MEIOSIS 11-4 Making gametes… .

transcript

MEIOSIS11-4

Making gametes…

http://waynesword.palomar.edu/lmexer2a.htm

Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htmFamily http://babyhearing.org/Parenet2Parent/index.asp

Remember from Chapter 1:CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________

ASEXUAL REPRODUCTIONBacteria reproduce using__________________________________

Budding & regeneration are used by plants and animals to reproduce asexually (mitosis)

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookmito.html

http://fig.cox.miami.edu/~cmallery/150/mitosis/c7.13.2.hydra.jpg

Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm

MITOSIS

Produces cells that are __________ copies of parent cell

ADVANTAGES OF ASEXUAL REPRODUCTION

Can make offspring faster

Don’t need a partner

http://www.mrgrow.com/images/cutting.jpg

DISVANTAGES OF ASEXUAL REPRODUCTION

ALL ALIKE

Species CAN’T change and adapt

One disease can wipe out whole population

http://www.mrgrow.com/images/cutting.jpg

SEXUAL REPRODUCTION

Combines genetic material

from 2 parents (sperm & egg)

so offspring aregenetically __________ from parents

Family image from: http://babyhearing.org/Parenet2Parent/index.asp

ADVANTAGES OF SEXUAL REPRODUCTION

Allows for variation in population

Individuals can be different

Provides foundation for EVOLUTION

Allow species adapt to changes intheir environment

http://naturalsciences.sdsu.edu/classes/lab8/spindex.html

EGG + SPERM

If egg and sperm had same number of chromosomes as other body cells . . . baby would have too many chromosomes!

http://www.angelbabygifts.com/Image by Riedell Image by Riedell

http://www.acmecompany.com/stock_thumbnails/13217.forty-six_chromosomes.jpg

MEIOSIS is the way…

to make cells with ½ the number of chromosomesfor sexual reproduction

Click the image to play the video segment 11A.

Video 1

Meiosis Overview

DIPLOID & HAPLOIDMost cells have 2 copies of each

chromosome = ______________(one from mom; one from dad)

All BODY (___________) cells are diploid

HOMOLOGOUSCHROMOSOMES

DIPLOID & HAPLOID

Some cells have only one copy of each chromosome = _____________

All sperm and egg cells are haploid

MITOSIS•Makes ___ cells genetically _________ to parent cell & to each other

•Makes ___ cells•Makes __________•Used by organisms to: increase size of organism, repair injuries, replace worn out cells

MEIOSIS•Makes ____ cells

genetically different from parent cell & from each other

•Makes _____ cells•Makes ______________

•Used for ____________

WHAT MAKES MEIOSIS DIFFERENT ?

1. SYNAPSIS & CROSSING OVER (PROPHASE I)

2. SEGREGATION & INDEPENDENT ASSORTMENT

(ANAPHASE I)

3. Skip INTERPHASE II (NO S) CELL DIVIDES TWICE, BUT…

ONLY COPIES DNA ONCE

1.Homologous chromosomes pair up during ____________= ______________

Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

This group of FOUR (4)chromatids is called a_________________

WHAT MAKES MEIOSIS DIFFERENT?

1. Exchange of DNA betweenhomologous pairs = _____________during PROPHASE I

Allows shuffling of genetic material

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif

• Click the image to play the video segment. 11E

Video 5

Crossing Over

SEE CROSSING OVERANIMATION

HOMOLOGOUS CHROMOSOMES

Image modified by Riedell • SAME SIZE• SAME SHAPE• CARRY GENES for the

SAME TRAITS• BUT ______________! (Don’t have to have

the SAME CHOICES)

http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

CROSSING

Image modified by Riedell

• Allows for_________________in different combinations

• After crossing over, chromatid arms are________________ anymore

http://sps.k12.ar.us/massengale/genetics%20tutorial.htm

2.Separation during ANAPHASE I

_______________________

Separates gene choices and allows shuffling of genetic material

__________________ &

Click the image to play the video segment 11D.

Video 4

Segregation of Chromosomes

SEGREGATION(Anaphase I)

SEGREGATION & CROSSING OVERtogether make even more

combinations

See ananimation

INDEPENDENT ASSORTMENT

http://fig.cox.miami.edu/~cmallery/150/mitosis/c13x9independent-assortment.jpg

INDEPENDENT ASSORTMENTat ANAPHASE I

Lots of different combinations are possible!

