Genetics:

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Genetics

• The study of heredity

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Heredity the passing of traits from
parents to offspring
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Heredity the passing of traits from
parents to offspring

• Trait A feature or characteristic of a person
• Physical appearance
• Behavior tendencies
• Predisposed to medical conditions
• A persons traits are influenced by
• their genetic inheritance
• environmental factors

What is a trait?
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Trait a feature or characteristic of
a person

• Physical appearance
• ex Hair Color
• Genetics
• Environment

hair color
eye color
face shape
hair texture
smile shape
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Trait a feature or characteristic of
a person

• Physical appearance
• ex Hair Color
• Genetics genes determine natural hair color
• Environment

hair color
eye color
face shape
hair texture
smile shape
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Trait a feature or characteristic of
a person

• Physical appearance
• ex Hair Color
• Genetics genes determine natural hair color
• Environment sun or hair dyes change hair
  color

hair color
eye color
face shape
hair texture
smile shape
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Trait a feature or characteristic of
a person

• Behavior tendencies
• ex Handedness
• Genetics
• Environment

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Trait a feature or characteristic of
a person

• Behavior tendencies
• ex Handedness
• Genetics genes determine the tendency to use a
  certain hand
• Environment

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Trait a feature or characteristic of
a person

• Behavior tendencies
• ex Handedness
• Genetics genes determine the tendency to use a
  certain hand
• Environment
• can learn to use
• the opposite
• hand

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Trait a feature or characteristic of
a person

• Predisposed to medical conditions
• ex Heart disease
• Genetics
• Environment

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Trait a feature or characteristic of
a person

• Predisposed to medical conditions
• ex Heart disease
• Genetics genes determine a risk of heart
  disease
• Environment

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Trait a feature or characteristic of
a person

• Predisposed to medical conditions
• ex Heart disease
• Genetics genes determine a risk of heart
  disease
• Environment lifestyle
• choices (diet, exercise,
• habits) can increase
• or decrease risk

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Trait a feature or characteristic of
a person

• Phenotype a persons version of a trait
• physical appearance

hair color black
eye color blue
hair texture straight
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Practice

• List 3 traits Dash has.
• List Dashs phenotype for each trait.

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Trait a feature or characteristic of
a person

• Gene part of a persons DNA that influences a
  trait

Eye color gene
Face shape gene
Hair color gene
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Gene part of a persons DNA that controls
a trait

• Alleles different versions of a gene

Eye color gene brown allele
Eye color gene blue allele
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Practice

• List 3 possible alleles for the hair color gene.

Hair color gene
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Alleles different versions of a gene

• Dominant Allele
• Represented by a capital letter
• Example B for brown eyes
• Recessive allele
• Represented by a lowercase letter
• Example b for blue eyes

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Alleles different versions of a gene

• All people have 2 alleles for every gene (one
  from each parent)

Allele of eye color gene from dad
Allele of eye color gene from mom
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Alleles different versions of a gene

• All people have 2 alleles for every gene (one
  from each parent)
• Genotype a persons
• combination of alleles
• genetic makeup

Allele of eye color gene from dad
Allele of eye color gene from mom
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Genotype a persons combination of
alleles

• A person may inherit 2 of the same alleles
  homozygous/purebred
• 2 dominant alleles homozygous dominant
• Example B and B
• Genotype
• Phenotype

Mom
Dad
B
B
Child
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Genotype a persons combination of
alleles

• A person may inherit 2 of the same alleles
  homozygous/purebred
• 2 dominant alleles homozygous dominant
• Example B and B
• Genotype BB
• Phenotype

Mom
Dad
B
B
Child
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Genotype a persons combination of
alleles

• A person may inherit 2 of the same alleles
  homozygous/purebred
• 2 dominant alleles homozygous dominant
• Example B and B
• Genotype BB
• Phenotype brown eyes

Mom
Dad
B
B
Child
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Genotype a persons combination of
alleles

• A person may inherit 2 of the same alleles
  homozygous/purebred
• 2 recessive alleles

Mom
Dad
b
b
Child
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Genotype a persons combination of
alleles

• A person may inherit 2 of the same alleles
  homozygous/purebred
• 2 recessive alleles homozygous recessive
• Example b and b
• Genotype
• Phenotype

Mom
Dad
b
b
Child
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Genotype a persons combination of
alleles

• A person may inherit 2 of the same alleles
  homozygous/purebred
• 2 recessive alleles homozygous recessive
• Example b and b
• Genotype bb
• Phenotype

Mom
Dad
b
b
Child
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Genotype a persons combination of
alleles

• A person may inherit 2 of the same alleles
  homozygous/purebred
• 2 recessive alleles homozygous recessive
• Example b and b
• Genotype bb
• Phenotype blue eyes

Mom
Dad
b
b
Child
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Alleles different versions of a gene

• A person may inherit 2 different alleles
• heterozygous/hybrid
• Dominant allele masks recessive allele
• Example B and b
• Genotype Phenotype

Mom
Dad
Mom
Dad
b
B
B
b
-or-
Child
Child
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Alleles different versions of a gene

• A person may inherit 2 different alleles
• heterozygous/hybrid
• Dominant allele masks recessive allele
• Example B and b
• Genotype Bb Phenotype

Mom
Dad
Mom
Dad
e
E
E
e
-or-
Child
Child
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Alleles different versions of a gene

• A person may inherit 2 different alleles
• heterozygous/hybrid
• Dominant allele masks recessive allele
• Example B and b
• Genotype Bb Phenotype brown eyes

Mom
Dad
Mom
Dad
e
E
E
e
-or-
Child
Child
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Practice

• Brown hair (B) is dominant to blond hair (b).

Genotype Phenotype
homozygous dominant
homozygous recessive
heterozygous
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Practice

• Brown hair (B) is dominant to blond hair (b).

Genotype Phenotype
homozygous dominant BB Brown hair
homozygous recessive
heterozygous
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Practice

• Brown hair (B) is dominant to blond hair (b).

Genotype Phenotype
homozygous dominant BB Brown hair
homozygous recessive bb Blond hair
heterozygous
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Practice

• Brown hair (B) is dominant to blond hair (b).

Genotype Phenotype
homozygous dominant BB Brown hair
homozygous recessive bb Blond hair
heterozygous Bb Brown hair
Which genotypes are purebred? Which is hybrid?
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Practice

• Right-handedness (R) is
• dominant to left-handedness (r).
• What genotype(s) could a right-handed person
  have?
• What genotype(s) could a left-handed person
  have?

RR or Rr
rr
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Practice

• In pea plants, green peas (G) are dominant to
  yellow peas (g).
• What would be the genotype of a
• -purebred green pea?
• -hybrid green pea?
• -yellow pea?

GG
Gg
gg