Genetics

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Genetics

• Who do you look like????

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Vocab

• Homozygous dominant/ homozygous recessive
• Heterozygous
• Genotype/ phenotype
• Gamete
• Hybrid
• Gene
• Segregation
• P/ F1 generation/ F2 generation

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Gregor Mendel

• Austrian Monk crossed some pea plants
• Laws of ____________
• There are alternative forms of genes, the units
  determining heritable characteristics. This is
  now known as an ____________
• An organism inherits one allele from each parent.

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Segregation

• A sperm or egg carries only one allele for each
  characteristic which pair upon fertilization.
• When the alleles are different, one is fully
  expressed and the other is masked, now known as
  ____________ and recessive genes.

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Genes and Dominance

• Dominance - the ability of one allele to express
  its ____________ at the expense of an alternate
  allele
• Generally the dominant allele will make a gene
  product that the recessive can not therefore the
  dominant allele will ____________ itself whenever
  it is present

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Lets Practice

• What do you get for F1 when your P generation is
  Homozygous dominant Yellow and green?
• What if you cross two of the offspring from that
  cross? What is the F2 generation?
• What if I said to cross a Tall with a Tall? What
  are the possible outcomes?

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Test Cross

• When you are not sure of the genotype of the
  dominant phenotype you do a test cross

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More Practice

• What if I wanted to know if a flower was likely
  to be tall/ short and purple/ white?
• How would I do that?

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Dihybrid Cross

• In any case where the parents are heterozygous
  for both traits (AaBb x AaBb) you will get a
  9331 ratio

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Independent Assortment

• This law states that allele pairs separate
  independently during the formation of
  ____________ Therefore, traits are transmitted
  to offspring independently of one another.

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Dihybrid Cross
A cross (or mating) between two organisms where
two genes are studied is called a DIHYBRID cross.
The genes are located on separate chromosomes,
so the traits themselves are unrelated.
BB black Bb black bb white LL short
hair Ll short hair ll long hair
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Also in rabbits, black eyes are dominant to red
eyes.These letters represent the genotypes of
the rabbits
GG gray hairGg gray hairgg white hair BB black eyesBb black eyesbb red eyes
      1. What are the phenotypes (descriptions)
of rabbits that have the following
genotypes Ggbb ____________________ ggBB
________________________ ggbb ____________________
GgBb _________________________
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• A male rabbit with the genotype GGbb is crossed
  with a female rabbit with the genotype ggBb The
  square is set up below. Fill it out and determine
  the phenotypes and proportions in the offspring.

How many out of 16 have grey fur and black eyes?
________ How many out of 16 have grey fur and
red eyes? ________ How many out of 16 have white
fur and black eyes? ________ How many out of 16
have white fur and red eyes?
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Incomplete Dominance

• When there is no dominant or recessive, the
  heterozygous condition results in a "blending" of
  the two traits. Example Snapdragons can be red,
  white, or pink (heterozygous)
• neither allele is dominant, red x white pink

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Codominance

• Both are expressed in some way, red x white
  white/red spots
• Use all capital letters - Red (RR) x White (WW)
  Red and white (RW)The old way still works,
  though.

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Sex linked Traits

• The genes for these traits are on the _____
  chromosome
• because boys only receive one X chromosome they
  are more likely to inherit disorders passed to
  them from their ____________ who would be a
  carrier.
• Hemophilia and Colorblindness are sex linked
  traits, the punnet square below shows how a woman
  who is a carrier passes the trait to her son, but
  not her daughters.

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Pedigree Chart
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Muliple Allele Traits

• Traits that are controlled by more than two
  alleles. Blood type in humans is controlled by
  three alleles A, B, and O
• Blood can only be transferred to a body of a
  person who's immune system will "recognize" the
  blood. A and B are antigens on the blood that
  will be recognized. If the antigen is unfamiliar
  to the body, your body will attack and destroy
  the transfused blood as if it were a hostile
  invader (which can cause death).

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• O is like a blank, it has no antigens. O is
  called the universal donor because a person can
  receive a transfusion from O blood without having
  an immune response
• AB is the universal acceptor, because a person
  with AB blood has both the A and B antigens
  already in the body, A and B blood can be
  transfused to the person (as well as O) and the
  body will recognize it and not attack.

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Environmentally Influenced Traits

• Siamese cats have dark ears and feet due to the
  temperature. Height in humans is influenced by
  the environment (diet)
• Traits are influenced by the environment. Pattern
  baldness affects men because testosterone
  activates the genes.
• THE ENVIRONMENT EFFECTS THE EXPRESSION OF
  GENES!!!!!!