Transcript Bwyoung

From whom did you get
your traits?
• Parents
• Mom
• Dad
What kind of traits do you think you got
from your parents?
• Eye color
• Hair color
• Height
• Nose shape
Which traits do you
prefer?
What is the next chapter?
• A. Ecology
• B. Viruses
• C. Genetics
• D. Plants
10.1 Mendelian Genetics!
Pg. 177
What is genetics?
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Genetics:
Study of heredity and variation in organisms.
Heredity:
Passing of genetic information from parent to
offspring.
Traits
• Traits:
• Variation of a particular character.
• Ex. Eye color, hair color, and nose shape.
What are some different
traits?
• Tail length
• Hair color
• Ear direction
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Mendelian Genetics
• In the 1800s an Austrian monk studied plants. His
name was Gregor Mendel. He is called the “Father
of Genetics”.
• Mendel wanted to describe how traits were passed
between generations.
What happens when you
cross red with yellow?
• Red mixed with yellow makes….
• Orange.
• If you crossed a red flower and a yellow flower…
what color would the offspring be?
• Red and yellow.
Mendel’s Experiment
• Performed experiments using pea plants.
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Why pea plants?
Easy to grow
Have easy observable traits
Reproduce quickly
Pea Plant Traits
• 1. Flower color
• 2. Flower position
• 3. Seed color
• 4. Seed shape
• 5. Pod shape
• 6. Pod color
• 7. Plant height
Mendel’s Experiment
• Step 1:
• Looked at one trait, the flower color.
• Mendel allowed the pea plants to self-pollinate. This
gave him purebred plants for the offspring.
• Purebred: Genetically uniform (identical).
• He called these plants the P generation (Parental).
Mendel’s Experiment
• Step 2:
• Cross-pollinated two P generation plants.
• Monohybrid cross: Parent plants differ in one characteristic.
• Flowers were all purple. He called these plants the F1
generation. F1 generation is the offspring of the P generation.
Mendel’s Experiment
• Step 3:
• Allowed F1 generation to self-pollinate.
• Produced a mix of white and purple flowers. He called this
generation the F2 generation.
Mendel kept growing pea
plants!
Overall
10.2 Inheritance Theory
• For each inherited characteristic an individual has 2
copies of a gene.
• These copies are called alleles.
• Alleles are represented by letters.
• Ex. PP or Pp or pp
Alleles
• Dominant alleles:
• Will always be expressed with 1 or 2 uppercase
letters.
• Ex. PP or Pp
• Recessive alleles:
• Will only be expressed with 2 lowercase letters.
• Ex. pp
Let’s Try
• Ex. Flower color
• Purple is dominant to white.
• What color is PP?
• Purple
• What color is pp?
• White
• What color is Pp?
• Purple
Vocabulary
• Homozygous:
• When the alleles are the same.
• Homozygous Dominant:
• Alleles are both uppercase letters. Ex. PP or BB
• Homozygous Recessive:
• Alleles are both lowercase letters. Ex. pp or bb
• Heterozygous:
• Different. One uppercase and one lowercase letter.
• Ex. Pp or Bb
Genotype/Phenotype
Genotype:
Genetic makeup of an organism.
Ex. PP or Pp or pp
Phenotype:
Physical characteristic expressed from the
genotype.
• Ex. Purple, purple, white
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Mendel's First Law
• Law of Segregation:
• Organism inherits two copies of genes, one from
each parent. Alleles are separated during gamete
formation.
Punnett Squares
• Diagram that shows the probabilities of the possible
outcome of a genetic cross.
Your mother is homozygous for black hair and
your dad has blonde hair. Black is dominant to blonde.
Testcross
• What is the genotype of an organism that displays
the dominant phenotype?
• Let’s say purple flower color. And we use the allele
P.
• PP or Pp
• How can we figure out if the organism is PP or Pp?
Perform a Testcross using
Punnett Square
• What would the other organism’s genotype and
phenotype be?
• Would have to use pp and white color flower.
Mendel's Second Law
• Law of Independent Assortment:
• Alleles for different genes separate independently
of one another during gamete formation.
• Dihybrid cross:
• Crossing organisms differing in two characteristics.
• Mendel crossed a true-breeding plant with round
yellow seeds (RRYY) with a true-breeding plant
grown from wrinkled green seeds (rryy)
• What would the offspring's phenotype be?
• All round and yellow.
• He then self pollinated the offspring.
10.3 Variations of
Inheritance
• What is the offspring when you cross a Black
chicken with a White chicken?
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• Blue chicken
x
• This is called intermediate inheritance or incomplete
dominance.
• Intermediate inheritance:
• Inheritance in which heterozygotes have an
intermediate phenotype. Neither phenotype is
expressed in offspring.
P
RR x rr
F1
Rr x Rr
F2
1 RR
2 Rr
1 rr
Multiple Alleles
• Codominance:
• Both dominant alleles are expressed.
• For example blood. What are the four blood types?
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A
B
AB
O
ABO Blood Alleles
IA – dominant allele for type A
blood
IB – dominant allele for type B
blood
i – recessive allele for type O
blood
ABO Blood Grouping
Blood type
Genotype
A
IAIA or IAi
B
IBIB or IBi
AB
IA IB
O
ii
NOTE: Blood type AB is also an example of codominance
Polygenic Inheritance
• Polygenic inheritance:
• Multiple genes affect a characteristic, the variation
in phenotypes can become greater.
• Example.
• Humans height and skin color.
Importance of
Environment
• If a woman who is 6 ‘3’ and mates with a male who
is 6 ‘7’… does that mean their son or daughter will
be tall? Why?
• No, their offspring could be malnourished.
• Think of plants. Depending of the plant gets sunlight
and water it affects how it will grow.
• Think of professional athletes and their parents.
Environment
• Temperature can also effect the phenotype.
Siamese cats usually have white fur but when there
is cooler temperatures it changes the cats enzyme
which makes the coat color darker.
10.4 Meiosis Explains
Mendel’s Principles
• Chromosomes theory of inheritance:
• States that genes are located on chromosomes,
and the behavior of chromosomes during meiosis
and fertilization accounts for inheritance patterns.
• All advanced organisms have chromosomes. Half
the chromosomes comes from the father and half
from the mother.
Genetic Linkage and
Crossing Over
• When genes are located on separate
chromosomes, they sort independently of each
other.
• When genes are located close to each other the
greater the genetic linkage.
• Genetic linkage:
• The tendency for the alleles on one chromosome to
be inherited together.
10.5 Sex-linked traits
• Humans have 23 pairs of chromosomes.
• One set of chromosomes are called sex
chromosomes.
• If you are XX you are a female.
• XY you are a male.
Chromosomes
Sex Linked Genes
• Any gene that is located on the sex chromosome is
called sex linked gene.
• In humans most sex linked genes are located on the
X chromosome because it is much bigger than the
Y chromosome.
Colorblindness
• Colorblindness is inherited as sex linked X
recessive traits.
XB
Xb
Xb
XB Xb
Xb Xb
Y
XB Y
Xb Y
WHAT NUMBERS DO YOU SEE?
WHAT NUMBERS DO YOU SEE?
WHAT NUMBERS DO YOU SEE?
NOW WHAT NUMBER DO YOU
SEE???