GENETICS: 3.2 - chromosomes

What are the two types of cells in the human body?

Somatic cells and gametes

What are somatic cells?

Every cell in the body except egg and sperm (e.g., bone, skin, hair, blood)

What are gametes?

Sex cells – egg (females) and sperm (males)

How many chromosomes do human somatic cells have?

46 chromosomes (23 pairs)

How many chromosomes do human gametes have?

23 chromosomes

How do somatic cells reproduce?

By mitosis

Can gametes reproduce on their own?

No; they must be made by special cells through meiosis

What are the two types of chromosomes?

Autosomes and sex chromosomes

How many autosomes do humans have?

44 (22 pairs)

What are the sex chromosomes in humans?

X and Y chromosomes

What is the total chromosome count in a human somatic cell?

46 total: 44 autosomes + 2 sex chromosomes

What is a karyotype?

A picture of chromosomes arranged in pairs from largest to smallest

How is a karyotype made?

An actual photo of chromosomes is enlarged, cut out, and arranged in pairs

How many autosomes and sex chromosomes are in a somatic cell?

44 autosomes and 2 sex chromosomes

How many autosomes and sex chromosomes are in a gamete?

22 autosomes and 1 sex chromosome

Where do your chromosomes come from?

One set from mom’s egg and one from dad’s sperm

What are homologous pairs?

Chromosome pairs with the same shape, size, and gene locations

Do homologous pairs carry identical genes?

No, they carry different versions of the same genes

What are the different versions of genes called?

Alleles

What are alleles?

Different versions of the same gene at the same position (locus)

Which chromosomes are not always the same shape and size?

Sex chromosomes (X & Y)