Sexual Reproduction & Meiosis

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sexual reproduction

is a type of reproduction in which the genetic materials from two different cells combine, producing an offspring

Where do Sex cells form?

reproductive organs

How many types of sex cells?

Two

What are the types of sex cells?

egg and sperm

What is the female sex cell?

Eggs

What is the male sex cell?

sperm

Fertilization

Fusion of an egg and sperm cell

After fertilization, what is the new cell that's formed is called?...

Zygote

What happens after fertilization?

A zygote goes through mitosis and cell division.

Mitosis and cell division produce nearly all of the cells in a __________?

Multicellular Organism

In the body cells of most organisms, chromosomes occur

in pairs

Cells that have pairs of chromosomes are called_____?

Diploid Cells

Organisms that reproduce sexually form two kinds of cells, what are they?

Body Cells & Sex Cells

In the body cells of most organisms, chromosomes occur in pairs. Cells that have pairs of chromosomes are called

diploid cells

Pairs of chromosomes that have genes for the same traits arranged in the same order are called

homologous chromosomes

Are chromosomes always identical?

No, because one chromosome is inherited from each parent

Different organisms have different numbers of

chromosomes

Human diploid cells have ____ of chromosomes

23 single

Human diploid cells have a total of (how many) chromosomes.

46

What happens is a zygote has too many or too few chromosomes?

It will not develop properly

What does the process of meiosis help do?

Maintain the correct number of chromosomes

What happens if a mistake occurs in animal cells?

Sometimes the zygote dies. But if it lives, every cell in that organism will have the wrong amount of chromosomes and may not grow normally.

What does a person with down syndrome have?

An extra chromosome.

Organisms that reproduce sexually also form ...

egg and sperm cells, or sex cells

Sex cells have (how many chromosomes) from each pair of chromosomes.

1

Haploid cells

cells that have only one
chromosome from each pair.

Meiosis

Organisms produce sex cells using a special type of cell division

What happens in meiosis?

one diploid cell divides and makes four
haploid sex cells.

Meiosis occurs only during the formation of?

sex cells

Mitosis and cytokinesis involve ____
division of the _____ & _____

one; nucleus and cytoplasm

Meiosis involves ___divisions of the ___ & ___

Two; nucleus and the cytoplasm.

The two divisions in meiosis are phases called...

Meiosis I & Meiosis II

Meiosis results in how many haploid cells

four

Meiosis results in (#) haploid cells, each with (?)
the number of chromosomes as the original cell.

4; half

A reproductive cell goes through interphase before beginning which phase?

Meiosis I

What happens during interphase?

the reproductive cell grows and copies, or duplicates, its chromosomes.

Each duplicated chromosome consists of (#?) sister ___ joined by a ___

2 - chromatids - centromere

What happens during prophase I

duplicated chromosomes condense, or shorten, and thicken.

Homologous chromosomes

come together and form pairs

During the meiosis I prophase, the membrane around the nucleus does what?

Breaks apart and the nucleolus disappears

What does a cell go through before beginning meiosis I

Interphase

What happens in metaphase I ?

homologous chromosome pairs line up along the middle of the cell.

What happens during anaphase I

Chromosome pairs separate and are pulled toward opposite ends of the cell. The sister chromatids stay together.

What happens During telophase I

-A membrane forms around each group of duplicated chromosomes.

-The cytoplasm divides through cytokinesis, and two daughter cells form.

-Sister chromatids remain together.

During which phase does sister chromatids remain together?

Telophase I

What happens to chromosomes before prophase II ?

chromosomes are not copied again before prophase 11. They remain short and thick sister chromatids.

What happens during prophase II?

the membrane around the nucleus breaks apart, and the nucleolus disappears in each cell.

What happens during metaphase II?

The chromosomes (sister chromatids) line up along the middle of the cell in single file

What happens during anaphase II?

The sister chromatids of each duplicated chromosome are pulled apart then they move toward opposite ends of the cells

What is the final phase of meiosis?

Telophase

what happens during telophase II?

-a nuclear membrane forms around each set of chromatids.

-The chromatids are again called chromosomes.

-The cytoplasm divides through cytokinesis, and four haploid cells form.

What phase is this?

Review: Meiosis Phase II

List 3 reasons why meiosis is important

1. Meiosis is important to sexual reproduction.
2. It forms the correct haploid number of chromosomes.
3. This maintains the correct diploid number of chromosomes in organisms when sex cells join.
4. Leads to genetic variation

Review: Differences between mitosis and meiosis

Review: Creating Haploid Cells

Review: Advantages of sexual reproduction

Review: Genetic Variation II

Review: Genetic Variation

Review: Disadvantages of sexual reproduction