This is why you don’t look exactly like your brothers and sisters even though you share the same parents!

http://www.tokyo-med.ac.jp/genet/anm/mimov.gi

Crossing over Segregation Independent assortment

are ALL ways MEIOSIS results in =______________________________

So daughter cells are ______________from parents and from each other

3. Skip INTERPHASE II (No S) CELL DIVIDES TWICE, BUT … ONLY COPIES ITS DNA ONCE

G1 G2S P M A T C

MITOSIS:

MEIOSIS:

S G2 P M A T CP M A T C

( II )

Video 2

Click the image to play the video segment 11B. & C

Video 2

Animal Cell Meiosis, Part 1 & Part 2

Go to Section:

Section 11-4

Figure 11-15 Meiosis

Meiosis I

Go to Section:

Meiosis II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.

Prophase II Metaphase II Anaphase II Telophase IIThe chromosomes line up in a similar way to the metaphase stage of mitosis.

The sister chromatids separate and move toward opposite ends of the cell.

Meiosis II results in four haploid (N) daughter cells.

Section 11-4

Figure 11-17 Meiosis II

MITOSIS vs MEIOSISINTERPHASE INTERPHASE I

• DNA is spread out as chromatin• Nuclear membrane/

nucleolus visible• DNA is copied during S phase• Makes stuff new cell needs in G2

_______________

http://www.pbs.org/wgbh/nova/baby/divi_flash.html

MITOSIS vs MEIOSIS PROPHASE PROPHASE I

DNA scrunches into chromosomes

Nuclear membrane/ nucleolus disappearCentrioles/

spindle fibers appear

DNA scrunches into chromosomesNuclear membrane/ nucleolus disappear Centrioles/spindle fibers appear _________________________

MITOSIS vs MEIOSIS METAPHASE METAPHASE I

• Chromosomes line up in middle

Chromosomes line up in middle

______________________________

MITOSIS vs MEIOSIS ANAPHASE ANAPHASE I

APART:Chromatids split

APART:

Chromatids stay together________________________

MITOSIS vs MEIOSIS TELOPHASE TELOPHASE I

See TWO nucleiNuclear membrane/ nucleolus returnDNA spreads out as chromatinSpindle/centrioles disappear

____________________

MITOSIS vs MEIOSIS CYTOKINESIS CYTOKINESIS I

Cytoplasm splits

into 2 cells

______________________

MITOSIS vs MEIOSIS INTERPHASE II

• DNA is spread out as chromatin• Nuclear membrane/

nucleolus visible• DNA is copied during S phase

______________________________________________________

MITOSIS vs MEIOSIS PROPHASE PROPHASE II

• DNA scrunches into chromosomes

• Nuclear membrane/nucleolus disappear

• Centrioles/ spindle fibers appear

____________________

MITOSIS vs MEIOSIS METAPHASE METAPHASE II

• Chromosomes line up in middle ______________________

MITOSIS vs MEIOSIS ANAPHASE ANAPHASE II

Chromatids split and move apart

__________________________

MITOSIS vs MEIOSIS TELOPHASE TELOPHASE II

Two nucleiNuclear membrane/

nucleolus returnsCentrioles/spindle fibers

disappearDNA spreads out as chromatin

_______________________

MITOSIS vs MEIOSIS CYTOKINESIS CYTOKINESIS II

Cytoplasm splits _____________________

Ways Meiosis is different?• Homologous pairs match up & trade DNA

(SYNAPSIS & CROSSING OVER) in PROPHASE I

•SEGREGATION

& INDEPENDENT ASSORTMENT in Anaphase I

create genetic recombination• Skipping INTERPHASE II- (Dividing TWICE but copying DNA once)

produces 1n cells

MAKING SPERM & EGGS

___________________= MAKING MATURE SPERM

Mature & grow flagella

Sperm provides DNA

All the starting nutrients, organelles, molecule building blocks, etc. have to come from the egg.

Produces: 1 “good” egg

3 __________

CYTOPLASM DIVIDES UNEVENLY

__________________ = MAKING a MATURE EGG

Sperm donates mostly DNA

http://bestweekever.blogs.com/photos/uncategorized/imagemain_sperm_egg1_1.gif

WHY MAKE ONLY ONE “GOOD” EGG?

Most of the cell parts and nutrients needed for baby come from EGG!

“Self digest”

Using ________________

POLAR BODIES DEGENERATE (DIE)

= __________________ “cell suicide” for good of organism

MEIOSIS 11-4 Making gametes… .

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