Genetics and Heredity

1
Genetics and Heredity

• Chapter 8

2
Mendel Studied 7 Characters in the Garden Pea
(Pisum sativum)

• Flower color.
• Flower position.
• Seed color.
• Seed shape.
• Pod color.
• Pod shape.
• Stem length.

3
Mendels Methods

• Cross-pollination- the transfer of pollen from
  one plant to the stigma of another.
• Self-pollination
• Artificial cross-pollination
• Monohybrid crosses- an experimental cross between
  individuals that differ by a single trait.
• First (F1) and second (F2) generations.

4
Mendels F1 Observations

• One of the traits could be seen in the F1
  generation Dominant
• One of the traits could not be seen in the F1
  generation Recessive

100 Purple
5
Genetic Terminology

• Phenotype- an organisms traits.
• Genotype- an organisms genetic makeup.
• Homozygous- identical alleles for a gene.
• Heterozygous- two different alleles for a gene.

6
Genetic Terminology 2

• Allele- one of 2 or more alternative forms of the
  same gene.
• Gene- a sequence of DNA that codes for a protein.
• Locus- the position on a chromosome occupied by a
  gene.

w
W
7
Mendels F2 Observations

• Flower color
• Purplewhite
• 705224
• 31

8
Mendels Dihybrid Cross

• 31510810132
• 9331

9
Mendels Work Yielded These Genetic Rules

• Alternative versions of genes (different alleles)
  account for variations in inherited characters.
• For each character an organism inherits two
  alleles, one from each parent.
• If two alleles differ, then one, the dominant
  allele is fully expressed in the organisms
  appearance.
• The two alleles for each character segregate
  during gamete production.
• Alleles of a gene segregate independently of the
  alleles of other genes.

10
Punnett Squares and the Testcross
?

• Punnett square- a diagram used to predict the
  result of a genetic cross.
• Testcross- a genetic experiment used to determine
  an organisms genotype.

w
w
W
Ww
Ww
w
ww
ww
?
w
w
W
Ww
Ww
W
Ww
Ww
11
Incomplete Dominance

• Incomplete dominance- type of inheritance in
  which the F1 is intermediate in phenotype between
  the parents.
• Neither allele is dominant.
• Self-pollination of the F1 yields a 121 F2
  population.

12
Continuous Variation

• Continuous variation- a gradation in phenotype
  indicates that a trait is controlled by two or
  more genes.
• Polygenic inheritance.

13
Linkage

• Linkage- the tendency for certain genes to be
  inherited together, owing to the fact that they
  are located on the same chromosome.
• Linked genes- genes that are inherited together.

14
Genetically Engineered Rice
15
Genetically Modified Rice
16
(No Transcript)
17
Genetic Engineering

• Genetic Engineering- the technique of removing,
  modifying, or adding genes to a DNA molecule.
• Improvements in crops
• Longevity
• Resistance to insects
• Resistance to herbicides

18
Transgenic Plants

• Tomato with BT gene and without.
• Transgenic tomatoes with and without etr1-1 gene.
• Petunia with and without etr1-1 gene.
• Tobacco with and without a cytokinin gene.

19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
Transfer of Genes
23
Agrobacterium tumefaciens
24
(No Transcript)
25
Genomics

• Genomics- a field of genetics that attempts to
  understand the content, organization, function,
  and evolution of genetic information in a whole
  organism.

26
Arabidopsis thaliana
27
Genome

• Genome- all of the genetic information of an
  organism.