Human Inheritance

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Human Inheritance

• Mrs. Wharton Science Class

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Height and skin color

• Some human traits are controlled by many genes
• There is an enormous variety of phenotypes for
  height for example and skin color ranges from
  nearly white to almost black

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Multiple Alleles

• Human traits that are controlled by a single gene
  that has more than two alleles (three or more
  forms of a gene that codes for a single trait)
• Blood type is an example

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Sex chromosomes

• One of 23 pairs of chromosomes in each body cell
• Carries genes that determine whether a person
  male or female.
• Also may determine other traits
• Males XY Female XX

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Sex Linked Genes

• The X or Y chromosomes that determines your
  gender
• Traits controlled by sex linked genes are called
  sex linked traits
• Because males have only one X chromosome they are
  more likely to get a sex linked trait controlled
  by a recessive allele.

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Sex Linked Genes

• Example Colorblindness
• Carrier- a person who has one recessive allele
  for a trait and one dominant.
• Although a carrier does not have the trait, that
  carrier can pass the recessive allele to their
  offspring.
• In sex linked genes only females can be carriers

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Effects of the environment

• Many of a persons characteristics are determined
  by an interaction between genes and the
  environment
• Several genes determine a persons height however
  environment also influences a persons height (A
  poor diet can prevent a person from growing as
  tall as might be possible).