MEIOSIS - O'Mara's Science Siteomarascience.weebly.com/uploads/2/7/7/4/2774881/meiosis.pdf ·...

MEIOSIS

Making gametes…

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

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

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

Remember from Chapter 1:CHARACTERISTICS OF LIVING THINGS

ALL LIVING THINGS __________REPRODUCE

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

BINARY FISSION

BINARY FISSION & MITOSIS

Produces cells that are __________ copies of parent cell

identical

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 are

genetically __________

from parents

DIFFERENT

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 to 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


DIPLOID & HAPLOIDMost cells have 2 copies of each chromosome = ______________

(one from mom; one from dad)

All BODY (___________) cells are diploid

DIPLOID 2n

HOMOLOGOUSCHROMOSOMES

= SOMATIC

DIPLOID & HAPLOID

Some cells have only one copy of each chromosome = _____________

All sperm and egg cells

are haploid. Called gametes or sex cells.

HAPLOID 1n

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


2identical

2n

SOMATIC (body)

MEIOSIS• Makes ____ cells genetically different from parent cell & from each other

• Makes _____ cells

• Makes ______________

• Used for ____________

4

1n

Gametes (sperm & eggs)

sexual reproduction


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 ________________

= ______________SYNAPSIS

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

This group of FOUR (4)chromatids is called a_________________TETRAD

PROPHASE I

HOMOLOGOUS CHROMOSOMESImage 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

NOT IDENTICAL

WHAT MAKES MEIOSIS DIFFERENT?

2. Exchange of DNA betweenhomologous pairs = _____________during PROPHASE I

CROSSING OVER

Allows shuffling of genetic material

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

CROSSING OVER

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

rearranging of DNA

NOT IDENTICAL


Separation of chromosomes during ANAPHASE I

INDEPENDENT ASSORTMENT

Separates gene choices and allows shuffling of genetic material

SEGREGATION &

SEGREGATION(Anaphase I)

SEGREGATION & CROSSING OVERtogether make even more combinations


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


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

ONLY COPIES ITS DNA ONCE

G1 G2S P M A T C

G1

MITOSIS:

MEIOSIS:

S G2 P M A T C

P M A T C

( I )

( II )


1. Crossing over 2. Segregation 3. Independent assortment

are ALL ways MEIOSIS results in =______________________________

So daughter cells are ______________

from parents and from each otherdifferent

GENETIC RECOMBINATION

Go to Section:

Meiosis I

Section 11-4

Figure 11-15 Meiosis

Go to Section:

Meiosis I

Section 11-4


Meiosis I

Go to Section:

Section 11-4


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 MEIOSIS

INTERPHASE INTERPHASE I

• DNA is spread out as chromatin

• Nuclear membrane/nucleolus visible

• DNA is copied during S phase

SAME AS

MITOSIS

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

http://www.biostudio.com/d_ Mitosis.htm

http://www.biostudio.com/d_ Meiosis.htm

MITOSIS vs MEIOSIS

PROPHASE PROPHASE I

DNA scrunches into replicated chromosomes

Nuclear membrane/

nucleolus disappear

Centrioles/spindle fibers appear

DNA scrunches into

replicated chromosomes

Nuclear membrane/

nucleolus disappear

Centrioles/spindle fibers

appear Homologous pairs match up


MITOSIS vs MEIOSISMETAPHASE METAPHASE I

Replicated

chromosomes line up

in middle

Replicated chromosomes line up

in middle


with homologous partner

MITOSIS vs MEIOSIS

ANAPHASE ANAPHASE I

APART:

Chromatids split

APART:


Chromatids stay together

Homologous pairs split

MITOSIS vs MEIOSIS

TELOPHASE TELOPHASE I

See TWO nuclei

Nuclear membrane/

nucleolus return

DNA spreads out as chromatin

Spindle/centrioles disappear

SAME AS MITOSIS


MITOSIS vs MEIOSIS

CYTOKINESIS CYTOKINESIS I

Cytoplasm splits

into 2 cells

SAME AS

MITOSIS


MITOSIS vs MEIOSIS

PROPHASE PROPHASE II

• DNA scrunches into replicated chromosomes

• Nuclear membrane/nucleolus disappear

• Centrioles/ spindle fibers appear

Two cells in meiosis II; no

Homologous pairs


MITOSIS vs MEIOSISMETAPHASE METAPHASE II

• Replicated chromosomes line up in middle

SAME AS MITOSIS


MITOSIS vs MEIOSIS

ANAPHASE ANAPHASE II

Chromatids split and move apart SAME AS MITOSIS


MITOSIS vs MEIOSIS

TELOPHASE TELOPHASE II

Two nuclei

Nuclear membrane/nucleolus returns

Centrioles/spindle fibersdisappear

DNA spreads out as

chromatin

SAME AS MITOSIS


MITOSIS vs MEIOSIS

CYTOKINESIS CYTOKINESIS II

Cytoplasm splits

2 daughter cells

Cytoplasm splits

4 cells




MAKING

SPERM & EGGS

___________________= MAKING MATURE SPERMMature & grow flagella

SPERMATOGENESIS

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!

Sperm provides DNA

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

POLAR BODIES

Produces:

1 “good” egg

3

CYTOPLASM DIVIDES UNEVENLY

__________________ = MAKING a MATURE EGG

OOGENESIS

“Self digest”

Using________________

POLAR BODIES DEGENERATE (DIE)

LYSOSOMES

= __________________“cell suicide” for good of organism

APOPTOSIS

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