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14.1 Human Heredity

14.1 Human Heredity. Notes: Karyotypes, inheritance patterns, sex-linked, pedigrees. Studying human heredity. To understand human genetics, we look at the ENTIRE set of genetic information in a person Called a GENOME

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14.1 Human Heredity

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  1. 14.1 Human Heredity Notes: Karyotypes, inheritance patterns, sex-linked, pedigrees

  2. Studying human heredity • To understand human genetics, we look at the ENTIRE set of genetic information in a person • Called a GENOME • Scientists look at a picture of every chromosome, taken from a person’s nucleus • Called a KARYOTYPE • Diploid chromosomes are grouped in pairs, arranged by decreasing size

  3. Types of Chromosomes Sex Chromosomes Autosomal Chromosomes 44 of 46 “Body” chromosomes Determines everything else, basically Majority of your traits are in autosomal chromosomes • 2 of 46 in human genome • Determine sex of individual • Females have X X, males have X Y • All female eggs have 1 X • 50% of male sperm have 1 X, and 50% have 1 Y • This is what makes having a boy versus having a girl, 50/50 probability

  4. Genes on Sex Chromosomes • 1200 genes are on the X chromosome • 140 genes are on the Y, most of which deal with male sex determination and sperm development

  5. Dominant & Recessive Alleles • Humans, like pea plants, also follow “normal” dominant or recessive patterns • Ex: Skin and hair color (darker colors are more dominant than lighter colors) • Recessive – red hair (2 recessive alleles) • Ex: Rhesus (Rh) factor- protein found in blood • Rh+ is dominant, Rh- is recessive

  6. Codominant & Multiple Alleles • Many alleles show codominant inheritance • Ex: blood type: IA , IB , i • Type A – produces antigen A • Type B – produces antigen B • Type AB – produces both antigens (CODOMINANT) • Type i (O) – produces no antigens

  7. Blood Groups:

  8. Sex-Linked Inheritance • Genes found on X or Y chromosome show “sex-linked” inheritance patterns • Genes on Y are ONLY found in males • Genes on X are found in males/females, but show different patterns… hmm…….

  9. For females to show recessive traits from X chromosome, BOTH chromosomes need to carry the recessive alleles • If one X has a recessive, and one X has dominant, the trait will not appear • Males only have 1 X, so if they inherit a recessive trait on it, they MUST show that trait since nothing can cover it up Sex-Linked

  10. Human Pedigrees • Show how traits flow through families • Help determine the pattern in which traits are inherited (recessive, dominant, sex-linked)

  11. Pedigree Analysis • Does the grandmother or grandfather show the white forelock trait? • How many daughters they have ______ • How many sons they have _______ • How many of their children married ______ • _____ of 3 children inherited the trait • Grandfather’s genotype must be ________ • Son = ________, and wife = _________ Grandfather 2 1 2 2 Hh Hh Hh

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