Human Life Cycle

What is a karyotype?

The process of lining up the chromosomes in a cell for study.

How many chromosomes does a human somatic cell have?

46 total (44 autosomes and 2 sex chromosomes).

What are homologous chromosomes?

The 23 pairs of chromosomes with one from each parent, identical in length, function, location, and band pattern.

What do homologous chromosomes carry?

Genes that control the same inherited characteristics.

Example of homologous chromosome variation

One chromosome may have a gene for freckles, while the other lacks it.

What is the exception to homologous pairs?

The sex chromosomes (X and Y)

What sex chromosomes do males and females have?

Males: XY; Females: XX.

How many chromosomes do gametes have?

23 (haploid number, n)

What happens when an egg is fertilized by a sperm?

A zygote forms with 46 chromosomes (diploid number, 2n).

How are genes passed on to somatic cells?

Through mitosis as the human develops.

What process makes gametes?

Meiosis

What process conserves the chromosome number?

Mitosis (46 in parent and 46 in daughter cells).

What process reduces the chromosome number?

Meiosis (46 in parent and 23 in daughter cells).

What restores the diploid number after meiosis?

Fertilization