monk in the 1800’s
observations which are the foundation of genetics.
math to describe biology for the first time.
Principles of Genetics
parents differ in a trait, the offspring show only one trait.
of parents differing in some trait will produce eggs or sperm, half with the
trait of one parent and half with the trait of the other.
fact that an organism carries genetic material for one trait does not mean
it carries the genetic information for any other trait (independent
studied 7 characteristics in pea plants each which could be expressed in 2
form observed is called PHENOTYPE. (How offspring look).
of phenotype in pea plants.
seed form, round or wrinkled
color of seed content, yellow or green
color of seed coat, white or gray
color of unripe seed pods, green or yellow
shape of ripe seed pods, inflated or restricted
length of stem, short or long
position of flower, axial or terminal
two pure strains that differ in only one characteristic, i.e. seed color.
called P1, offspring called F1, offspring of the F1 generation called F2.
yellow x green
No blending, no yellowish green offspring, instead F1 was all yellow.
trait that appears in the F1 is DOMINANT. Yellow is a dominant trait.
trait that does not appear in the F1 is called RECESSIVE. Green is
factor is preventing the expression of the other. This is known as the
principle of Dominance.
F1 is crossed with the F1 the recessive trait reappears in the F2.
However the ratio of dominant vs. recessive is consistent.
- F2 x
F2. Those with recessive traits only produced recessive offspring but those
that were dominant made both dominant and recessive offspring.
3:1 ratio dominant to recessive.
Yellow x Green. Yellow
is dominant and green is recessive. P1
Yellow x Green. F1 Yellow, F2 3
Yellow; 1 Green
trait is controlled by two factors, one from each parent.
unit of inheritance is called a gene.
alternative form of a gene are called alleles.
alleles of a gene are at specific locations called loci on chromosomes.
and Green are examples of alleles of the same trait.
allele is dominant and one is recessive.
is a difference between what kind of information you have (GENOTYPE) and
what you look like (PHENOTYPE).
pattern seen at F2 is only possible if alleles separate during the formation
of segregation-two alleles for a trait separate when gametes are made.
A closer look
parents are a pure strain Also known as HOMOZYGOUS.
alleles code form the same form of the trait. But ½ of the genes come from
Rr the alleles code for different forms of the trait (HETEROZYGOUS).
R or r
F2 Rr x Rr
Square with Genotype, Phenotype and gametes table.
Principal of Independent Assortment
with 2 characteristics called dihybrids.
Round and wrinkled seeds and Yellow and Green seeds.
two traits don’t influence each other.
RRYY x rryy
Table 9:3:3:1 phenotypic ratio
of genes for one characteristic was not affected by the other gene.
round has no effect on whether you are yellow.
pair of alleles segregate individually during gamete formation.
your unknown with a homozygous recessive.
unknown is dominant homozygous the all the F1 will carry the unknown trait.
unknown is dominant heterozygous ½ F1 will be dominant and ½ will be
Chromosomal theory of inheritance.
are not identical but come in a variety of sizes and shapes.
come in pairs called homoloques.
meiosis, each gamete gets the same # and kind of chromosomes.
chromosomes line up at metaphase, there is no way to tell which way the
maternal or paternal chromosomes will go. This is independent assortment.
must be associated with chromosomes.
are more traits than chromosomes so many traits must be on a chromosome.
in Drosophila Melangaster
otherwise known as a fruit fly.
are easily mutated using cold, heat, x-rays, chemicals, or radioactivity.
flies have red eyes, and are called wild type.
mutant fly has a white eye.
is red eye female x white eye male
All red eyes
3470 red eye and 782 white eyes. Not 3:1.
the white eyes are male, 2459 red eye female and 1011 red eye male.
only males can have white eyes.
white eye male x red eye daughter
red female, 132 red males, 86 white male, 88 white female.
may assort independently but genes may not. Sex and eye color could be
x XwY punnett square
has 4 chromosomes; 2 autosomes, 2 sex chromosomes.
female one X chromosome forms a barr body and is inactivated
Gene linkage and Crossover
traits on different chromosomes will sort independently.
traits on the same chromosome will tend to be passed together.
genes are on same chromosome it is called gene linkage.
body(b) and curved wing (c)are on
the same chromosome.
(B) and normal(C)
xbbcc expect ½ BC and ½ bc
you get 37 % BC, 37 % bc , 13% bC and 13% Bc
color and wings are on the same chromosome. The alternative alleles are on
are able to exchange genes. Recombination in Meiosis.
linked traits, eye color in fruit flies, color blindness in humans, muscular
genes are arranged linearly those closer would become seperated via chrossover less often.
Being close increases the probability of being passd as a unit.
crossover is proportional to the distance between 2 genes. % crossover is #
of crossovers between 2 genes per 100 prophase opportunities.
rays, UV light, Chemicals
mutatgens include cigarette smoke, automobile exhaust, cleaning agents,
pesticides, charcoaled steak.
mutations are point mutations can occur during DNA replication.
or subtraction of nucleotide, or change the nucleotide.
can be beneficial to natural selection.
Stability of DNA
pairing makes DNA resistant to change.
cancer is failure of DNA repair systems.
Really Beyond Mendel
dominance red and white flower produces pink flower.
alleles ie ABO blood system
one gene masks the effects of another. Mouse coat color. When albino gene is
homozygous the black and brown coat color does not develop.
inheritance. Genes have additive effect, for example height.
Genotype may be expressed differently in different environment, or different
sex, and aging or from which parent the gene was inherited from.
frequency of alleles for any characteristic will remain unchanged in a
population through any number of generations unless some outside force acts
on the populationl.
priciple p2 + 2 pq +
Advances in Genetics
separated by heat
anneals to DNA
polymerase extends primer.
Molecular Mug Shots
with restriction enzymes.
transferred to nitrocellulose.
–stranded probe used to bind to complementary fragments.
film detects pattern, or fingerprint.
Diagnosis of Disease
Enzymes can be used to find mutations in genes.
and Huntigtons disease.
Advances in Agriculture
resistant to inscects, bacteria, fungi and unsuitable growing conditions.
size edible parts.
Gene Replacement Therapy
defective genes with normal genes.
a 4 year old girl was given gene
to bosst her immune system.
cellular defect of cystic fibrosis by adding normal protein.