Biology in Focus Chapter 10

heredity

the biological process whereby genetic factors are transmitted from one generation to the next

variation

an organism that has characteristics resulting from chromosomal alteration

genetics

scientific study of heredity

genes

DNA segments that serve as the key functional units in hereditary transmission.

gametes

A haploid cell such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.

somatic cells

Basically, all the cells in the body except those involved with reproduction.

locus

A specific place along the length of a chromosome where a given gene is located.

clone

A group of genetically identical cells or organisms derived from a single cell or individual by some kind of asexual reproduction

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

life cycle

The entire span in the life of an organism from one generation to the next.

karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

homologous chromosomes

Chromosomes that have the same sequence of genes and the same structure

sex chromosomes

Called by X and Y. It determines the sex of the individual.

autosomes

Any chromosome that is not a sex chromosome

diploid cell

A cell containing two sets of chromosomes (2n), one set inherited from each parent.

haploid cell

A cell that has only one representative of each chromosome pair

fertilization

Process in sexual reproduction in which male and female reproductive cells join to form a new cell

zygote

Fertilized egg

meiosis

(genetics) cell division that produces reproductive cells in sexually reproducing organisms

alternation of generations

the alternation between the haploid gametophyte and the diploid sporophyte in a plant's life cycle

sporophyte

In plants and algae that have alternation of generations, the diploid individual or generation that produces haploid spores

gametophyte

In organisms (plants and some algae) that have alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. The haploid gametes unite and develop into sporophytes.

meiosis I

Homologous chromosomes separate

meiosis II

Sister chromatids separate

allele

An alternative form of a gene.

synaptonemal complex

A zipper-like protein structure that causes replicated homologs to become physically connected during prophase of meiosis I; sets the stage for crossing over.

synapsis

Pairing of homologous chromosomes

crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

chiasmata

Point where two chromatids are intertwined

independent assortment

Independent segregation of genes during the formation of gametes

recombinant chromosome

A chromosome created when crossing over combines the DNA from two parents into a single chromosome.