Download history of genetics

MR. DALLINGA’S…………BIOLOGY
Gregor Mendel Facts
 Born July 22nd 1822 in Czechoslovakia A region of Austria. Today is Czech republic.
 Life of Poverty
 Entered a monastery to get an education
 The monastery was known for teaching Science and Scientific research and math
 To further his education he attended the University of Vienna to get a teaching diploma
 He failed and returned to the monastery
WHAT TO DO NEXT?
 He stayed at the monastery to research traits and how they are passed on from generation to generation
heredity
The study of how traits are passed on is called _______.
Video Cracking the code
Genetics
The study of heredity is ________.
Mendel’s pea’s
and their traits
Mendel Chose Pea plants for 3 reasons.
• First they grow and reproduce quickly
• Second pea plants had a variety of different traits (7) that could be studied at the same time.
1.
2.
3.
4.
5.
6.
7.
Flower color
Flower position
Seed color
Seed shape
Pod shape
Pod color
Stem length
• Third he could easily cross them through pollination
Pollination
Two Kinds:
Self Pollination and Cross Pollination
Structure of a Flower
Test #1
Test #2
Studied Stem Length
Tall X Tall = All Tall
P1
P1
Short X Short = All Short
P1
Test #3
Tall X Short = All Tall
P1
Test #4
P1
P1
Tall X Tall =
F1
F1
3 Tall 1 Short
Two different types
TALL / short
Rules For Genetics
•
•
•
•
Symbols used for Genotypes = Letters
Always use the letter of the dominant trait
Early 1900s Reginald Punnett
Dominance show with a capital letter
Recessive show with a lower case letter
• Always write the capital letter first when there
G
g
is
a
Hybrid
or
Heterozygous
cross
G
G
G GG
Gg
Gg
g Gg
Gg X Gg
GG X gg
P1
F1
Gg
gg
g Gg
g
Gg
Principals Learned from Mendal’s Work
Terms: Purebred or Homozygous = TT dominant or tt recessive
Hybrid
or Heterozygous = Tt
 The rule of unit factors: Mendel concluded that each organism has two factors that
Control each of its traits called ________
these different forms are called _______.
Genes
Alleles
More Terms:
Genotype = the organism’s allele pairs.
Phenotype = the observable characteristic or outward expression of an allele pair.
 The rule of dominant and recessive traits.
 The Law of Segregation = states that the two alleles for each trait separate during meiosis
Principals Learned from Mendal’s Work continued
 The Law of independent assortment: states that a random distribution of alleles occurs
during gamete formation. Genes on separate chromosomes sort independently during meiosis
End of Part I
Incomplete
Dominance
Part II
= is when the heterozygous phenotype is an intermediate
(blend) phenotype between two homozygous phenotypes.
X
Page 302
Paul Andersen
video
=
Video
= is when both
Codominance
alleles are expressed in
B
heterozygous condition.
video Blood types
X
B
W
W
BW
BW
BW
BW
=
Page 302
Multiple Alleles
Page 304
Page 285
Page 313
Polyploidy = most species have diploid cells, Nondisjunction
but some have polyploidy cells. Polyploidy is the
occurrence of one or more extra sets of all
chromosomes in an organism. A triploid organism,
for instance, would be designated 3n, which means
that it has three complete sets of chromosomes.
Polyploidy rarely occurs in animals. In humans
polyploidy is always lethal.
This image shows haploid (single), diploid (double),
triploid (triple), and tetraploid (quadruple) sets of
chromosomes. Triploid and tetraploid chromosomes are
examples of polyploidy.
= During cell division, the
chromosomes separate, with one of each of the sister
chromatids going to opposite poles of the cell. Therefore,
each new cell has the correct number of chromosomes.
Cell division during which sister chromatids fail to
separate properly, which does happen occasionally,
is called nondisjunction. Having a set of three
chromosomes of one kind is called trisomy. Having only one
of a particular type of chromosome is called monosomy.
The left image at the blue arrow
is nondisjunction taking place
during meiosis II. The right
image at the green arrow is nondisjunction taking place during
meiosis I. Nondisjunction is when chromosomes fail to
separate normally resulting in a gain or loss of chromosomes.
Pedigrees
Basic symbols
In organisms such as peas and fruit flies,
scientists can perform crosses to study genetic
relationships. In the case of humans, a scientist
studies a family history using a pedigree, a diagram
that traces the inheritance of a particular trait
through several generations. A pedigree uses
symbols to illustrate inheritance of a trait.
Pedigree video
Practice
Page 299
Sex-Linked Traits
Page 307
Traits controlled by genes located on the X chromosome are
called sex-linked traits, or X-linked traits. Because males have
only one X chromosome, they are affected by recessive
X-linked traits more often than are females. Females are less
likely to express a recessive X-linked trait because the other
X chromosome may mask the effect of the trait.
Show video before charts
Some traits that are located on autosomes may appear
to be sex-linked, even though they are not.
This occurs when an allele appears to be dominant
in one gender but recessive in another. For example,
the allele for baldness is recessive in
females but dominant in males, causing
hair loss that follows a typical pattern
called male-pattern baldness. A male
would be bald if he were heterozygous
for the trait, while a female would be
bald only if she were homozygous recessive.
Fredrick Griffith (1928)
DNA & ITS DISCOVERY
 He was studying two strains of bacteria ( Streptococcus pneumonia)
which cause pneumonia. Of the two strains he studied, one had a
sugar coat and one did not. The coated strain causes pneumonia
and is called the smooth (S) strain. The noncoated strain does not
cause pneumonia and is called rough (R) strain because, without
the coat, the bacteria colonies have rough edges.
 Griffith isolated live bacteria from the dead mouse.
When these isolated bacteria were cultured, the smooth
trait was visible, suggesting that a diseases-causing factor
was passed from the killed (S) bacteria to the live (R) bacteria.
 His experiment led to a discovery of a process called ___________.
transformation A process in
which one strain is permanently changed by taking in the genes from a different strain.
Mr. Andersen’s video good review or overview
DNA & ITS DISCOVERY
Fredrick
Griffith’s
Experiment
One gene = 1 protein
Remember a gene is
a segment of DNA
A Genome is all of
one organisms DNA
Conclusion:
R strain was transformed
into S strain.
Control
Experimental
Video
Control
Experimental
Oswald Avery
(1944)
DNA & ITS DISCOVERY
 His goal was to determine what molecule Was used during
the transformation process of Griffith’s experiment.
 By a process of elimination, he discovered that DNA was the
transforming factor.
He took enzymes that break down
these macromolecules and inserted
them into each kind.
Video
Alfred Hershey &
Martha Chase (1952)
 They did an experiment
involving viruses to prove the
work of both Griffith and Avery
 Viruses are made of only 2 things
- Protein coat
- Nucleic Acid
Video
Experiment
Step1: They tagged the protein to
see if that was the transforming
factor. It was not.
Tag (sulfur 35) = Radioactive isotope that glows when
inserted.
Step 2: They tagged the DNA core to see if
that was the transforming factor, it glowed
showing that it was the transforming factor.
Video: Watson and Crick
discover the DNA Molecule
P. A. Levene = in 1920s determined the basic structure of nucleotides
Erwin Chargraff’s
Rosalind Franklin
James Watson & Francis Crick
DNA Structure
Nucleotide
4 Nitrogen Bases
Video: DNA Structure
Crash Course Science
Purines & Pyrimidine's