meiosis n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Meiosis PowerPoint Presentation
Download Presentation
Meiosis

Loading in 2 Seconds...

play fullscreen
1 / 28

Meiosis - PowerPoint PPT Presentation


  • 261 Views
  • Uploaded on

Meiosis. Honors Biology Spring 2013. Warm-Up. With a neighbor, discuss the following: What is meiosis? How does it differ from mitosis?. Essential Questions. What is meiosis and why is it necessary? What are the stages of meiosis? How does meiosis compare to mitosis?.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Meiosis' - pancho


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
meiosis

Meiosis

Honors Biology

Spring 2013

warm up
Warm-Up
  • With a neighbor, discuss the following:
    • What is meiosis?
    • How does it differ from mitosis?
essential questions
Essential Questions

What is meiosis and why is it necessary?

What are the stages of meiosis?

How does meiosis compare to mitosis?

haploid vs diploid
Haploid vs. Diploid

Diploid cells

1. Body cells

2. Contains homologous chromosomes

3. 2N

B. Haploid cells

1. Sex cells

2. contains one member of each pair

3. 1N

meiosis1
Meiosis
  • Meiosis
    • process which reduces by half the number of chromosomes in a diploid cell
  • meiosis occurs in sex organs of individual
overview of meiosis
Overview of Meiosis

A. Meiosis - formation of sex cells

1. Meiosis is cell division that results in a gamete containing half the number of chromosomes of its parent.

2. Meiosis includes 2 steps that each closely resemble corresponding steps in mitosis.

slide7

Phases of Meiosismeiosis I

    • Prophase I
    • Metaphase I
    • Anaphase I
    • Telophase I &?
    • CytokinesisPMAT I
  • Meiosis II
    • Prophase II
    • Metaphase II
    • Anaphase II
    • Telophase II &?
    • Cytokinesis PMAT II
meiosis 1
Meiosis 1

Meiosis I - reduction division

1. Interphase I

2. Prophase I

3. Metaphase I

4. Anaphase I

5. Telophase I

meiosis 1 prophase 1
Meiosis 1: Prophase 1
  • chromatin condenses to form chromosomes
  • homologous chromosomes attach to form tetrads
meiosis 1 prophase 11
Meiosis 1: Prophase 1
  • when tetrads form, crossing over can occur
  • crossing over is the

exchange of part of

homologous chromatids

meiosis 1 metaphase 1
Meiosis 1: Metaphase 1
  • tetrads line up on equator
  • spindle fibers attach to centromeres
meiosis 1 anaphase 1
Meiosis 1: Anaphase 1
  • homologous chromosomes

separate

  • spindle fibers pull them

to opposite poles

meiosis 1 telophase and cytokinesis
Meiosis 1: Telophase and Cytokinesis
  • telophase I
    • nuclear membrane

reforms

  • cytokinesis
    • cytoplasm splits
meiosis 1 results
Meiosis 1: Results
  • results
    • two haploid (n) daughter

cells = ½ the number of

chromosomes as parent cell

meiosis ii
Meiosis II

Meiosis II - separation of chromatids

1. Interphase II

2. Prophase II

3. Metaphase II

4. Anaphase II

5. Telophase II

slide17

Meiosis II: Prophase II

  • chromosomes already

formed

meiosis ii metaphase ii
Meiosis II: Metaphase II
  • chromosomes line up

along equator

meiosis ii anaphase ii
Meiosis II: Anaphase II
  • sister chromatids separate
  • move to opposite ends
meiosis ii telophase and cytokinesis
Meiosis II: Telophase and Cytokinesis
  • telophaseII
    • nuclear envelope reforms
  • cytokinesis
    • cytoplasm splits
meiosis ii results
Meiosis II: Results
  • 4 haploid (n) daughter cells
  • all genetically different
ploidy
Ploidy
  • parent cell?
  • dipliod (2n)
  • after meiosis I?
  • haploid (n) (monopliod)
  • after meiosis II?
  • hapliod (n)
purpose of meiosis diversity
Purpose of Meiosis: Diversity
  • Meiosis and sexual reproduction significantly contribute to genetic variation among offspring.
purpose of meiosis gametes
Purpose of Meiosis: Gametes
  • role of meiosis is to produce gametes
  • meiosis in males
    • spermatogenesis
    • produces 4 sperm cells
  • meiosis in females
    • oogenesis
    • produces 1 ovum (egg cell) and 3 polar bodies
mitosis vs meiosis
Mitosis vs. Meiosis
  • where does is occur?
  • meiosis – sex organs; mitosis – somatic cells
  • number of cell divisions?
  • meiosis – 2; mitosis – 1
  • number of cells produced?
  • meiosis – 4; mitosis – 2
  • ploidy of daughter cells?
  • meiosis – hapliod (n); mitosis – dipliod (2n)
  • # of chromosomes compared to parent cell?
  • meiosis – ½ # chromosomes; mitosis – same