Mitosis, Meiosis, Heredity

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Mitosis, Meiosis, Heredity

• GHSGT Content Review
• Domain I (cont)

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Mitosis
Meiosis

• Makes copies of cells
• Occurs in somatic cells
• No pairing of homologous chromosomes
• No crossing over
• Two new cells are produced, each having the same
  amount DNA as the old cell
• Creates diploid cells
• Organisms that reproduce this way are said to
  undergo asexual reproduction

• Makes gametes (sperm and egg)
• Homologous chromosomes pair
• Crossing over occurs, providing genetic variation
• Four daughter cells are produced, each having ½
  the original DNA
• Creates haploid cells
• Meiosis is involved in sexual reproduction

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Remember-

• Mitosis
• Repairs your toe when you hurt it, creating cells
  that are identical
• Meiosis
• Creates egg and sperm

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Mitosis just serves to make sure that all cells
made from the original zygote are identical, so
they all contain the same genetic information
In mitosis, 2 diploid cells are made that are
identical to the original
http//www.healthofchildren.com/images/gech_0001_0
003_0_img0218.jpg
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Mitosis makes copies of cells
http//library.thinkquest.org/C0123260/basic20kno
wledge/images/basic20knowledge/cell20division/mi
tosis.gif
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Click to view Mitosis
Mitosis and Meiosis. United Learning(1994).
Retrieved December 9, 2007, fromunitedstreaming
http//streaming.discoveryeducation.com/
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Meiosis creates gametes
From one diploid (2n) cell, four haploid (n)
cells are made. Meiosis reduces the chromosome
number in half. The diploid number is restored
when gametes unite to form a zygote.
http//www.accessexcellence.org/RC/VL/GG/images/me
iosis.gif
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Click to view Meiosis
Mitosis and Meiosis. United Learning(1994).
Retrieved December 9, 2007, fromunitedstreaming
http//streaming.discoveryeducation.com/
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• To compare mitosis and meiosis see the movie on
  http//www.pbs.org/wgbh/nova/miracle/divide.html
  

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Review

• To review Mitosis and Meiosis, play Party on Down!

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Mendelian Genetics- some vocabulary
YY or Yy
yy

• In peas, yellow peas are dominant to green peas
• That means only one gene for yellow must be
  present to be seen two genes for green must be
  present for the pea to appear green
• The gene composition, YY, Yy, or yy is the
  genotype
• The appearance, yellow or green, is the phenotype
• YY and yy are homozygous
• Yy is heterozygous

Green pea image from http//www.germes-online.com/
direct/dbimage/50289949/Freeze_Dried_Green_Pea.jpg

Yellow pea image from http//img.alibaba.com/photo
/10154914/Yellow_Pea_Starch_Flour_Fibre_Protein.jp
g
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Monohybrid cross F1 generation
Y
Y
y
y
x
Yy
Yy
Yy
Yy
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Monohybrid cross F2 generation
Y
y
y
Y
x
YY
Yy
yy
Yy
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Click on link to view Gregor Mendels Rules of
Heredity Using Punnett Squares
You may need to hit the Escape key and maximize
Windows Media Player.
Genes, Genetics, and DNA. Rainbow Educational
Media(2003). Retrieved December 9, 2007,
fromunitedstreaming http//streaming.discoveryed
ucation.com/
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Test Cross- determines whether an organism
displaying a dominant phenotype is homozygous or
heterozygous
http//www.zo.utexas.edu/faculty/sjasper/images/14
.6.gi f
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Click on link to view The Significance of the
Test Cross as a Genetic Tool
You may need to hit the Escape key and maximize
Windows Media Player.
Biologix Introduction to Classical Genetics and
Monohybrid Crosses. United Learning(1997).
Retrieved December 9, 2007, fromunitedstreaming
http//streaming.discoveryeducation.com/
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Incomplete dominance
http//fig.cox.miami.edu/cmallery/150/mendel/c14x
9incomplete-dominance2.jpg
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Review

• To review, do the problem set on Monohybrid
  crosses at the University of Arizona website (or
  continue to the next five slides, which have
  their problems)

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Problem 1all problems are from The Biology
Project at the U of Ariz.
A genetic cross between two F1-hybrid pea plants
having yellow seeds will yield what percent
green-seeded plants in the F2 generation?
Yellow seeds are dominant to green. A. 0 B.
25 C. 50 D. 75 E. 100
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Problem 2
In Mendel's experiments, if the gene for tall (T)
plants was incompletely dominant over the gene
for short (t) plants, what would be the result
of crossing two Tt plants? A. 1/4 would be tall
1/2 intermediate height 1/4 short B. 1/2 would
be tall 1/4 intermediate height 1/4 short. C.
1/4 would be tall 1/4 intermediate height 1/2
short. D. All the offspring would be tall. E.
All the offspring would be intermediate.
                           
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Problem 3
In a cross between a pure bred, red-eyed female
fruit fly and a white-eyed male, what percent of
the male offspring will have white eyes? (white
eyes are X-linked, recessive) A. 100 B. 75
C. 50 D. 25 E. 0
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Problem 4
A test cross is used to determine if the genotype
of a plant with the dominant phenotype is
homozygous or heterozygous. If the unknown is
homozygous, all of the offspring of the test
cross have the __________ phenotype. If the
unknown is heterozygous, half of the offspring
will have the __________ phenotype. A. dominant,
incompletely dominant B. recessive, dominant C.
dominant, epistatic D. codominant, complimentary
E. dominant, recessive
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Problem 5
In a cross between a white-eyed female fruit fly
and red-eyed male, what percent of the female
offspring will have white eyes? (White eyes are
X-linked, recessive) A. 100 B. 25 C. 50 D.
75 E. 0