1. Cell division / Asexual reproduction
Mitosis
produce cells with same information
identical daughter cells
exact copies
clones
same amount of DNA
same number of chromosomes
same genetic information
Aaaargh! I’m seeing double!

2. Mitosis & Asexual reproduction
Single-celled eukaryotes
yeast (fungi)
Protists
Paramecium
Amoeba
Simple multicellular eukaryotes
Hydra
budding
budding
What are the disadvantages of asexual reproduction?
What are the advantages?

3. + 46 46 92 How about the rest of us?
What if a complex multicellular organism (like us) wants to reproduce?
joining of egg + sperm
Do we make egg & sperm by mitosis?
No!
What if we did, then…. 46 + 46 92
egg
sperm
zygote
Doesn’t work!

4. This is where we start talking about MEIOSIS
MEIOSIS - Cell division that leads to creation of Egg and Sperm cells – ________________!
This leads us into a discussion of how traits are passed from one generation to the next
______________________
The scientific study of heredity and hereditary information

5. Note! When we pass on traits…
We certainly do pass on similarities, but we are not CLONES!
___________________ exists as well
MEIOSIS is one important key in ensuring that VARIATION exists (at least among sexually reproducing organisms)
What’s the big deal
About variation??

6. Units of Heredity… ___________________
SEGMENTS or regions of our long DNA molecules
Each chromosome is ________ long strand of DNA
If the chromosome has been replicated, it is ______ long strands of DNA joined at the centromere…
Highly coiled (remember __________________ proteins)
Genes Program our _________________________
May be ____________s of genes on a single chromosome
Each chromosome is subdivided into many GENES
Specific location of a gene on a chromosome
__________________________
Genes have predictable “addresses” or loci on chromosomes
Generally the same from person to person…though there is VARIATION sometimes
ALL the genes contained in an organism
___________________________

7. What is a Karyotype?
A display that shows the chromosomes from an individual cell arranged in pairs starting with the longest chromosome pair.

8. What does a human karyotype tell us about chromosomes?
How many?
_____
Arranged in PAIRS that are SIMILAR, though NOT IDENTICAL.
_________________________
How many pairs?
______
Also, Staining methods and general visual inspection can tell us if a chromosome is “normal”
Banding patterns
Length of “arms”, etc.

9. What is the origin of each member of a homologous pair?
One member of each pair comes from the organism’s…
_________________
The other member of each pair comes from the organism’s…
THEREFORE, while each homologous pair will contain genes for the same general trait (for example, eye color), they may _______ carry _________________ information for that trait.
For example mom may pass a chromosome with the gene for _________ eyes, while dad may pass a chromosome with the gene for ______________ eyes.
____________ but not ___________________!

10. Homologous chromosomes
Paired chromosomes
both chromosomes of a pair carry “matching” genes
control same (actually, just similar) inherited characters
homologous = same (similar) information
_________ stranded homologous chromosomes
__ phase of interphase – csomes are replicated
Gene for “eye color”
__________ stranded homologous chromosomes

11. Karyotypes also tell us about SEX…
____________________
“normal” chromosomes that EVERYONE shares in common, regardless of gender
In humans, pairs ___-____ are autosomes
Sex Chromosomes
Chromosomes that are associated with a particular gender
Two types
____ and _____
Females have ____ and _____
Males have _____ and _____
X and Y are _________ homologous!!
X is MUCH ____________ than Y
Codes for LOTS of important stuff that has nothing to do with sex.
Y codes pretty much only for genes that cause “____________”
No Y? You’re _______________. X Y

12. Ploidy N = number of chromosomes in ONE set –
Varies according to species
__________________
____n
Cell with ___ complete ______ of chromosomes
1 set from _________ = ______ chromosomes
________________ cells are diploid
So are cells that are ____________ to become _______________ (that are going to undergo meiosis), but haven’t done so yet.
________________
______
Cell with only ___ complete set of chromosomes
__________ of ______________
GAMETES - Sperm or egg!
What’s the diploid #
for humans?
What’s the haploid #
for humans?

13. How do we make sperm & eggs?
Must reduce _____ chromosomes  _____
must reduce the number of chromosomes by _____ 23 46 23
________ 46
egg 23
________ 46 23
____________
sperm
gametes

14. Meiosis: production of gametes
____________ stages
chromosome number must be __________
_________  ________
2n  n
humans: 46  23
____________ reduces chromosome number
makes ___________
fertilization __________ chromosome number
_______  __________
n  2n
haploid
diploid

15. Sexual reproduction lifecycle
2 copies
diploid 2n
1 copy
haploid 1n
1 copy
haploid 1n
fertilization
meiosis
In the next generation… We’re mixing
things up here!
A good thing?
gametes
gametes

16. Meiosis ____________________
special cell division for sexual reproduction
reduce ___n  ___n
_______  ________
“two”  “half”
makes gametes
sperm, eggs
Warning: meiosis evolved from mitosis, so stages & “machinery” are similar but the processes are radically different. Do not confuse the two!

17. Overview of meiosis I.P.M.A.T.P.M.A.T 2n = ____ interphase 1
prophase 1
metaphase 1
anaphase 1
n = ___
n = ___
prophase 2
metaphase 2
anaphase 2
telophase 2
n = ___
telophase 1

18. Double division of meiosis
DNA replication
Repeat after me!
I can’t hear you!
Meiosis 1
_____ division of meiosis separates _________________
Meiosis 2
_____ division of meiosis separates _________________

19. ___________ for meiosis
____ of Interphase
__________ of DNA
Why bother?
meiosis evolved after mitosis
convenient to use “machinery” of mitosis
DNA replicated in S phase of interphase of MEIOSIS (just like in mitosis)
2n = 6
single
stranded
2n = 6
double
stranded
M1 prophase

20. Meiosis ___ _____ division of meiosis separates _______________
single
stranded
Meiosis ___
_____ division of meiosis separates _______________
___n = 4
double
stranded
prophase 1
_________
___n = 4
double
stranded
metaphase 1
________
reduction
___n = 2
double
stranded
telophase 1
Repeat after me!
I can’t hear you!

