Genetics

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Genetics Heredity
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Who was Gregor Mendel?

• Austrian monk who studied mathematics and science
• As a boy he could predict the possible types of
  flowers and fruits that would result from
  crossbreeding two plants in his fathers garden

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Who was Gregor Mendel?

• Curiosity about the connection between the color
  of a pea flower and the type of seed that same
  plant produced inspired him to begin
  experimenting with garden peas in 1856.
• Made careful use of scientific methods, which
  resulted in the first recorded study of how
  traits pass from one generation to the next.

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What is GENETICS?

• The study of how traits are inherited through the
  interactions of genes.

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What is a GENE?

• The material that controls which traits are
  expressed in an organism
• Genes come in pairs and offspring inherit one
  copy of each gene from each parent

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Define HEREDITY

• The passing of traits from parent to offspring

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Define ALLELE

• The different forms of a trait that a gene may
  have
• One form of a gene

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Define TRAIT

• Ways of looking, thinking, or being
• Traits that are genetic are passed down through
  the genes from parents to offspring

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Describe RECESSIVE

• A trait that is covered over, or dominated, by
  another form of that trait and seems to disappear
  
• Hidden when the other copy of the gene contains
  the dominant allele.
• A recessive trait shows up only when there is no
  dominant allele present
• Shown with a lower-case letter

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What is HOMOZYGOUS?

• Both alleles forms of the gene are the same
• When offspring inherit two dominant genes, (one
  dominant gene from each parent) they are said to
  be homozygous dominant
• When offspring inherit two recessive genes, (one
  recessive gene from each parent) they are said to
  be homozygous recessive

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What is HETEROZYGOUS?

• When alleles occur in different forms
• When offspring inherit one dominant gene and one
  recessive gene, they are said to be heterozygous
• Since the dominant gene will be expressed, they
  are said to be heterozygous dominant

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What is HETEROZYGOUS?

• When alleles occur in different forms
• When offspring inherit one dominant gene and one
  recessive gene, they are said to be heterozygous
• Since the dominant gene will be expressed, they
  are said to be heterozygous dominant

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Describe CO-DOMINANCE

• When both alleles can be observed in a phenotype
• Example-Coat color of a cow shows co-dominance
  when he inherits the allele for white coat color
  from one parent and red coat color from the other
  parent. This cow would show co-dominance if he
  has both red and white hair that can be seen.

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Describe Incomplete Dominance

• For example
• The gene for the color of some flowers has one
  allele for red and one for white. When both
  alleles are present, neither is dominant, and the
  flower color is pink

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Describe DOMINANT

• A trait that covers over, or dominates, another
  form of that trait
• Trait that always shows up, even when only one of
  the two alleles is in the dominant form
• Shown by a capital letter

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Define GENOTYPE

• An organism's genetic makeup

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Define PHENOTYPE

• Outward physical appearance and behavior of an
  organism

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What is a PUNNETT SQUARE?

• A tool to predict the probability of certain
  traits in offspring that shows the different ways
  alleles can combine
• A way to show phenotype genotype
• A chart that shows all the possible combinations
  of alleles that can result when genes are crossed

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What is a PUNNETT SQUARE?

• Letters stand for dominant and recessive alleles
• An uppercase letter stands for a dominant allele
• Lowercase letters stand for recessive alleles

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Principles of Heredity

• Traits are controlled by alleles on chromosomes
• An alleles effect is dominant or recessive

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What is meant by MULTIPLE ALLELES?

• A trait that is controlled by more than two
  alleles is said to be controlled by multiple
  alleles
• Traits controlled by multiple alleles produce
  more than three phenotypes of that trait

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What is meant by MULTIPLE ALLELES?

• For Example
• The alleles for blood types in humans are called
  A, B, and O
• The O allele is recessive to both the A and B
  alleles

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What is meant by MULTIPLE ALLELES?

• When a person inherits one A allele and one B
  allele for blood type, both alleles are expressed
• The person has the blood phenotype AB

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What is meant by MULTIPLE ALLELES?

• A person with phenotype A blood inherited an A
  and an O allele (AO)
• OR
• an A and an A allele (AA)

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What is meant by MULTIPLE ALLELES?

• Someone with phenotype B blood has the genotype
  BB or BO
• This person inherited either a B and an O allele
• OR
• Two B alleles

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What is meant by MULTIPLE ALLELES?

• A person with phenotype O blood has the genotype
  OO

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What is POLYGENIC INHERITANCE?

• Occurs when a group of gene pairs acts together
  to produce a trait
• The effects of many alleles produces a wide
  variety of phenotypes

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Examples of POLYGENIC INHERITANCE

• Height
• Skin tone/color