Cell Division

Question 1

Diploid

definition

Answer 1

Referring to cells that contain two sets of chromosomes (i.e. pairs of homologous chromosomes). One set of chromosomes is inherited from the mother and the other set is inherited from the father. Diploid cells are 2n. Somatic and germ cells are diploid.

Question 2

Homologous

definition

Answer 2

Refers to two chromosomes that are a matched pair in a diploid cell. A matched pair of chromosomes are the same length and contain genes for the same characteristics at the same position on them. For each homologous pair, one chromosome is inherited from the mother and the other is inherited from the father.

Question 3

Sister Chromatid
(definition)

Answer 3

One of two identical copies of a chromosome duplicated during the S phase of the cell cycle. A centromere connects two sister chromatids together. When joined together sister chromatids compose one chromosome, and chromatids are separated from each other during mitosis or meiosis.

Question 4

Gamete

definition

Answer 4

A haploid, sex cell (egg or sperm) produced from germ cells that have undergone meiosis. When two gametes join in fertilization the resulting zygote is a complete diploid cell.

Question 5

Homologue

definition

Answer 5

Refers to one of the other of a homologous pair of chromosomes. Each is considered the homologue of the other.

Question 6

Somatic Cell
(definition)

Answer 6

Any nonreproductive cell found in multicellular organisms. That is, any cell except a germ cell or gametes (sperm and egg cells) found in a muticellular organism. Examples are lung and heart cells, nerve cells, and blood cells.

Question 7

Gene

definition

Answer 7

A segment of DNA that carries specific information, ultimately coding for a protein, which determines certain traits in an organism. The gene is the basic unit of inheritance. It is a segment of DNA with instructions for protein synthesis. Genes are located on DNA stands, and each gene is composed of a specific nucleotide sequence that codes for the amino acid sequence of a protein.

Question 8

Karyotype

definition

Answer 8

Diagrammatic representation of an organism’s genome. An image of the chromosomes of a cell in metaphase where the chromosomes are arranged in pairs by centromere position and size. Karyotypes are used to count and analyze the chromosomes of an individual and can also be used in the determination of chromosomal abnormalities.

Question 9

Zygote

definition

Answer 9

The newly formed diploid cell that is produced when two haploid gametes unite. In animals this occurs when a sperm fertilizes an egg.

Question 10

Germ Cell
(definition)

Answer 10

A cell that in the body of a sexually reproducing organism that produces gametes (eggs or sperm) through meiosis. Germ cells are immature reproductive cells. In humans, germ cells are found in the testes of men and ovaries of women.

Question 11

Meiosis

definition

Answer 11

A type of cell division in which a single, diploid germ cell is divided into four, haploid gamete cells. Meiosis only occurs in organisms that sexually reproduce and results in the production of sperm in males and eggs in females.

Question 12

Haploid

definition

Answer 12

Cells that contain only one set of chromosomes. Haploid cells are referred to as “1n”. Gametes (sperm and eggs) are haploid. In human haploid gametes contain 23 chromosomes.

Question 13

Mitosis

definition

Answer 13

A type of cellular division in which a single, diploid, somatic cell is divided into two genetically identical daughter cells. Mitosis along with cytokinesis compose the mitotic (M) phase of the cell cycle.

Question 14

Genome

definition

Answer 14

All the genetic information in an organism. The complete DNA sequence of one set of chromosomes from an organism.

Question 15

Allele

definition

Answer 15

An alternative form of a gene. An example would be genes that encode eye color -some encode blue eyes (one allele), while others encode brown, green or hazel eye colors (other alleles).

Question 16

Anaphase

definition

Answer 16

A stage within the mitosis phase of cell division (also known as cell reproduction). Anaphase starts when sister chromatids separate from each other and ends when each set of separated, sister chromatids arrives at the opposite poles of the cell.

Question 17

Centrioles

definition

Answer 17

The place where the microtubules originate from during mitosis. Centrioles are contained within the centrosomes.

Question 18

Cytokinesis

definition

Answer 18

The division of the cytoplasm of a cell at the end of mitosis to form two separate daughter cells. In animals cells, this occurs through the pinching of the membrane at the center of the parental cell while in plants, this occurs through the formation of a cell plate as new cell wall forms to separate the daughter cells.

Question 19

Interphase

definition

Answer 19

The stage of the cell cycle when division (mitosis) does not occur. During interphase, the cell grows, acquires nutrients, and replicates both its chromosomes as well as its organelles. Interphase consists of the G1 (chromosomes condense), S (DNA duplicates), and G2 (DNA integrity checked and repaired) phases of the cell cycle. Cells spend the majority of their time in interphase.

Question 20

Kinetochore

definition

Answer 20

Proteins on the centromere where microtubules attach. These attached microtubules are called kinetochore microtubules.

Question 21

Metaphase

definition

Answer 21

This is a stage of mitosis where the sister chromatids connected by centromeres are lined up along the plane of the cell’s center (called the metaphase plate).

Question 22

Microtubules

definition

Answer 22

One type of fiber that makes up the cytoskeleton of a eukaryotic cell. Microtubules consist of proteins called tubulins. Microtubules aide in cell structure and movement and are also responsible for moving the chromosomes during mitosis and meiosis.

Question 23

Prophase

definition

Answer 23

This is the first stage of mitosis. In prophase, the nucleus is broken down, the chromosomes (duplicated during the S phase of the cell cycle) condense, and the mitotic spindles form.

Question 24

Telophase

definition

Answer 24

This is the final stage of mitosis. In telophase, new nuclear envelopes form around the separated chromosomes at each pole of the cell, the chromosomes unfold back into chromatin, nucleoli reappear, and the cell continues to elongate.

Question 25

Asexual Reproduction
(definition)

Answer 25

A type of reproduction where genetically identical offspring are created from a single parent. This type of reproduction does not utilize meiosis or gametes. Bacteria and fungi are examples of organisms that reproduce in this manner.

Question 26

Nondisjunction

definition

Answer 26

The failure of sister chromatids or homologous chromosomes to separate during anaphase of either mitosis or meiosis.

Question 27

Clones

definition

Answer 27

The genetically identical offspring produced from asexual reproduction.

Question 28

Sexual Reproduction
(definition)

Answer 28

A more complicated form of reproduction where two haploid, gametes (sperm and egg) fuse to create a diploid zygote. This type of reproduction produces offspring that are genetically different from their parents.

Question 29

Meiosis II
(definition)

Answer 29

The second half of the whole process of meiosis in which the sister chromatids in each of the two haploid cells produced during meiosis I are separated. Meiosis II results in the production of four haploid gamate cells and is similar in process to mitosis.