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Chap. 11/14 Genetics or Why do you look Like that!?!. Trait Inventory Activity Part 1. Complete H.O. on traits of peers Write “yes” or “no” based on what you see! How are we all alike? (trait) How do some of us differ? (characteristic) Part II later!!.

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slide1
Chap. 11/14

Genetics

or

Why do you look Like that!?!

trait inventory activity part 1
Trait Inventory ActivityPart 1
  • Complete H.O. on traits of peers
  • Write “yes” or “no” based on what you see!
  • How are we all alike? (trait)
  • How do some of us differ? (characteristic)
  • Part II later!!
i meiosis reduction division
I. Meiosis - Reduction Division
  • Produces gametes…
  • Gametes are 1n/haploid…
  • In males – 4 sperm cells produced
  • In females – 1 egg cell and 3 polar bodies (“duds”) produced.
recall
Recall…
  • Mitosis …
  • Somatic cells/body cells…
  • 2n/diploid…
terms
Terms-
  • Homologous pairs – original chromosome pair and their copies.
  • Tetrad – chromosome pair & corresponding homologous pair
  • A tetrad contains 4 chromatids
ii gregor mendel
II. Gregor Mendel –
  • “Father of genetics”
  • Pea plants…
  • Characteristics and traits
  • Some characteristics were visible, some were not
  • Ex. Plant height – tall or short…
3 principles of genetics
3 Principles of Genetics
  • They are based on alleles – contrasting genes that determine a trait.
  • Ex. BLUE vs BROWN EYES
a principle of segregation
*A. Principle of Segregation –
  • Alleles segregate/separate
  • Occurs during meiosis…
b prin of independent assortment
*B. Prin. of Independent Assortment –
  • Alleles are randomly arranged
  • Ex. Trait “a” is not dependant

on trait “b”

c prin of genes and dominance
*C. Prin. Of Genes and Dominance –
  • One allele “hides“ another.
  • Dominant…
  • Recessive…
  • Fig. 11-3
iii crash course in crossing
III. Crash course in crossing
  • P1 – original parents with

pure traits – called true

  • F1 – first generation with a mix of parent traits – hybrids
  • F2 – second generation with a mix of their parents traits
a punnett squares
A. Punnett squares -
  • Predicts…
  • Tells the –
    • Genotype …
    • Phenotype …
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Capitals represent dominant characteristics
      • AA, BB
  • Lower case represent recessive characteristics
      • aa bb
slide14
Purebred means two identical alleles
      • GG, mm,
  • Can be dominant or recessive
  • This is homozygous
      • “same trait/allele”
slide15
Hybrid means two different alleles
      • Nn,Oo
  • Will always be dominant --- why???)
  • This is heterozygous
      • “different trait/allele”
b types
B. Types:
  • Monohybrid cross - “One trait; one letter”
  • Dihybrid cross - “Two traits; two letters”
v gene expression is
V. Gene expression is…
  • Based on the environment, and the effect of other genes.
        • Toxins, disease, drugs…
  • “Nature vs nurture”
        • Over/under nutrition
        • Soil acidity & flower color
dominant alleles
Dominant Alleles
  • Conditions that are expressed provided one dominant allele is present
  • Ex. PP or Pp – Tall plants
  • HH or Hh – Huntington’s disease
b recessive alleles
B. Recessive Alleles
  • Trait is expressed provided two recessive alleles are present.
  • Ex. tt – short plants
  • In humans …
  • tt – Tay-sachs
  • aa - albinism
c incomplete dominance
C. Incomplete Dominance -
  • There is no dominance.
  • The heterozygous genotype shows a mix of both phenotypes.
  • Ex. White and red roses

make pink roses.

d codominance
D. Codominance –
  • A type of incomplete dominance.
  • Both alleles share dominance & are expressed in the organism.
  • Ex. Roan cattle have both red and white fur.\
  • In humans – sickle-cell anemia
codominance in humans
Codominance in humans …
  • Expressed in varying degrees
  • Sickle-cell anemia
    • Person is either unaffected, a carrier, or affected
e multiple alleles
E. Multiple Alleles –
  • Genes that have more than 2 possible alleles -

C, cch, ch, c

  • Each allele being expressed, not contrasting like in peas!
  • Ex. Rabbit fur – p. 273
multiple alleles in humans
Multiple Alleles in humans…
  • Blood types
  • A
  • B
  • AB (universal receiver)
  • O (universal donor)
  • Could be + or -
f polygenic traits
F. Polygenic traits –
  • “Many genes”– traits due to the interaction of more than 3 genes.
  • These traits tend to “blend” from one extreme to the other.
  • Ex. Skin/fur color, eye color…. Very dark to very light
polygenic traits in humans
Polygenic traits in humans
  • Height
  • Healthy weight
  • All vary from one to the other extreme
g determing sex
G. Determing Sex
  • Only one X is required for survival.
  • XX – female
  • XY - male
h sex linked conditions
H. Sex-linked Conditions –
  • Traits that are linked or found on the X or Y chromosomes
  • Ex. Colorblindness, hemophilia, muscular dystrophy
  • Y – says “just make me a boy!” P.350
vi determining genetics
VI. Determining Genetics
  • A. Karyotype - picture of an individual’s chromosomes
    • Homologous chromosomes are paired & analyzed
b pedigree
B. Pedigree
  • Family record that shows how a trait is inherited over several generations.
  • Identifies the carriers, those that are normal, & the affected individuals.
vii mutations human genetics
VII. MUTATIONS & HUMAN GENETICS

A. CHROMOSOMAL MUTATIONS affect the entire chromosome

  • May be deletion, duplication, inversion, or translocation

B. NUCLEOTIDE MUTATION

  • Affects the nucleotide of DNA which makes the chromosome
c nondisjunction
C. NONDISJUNCTION
  • Homologous chromosomes do not separate during meiosis.
  • Some effects may or may not be lethal.
  • Autosomal chromosome:
      • Ex. Down syndrome - due to trisomy 21 - having 3 of #21 chromosomes
slide33
Can affect sex chromosomes
    • Turner’s Syndrome – XO – affects females
    • Klienfelter’s Syndrome – XXY- affects males
slide34
Chromosomes carry the alleles that produce the trait that makes you look the way you do!!!