21. What does this division look like?
Meiosis ____
_____ division of meiosis separates _______
________________
____ = 2
double
stranded
prophase 2
What does this division look like?
_____ = 2
double
stranded
metaphase 2
___ = 2
single
stranded
telophase 2
_ cells

22. Steps of meiosis Meiosis 1 Meiosis 2 interphase prophase 1 metaphase 1
anaphase 1
telophase 1
Meiosis 2
prophase 2
metaphase 2
anaphase 2
telophase 2
1st division of meiosis separates homologous pairs
(2n  1n)
“_______________”
2nd division of meiosis separates sister chromatids
(1n  1n)
* just like ________ *

23. Trading pieces of DNA _________________
during ___________, sister chromatids ___________
_______________ ______ pieces of chromosome
DNA breaks & re-attaches
Also called ______________
prophase 1
synapsis
tetrad

24. What are the advantages of crossing over in sexual reproduction?
3 steps
____________
__________ of DNA
___________ of DNA
New combinations of traits
Sexual reproduction is advantageous to species that benefit from genetic variability. However, since evolution occurs because of changes in an individual's DNA, crossing over and chromosome segregation is likely to result in progeny that are less well-adapted than their parents. On the other hand, asexual reproduction ensures the production of progeny as fit as the parent since they are identical to the parent. Remember the adage, “if it's not broken, don't fix it.” There are several hypotheses regarding the evolution of sexual reproduction. One is associated with repairing double-stranded DNA breaks induced by radiation or chemicals. The contagion hypothesis suggests that sex arose from infection by mobile genetic elements. The Red Queen hypothesis theorizes that sex is needed to store certain recessive alleles in case they are needed in the future. Along similar lines, eukaryotic cells build up large numbers of harmful mutations. Sex, as explained by Miller's rachet hypothesis, may simply be a way to reduce these mutations. The “whole truth” is likely a combination of these factors. Regardless of how and why, the great diversity of vertebrates and higher plants and their ability to adapt to the highly varied habitats is indeed a result of their sexual reproduction.

25. Mitosis vs. Meiosis

26. Mitosis vs. Meiosis Mitosis Meiosis __ division
daughter cells genetically ________ to parent cell
produces ____ cells
___n  ___n
produces cells for ______ & ________
____ crossing over
Meiosis
___ divisions
daughter cells genetically ______
from parent
produces _____cells
___n  ___n
produces __________
crossing over

27. Putting it all together…
meiosis  fertilization  mitosis + development
gametes 46 23 46 23 46 46 46 46 46 23
________ 46 46
egg 46 46 23
zygote
_________
_________
sperm
development

28. The value of sexual reproduction
Sexual reproduction introduces genetic _________!
genetic ___________________
______________________ of chromosomes in ___________
random alignment of homologous chromosomes in Metaphase 1
____________________
mixing of alleles across homologous chromosomes
___________________________
which sperm fertilizes which egg?
Driving evolution
providing ____________ for natural selection
metaphase1

29. Variation from __________________
Independent assortment of chromosomes
meiosis introduces genetic variation
gametes of ____________ do _____ have same combination of genes as gametes from ___________
random assortment in humans produces 223 (8,388,608) different combinations in gametes
offspring
from Mom
from Dad
new gametes
made by offspring

30. Variation from _________________
Crossing over creates completely _______ ______________ of ______ on each ____________
creates an infinite ________ in __________

31. Variation from random fertilization
Sperm + Egg = ?
any 2 parents will produce a zygote with over ____________ (223 x 223) possible diploid combinations

32. Sperm production _____________________ continuous & prolific process
Epididymis
Testis
germ cell
(diploid)
Coiled
seminiferous
tubules
primary
spermatocyte
(diploid)
MEIOSIS I
secondary
spermatocytes
(haploid)
MEIOSIS II
Vas deferens
spermatids
(haploid)
spermatozoa
_____________________
continuous & prolific process
each ejaculation = million sperm
Cross-section of
seminiferous tubule

33. Egg production ________________
eggs in ovaries halted before Anaphase 1
Meiosis 1 completed during maturation
Meiosis 2 completed after fertilization
__ egg + _ polar bodies
unequal divisions
Meiosis 1 completed
during egg maturation
ovulation
What is the advantage of this development system?
Meiosis 2 completed
triggered by fertilization

34. ___________ triggers completion of ________
Advantages of Polar Bodies and Fertilization triggers for meiosis completion…
__________________
Enables manufacture of one REALLY GOOD egg.
All nutrition, organelles, etc. poured into one egg
Quality, NOT quantity
___________ triggers completion of ________
Ensures that further resources will NOT be wasted on an egg that does NOT get fertilized.

35. Putting all your egg in one basket!
Oogenesis
MEIOSIS I
MEIOSIS II
first polar body
second
polar body
ovum
(haploid)
secondary
oocyte
primary
(diploid)
germinal cell
primary follicles
mature follicle with
secondary oocyte
ruptured follicle (ovulation)
corpus luteum
developing
follicle
fertilization
fallopian tube
after fertilization

36. Differences across kingdoms
Not all organisms use haploid & diploid stages in same way
which one is ______________ (2n or n) differs
but still alternate between haploid & diploid
must for sexual reproduction