Inheritance of Traits

1
Inheritance of Traits

• Ch. 3

2
What are traits?

• Traits are ________________ or qualities
• Can be ________________ or behavioral
• Living things ________ (are different) in their
  _________

3
Gregor Mendel

• A _______ who lived in the mid _____________
• Studied math and science
• Liked to ________________
• Curious about why plants of the same type had
  ___________ traits

4
Gregor Mendel

• Noticed that plants often had the _____ traits as
  their ______________
• The _________ of traits from parents to offspring
  is known as ________________

5
Gregor Mendel

• Set up many _____________ using pea plants to
  understand heredity
• ______________ were a good choice because of
  their traits

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Mendels Experiments

• First he created __________ for each trait
• These plant always produced _____________ just
  like them
• Ex. Tall purebreds always produced _________
  offspring

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Mendels Experiments

• Then he _______ one type of purebred with another
• Ex. tall with short
• The purebreds the P(arent) _________________
• The offspring the ______1 generation

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Mendels 1st Experiment

• Purebred __________ crossed with Purebred
  __________
• Offspring all __________
• Surprise! __________ disappeared!

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Mendels 1st Experiment

• Crossed two of the tall __________
• ______ generation was ______ tall, _______ short
• ___________________ reappeared!

10
Further experiments

• Mendel did similar experiments for 6 other pea
  plant ___________
• ___________ of results was always the
  ______________

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Conclusions

• Used ______ to figure out that each trait must be
  ___________ by 2 ______________
• One factor must come from each _____________
• One factor could _________ the other
• Ex. Tall factor can mask short

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Father of Genetics

• Mendels work was _____________ in the 1900s
• Became the foundation of modern _________________
• Now we call factors _______

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Genes

• Sections of ___________
• We know that DNA contains ______________ for how
  to make ____________
• Each section ________ for a different protein

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Genes

• Genes? proteins? __________
• But how do genes tell the ____ how to make
  proteins?
• Proteins are made on ____________________
• DNA is in _______________
• Need away to get _______ from DNA to ribosome

15
Protein Synthesis

• Cell uses _____________
• Only _______ side
• ______ instead of T
• Pairs up with DNA or other RNA using same
  __________
• _____ types mRNA and tRNA

DNA A T C G
RNA __ __ __ __
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Protein Synthesis

• mRNA __________________
• _________ DNA of gene and goes to ribosome
• tRNA ____________________
• Translates mRNA code into a ________________
• Happens on _______________
• DNA(gene)?_______?protein ? trait

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Mutations

• Remember that __________ are any changes in the
  DNA
• If DNA is _________, mRNA is changed and
  ___________ is made differently
• This can change the ______

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Mutations

• If this happens in a _______ cell the mutation
  will only affect that ________
• If this happens in an ______ or a ______ cell, it
  can affect the ____________

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Mutations

• Not all mutations are ___________________
• Some _________ the protein or trait
• Some have ___ affect on the protein or trait

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Alleles

• The __________ forms of the factors Mendel
  described are known today as _______
• Alleles _________ of genes
• Every body cell has _______ copies of each gene

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Alleles

• One copy from one _______, one ________ from the
  other
• These copies can be the ________ allele or
  _________ alleles

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Alleles

• Alleles can be ____________ or recessive
• Dominant alleles can mask ___________________
  alleles
• If you have the dominant allele, that is the one
  that will be copied and translated into a
  _________________

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Alleles

• We use _________ to represent alleles
• Usually the letter is connected to the
  _________________ trait
• ____________ letters represent dominant alleles
• Lower case letters represent __________________
  alleles

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Alleles

• Example
• Trait Height
• Dominant allele ____ (tall)
• Recessive allele ___ (short)

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Alleles

• The combination of _________ the
  ___________________
• If the two alleles are the _____ the genotype is
  _____________
• Ex. TT or tt
• If the two alleles are ________ the genotype is
  ________________/___________
• Ex. Tt

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Alleles

• The genotype determines the ____________________
• This is the __________
• Examples

Genotype Phenotype
TT
Tt
Tt
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Inheritance

• Genes are carried on ____________________
• Each chromosome contains thousands of
  ____________
• The two alleles are carried on __________
  chromosomes that form a ____________

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Inheritance
Chromosome pair - Contain different alleles of
the same genes
From mom
From dad
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Inheritance

• One _______________ came from sperm, other from
  egg
• This means sperm and eggs only have one _____ of
  each chromosome
• These special cells are called ___________ cells

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Meiosis

• Organisms do a special process of _______ to
  create sex cells
• Process makes sure chromosome pairs are _____ so
  each sex cell has one __________________ set

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Meiosis
Sex cells
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Meiosis

• Each sex cell has a different _______________ of
  alleles
• This is why siblings are not ___________________

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Inheritance

• If we know the _________ of the parents, we can
  calculate the _____________ combinations in the
  offspring
• And the ___________ of each

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Punnett Squares
For one trait, we make a 4 square
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Punnett Squares
T
Mom
T
Down the left side we put the alleles that the
mom has
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Punnett Squares
Dad
t
t
T
Mom
T
across the top we put the alleles that dad has
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Punnett Squares
Dad
t
t
T
T
t
Mom
T
In each box we write the combination of the mom
allele from that row and the dad allele from that
column
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Punnett Squares
Dad
t
t
T
T
t
Tt
Mom
Tt
T
Tt
Each square represents a possible genotype of the
offspring
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Probability
Dad
t
t
T
T
t
Tt
Mom
Tt
T
Tt
In this cross, theres a _____ chance of
offspring having the Tt genotype. Theres a
________ chance of offspring having the tall
phenotype
40
Probability
Dad
T
t
T
TT
Tt
Mom
TT
T
Tt
In this cross, theres a ____ chance of having TT
and ____ of having Tt. Theres a _______ chance
of offspring having the tall phenotype
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Probability
Dad
T
t
T
TT
Tt
Mom
Tt
t
tt
In this cross, each offspring will have a ______
chance of being TT, _____ chance of being Tt, and
______ chance of being tt. Theres a ______
chance of being tall and ______ of being short