Genetics Chapter 2

Front 1

A unicellular organism with a relatively simple cell structure.

Back 1

Prokaryote

Front 2

Has a compartmentalized cell structure divided by intracellular membranes and may be unicellular or multicellular.

Back 2

Eukaryote

Front 3

This group includes Archaea and Eubacteria

Back 3

Prokaryotes

Front 4

___ may be evolutionarily closer to eukaryotes than to eubacteria.

Back 4

Archaea

Front 5

Has a nuclear envelope.

Back 5

Eukaryote

Front 6

Lacks a nuclear envelope

Back 6

Prokaryote

Front 7

In Eukaryotes, DNA is closely associated with a special class of proteins to form tightly packed chromosomes.

Back 7

Histones

Front 8

The complex of DNA and histone proteins.

Back 8

Chromatin

Front 9

___ limit the accessibility of enzymes and other proteins that copy DNA, but they enable to DNA to fit into the nucleus.

Back 9

Histones

Front 10

In addition to eukaryotes, ____ also have histones, but the makeup of their chromatin is much different than that of eukaryotes.

Back 10

Archaea

Front 11

Have membrane bound organelles.

Back 11

Eukaryotes

Front 12

Have no membrane bound organelles

Back 12

Prokaryotes

Front 13

Have a cytoskeleton

Back 13

Eukaryotes

Front 14

Lack cytoskeleton

Back 14

Prokaryotes

Front 15

Place on a bacterial chromosome where replication initiates

Back 15

Origin of replication

Front 16

Two chromosomes which correspond, one from the male and one from the female.

Back 16

Homologous Pairs

Front 17

Humans have ____ homologous pairs of chromosomes.

Back 17

23

Front 18

Cell with two sets of chromosomes

Back 18

Diploid

Front 19

Cell with one set of chromosomes

Back 19

Haploid

Front 20

Filaments responsible for moving chromosomes during cell division.

Back 20

Spindle Microtubules

Front 21

The attachment point for the spindle microtubules.

Back 21

Centromere (or more specifically, the kinetochore on the centromere)

Front 22

The natural ends, or tips of the chromosome

Back 22

Telomeres

Front 23

Serve to stabilize the chromosome ends

Back 23

Telomeres

Front 24

Two initially identical copies of a chromosome, held together at the centromere.

Back 24

Sister Chromatids

Front 25

Period in the cell cycle in which the cell grows, develops and prepares for cell division.

Back 25

Interphase

Front 26

Period of active cell division.

Back 26

M Phase, or Mitotic Phase

Front 27

Includes Mitosis and Cytokinesis.

Back 27

M Phase, or Mitotic Phase

Front 28

Includes G1, S, and G2 Phases.

Back 28

Interphase

Front 29

Extended period of development between cell divisions.

Back 29

Interphase

Front 30

The cell grows, and proteins necessary for cell division are synthesized (part of Interphase).

Back 30

G1

Front 31

After this checkpoint is passed, the cell is committed to divide.

Back 31

G1/S Checkpoint

Front 32

Nondividing Phase

Back 32

G0

Front 33

During this phase, each chromosome duplicates and DNA synthesis takes place.

Back 33

S Phase

Front 34

After the cell passes this checkpoint, it is ready to divide.

Back 34

G2/M

Front 35

During this part of cell division, chromosomes are in a relaxed state and cannot be seen with a microscope.

Back 35

Interphase

Front 36

After this checkpoint is passed, the cell is committed to divide.

Back 36

G1/S Checkpoint

Front 37

Nondividing Phase

Back 37

G0

Front 38

During this phase, each chromosome duplicates and DNA synthesis takes place.

Back 38

S Phase

Front 39

After the cell passes this checkpoint, it is ready to divide.

Back 39

G2/M

Front 40

During this part of cell division, chromosomes are in a relaxed state and cannot be seen with a microscope.

Back 40

Interphase

Front 41

Part of the cell cycle in which the copies of the cell's chromosomes (sister chromatids) separate and the cell undergoes division.

Back 41

M Phase

Front 42

Chromosomes condense and mitotic spindles form.

Back 42

Prophase

Front 43

The spindle which forms in Prophase grows out of the ____.

Back 43

Centrosomes

Front 44

Disintegration of the nuclear membrane marks the start of this phase.

Back 44

Prometaphase

Front 45

Spindle Microtubules enter the nuclear region in this phase.

Back 45

Prometaphase

Front 46

Microtubules anchor to the kinetochores of sister chromatids in this phase.

Back 46

Prometaphase

Front 47

During this phase, the chromosomes arrange themselves in a single plane.

Back 47

Metaphase

Front 48

This checkpoint ensures that each chromosome is aligned on the metaphase plate and attached to spindle fibers from opposite poles.

Back 48

Spindle-Assembly Checkpoint

Front 49

In this phase, the sister chromatids separate and move towards opposite poles.

Back 49

Anaphase

Front 50

This phase is marked by the arrival of the chromosomes at the spindle poles.

Back 50

Telophase

Front 51

Microtubules are composed of subunits called ____.

Back 51

Tubulin

Front 52

The ____ end of the microtubule is oriented toward the centrosome.

