Meiosis 2

What is the formula given for Meiosis?

2N ÷ 2 = N

What is the formula for a person with a normal diploid cell?

2N=46

Diploid

A cell that has a full set of chromosomes. A cell that is "2N" for chromosome amount

Haploid

A cell that has half the amount of chromosomes. A cell that is "N" for chromosome amount

Telophase 1

Cells get ready to divide.

Chromosome

Condensed/packed DNA for easy movement during cell division

importance of crossing over

Crossing over increases genetic diversity because every gamete produced is unique

When does interphase take place in meiosis?

First Division; DNA copies.

What is the final product of meiosis?

Four haploid cells result, each cell with a unique combination of chromosomes. Half of the chromosomes from the original cell.

Describe the main difference between Metaphase 1 and Metaphase 2.

In Metaphase 1, paired homologous chromosomes line up along the equator of the cell. However, in mitosis and Metaphase 2, it is sister chromatids that line up along the equator of the cell.

What is unique about the second division in mitosis?

It is a regular mitosis when chromosomes are not duplicated. At the end four cells are formed.

The stages of meiosis in the correct sequence

I→PMAT→C→PMAT→C

What is the variable normal haploid cell?

N

Is the DNA replicated after Meiosis 1? Why or why not?

No, because DNA is replicated in Interphase first and no interphase stage exists after after Meiosis 1.

Chromatid

One of the "arms" of a chromosome 'X'. Each sister chromatid is identical to the other because it is created by replication. A chromosome is made of two Sister Chromatids.

Centrioles

Organelles in the cell that help to move chromosomes during cell division

Meiosis

Results in the formation of 4 genetically unique gametes....used for sexual reproduction. Process produces haploid gametes.

When do the new cells being formed technically become "haploid"?

The cells are considered to be haploid when Anaphase I is complete. This is because homologous pairs of chromosomes are pulled apart but sister chromatids don't separate

What is unique about Meiosis II?

The cells do NOT replicate DNA between M-I and M-II. This will result in four haploid cells

Cytokinesis 1

The cytoplasm of the cell divides and two haploid daughter cells result. The daughter cells each have a random assortment of chromosomes, with one from each homologous pair. They go on to meiosis 2.

Prophase I

The nuclear envelope begins to break down, and the chromosomes condense. Centrioles start moving to opposite poles of the cell, and a spindle begins to form. Importantly, homologous chromosomes pair up, which is unique to prophase 1.

Fertilization

The process of making a zygote. When egg and sperm cells fuse and combine their genetic information (DNA)

Why do chromosomes look like an X?

They look like an X after the DNA has been replicated. (Crossing-over)

Chromatin

What you call the DNA during Interphase, Very easy to access the genes for transcription and translation to create proteins

Crossing over

When homologous chromosomes swap pieces during prophase I. Results in increased genetic diversity.

Anaphase I

When homologous pairs of chromosomes are pulled apart and moved to opposite poles in the cell...sister chromatids don't separate

Metaphase I

When homologous pairs of chromosomes line up in the middle of the cell.

State the phase where each of the following processes occur: (a) sister chromatids separate, (b) homologous chromosomes form phases, (c) two haploid cells form.

a: Anaphase 2 b: Prophase 1 c: Telophase 2

Somatic Cell

all diploid cells (body cells) that are not gametes

Where do the spindle fibers attach?

centromere of the sister chromatids

Zygote

fertilized egg cell formed form the joining of the gametes (sperm and egg)

Spindle Fiber

fibers created and used by the centrioles to move the chromosomes around during the division stages.

Results in 1 egg cell and 3 polar boides

happens in female animals and produces 1 egg..called oogeneisis

Results in 4 genetically unique sperm

happens in male animals... called spermatogenesis

centrioles go to the __________ to form the spindle

poles

Mitosis

produces 2 identical cells in the body for growth, replacement, repair, reproduction

What are the results of meiosis?

spermatogenesis: produces mature sperm cells oogenesis: produces one mature ovum or egg. the others are called polar bodies.

Gamete

the haploid "sex" cells (in animals they are sperm and egg cells)

Homologous Chromosomes

the same numbered chromosome that pair up from mother and father (ex: mom's chromosome 1 and dad's chromosome 1)...a matching set