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14.1 Human Heredity

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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 ... – PowerPoint PPT presentation

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Title: 14.1 Human Heredity


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 persons 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
  • Grandfathers genotype must be ________
  • Son ________, and wife _________

Grandfather
2
1
2
2
Hh
Hh
Hh
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