Back 52

Negative

Front 53

The ____ end of the microtubule is always oriented away from the centrosome.

Back 53

Positive

Front 54

The ____ ends of the microtubules make contact with the kinetochores.

Back 54

Positive

Front 55

Throughout Prophase, Prometaphase, and Metaphase, the sister chromatids of mitosis are held together by ____.

Back 55

cohesin

Front 56

At the onset of this phase, cohesin breaks down.

Back 56

Anaphase

Front 57

Specialized kinesin proteins are present at both ends of spindle microtubules and function as ____ ____.

Back 57

Molecular Motors

Front 58

Enzymes that activate or inactivate other proteins by adding phosphate groups to them.

Back 58

CDKs (Cyclin Dependent Kinases)

Front 59

CDKs are only functional when they associate with a protein called ____.

Back 59

Cyclin

Front 60

The G2/M Checkpoint is regulated by ____.

Back 60

Cyclin B

Front 61

Combines with CDK to form MPF.

Back 61

Cyclin B

Front 62

When Cyclin B binds with CDK it forms _____.

Back 62

MPF (Mitosis Promoting Factor)

Front 63

After MPF is formed, it must be activated by:

Back 63

Removal of a phosphate group from one of the amino acids of CDK.

Front 64

Cyclin B levels stay low until late in ____ phase.

Back 64

G2

Front 65

At the end of ____, Cyclin B is abruptly degraded and the cycle starts over again.

Back 65

Metaphase

Front 66

In general, low levels of MPF bring a return to ____ conditions.

Back 66

Interphase

Front 67

To determine the number of chromosomes in a cell, count the ____.

Back 67

Centromeres

Front 68

To determine the number of DNA molecules in a cell, count the number of ____.

Back 68

Chromatids

Front 69

Process that leads to gametes in which the chromosomes number is reduced by half.

Back 69

Meiosis

Front 70

Two haploid gametes fuse and restore chromosome number to its original dipliod value.

Back 70

Fertilization

Front 71

Genetically identical cells are produced during ____.

Back 71

Mitosis

Front 72

Genetically variable cells are produced during ____.

Back 72

Meiosis

Front 73

This is termed the reductional division.

Back 73

Meiosis I

Front 74

This is sometimes termed the equational division.

Back 74

Meiosis II

Front 75

In this part of Prophase I, the chromosomes contract and become visible.

Back 75

Leptotene

Front 76

In this part of Prophase I, the chromosomes continue to condense, and homolgous chromosomes pair up and begin synapsis.

Back 76

Zygotene

Front 77

A very close pairing association between chromosomes.

Back 77

Synapsis

Front 78

Synapsis occurs in ____.

Back 78

Zygotene

Front 79

Homologous pair of synapsed chromosomes.

Back 79

Tetrad or Bivalent

Front 80

In which part of Prophase I does the synaptonemal complex develop?

Back 80

Pachytene

Front 81

Crossing over is initiated in ____ of Prophase I.

Back 81

Zygotene

Front 82

The centromeres of the paired chromosomes move apart during ____ of Prophase I.

Back 82

Diplotene

Front 83

Chiasmata move towards the ends of the chromosomes as the strands slip apart.

Back 83

Diakinesis

Front 84

List the five stages of Prophase I in order.

Back 84

Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis

Front 85

Initiated when homolgous pairs of chromosomes line up along the metaphase plate.

Back 85

Metaphase I

Front 86

Marked by the separation of homologous chromosomes.

Back 86

Anaphase I

Front 87

Chromosomes arrive at the spindle poles, and the cytoplasm divides.

Back 87

Telophase I

Front 88

The period between Meiosis I and Meiosis II is called ____.

Back 88

Interkinesis

Front 89

Chromosomes condense, the mitotic spindle forms, and the nuclear envelope disintegrates.

Back 89

Prophase II

Front 90

Individual chromosomes line up on the metaphase plate.

Back 90

Metaphase II

Front 91

Cohesin is broken down by ____.

Back 91

Separase

Front 92

____ keeps separase inactive.

Back 92

Securin

Front 93

The production of gametes in a male animal.

Back 93

Spermatogenesis

Front 94

Diploid primordial germ cells divide mitotically to produce ____ (male).

Back 94

Spermatagonia

Front 95

A spermatagonium that enters Prophase I is called a _____.

Back 95

Primary Spermatocyte

Front 96

When a primary spermatocyte completes Meiosis I and enters Meiosis II it is a ____.

Back 96

Secondary Spermatocyte.

Front 97

The male gametes produced from Meiosis I and Meiosis II are called ____.

Back 97

Spermatids

Front 98

____ grow up to become sperm.

Back 98

Spermatids

Front 99

The production of gametes in the female

Back 99

Oogenesis

Front 100

Diploid primordial germ cells in the ovaries divide mitotically to produce ____.

Back 100

Oogonia

Front 101

When Oogonia enter Prophase I they are called ____.

Back 101

Primary Oocytes

Front 102

At the end of Meiosis I in a female, there will be:

Back 102

One secondary oocyte and a polar body.

Front 103

At the end of Meiosis II in the female, there will be:

Back 103

An Ovum and a second polar body.