Transcript Genetics and Heredity

Genetics and Heredity
Chapter 11 Section 1
p. 300-306
A. Heredity
• The passing of traits from parent to offspring.
A. Heredity
• 1. Genes on
chromosomes control
the traits that show up
in an organism
A. Heredity
• 1. Genes on
chromosomes control
the traits that show up
in an organism
• 2. The different forms
of a trait that a gene
may have are alleles
A. Heredity
• 3. During Meiosis a
pair of chromosomes
separates and the
alleles move into
separate cells
A. Heredity
• 3. During Meiosis a
pair of chromosomes
separates and the
alleles move into
separate cells
• 4. Each chromosome
now contains one gene
for each trait.
A. Heredity
• 5. The study of how
traits are inherited
is genetics
B. Gregor Mendel
• Known as the father
of genetics
– Austrian monk
– Studied mathematics and
science
– Began experimenting
with garden peas in 1856
B. Gregor Mendel
• 1. Mendel was the first
to use the mathematics
of probability to
explain heredity and to
trace one trait for
several generations
B2 Hybrid
• Receives different
genetic information
for a trait from each
parent
B2 Hybrid
• Receives different
genetic information
for a trait from each
parent
– a. Dominant allelecovers up or dominates
the other trait
B2 Hybrid
• Receives different
genetic information
for a trait from each
parent
– a. Dominant allelecovers up or dominates
the other trait
– b. Recessive alleletrait that seems to
disappear
B3 Probability
• 3. Probability helps
you predict that
chance that something
will happen
B4 Punnett Square
• 4. A Punnett square
can help you predict
what an offspring will
look like
B4 Punnett Square
• 4. A Punnett square
can help you predict
what an offspring will
look like
– a. Uppercase letters
stand for dominant
alleles
B4 Punnett Square
• 4. A Punnett square
can help you predict
what an offspring will
look like
– a. Uppercase letters
stand for dominant
alleles
– b. Lowercase letters
stand for recessive
alleles
B5 Genotype
• Genotype is the genetic makeup of an
organism
B5 Genotype
• Genotype is the genetic makeup
of an organism
• a. Homozygous- an organism
with two alleles for one trait that
are the same (Ex. Written TT, or
tt) – (Mendel would have called it
purebred)
B5 Genotype
• Genotype is the genetic makeup of an
organism
• a. Homozygous- an organism with two
alleles for one trait that are the same (Ex.
Written TT, or tt) – Mendel would have
called it purebred
• b. Heterozygous- an organism with
two alleles for one trait that are different
(ex. Written Tt) – Mendel would have
called it hybrid
B5 Genotype
• Genotype is the genetic makeup of an
organism
B6 Phenotype
• Phenotype – the way an organism looks
or behaves as a result of its genotype.
Punnett Practice
• This animated punnett square shows a cross
between a homozygous brown eyed father (BB)
and a homozygous blue-eyed mother (bb)
All of the children
will be heterozygous
for Brown eyes (Bb)
Punnett Practice
The orange bird has two dominant A
genes.
• We put two A s along the top of the
square.
The blue bird has two recessive a genes.
•
We put two a s down along the left
side of the square.
All the offspring have the genes Aa.
They will all have orange feathers, but will carry a recessive gene for blue
feathers.
This is called the F1 generation
Punnett Practice
Now suppose that two individuals from the F1 generation
become parents.
•
Here they are!
The baby birds are called the F2 generation.
•
You can see how their genes work out.-- The
offspring are coded in the squares.
• One bird will be orange with two AA genes.
• Two birds will be orange with genes coded Aa.
• One bird will be blue and will have two
recessive aa genes.
Individual nests of birds may not turn out exactly like this, but if there are
many baby birds, they will work out genetically with the ratios 1:2:1.