Chapter 4 Cell division and Reproduction (Defs.)

Question 1

The study of heredity and variation of living organisms and how genetic information is passed from one generation to the next.

Answer 1

Genetics

Question 2

A plant or animal cell that forms the body of the organisms; excludes reproductive cells.

Answer 2

Somatic cell

Question 3

A structure in the nucleus that contains DNA.

Answer 3

Chromosome

Question 4

One of two chromosomes that are genetically identical and held together at the centromere.

Answer 4

Sister chromatid

Question 5

The region where two sister chromatids are held together in a chromosome.

Answer 5

Centromere

Question 6

A microtubule structure that facilitates the movement of chromosomes within a cell.

Answer 6

Spindle fibre

Question 7

A structure that helps to form the spindle fibres.

Answer 7

Centrosome

Question 8

A combination of spindle fibres and centrosomes that moves and organizes the chromosomes during mitosis.

Answer 8

Spindle apparatus

Question 8

Fibres of DNA in its uncondensed form; exists during S phase of interphase to allow DNA to replicate.

Answer 8

Chromatin

Question 9

The stage of mitosis during which the cell’s chromatin condenses into chromosomes.

Answer 9

Prophase

Question 9

The stage of the cell cycle during which a cell carries out its normal functions, grows, and makes copies of its genetic material in preparation for the next stage of the cycle.

Answer 9

Interphase

Question 10

The stage of mitosis during which spindle fibres from opposite poles attach to the centromere of each chromosome, guiding the chromosomes to the equator of the cell.

Answer 10

Metaphase

Question 11

Stage of mitosis during which each centromere splits apart and the sister chromatids separate from each other.

Answer 11

Anaphase

Question 12

Stage of mitosis during which the chromosomes start to unwind into strands of chromatin, the spindle fibres break down, the nuclear membrane forms around the new set of chromosomes, and a nucleolus forms within each new nucleus.

Answer 12

Telophase

Question 13

Stage of the cell cycle that begins near the end of mitosis and involves the division of the cell cytoplasm and the creation of a new cell.

Answer 13

Cytokinesis

Question 14

Stage of cell cycle during which a cell’s nucleus and genetic material divide.

Answer 14

Mitosis

Question 15

A specialized area of chromatin inside the cell nucleus; responsible for making ribosomes, which help to make proteins.

Answer 15

Nucleolus

Question 16

A structure that forms between the two daughter nuclei during the process of cytokinesis in plant cells; cell walls then form on either side of the cell plate.

Answer 16

Cell plate

Question 17

A spiral shape formed by a DNA molecule.

Answer 17

Double helix

Question 18

The individual units of each strand of DNA; composed of a phosphate group, a sugar group, and a base - either adenine, guanine, thymine, or cytosine.

Answer 18

Nucleotides

Question 19

Nucleotide bases on opposite strands of the DNA backbone that interact in a DNA molecule; adenine pairs with thymine and guanine pairs with cytosine.

Answer 19

Complementary base pairs

Question 20

A permanent change in the genetic material of an organism; the only source of new genetic variation.

Answer 20

Mutation

Question 21

The complete DNA sequence of an organism.

Answer 21

Genome

Question 22

Describes a method of DNA replication that conserves half of the original DNA molecule when producing a new molecule of double-stranded DNA.

Answer 22

Semi-conservative

Question 23

An X or Y chromosome, which determines the genetic sex of an organism.

Answer 23

Sex chromosome

Question 24

A chromosome that is not involved in determining the sex of an organism.

Answer 24

Autosome

Question 25

A chromosome that contains the same sequence of genes as another chromosome.

Answer 25

Homologous chromosome

Question 26

A part of a chromosome that governs the expression of a trait and is passed on to offspring; it has a specific DNA sequence.

Answer 26

Gene

Question 26

One of two or more forms of a gene.

Answer 26

Allele

Question 27

A photograph of pairs of homologous chromosomes in a cell.

Answer 27

Karyotype

Question 28

A continuous sequence of cell growth and division; includes interphase, mitosis, and cytokinesis.

Answer 28

Cell cycle

Question 29

Reproduction that requires only one parent and produces genetically identical offspring.

Answer 29

Asexual reproduction

Question 30

Reproduction that requires two parents and produces genetically distinct offspring.

Answer 30

Sexual reproduction

Question 31

A male or female reproductive cell.

Answer 31

Gamete

Question 32

A cell formed by the fusion of two gametes.

Answer 32

Zygote

Question 33

In humans, the joining of male and female haploid gametes.

Answer 33

Fertilization

Question 34

A cell that contains half the number of chromosomes as the parent cell.

Answer 34

Haploid

Question 35

A cell that contains pairs of homologous chromosomes.

Answer 35

Diploid

Question 36

The cellular process that produces cells containing half the number of chromosomes as the parent cell.

Answer 36

Meiosis

Question 37

The aligning of homologous chromosomes during prophase I in meiosis I.

Answer 37

Synapsis

Question 38

The process of producing male gametes (sperm) in mammals.

Answer 38

Spermatogenesis

Question 39

The process of producing female gametes (eggs) in mammals.

Answer 39

Oogenesis

Question 40

A diploid cell that gives rise to the male gametes (sperm); beginning at puberty, it reproduces by mitosis and then undergoes meiosis to form four haploid sperm cells.

Answer 40

Spermatogonium (plural spermatogonia)

Question 41

A diploid cell that gives rise to the haploid female gametes (egg cells); before birth, it reproduces by mitosis and then begins meiosis, but stops at prophase I until puberty.

Answer 41

Oogonium (plural oogonia)

Question 42

The exchange of chromosomal segments between a pair of homologous chromosomes.

Answer 42

Crossing over

Question 43

The failure of homologous chromosomes pairs or sister chromatids to separate during meiosis.

Answer 43

Non-disjunction

Question 44

The loss of a chromosome as a result of non-disjunction.

Answer 44

Monosomy

Question 45

The gain of a chromosome as a result of non-disjunction.

Answer 45

Trisomy