MEIOSIS
This presentation is the property of its rightful owner.
Sponsored Links
1 / 43

MEIOSIS Chapter 11-4 PowerPoint PPT Presentation


  • 101 Views
  • Uploaded on
  • Presentation posted in: General

MEIOSIS Chapter 11-4. Warm Up Chapter11-4. What does diploid mean? What does haploid mean? How many chromosomes does mitosis produce in a cell? How many chromosomes does meiosis produce in a cell? What are homologous chromosomes?. Warm Up Chapter 10 and 11-4.

Download Presentation

MEIOSIS Chapter 11-4

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 chapter 11 4

MEIOSIS

Chapter 11-4


Meiosis chapter 11 4

Warm Up

Chapter11-4

  • What does diploid mean?

  • What does haploid mean?

  • How many chromosomes does mitosis produce in a cell?

  • How many chromosomes does meiosis produce in a cell?

  • What are homologous chromosomes?


Meiosis chapter 11 4

Warm Up

Chapter 10 and 11-4

  • How many chromosomes do humans have?

  • What does Meiosis do so that each cell does not have 92 chromosomes during fertilization?

  • Mitosis produces what kind of cells?

  • Meiosis produces what kind of cells?

  • How many cells does Mitosis produce?

  • How many cells does Meiosis produce?


Meiosis chapter 11 4

  • Meiosis cuts down the number of chromosomes in our cells to 23, so they can come together and create a cell with 46 chromosomes

  • -Meiosis creates variance - 23 chromosomes from mom, 23 chromosomes from dad

  • - Creates variants through reproduction


Meiosis chapter 11 4

1) Meiosis takes a cell with two copies of every chromosome (diploid) and makes cells with a single copy of every chromosome (haploid).

a. This is a good idea if you’re going to combine two cells to make a new organism. B. This trick is accomplished by halving chromosome number.


Meiosis chapter 11 4

2) Meiosis scrambles the specific forms of each gene that each sex cell (egg or sperm) receives.

a. This makes for a lot of genetic diversity. This trick is accomplished through and crossing-over.

b. Genetic diversity is important for the evolution of populations and species.


Meiosis chapter 11 4

The purpose of MITOSIS is to produce twoIDENTICAL(diploid) cells.

The purpose of MEIOSIS is to produce fourASSORTED and DIFFERENT(haploid)cells.


Meiosis chapter 11 4

Mieosis vs. Mitosis Animation 1:00

Mitosis/Meiosis Quiz

Meiosis/Mitosis side by side PPT

Dr. Thinkwell. Meiosis I and II 5:15


Meiosis chapter 11 4

Cornell Notes…

  • Meiosis and Mitosis

  • Mitosis goes through PMAT once.

  • Meiosis goes through PMAT twice.

  • Prophase I

  • Metaphase I

  • Anaphase I

  • Telophase I

  • Cytokinesis

  • Prophase II

  • Metaphase II

  • Anaphase II

  • Telophase II

  • Cytokinesis

MEIOSIS I

MEIOSIS II


Meiosis chapter 11 4

Cornell Notes…

MEIOSIS I


Meiosis chapter 11 4

Mieosis vs. Mitosis Animation 1:00

Mitosis/Meiosis Quiz

Meiosis/Mitosis side by side PPT

Dr. Thinkwell. Meiosis I and II 5:15

Thinkwell.Spermatogenesis 2.3


Concept check 10 and 11 fill out the chart what are the differences

Concept Check 10 and 11 – Fill out the chart (What are the differences)


Meiosis chapter 11 4

Cornell Notes…

  • Meiosis and Mitosis

  • During Prophase I, Meiosis undergoes “Crossing Over” between the paired chromatids.

  • Mitosis has NO crossing over.

  • Prophase I has crossing over between the chromatids resulting in the chromosomes of the offspring being DIFFERENT than either parent.


