Transcript Chapter 1-2: Genetics Progressed from Mendel to DNA in Less Than

Chapter 1-2:
Genetics Progressed
from Mendel to DNA in
Less Than a Century
By PresenterMedia.com
A Breakdown
Mendel’s Work
Item 1
Chromosome Theory of Inheritance
Item 2
Item 3
Item 4
Genetic Variation
Search for the Chemical Nature of Genes
Mendel’s Work
•
Essential Point #1: Mendel’s work
on pea plants established the
principles of gene transmission
from parent to offspring that serve
as the foundation for the science
of genetics.
Chromosome Theory of Inheritance
•
Essential Point #2: The
Chromosome Theory of
Inheritance explains how
genetic information is
transmitted from generation to
generation.
Chromosome Theory of Inheritance
•
Terms to know:
• Diploid (2n): 2 copies; found in body cells.
• Homologous chromosomes:
chromosomes appear in pairs. They are
identical in size and location of
centromeres.
• Mitosis/Meiosis: Replication and division of
chromosomes for cell distribution.
• Haploid (n): half the copies; found in
gametes.
• Allele: alternative forms of a gene
• Phenotype: observable features.
• Genotype: the set of alleles for a given
trait in the genetic code.
Genetic Variation
Results from any heritable change.
• Discovery of mutations in eye color in
Drosophila, fruit fly, the most common
model organism in genetics.
• These mutations can be found in the
genes of gametes and are passed
through sexual reproduction.
•
Genetic Variation
•
Heritable changes are
called MUTATIONS.
•
MUTATIONS can:
•
Cause no change
•
Cause beneficial changes/
Natural Selection
•
Cause harmful changes
The Search for DNA or Protein?
•
•
Many researchers
thought proteins were
the chemical
responsible for the
passage of genes from
parent to offspring.
1944: Avery, etal
proved that DNA was
responsible for carrying
genetic information in
bacteria.
Questions to Consider
•
•
Can we apply Mendel’s theories to the inheritance of
all traits? Give examples.
Why was it difficult for scientists to accept Avery, etal
claim that DNA was the mechanism of heredity in
1944? (hint: when did Watson, Crick, and Franklin
publish their findings?)
1.3: Discovery of the Double Helix and
Molecular Genetics
•
•
Once Avery, etal proved that DNA was the
mechanism of inheritance, the stage was set in the
discovery of its structure.
1953: Watson & Crick described the molecular
structure of DNA.
•
Awarded the Nobel Prize in
1962
Gene Expression:
from DNA to phenotype
Also known as the Central Dogma
Proteins and Biological Function
•
Proteins are the product of genetic
expression.
•
•
•
20 different Amino Acids = the building
blocks of proteins.
Lets do the math…
•
•
•
•
What is/are the functions of proteins in living
organisms?
Protein that contains 100 amino acids can
have any one of the 20 A.A.’s at each location
20 100 = 5 trillion possibilities!!!
3-dimensional conformation of the protein
is essential to its biological function.
Enzymes = shape is ESSENTIAL for bonding
with chemicals at the active site.
Case Study
Sickle Cell
Trait
Phenotype and Genotype:
Sickle cell trait
RESULT: Can’t bind to
oxygen for transport.