Download What are the advantages to sexual reproduction? Disadvantages?

29 Heredity
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= sources of
genetic variation
Work together...In genetic
n = haploid (23)
terms, what is the human
life cycle?
2n = diploid (46)
n
n
2n
EXERCISE
YOUR
BRAIN...
What are the advantages to
sexual reproduction?
Disadvantages?
Advantages of Sexual
Disadvantages of Sexual
Reproduction
Reproduction
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(chromosome pairs 1 -22)
karyotype - visual
representation of
your genetic
make-up
chromosome from
the egg matched
with the same
chromosome from
the sperm (called
homologous
chromosomes)
(pair 23)
XY - male
XX - female
Boy or girl?
What can you tell me about this individual?
dominant = expressed allele; can
mask or suppress recessive allele
recessive = only expressed if two
recessive alleles are present; can be
masked or suppressed by dominant
same genes @ same locus
(location)
each homologous chromosome carries an
allele (option) for a gene (characteristic)
if the alleles are different (Pp or Yy) = heterozygous
if the allele are the same (PP, YY, pp, or yy) = homozygous
allele
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genotype - genetic makeup (alleles
...What do you know so far?
inherited from egg & sperm; letter
combo)
phenotype - expression of your
genotype (use words to describe a
characteristic)
1 MATA: Tt
A
genotype
B
phenotype
C
homozygous
D
heterozygous
E
dominant
F
recessive
3 Homologous chromosomes contain the same genes
at the same loci, but not necessarily the same
alleles for that gene.
2 The physical expression of a trait is called a person's
A phenotype
B genotype
C karyotype
D haplotype
4 MATA: A karyotype
A
is a visual representation of a
person's genetic makeup
B
can reveal chromosomal
abnormalities
C
can reveal gender of an offspring
D
pair homologous chromosomes
together
True
False
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traits A, B, and C are called linked genes because they are
located on the same chromosome
= sources of
genetic variation
crossover - breaks occur between the linked genes and
recombinant chromosomes are created
chromosomes can
What gametes were created as the result of crossing over?
OR this
Pull
line up like this
Independent Assortment
results in 223
different
gamete types!
Random Fertilization
You are 1 out of
72 trillion
zygotes possible!
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Best 2 out of 3
Just making sure you got the message...
Winner...What are
three sources of
genetic variability in
humans?
.
Pull
5 Chromosomes line up in random order.
A
crossover
B
linked genes
C
independent assortment
D
random fertilization
= sources of
genetic variation
6 Linked genes break and create
recombinant chromosomes.
7 The MAIN reason siblings can looks so
different, and others can looks so similar.
A
crossover
A
crossover
B
linked genes
B
linked genes
C
independent assortment
C
independent assortment
D
random fertilization
D
random fertilization
PUNNETT SQUARES
*show what could happen
during fertilization
Bb
Genotypes:
Bb
Phenotypes:
B = bright
Incomplete Dominance -
"blended" phenotype
NOT COMMON IN HUMANS
*heterozygous has its own
b = dumb
Human Traits Caused by Simple
Dominant-Recessive Inheritance
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Sickle Cell Anemia
*abnormal hemoglobin
*mix of normal and abnormal hemoglobin
*normal hemoglobin
(can have type AB blood)
Pull
multiple alleles: (3 options instead or 2)
Work together...can you figure
out each person's genotype?
*still get one allele from mom and one from dad
Sample
Proble
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X chromosome
Y chromosome
78 genes
over 2,500 genes
*sex-linked - genes on the sex chromosomes
OLDER...Why is blood type an example of multiple alleles?
*X-linked - genes found only on the X chromosome
*traits past from mother to son...WHY???
YOUNGER...Why is it an example of codominance?
LEFT...explain this diagram
RIGHT...explain this one
red-green colorblindness
hemophilia
fragile-X syndrome
Duchene's muscular dystrophy
Human Sex-Linked Traits
Polygene Inheritance
8 What type of inheritance pattern can
result in a "blended" offspring?
A
multiple alleles
B
incomplete dominance
C
polygene
D
sex-linked
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A
multiple alleles
multiple alleles
B
codominance
B
codominance
C
dominant-recessive
C
polygene
D
sex-linked
D
sex-linked
A
Environmental Factors in Gene Expression
Pre-Birth Changes due to...
• maternal drug use or pathogens
GENOTYPES EXAMPLE
Post-Birth Changes due to...
• poor/inadequate diet
• hormonal deficiencies
PHENOTYPES -
Nontraditional Inheritance - Small RNAs
Epigenetic marks - chemicals or protein modifications that
influence gene expression
*help regulate gene expression
(protein formation)
*gene off limits
*determines how accessible DNA is for transcription
*mutations in RNA-only areas linked to prostate and lung
cancer, schizophrenia
*lots of research into synthesizing RNA-interfering drugs
to silence or shut down genes (macular degeneration,
Parkinson's disease, cancer)
*can be influenced by diet, age, exercise, stress, etc.
thalidomide babies
10 What type of inheritance occurs when
traits are most often passed from
mother to son?
cretinism
9 What type of inheritance pattern can
result in a wide range of phenotypes,
with most individuals somewhere in the
middle range?
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mitochondrial DNA (mtDNA) - 37 genes
• passed from mother to offspring
Ping Pong Back &
FOrth describing
extranuclear
influences on gene
expression.
11 Genotypes do not change, but
phenotypes can be influenced.
12 All of the following are extranuclear
ways to regulate gene expression
EXCEPT
True
False
A
small RNAs
B
methylation of DNA
C
modification to histones
D
mutations
Fetal Testing
Pedigree for Cystic Fibrosis
Let's figure out the
genotypes of the
individuals in the fourth
and third rows.
START
HERE
*pedigrees are used to determine the likelihood of
being a carrier (heterozygous) and to determine
the inheritance pattern of a trait
*carriers are not affected but can pass the trait on
to their offspring
CAN ALSO BE DETERMINED USING
A BLOOD TEST (not for all traits)
*takes longer, less risk to fetus
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GENE
Fetal Testing - Ultrasound
THERAPY
*embryonic stem
13 Name this fetal test.
14 What type of inheritance pattern is
depicted in this pedigree?
A
dominant
B
recessive
C
sex-linked
D
incomplete
*Huntington's Disease