Meiosis chapter 11 4

Cornell Notes…


Meiosis chapter 11 4

Crossing-Over


Meiosis chapter 11 4

The Key Difference Between Mitosis and Meiosis is the Way Chromosomes Uniquely Pair and Align in Meiosis

The first (and distinguishing) division of meiosis

Mitosis


Meiosis chapter 11 4

End

P6


Meiosis chapter 11 4

The process of Meiosis

  • 2 Parts to Meiosis… Meiosis I and Meiosis II

  • Meiosis I is very similar to Mitosis

  • Interphase I – same as mitosis – the cell is growing – DNA replicates tetrads (4 sets of chromosomes)

  • Prophase I – chromosome pair together to make homologous pairs

  • Metaphase I – tetrads(4) stack and form in the middle (crossing over occurs) allows for more diversity

  • Anaphase I – homologous chromosome go to each side – they don’t separate they form dyads (2)

  • 5. Telophase I – nuclear membranes form – cytokinesis


Meiosis chapter 11 4

Meiosis II – going straight from Telophase I

6. Prophase II – diploid cells now – (2n) – each

cell has same amount as the parent cell

7. Metaphase II – similar to mitosis – line up in

the middle (centromeres on midline)

8. Anaphase II – chromosomes separate

9. Telophase II – nucleus forms and cytokinesis

results in 4 haploid cells (n).


Meiosis chapter 11 4

End

P5

P7


Meiosis chapter 11 4

Understanding Chromosomes

  • Somatic Cells ( Normal Human Body cells)

  • = 46 chromosomes (23 sets)

  • Diploid = 2 n

  • 2. Gametes (sex cells – sperm and egg) = 23 Chromosomes with one set

  • Haploid – 1n - not paired

  • 3. Ploidy – the number of chromosomes in a single cell.

  • some diseases happen when there is a different #

  • (Down’s syndrome has 47 chromosomes)

  • Down’s syndrome has 3 chromosomes for chromosome #21.


Meiosis chapter 11 4

Keys to Understanding Meiosis

1. Chromosomes are paired.

2. Chromosomes carry genes.

3. The gene forms on a pair of chromosomes may be homologous or non-homologous


Meiosis chapter 11 4

Crossing-Over


Meiosis chapter 11 4

Spermatogenesis

Men are busy – meiosis produces roughly 250,000,000 sperm per day.


Meiosis chapter 11 4

Oogenesis –

Women are less busy in meiosis than men – meiosis produces only a few hundred mature eggs over a lifetime.


Meiosis chapter 11 4

What Meiosis is About

Meiosis allows the creation of unique

individuals through sexual reproduction.


Meiosis chapter 11 4

End

P3


Meiosis chapter 11 4

We are all unique – 1 chromosome from mom and one from dad

we are half like our parents, which are half like their parents, which are half like their parents and so on … That creates diversity! – We are 1/2 our parents, 1/4 like our grandparents, 1/8 of our great grandparents  go back so many years – that’s how different we all are from each other.


Meiosis chapter 11 4

Meiosis I – Prior to Meiosis I, each chromosome is replicated to form a tetrad = X X

Name ________

Date_________

Phase

Metaphase I

Spinal fibers attach to entire chromosome

Phase Prophase I

Each chromosome pairs with its corresponding chromosomes “homologous” to form a tetrad.

\

Phase

Crossing Over

Exchange portions of chromatids


Meiosis chapter 11 4

Between Independent Assortment and Crossing-Over, No Two Gametes Are Identical.


Meiosis chapter 11 4

Y chromosome

X chromosome

Boy or Girl? The Y Chromosome “Decides”


Meiosis chapter 11 4

Boy or Girl? The Y Chromosome “Decides”


Meiosis chapter 11 4

“Putting It All Together” - Fertilization


Meiosis chapter 11 4

One Way Meiosis Makes Lots of Different Sex Cells (Gametes) – Independent Assortment

Independent assortment produces 2n distinct gametes, where n = the number of unique chromosomes.

In humans, n = 23 and 223≈ 8,000,0000.

That’s a lot of diversity by this mechanism alone.


Meiosis chapter 11 4

Crossing over

Meiosis Following a Single Chromosome Pair


  • Login