Transcript Heredity & Genetics

Heredity & Genetics
Chapter 5.1 p. 120
Gregor Mendel
The “Father of
Genetics”
An Austrian monk who
lived during the mid
1800’s. He studied
genetics using mainly
pea plants.
What is Heredity?
The passing of traits from parent to
offspring
What is a trait?

A characteristic
Genetics
The study of how
traits are inherited
through interactions
of alleles.
Why is studying
genetics important?
Allele
The different forms of a trait that a gene may
have
Each parent gives the offspring one allele for
each trait
For example, one parent may give the offspring
an allele for red hair. The other gives an allele for
brown hair.
How can we use dominant
and recessive alleles to
predict traits of offspring?
Probability and Punnett Squares!
How do you know which trait will
“win?”
Table 1 p. 122
Dominant Alleles

Dominates recessive
traits
Recessive Alleles

Only expressed if
alleles from both
parents are recessive
Genotype vs. Phenotype
Genotype


The letters that
represent dominant
and recessive alleles
Ex. Bb, bb
Phenotype


The way that the
organism looks as a
result of the genotype
Ex. Brown hair, blue
eyes
Homozygous vs. Heterozygous
Alleles
Homozygous


An organism with two
alleles that are the
same
Ex. TT, tt
Heterozygous


An organism that has
two different alleles for
a trait
Ex. Tt
Hybrids
What is a hybrid?

A cross of two or more components
Monohybrid

Crossing one trait
Dihybrid

Crossing two traits
Punnett Squares
Used to predict the traits (alleles) that will
be inherited by the next generation of
offspring
Making A Punnett Square to predict
probablity p. 125
A Punnet square can give the probability
(chance) that certain traits will appear in
the next generation.
http://www.youtube.com/watch?v=prkHKjf
UmMs
Punnett Square Practice
(Monohybrid)
Cross a male dog that is heterozygous for
black fur and a female dog that is
homozygous for blonde fur
Step 1: Assign both genotypes letters
Step 2: Set up a grid
Step 3: Determine the probability of alleles
Chapter 5: Section 2
“Genetics Since Mendel” p. 128
Incomplete Dominance
When the offspring of two homozygous
parents display a trait that is a blend of
dominate and recessive
Ex. A red and white flower = pink flower
Co - Dominance
In COdominance, the "recessive" &
"dominant" traits appear together in the
phenotype of hybrid organisms.
Polygenic Inheritance
Many alleles (not just dominate and
recessive) working together to produce a
trait
Ex. Skin color, height, eye color
Effect of Environment on Genetics
Although genes determine many of your
traits, environment plays a role in how
some of your genes are expressed or
whether they are expressed at all.
Ex. Tanning or limiting exposure to the sun
Question: What environmental factors
might affect the size of leaves on a tree?
Genetic Disorders
Recessive Genetic Disorders: Occur when
both parents are Heterozygous for the
disease, but do not have the disease.
They are called “carriers.”
Ex. Cystic Fibrosis
Genetic Disorders
Down’s Syndrome
A result from 3 copies of chromosome 21
Individuals with Down’s can exhibit
learning disabilities and have heart
problems, but can also lead “normal” lives
Different Colored Eyes
“Heterochromia”
Eye Color is polygenic
Eye color is the result of how much
pigment is made in the front part of the
eye.
The amount of pigment is controlled by
genes in special cells called melanocytes.
One way to end up with two different
colored eyes is when an eye color gene
works in one eye but not the other.
Albinism
The cause of albinism is a mutation in one of several
genes involved in the production of melanin.
A mutation may result in no melanin production at all or a
significant decline in the amount of melanin.
In most types of albinism, a person must inherit two
copies of a mutated gene — one from each parent — in
order to have albinism (recessive inheritance). If a
person has only one copy, then he or she won't have the
disorder.
Tracing Traits
Pedigree = A visual diagram that follows a trait through
generations
Used to trace disease or breeding plants & animals
Chapter 5: Section 3
“Biotechnology” p. 135
What is Biotechnology?
Hint: Use your root word skills!
Biotechnology = The application of the
principles of engineering and technology
to the life sciences; bioengineering.
Genetic Engineering
Through genetic engineering scientists
can change the arrangement of DNA that
make up a gene.
What are the benefits of genetic
engineering?
Improving crop & livestock production
Curing diseases
Gene Therapy (p. 136)
Francis Crick & James Watson
Discovered the double helix structure of
DNA in 1953
Severo Ochoa
Severo Ochoa was a
Spanish-born U.S.
scientist. In 1959, he was
awarded a Nobel Prize for
discovering an enzyme
that enables the synthesis
of RNA, enabling scientists
to recreate the cell process
which translates hereditary
genes.
Barbara McClintock
Botanist who found that some corn plant
genes appeared to move from cell to cell
during development of corn kernels. She
discovered that the genes moved on and
between chromosomes.
In 1983, when she was 81, she was
awarded a Nobel Prize for her discoveries.
This made McClintock the first American
woman to win an unshared Nobel.
An international scientific research project
that began in 1990 with a primary goal of
determining the sequence of chemical
base pairs which make up DNA, and of
identifying and mapping the approximately
20,000–25,000 genes of the genome.