Meiosis and sexual reproduction and punnet squares

Meiosis

A cell division process that leads to the formation of gametes.

Reproduction

The process of producing offspring.

Sexual Reproduction

Involves two parents contributing genetic material, resulting in genetically different offspring.

Asexual Reproduction

Involves one parent and is highly efficient with rapid reproduction.

Germ Cells

Specialized for sexual reproduction (e.g., sperm and egg).

Somatic Cells

All other body cells; do not participate in reproduction.

Chromosome Number

Each species has a distinct number of chromosomes (e.g., mosquitoes: 6, humans: 46, ferns: 500).

Fertilization

Combines two germ cells into a zygote.

Haploid Cells

Have one set of chromosomes (e.g., gametes).

Diploid Cells

Have two sets of chromosomes (e.g., somatic cells).

Homologous Chromosomes

Pairs of chromosomes similar in size, shape, and gene content, inherited from one parent.

Autosomes

Non-sex determining chromosomes.

Sex Chromosomes

Determine individual sex; XX is female and XY is male.

Meiosis Process

Involves two divisions, resulting in four haploid cells from one diploid cell.

Genetic Variation

Beneficial for a population, improving chances for survival against significant environmental changes.

What happens in Meiosis II?

Involves reduction division, resulting in cells with half the number of chromosomes.

What happens in Meiosis II?

Involves separating sister chromatids and leads to a total of four haploid cells after completion.

S Phase

Refinement of DNA; important to note that while it resembles mitosis, it precedes Meiosis I.

Where does sexual reproduction occur?

mainly in eukaryotic cells

What does each parent create?

gametes

What happens to gametes?

They fuse and form a zygote known as fertiliation

asexual reproduction advantages

Very efficient - can reproduce a lot in a short period of time

asexual reproduction disadvantages

Organisms can die off easily if the environment changes and less diverse

sexual reproduction advantages

Produces genetically different organisms so a population could survive in a changing environment

sexual reproduction disadvantages

It could take a lot of energy to find a mate

What does meiosis do?

makes 4 genetically different haploid daughter cells, happens in reproductive structures

What happens in mitosis?

Produces 2 genetically identical diploid daughter cells.

Used for growth and repair in body cells.

What happens in prophase 1?

each replicated chromosome pairs with its corresponding homologous chromosome

What happens in metaphase?

Chromosomes line up in the middle of the cell

What happens in anaphase?

Sister chromatids split and move to either pole

What happens in telophase?

Nuclear membrane reforms, Chromosomes decondense

What are the stages of meiosis 1?

Prophase 1, Metaphase 1, Anaphase 1, Telophase 1

product of meiosis 1?

2 cells with half the number of chromosomes

product of meiosis 2?

4 haploid daughter cells

What is a genotype?

genetic makeup of an organism

What is a phenotype

physical appearance

What is a allele?

Different forms of a gene