unit 7 notes 3 Flashcards
Define Meiosis
A type of cell division where 1 body cell divides to make 4 gametes (sex cells)
What are the 2 stages of Meiosis?
Meiosis 1 and Meiosis 2
Define sex cells
Egg and Sperm cells
where egg cells made?
in the ovaries of a female
where are Sperm cells made?
in the testes of a male
What are the reproductive organs?
ovaries and testes
Define diploid cells?
Body cells
- they have 2 of each type of chromosome
How many chromosomes are diploid cells in humans?
46
Define haploid cells?
Sex cells
- They have one of each type of chromosomes
Why do gametes have 1/2 the number of chromosomes?
An egg and Sperm cell will combine to from a zygote. The zygote needs to have the diploid number of chromosomes
Define zygote
Fertilized egg cells
Define homologous chromosomes
pair of chromosomes (1 from mom and 1 from dad)
- each pair will have the same type of genes
- diploid cells have homologous chromosomes
Define karyotype
shows 23 pairs of homologous chromosomes
How many times must Meiosis happen?
twice
What are the phases of meiosis?
prophase 1, metaphase1, anaphase 1, telophase1, prophase 2, metaphase 2, anaphase 2, telophase 2
What happens during interphase of meiosis?
Chromosomes duplicate and become visible
What happens during prophase 1 of meiosis?
homologous chromosomes pair up
- they from tetrad
- the process of crossing over
Define tetrad
2 homologous chromosomes (4 sister chromatids)
define crossing over
the process where homologous chromosomes break apart and exchange genes
Why is crossing over an important process?
Allows to get genes from both mom and dad
- allows for genetic variation
What is produced at the end of meiosis?
4 haploid gametes
- each gamete will have different genetic material
Define oogenesis
the creation of an egg cell and 3 polar bodies
Define spermatogenesis
the creation of 4 sperm cells
What are polar bodies?
small cells, only the size of the nucleus
