Download Unit 8a-Classical Genetics

Unit 8­ Genetics­Notes.notebook
1. Classical Genetics
a. Mendel
i. Mendel’s Laws
ii. Advanced Genetic Principles
b. Modern Genetics
i. Scientists
ii. Nucleic Acids DNA/RNA – Function
iii.Replication
iv.Protein Synthesis
v. Mutations (gene and chromosomal)
vi.Biotechnology
vii. Genetic Engineering
I. Classical Genetics
1. What makes these parakeets so varied in color?
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Unit 8­ Genetics­Notes.notebook
2. The color of these parakeets is an trait
example of a _________________
3. What determines our traits?
Genes
Genesgenes
4. We're missing a very important step in this process though, known as the central dogma of genetics:
(For now just keep this flow in mind. We'll come back to this throughout this unit.)
5. Who is Gregor Mendel?
a. What was Mendel's contribution to genetics?
"Father of genetics"
Worked with pea plants (took meticulous notes)
Developed laws of inheritance
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c. How did Mendel carry out his experiments?
Mendel crossed two PURE STRAINS (P­ generation or parents) of pea plants with purple and white flowers and discovered that the FIRST FILIAL GENERATION (1st offspring) were ALL purple
i. What happened to the white flower trait? Covered up by dominant purple trait How do we know? it reappears in the next generation
d. What did Mendel
conclude from his experiments?
i. Biological inheritance is determined by "factors" that are passed from one generation to the next.
e. With modern genetic advances, we now know these "factors" are genes
__________
f. There are different forms (versions) of a gene, and some are dominant and some are recessive­ Alleles
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Unit 8­ Genetics­Notes.notebook
f. Vocabulary Checkpoint:
1. Label the following:
Nucleus, cell, chromosome, DNA, gene
B.
A.
E.
C.
D.
1. Traits: Look back at Mendel's pea plants and give three examples of traits he observed 2. Alleles:
What are the alleles for the three traits you chose?
3. Dominant allele:
4. Recessive allele:
Which of the alleles for each of the 3 traits you chose are dominant?
1)
6. Label the Sex Chromosomes & the Autosomes:
Autosomes (all except sex)
Sex Chromosomes
XX­Female
XY­Male
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Unit 8­ Genetics­Notes.notebook
6. What is a genotype?
Genetic makeup (alleles)
P = dominant allele (uppercase)
p = recessive allele (lowercase)
7. What is a phenotype?
physical appearance
purple or white flowers
8. do we express genotypes?
PP = Homozygous Dominant pp = Homozygous Recessive
Pp = Heterozygous
9. What is a phenotype determined by?
Genotype (nature) + Environment (nurture/gene expression)
10.
Homozygous­ "Same alleles"
a. Homozygous dominant­ PP (purple)
b. Homozygous recessive pp (white)
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Heterozygous­ "different alleles"
c. Heterozygous­ Pp (purple)
(hybrid)
12.
When will a recessive allele
show up in a phenotype?
only when there are 2 recessive alleles
Homozygous recessive
pp = white
(1 recessive allele must come from each parent
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Unit 8­ Genetics­Notes.notebook
recessive alleles will always be masked by dominant alleles
(Mendel crossed a pure PP (purple) plant with a pure pp (white) plant, all F1 were Pp (purple)) during gametogenesis, chromosomes
separate (segregate) so that offspring
receive one copy from each parent
(Mendel: pea pods in F1 generation
(sex cells =n)
were all dominant (green), but recessive
yellow reappeared in F2 generation
chromosomes assort independently during gametogenesis, giving different traits an equal opportunity SsYy x SsYy
of occurring together. (Mendel: observed the following SY= round, yellow seeds
combinations of traits:
Sy = round, green seeds
Green­round seeds, Green­wrinkled seeds,
sY = wrinkled, yellow seeds
Yellow­round seeds, Yellow­wrinkled seeds)
sy = wrinkled, green seeds
F1
all SsYy
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Unit 8­ Genetics­Notes.notebook
14. What is a test cross?
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Two Exceptions to the Basic Rules of Genetics:
a) Codominance:
Both alleles are dominant
Heterozygous- will see both
traits
ex. Red + white (red and white spotted)
b) Incomplete Dominance
(Intermediate Inheritance):
Neither allele is completely
dominant
Heterozygous - Intermediate
or blended
ex. Red + white (pink)
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Unit 8­ Genetics­Notes.notebook
Why is gene expression (especially in humans) more complicated than Mendel's laws?
17. Polygenic traits
‐ many genes control
one trait
‐ usually see continuous
distribution
for example, height or skin color
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a. Multiple alleles:
More than two allele
options
(Please note that an offspring
will still inherit one allele from
each parent, however there are
more than two variations
b. Blood types:
IA and IB are codominant, i (o) is recessive
18. Pleiotropy:
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Epistasis - one gene affects
the expression of another
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Light vs. Dark ENVIRONMENT affects gene expression
in these seeds
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50% chance XY- Male
50% chance XX- Female
Disorders that occur
because of mutations
on the autosomes
Autosomal recessive
AA= normal
Aa= normal (carrier)
aa= affected
Autosomal Dominant
AA=Affected
Aa= Affected
aa= Normal
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"Family tree"
that follows the inheritance
of a particular trait
Male
Female
Affected individuals
Needs to be inherited from
both parents in order to express
the trait
ex. aa
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Only need one allele
to express the trait
ex. AA or Aa
Disorders occur because
of mutations on the X
chromosome
Females can be carriers, males can not, because they
only have 1 X
There are some disorders on the y chromosome, but it
is MUCH smaller, so not as many
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