Genetics - the study of heredity, or the passing of traits from parents to offspring.

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• Genetics - the study of heredity, or the passing
  of traits from parents to offspring.
• Traits - the characteristics of an organism.

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Gregor MendelThe Father of Genetics
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• A monk that studied pea plants and how they
  passed on their traits (size, seed shape and
  color, flower position, etc.)

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Genes - the basic unit of heredity that Mendel
discovered from his observations. We have a pair
of genes for every trait, one from each parent.
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a. dominant genes - genes that mask other genes
and are more likely to appear in the offspring
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Dominance
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b. recessive genes The weaker genes or the ones
that are less likely to appear.
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Allele Each member of a set of genes for a
particular trait. ex.in Tt, the T is one allele
and the t is another.
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• Purebred
• An organism that has the same genes for a
  particular trait. ex. both parents are tall (TT)
  or both are short (tt)

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• Hybrid
• An organism that has different genes for a
  particular trait. ex. one parent is tall and one
  short (Tt)

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• Multiple alleles
• some traits are determined by more than the usual
  pair of alleles. ex. skin color, blood type.

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• Incomplete Dominance - neither gene in a pair
  masks the other, instead the genes blend together
  when inherited. ex. gray kitten from a black mom
  and white tomcat.

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Incomplete Dominance
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• Punnett Square
• a chart that shows the possible combinations of a
  cross between two organisms.

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Punnett Square
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Punnett Square
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Dihybrid cross
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Dihybrid Cross
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• Phenotypes
• the visible characteristics of an organism.
• ex. black hair

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• Genotypes
• the actual genetic makeup that can not be seen.
  ex. may have black hair, but are the genes BB or
  Bb? can't tell by looking.

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Chromosomes The genes are found on the
chromosomes. Each chromosome contains many genes
and they control how the genes are passed on to
their offspring.
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DNA Deoxyribonucleic Acid - the basic substance
of heredity. DNA molecules in the chromosomes
make up the genes. James Watson and Francis
Crick discovered the structure of DNA. They
found it looks like a twisted ladder with steps
of nitrogen bases.
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DNA
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Replication the way DNA duplicates itself
during mitosis. It unzips itself and free
nitrogen bases floating around in the nucleus
pair up on each half to form another DNA strand
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• Sex Chromosomes
• determine if offspring will be a girl or a boy.
  XX will be a girl. XY will be a boy. You can
  only get a Y gene from the father.

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Mutations a change in genes that causes a new
trait to be inherited may be helpful or harmful
or may have no effect. ex. Albino, seedless
oranges
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Albino
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Albino
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Albino
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Polydactyl
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Hypertrichosis
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• Sex - linked traits - traits that are passed on
  the X chromosome, from the mom.
• ex. hemophilia and colorblindness.

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Sex linked Color blind
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• Nondisjunction - the failure of chromosomes to
  separate during meiosis, so cells inherit either
  extra or fewer chromosomes than normal.exs. Downs
  syndrome has extra on 21st chromosome.

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Nondisjunction
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Genetic Engineering
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Cloned Kitty
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Stem Cells
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