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MEIOSIS: Reduction Division
http://www.youtube.com/watch?v=rB_8dTuh73c
Concept: 13.1 Offspring acquire genes from
parents by inheriting chromosomes
Gene: hereditary unit that codes for a protein
Locus: a gene’s specific location on a
chromosome
Gamete: sex cell
Male gamete: sperm
Female gamete: egg (ovum)
Asexual reproduction: a single individual is the
sole parent and passes copies of all its genes to
its offspring (which is a clone of its parent)
Sexual reproduction: two parents give rise to
offspring that have unique combinations of
genes inherited from both parents
2. 46
3.DNA wrapped around histones (packing
proteins), that becomes coiled upon itself
in preparation for cell division
4. A normal body cell. Skin cell, muscle cell,
adipose cell
5. Somatic cells are diploid; gamete cells are
haploid
6. Sex chromosomes: X and Y in humans.
Determine sex of the individual. 2 per cell
(either XX= female or XY = male); set # 23
Autosomes: Homologous chromosomes
sets # 1-22
7. Karyotype: Photographic display of
homologous chromosome pairs from
longest to shortest based on length,
centromere location, and staining patterns
8. Homologous chromosomes: pair of
chromosomes carrying genes controlling
the same inheritance characters.
9………regular body cells are diploid!
………sex cells are haploid!
10. Bone cell = 78
Sperm = 39
Haploid = 39
Somatic = 78
Zygote (is a fertilized cell, the beginnings of
an embryo) = 78
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sister chromatids
Homologous chromosomes
centromere
Replicated chromosome
Maternal chromosome (color it red or pink)
Paternal chromosme (color it blue..look on
page 251)
12.
12
3
12
diploid
13.Eggs are produced in the ovaries
• Sperm are produced in the tesicles
14. Meiosis: oogenesis (female meiosis)
spermatogenesis (male
meiosis)
15. Zygote; 2n diploid
16. Reduce the diploid chromosome number
in half to haploid
17. diploid; haploid
18. Life cycle that includes both diploid and
haploid stages that are multicellular
18. Life cycle that includes both diploid and
haploid stages that are multicellular
• Sporophyte (diploid)
• Gametophyte (haploid)
• Page 252 Moss life cycleM
19. alleles: contrasting forms of a gene
Synapsis: when homologous chromosomes
are held tightly together by proteins along
their length
Crossing over: the exchange of
corresponding segments of DNA
molecules by non sister chromatids (this
give rise to new gene combinations )
Chiasmata: points where crossing over has
occurred
21. One chromosome of each homologous
pair is facing each pole, I mitosis the pairs
are on top of each other and the copies go
to opposite poles
22. The homologous pairs
23. 6 chromosomes; haploid….but like a
double haploid
25. The replicated sister chromatids
26. a. it is reduced by half
b. Meiosis I
c. Reduction division= to produce haploid
gametes
d. twice
e. once
f. 4 (note: in oogenesis, 3 polar bodies will
disintegrate, leaving only one egg; in
spermatogenesis 4 sperm are produced)
g. n (half the original 2n number)
h. chromosome of a pair that have
matching genes
i. homologs are held tightly together
j. the exchange of genes between non
sister chromatids
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27.
Mitosis
Meiosis
Role in the animal body
Development of zygote;
growth, repair and
asexual reproduction
Produces haploid
gametes; introduces
genetic variability
Number of DNA
replications
1
1
Number of divisions
1
2
Number of daughter
cells
Two, each genetically
identical to the parent
cell
Four, each
genetically different
from the parent cell
and from each other
Chromosome number
of daughter cells
Diploid
Haploid
28.
29. Prophase I
30. Replicated homologs pair up and
become physically connected along their
lengths by a zipper-like protein structure
called the synaptonemal complex in a
process called synapsis. Chiasmata are Xshaped regions where crossing over has
occurred as the homologs are trying to
separate, yet the sister chromatid
cohesion is still operating
31. Independent assortment of chromosomes:
random orientation of homologs in Metaphase I
resulting in each pair sorting its maternal and
paternal homologs into daughter cells
independently of the other pairs
Crossing over: yields recombinant chromosomes
(individual chromosomes that carry genes from
two different parents)
Random fertilization: The fusion of a human
sperm and egg during fertilization will produce a
zygote with any of about 70 trillion (223 x 223)
diploid combinations
32. a. 223 (about 8.4 million)
b. 70 trillion (223 x 223)
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