Transcript Genetics powerpoint

If your body can digest the milk sugar
lactose, your DNA contains a mutation.
Do you think this is TRUE or
FALSE? Why or why not?
Every day, 22 people in the U.S. die while waiting for
an organ transplant. What if human organs could
be grown outside of a human body?
What if human organs could be grown
inside of another animal’s body? What
do you think about this?
It is possible for an offspring to have 3
genetic parents.
Do you think this is TRUE or
FALSE? Why or why not?
Heritable (can be inherited) genetic diseases are
more likely to arise in a group of organisms that
breed with close family members.
This brings up the
topic of
inbreeding. How
do you think
inbreeding and
certain
characteristics
might be
related?
Speaking of X-men, what do you think about
mutations? Are X-men possible?
Are mutations always bad? Can
mutations ever be a good thing?
The Basis of Heredity
Inheritance and Meiosis
Definitions
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Genetics = study of genes, the units on
chromosomes that code for traits
Heredity = study of how traits are passed
on
The Inheritance of Traits:
Mendel’s Discoveries
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Czechoslovakian
monk
First to discover rules
of inheritance
Published work in
1865
Mendel’s
Hybrid Peas
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Pure lines: tall plants
made tall plants
Studied 7 contrasting
characteristics
Mendel’s Crosses
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Mendel looked at one trait at a time by
crossing inbred lines.
Hybrid = offspring produced by breeding
two pure lines.
P1 = purebred parents.
F1 = first generation of offspring.
F2 = second generation of offspring.
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P = parental F = filial or offspring.
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Cross of green and
yellow pods
Mendel Crossed Short X Tall
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P1
tall x short
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F1
all tall
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F2
3/4 tall 1/4 short.
hypothesis: 2 factors controlling height.
Factor for shortness was hidden in F1.
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(expected medium)
Short X Tall Continued
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Tall factor = dominant (masked short)
Short factor = recessive (was hidden)
Mendel tested his hypothesis - crossed
plants with other 6 traits
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All other traits acted in same way
The Law of Segregation
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Mendel noticed 2 things
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Explained results with Law of Segregation
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factors controlling traits were distinct units
traits appeared in constant proportions in F2
individual carries 2 factors for each trait
each parent contributes 1 of the 2 factors
TT and Tt = tall and tt = short
genes = units of heredity
Alleles = 2 separate forms of a gene
Genotype Vs. Phenotype
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Genotype = the alleles of an organism
Phenotype = the appearance of an
organism
Homozygous = having 2 identical alleles
TT or tt
Heterozygous = having unlike alleles - Tt
Using Punnett Squares
Test Cross
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Used to determine if an individual is
homozygous or heterozygous
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Incomplete
Dominance
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heterozygote is a
blend of the two
homozygotes
Law of Independent Assortment
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monohybrid cross: involves one pair of
alleles or one gene
dihybrid cross: crosses involving two genes
Mendel did thousands of dihybrid crosses
which led to law of independent assortment
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the inheritance of one gene does not affect the
inheritance of another gene
a tall plant can have either smooth or wrinkled
seeds
Meiosis
The Cellular Basis of Heredity
Chromosome Number
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somatic cells = body cells
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diploid = 2 sets of chromosomes - 2n
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n = # of different kinds of chromosomes
haploid = 1 set of chromosomes
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most organisms contain two complete sets of
chromosomes
humans n = 23(haploid) and 2n = 46(diploid)
homologous chromosomes = matching pairs
Asexual and Sexual Reproduction
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Asexual reproduction
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offspring genetically
identical to parent
offspring formed by
mitosis
potato production
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Sexual reproduction
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2 haploid cells unite to form
a diploid cell
haploid cells = gametes
(sperm and eggs)
fertilization = union of two
gametes to form zygote
zygote grows by mitosis to
form new organism