Chromosomes and Cell Division

Fill-in-the-blank practice flashcards covering Chapter 19: Chromosomes and Cell Division, including mitosis, meiosis, cell cycle phases, gametogenesis, and chromosomal abnormalities.

A single-celled __________ ($2n$) is formed by the union of an egg and a sperm at the beginning of life.

zygote

Nuclear division that results in genetically identical body cells is called __________.

mitosis

Nuclear division that gives rise to gametes with half the number of chromosomes is called __________.

meiosis

In human males, meiosis occurs in the __________ to produce sperm.

testes

In human females, meiosis occurs in the __________ to produce eggs.

ovaries

Chromosomes consist of a DNA molecule combined with specialized proteins called __________.

histones

A specific segment of DNA that directs the synthesis of a protein is known as a __________.

gene

Human somatic cells contain __________ chromosomes, consisting of 23 pairs.

46

Pairs of chromosomes that contain genes for the same traits, with one inherited from each parent, are called __________ pairs.

homologous

The 22 pairs of chromosomes that determine expression of most inherited characteristics, excluding gender, are called __________.

autosomes

In human sex determination, genetic females have XX chromosomes, while genetic males have __________ chromosomes.

XY

Interphase is divided into three distinct phases: $G_1$, S, and __________.

$$G_2$$

During the __________ phase of interphase, DNA is replicated to form two identical chromatids attached at the centromere.

S

In adult humans, most __________ lose their ability to divide entirely.

neurons

During __________ of mitosis, chromatin condenses into chromosomes, the nuclear membrane breaks down, and the mitotic spindle forms.

prophase

During metaphase of mitosis, chromosomes line up along the __________ of the cell.

center

During anaphase of mitosis, sister chromatids split apart at the __________.

centromere

Division of the cytoplasm to form two separate daughter cells is called __________.

cytokinesis

During cytokinesis in animal cells, a ring of __________ contracts at the midline to pinch the cell in two.

microfilaments

An image showing the arrangement of a person's chromosomes based on size and centromere location is called a __________.

karyotype

Meiosis I is a reduction division because it separates homologous pairs, converting a diploid cell ($2n$) into two __________ cells ($n$).

haploid

The process during Prophase I where homologous chromosomes pair and become perfectly aligned is called __________.

synapsis

The exchange of gene segments between nonsister chromatids during synapsis in Prophase I is called __________.

crossing over

The random alignment of maternal and paternal homologous pairs at the equatorial plate during Metaphase I is known as __________.

independent assortment

The brief interphase-like period between meiosis I and meiosis II where NO DNA replication occurs is called __________.

interkinesis

Spermatogenesis results in the formation of __________ functional sperm cells.

four

Oogenesis results in the production of one functional ovum and up to three nonfunctional __________.

polar bodies

The failure of homologous chromosomes or sister chromatids to separate during meiosis is called __________.

nondisjunction

The presence of three representatives of a chromosome in a cell is known as __________.

trisomy

Down syndrome occurs when an infant is born with three copies (trisomy) of chromosome __________.

21

A female affected by Turner syndrome has the sex chromosome genotype __________.

XO

A male affected by Klinefelter syndrome has the sex chromosome genotype __________.

XXY

According to the comparison table, mitosis occurs in somatic cells, while meiosis occurs only in the __________ and testes.

ovaries