Transcript Intro to Genetics

Introductions to Genetics
Mendel and all that…
Questions for you
In your notes, answer these ?s:
• Who in your family do you
most look like?
• In what ways do you NOT
look like that person?
• Who in your family has
interests and preferences
most like yours?
Who Is This??
Mrs. Hunter’s relative….
Which
relative?
Yep, you guessed it…
It’s Mrs. Hunter’s…….
Grandmother!
I. Some terms
A. Genetics =
B. Heredity=
study of heredity
passing traits to offspring
C. Traits
1. =
characteristics that parents can pass to
offspring
2. Examples of traits:
Eye color
Hair color
Shape of eyebrows
What traits do you share?
3. What traits do share with
your
parents?
siblings?
cousins?
II. Gregor Mendel
(1822-1884)
A. Who was he?
 Austrian monk
 Studied the traits of pea
plants
 “Father” of modern
genetics
http://www.scienceshorts.com/gmendel.htm
B. Mendel’s Work
1. Background
a. In peas, ♂ & ♀ parts are in every flower
b. Pollen = plant sperm
c. Self-pollination= flower fertilizes itself
d. Cross-pollination= flower fertilized by
another
flower
http://www.sciam.com/article.cfm?articleID=F4604E0F-E7F2-99DF-30C88C9489BD83A2
1. Background
e. Peas have a lot of traits
f. Can’t study them all at once
g. Mendel studied one at a time
http://fig.cox.miami.edu/~cmallery/150/mendel/heredity.htm
2. Mendel’s Experiments
a. Mendel controlled the pea pollination
b. ¿ How did he do this?
2. Mendel’s Experiments
• Removed ♂ parts from a flower
• Dusted ♀ parts with pollen from another flower
• ¿ Was this self-pollination or cross-pollination?
cross-pollination
2. Mendel’s Experiments
c. First Mendel crossed:
purebred
purebred
white flowered plant x purple flowered plant
(P1 generation)
(P1 generation)
all offspring were purple
(F1 generation)
2. Mendel’s Experiments
d. Then, he crossed the F1 generation
with itself (self-cross)
F1
X
F1
3 offspring were purple
1 was white
(F2 generation)
2. Mendel’s Experiments
e. What happened?

Did the traits blend?

Why were all the F1
flowers purple?

Why did we get 3 purple
& 1 white in F2?
http://www.biology.iupui.edu/biocourses/N100/images/heade
rnotes.gif
2. Mendel’s Experiments
f. Vocabulary we need:

Gene = part of a chromosome
that codes for a trait
or a protein
(we have two genes for
every trait)

Allele = a form of a gene
E.g.
white or
purple flowers
http://www.healthsystem.virginia.edu/internet/huntdisease/geninfo.cfm
http://www.csulb.edu/~kmacd/361-6-Ch2.htm
Vocabulary

Dominant = if present,
is always expressed

Recessive = both recessive alleles
must be present
for expression
g. Back to Mendel
Let B = purple
 Let b = white
 P1 x P1

P1
BB
bb
F1
Bb
http://www.biology.iupui.edu/biocourses/N100/2k4ch10genetics.html
g. Back to Mendel
F1 x F1 (self-cross)
Bb x Bb
1 BB (purple)
2 Bb (purple)
1 bb (white)
3 purple
1 white
http://uz.wikipedia.org/wiki/Genetika
Questions
Which allele is dominant?
Purple flowers or white flowers?
 Did the alleles blend?
NO, flowers were either white or purple,
but not in between
 Why were all the F1 flowers purple?
purple is dominant
 Why did we get 3 purple & 1 white in F2?
purple is dominant

More Vocabulary
Homozygous =
2 of SAME alleles for
the same trait
(BB or bb)
 Heterozygous =
2 different alleles for
the same trait
(Bb)

Practice
Copy the table in the Quick Lab
on page 166 of the textbook
into your notes
 Circle your phenotype (physical appearance)
for each trait
 Count the # in class with each trait
 Write the numbers in the boxes

Questions
1.
2.
3.
4.
5.
How many cleft chins: no clefts?
How many dimples: no dimples
How many hair above knuckles : hairless
fingers?
How many freckles: no freckles?
For which phenotypes do we know the
genotype (which genes are present)?
Bibliography
Graphics
1.
2.
Mendel picture http://www.scienceshorts.com/gmendel.htm 11/3/07
Garden pea picture http://www.sciam.com/article.cfm?articleID=F4604E0F-E7F2-99DF-30C88C9489BD83A2
11/3/07
3.
4.
5.
6.
7.
Pea characters http://fig.cox.miami.edu/~cmallery/150/mendel/heredity.htm 11/3/07
F1 cross http://www.biology.iupui.edu/biocourses/N100/2k4ch10genetics.html 11/3/07
Punnett Square http://uz.wikipedia.org/wiki/Genetika 11/3/07
Alleles http://www.csulb.edu/~kmacd/361-6-Ch2.htm 11/4/07
DNA, genes, chromosomes http://www.healthsystem.virginia.edu/internet/huntdisease/geninfo.cfm 11/4/07