Chromosome Structure and Function

number of sex chromosomes in human somatic cells

2 or 1 pair; female: XX; male: XY

human chromosome number

2N=46

number of autosomes in human somatic cells

44 or 22 pairs

sex chromosomes

Chromosomes that determine the sex of an individual

histones

Protein molecule around which DNA is tightly coiled in chromatin

fertilization

The union of haploid (N) gametes to produce a diploid (2N) zygote.

somatic cells

all body cells except the reproductive cells

haploid

an organism or cell having only one complete set of chromosomes and is a mixture of the chromosomes of parents (N=23)

centromere

area where the chromatids of a chromosome are attached

chromatin

chromosomes in a cell that is not actively dividing/reproducing; less tightly coiled

autosomes

chromosomes other than sex chromosomes

nucleus

control center of the cell

homologous chromosomes; homologues

each of the 23 pairs of human chromosomes consists of 2 homologues w/ similar size, shape, and genetic content; each homologue is inherited from 1 of 2 parents.

zygote

fertilized egg (2N)

karyotype

photograph of chromosomes grouped in order in pairs

sex cells

specialized cells that are used in reproduction;egg and sperm; gametes

2N

symbol for diploid

N

symbol for haploid

diploid

term used to refer to a cell that contains both sets of homologous chromosomes, one set from each biological parent (2N=46)

chromosomes

threadlike structures made of DNA molecules that contain the genes (hereditary material)

chromatids

two exact copies of DNA that make up each chromosome