Laboratory

1
Laboratory 11

• Exercise 15
• Mendelian Genetics

2
Intro to Genetics

• Traits phenotype (expression of genetic makeup
  what you see)
• blending inheritance idea that traits were
  blended in offspring

3
Chromosome

• Consists of DNA plus protein
• Diploid 2 sets of chromosomes
• Homologous Chromosomes have same genes
• Haploid 1 set of chromosomes
• Gene region of DNA coding for a product (RNA or
  protein)
• Allele variation of a gene
• Diploid organism has two alleles for each trait

4
Genotype

• Based on types of alleles present
• Homozygous (homozygote) two of the same allele
  on homologous chromosomes
• true-breeding
• Heterozygous (heterozygote) two different
  alleles on homologous chromosomes

5
Phenotype

• What you see (expression of alleles)
• Dominant shows up even when homozygous or
  heterozygous (present as only 1 copy along with
  another allele)
• Recessive hidden in heterozygote, only seen in
  homozygote

6
Mendels Laws

• Segregation each gamete gets one copy of each
  gene
• Independent assortment inheritance of one gene
  does not influence the inheritance of another if
  the other is
• 1) on another chromosome
• 2) far enough away on a single chromosome that
  the probability of crossing-over is high

7
Hybrid Crosses

• Crosses true-breeding (homozygous) parents to get
  F1 generation
• Monohybrid cross looks at one trait
• Crosses members of F1 generation
• Dihybrid cross - looks at two traits
• Crosses members of F1 generation
• Punnett Square used to determine theoretical
  outcome

8
Monohybrid Cross

• Crosses hybrid green pea plants
• P. 201 table p. 203
• Parents Green X Yellow
• Parental Genotypes yy X YY
• F1 genotypes Yy (all yellow)

9
Chi-square Test

• Tests how close your observed values are to
  theoretical values
• X2 (o1-e1)2/e1 (o2-e2)2/e2

10
Test Cross

• Between a phenotypically dominant individual of
  unknown genotype and an individual of recessive
  phenotype
• If any recessive individuals appear, then the
  dominant parent was heterozygous
• E.g., person with type O blood (recessive) and
  person with Type A blood

11
Dihybrid Cross
Crosses two hybrids looking at two genes Green
axial X yellow terminal all yellow
terminal yyAA X Yyaa YyAa F1 gametes YA,
Ya, yA, ya
9 dom. dom. 3 dom. rec. 3 rec. dom. 1 rec. rec.
12
Intermediate Inheritance (Incomplete Dominance)

• Heterozygote is different from either parent
• E.g., pink flowers from red and white
• E.g., AB blood from A and B