MEIOSIS 11-4. http://waynesword.palomar.edu/lmexer2a.htm. Making gametes…. Remember from Chapter 1: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________. Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm Family http://babyhearing.org/Parenet2Parent/index.asp.
Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htmFamily http://babyhearing.org/Parenet2Parent/index.asp
Bacteria reproduce using
Budding & regeneration are used by plants and animals to reproduce asexually (mitosis)
Planaria animation: http://www.t3.rim.or.jp/~hylas/planaria/title.htm
Produces cells that are __________ copies of parent cell
Can make offspring faster
Don’t need a partner
Species CAN’T change and adapt
One disease can wipe out whole population
Family image from: http://babyhearing.org/Parenet2Parent/index.asp
Combines genetic material
from 2 parents (sperm & egg)
so offspring are
Allows for variation in population
Individuals can be different
Provides foundation for EVOLUTION
Allow species adapt to
Image by Riedell
Image by Riedell
If egg and sperm had same number of
chromosomes as other body cells . . .
baby would have too many chromosomes!
to make cells with ½ the number of chromosomes
Click the image to play the video segment 11A.
Most cells have 2 copies of each chromosome = ______________
(one from mom; one from dad)
All BODY (___________) cells are diploid
Some cells have only one copy of each chromosome = _____________
All sperm and egg cells
INDEPENDENT ASSORTMENT (ANAPHASE I)
3. Skip INTERPHASE II (NO S)
CELL DIVIDES TWICE, BUT…
ONLY COPIES DNA ONCE
This group of FOUR (4)
chromatids is called a
Images modified from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/Crossover.gif
1. Exchange of DNA betweenhomologous pairs = _____________during PROPHASE I
Allows shuffling of genetic material
SEE CROSSING OVERANIMATION
Image modified by Riedell
(Don’t have to have the SAME CHOICES)
Image modified by RiedellCROSSING OVER
in different combinations
2.Separation during ANAPHASE I
Separates gene choices and allows shuffling of genetic material
Segregation of Chromosomes
Click the image to play the video segment 11D.
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!
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
( I )
( II )
Animal Cell Meiosis, Part 1 & Part 2
Click the image to play the video segment 11B. & C
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The 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.
DNA scrunches into chromosomes
Centrioles/spindle fibers appear
DNA scrunches into chromosomesNuclear membrane/ nucleolus disappear Centrioles/spindle fibers appear
Chromosomes line up in middle
Chromatids stay together________________________
See TWO nuclei
DNA spreads out as chromatin
into 2 cells
Chromatids split and move apart
Nuclear membrane/nucleolus returns
DNA spreads out as
___________________= MAKING MATURE SPERM
Mature & grow flagella
All the starting nutrients,
organelles, molecule building blocks,
etc. have to come from the egg.
MAKING a MATURE EGG
1 “good” egg
CYTOPLASM DIVIDES UNEVENLY
Sperm donates mostly DNA
Most of the cell parts and nutrients needed for baby come from EGG!
POLAR BODIES DEGENERATE (DIE)
“cell suicide” for good of organism