitosis): in anaphase 1 of meiosis, the _______ _______ separate and move towards opposite poles; in anaphase of mitosis, the _______ ________ separate and move towards opposite poles.

A

homologous chromosomes; sister chromatids

106
Q

T or F: the centromere splits in anaphase 1.

A

False: anaphase 1 takes place in meiosis 1, and the homologous pairs (maternal and paternal) separate after crossing over, not the sister chromatids.

107
Q

_______ 1 follows anaphase 1, and in this phase, _____ chromosomes arrive at the ______ poles and cytoplasm divides.

A

telophase 1; homologous; spindle

108
Q

Meiosis 2 is functionally ______ to mitosis in that ______ _______ divide at the _______.

A

equivalent; sister chromatids; centromere

109
Q

Recombinant vs non-recombinant?

A

Recombinant = crossing over (in prophase 1); non-recombinant = no crossing over / clone of parental.

110
Q

Are any of the daughter cells genetically identical if there is no crossing over?

A

Yes - 50/50 identical to each other.

111
Q

What caused genetic variation in Mendel’s experiments? At what point does this phenomenon occur?

A

Random assortment of chromosomes. At the end of meiosis 1, specifically at anaphase 1 (after the chromosomes randomly aligned in metaphase 1). NOTE: the sister chromatids are still attached, but the homologous pairs are randomly distributed.

112
Q

At the end of meiosis 1, there are ____ daughter cells; at the end of meiosis 2, there are ______ daughter cells.

A

2; 4

113
Q

The consequence of meiosis vs. mitosis is that at the end of meiosis there are genetically ______ haploid daughter cells; and at the end of mitosis there are genetically ______ haploid daughter cells.

A

distinct; identical

114
Q

Genetic diversity in meiosis comes from what two mechanisms?

A

Crossing over (aka genetic recombination) and independent assortment (random distribution) of chromosomes.

115
Q

The number of possible chromosomal combinations in gametes is equal to (without genetic redistribution)? What would it be in humans? (give the answer in exponent form).

A

2^n where n = the number of homologous pairs. In humans, 2^23

116
Q

List the major/upper level stages of meiosis 1 and 2 (Px3, M, A T C)(PMATC)

A

Middle through late prophase (3 stages), metaphase 1, anaphase 1, telophase 1, cytokinesis 1. Prophase 2, metaphase 2, anaphase 2, cytokinesis 2.

117
Q

During prophase 1, chromosomes ______, homologs synapse, ______ over takes place, the ___ membrane breaks down, and the mitotic _____ forms.

A

condense; crossing over; nuclear; spindle

118
Q

During metaphase 1, homologues line along the ______ _____ in a ______ order.

A

metaphase plate; random

119
Q

During anaphase 1, homologous pairs ______ in a random fashion (but ___ ____ remain attached) and move toward opposite poles.

A

separate; sister chromatids

120
Q

During prophase 2, chromosomes _____, the mitotic ____ forms, and the _____ _____ disintegrates.

A

condense; spindle; nuclear membrane

121
Q

during metaphase 2, individual ______ line up along the _____ _____ with the ________ down the middle.

A

chromosomes; metaphase plate; centromeres

122
Q

During anaphase 2, _____ _____ separate.

A

sister chromatids

123
Q

During telophase 2, chromatids arrive at the ______ ______, the ___ breaks down, and the ____ ____ reforms.

A

spindle poles; spindle; nuclear membrane.

124
Q

Explain what is meant by reduction division (in meiosis 1). Include why this can be confusing.

A

The parent cell starts as a diploid cell, but the first pair of daughter cells become haploid after anaphase. This is confusing because after DNA synthesis in S phase, there’s more DNA molecules/chromatids, but they are still sister chromatids and not separate - it’s the separation of the homologs that counts as the ‘reduction’.

125
Q

_____ is a protein that holds sister chromatids together (not to be confused with the DNA sequence where the kinetochore forms).

A

Cohesin

126
Q

A homologous pair of chromosomes means that one chromosome is ______, the other is _______.

A

Maternal, paternal.

127
Q

Bottom line, meiosis gives rise to ______ cells that are _______ variable and that fuse during ______ to produce diploid progeny.

A

haploid; genetically; fertilization

128
Q

T or F: Plasmids replicate independent of the genome.

A

True

129
Q

A diploid cell with 3 pairs of homologous chromosomes will have ____ discrete chromosomes in a germline cell (e.g. egg or sperm) after completing meiosis.

A

3

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