Gregor Mendel Born in 1822 in Czech Republic Priest who studied
mathematics and science at the University of Vienna Spent the next
14 years working at a monastery and teaching high school Carried
out his experiments on the side while working for the monastery.
Slide 2 Mendels ideas: Particulate inheritance: the determinants of
inherited traits are discrete units that are passed between
generations unaltered, not mixed together. Slide 3 The male gamete,
equivalent to the sperm, is the pollen grain. The female gamete,
equivalent to the egg, is the ovule. Pea plants are
self-fertilizingpollen (male sex cells) produced by one plant
fertilize eggs (female sex cells) in that same plant Several
true-breeding varieties of peas were available to him if allowed to
self- pollinate, they produced identical offspring
Cross-pollination could be controlled by cutting away male parts
and dusting flowers with pollen from other plants with a paintbrush
One disadvantage it took a year to grow each generation of plant
Slide 4 We are first going to look at what happens when plants with
different traits are crossed, then go through Mendel's explanation.
Purple flowers vs. white flowers. The original parental lines are
true-breeding, or pure- breeding. All offspring within the lines
gave the same flower color for an arbitrary number of generations.
Slide 5 Slide 6 True-breeding purple x true-breeding white. All
offspring are purple. The parent lines are the P generation; the
offspring are the F1 (first filial) generation. All the F1's are
purple regardless of which parent (father or mother) was purple and
which was white. Note: no blending occurs. The purple F1 plants
look exactly like the purple parentals. We say that purple is
dominant because it appears in the F1 hybrid. White is recessive
because it does not appear in the F1 hybrid. Slide 7 AA X aa
Homozygous alleles A X a gametes Aa first generation F1 Test for
dominant or recessive alleles at one locus Slide 8 Slide 9 Test for
dominant or recessive alleles at 2 loci AABB X aabb parents AB AB X
ab ab gametes AaBb F1 Hybrid offspring Slide 10 Slide 11 Determined
by membrane proteins in the RBC cell membrane. Called surface
antigens (agglutinogens). Most common group: ABO blood group Two
antigens: A and B ABO blood types: Type A: have the A surface
antigen Type B: have the B surface antigen Type AB: have both the A
and the B surface antigens Type O: have neither the A or the B
surface antigen. 21-11 Slide 12 12 Slide 13 Antibodies
(agglutinins) to the surface antigens are in the plasma ABO group
has anti-A antibodies and anti-B antibodies Type A: have anti-B
Type B: have anti-A Type AB: has neither anti-A or anti-B Type O:
has both anti-A and anti- B 21-13 Slide 14 An antibody interacts
with a specific antigen. The ABO blood group has both anti-A and
anti-B antibodies that react with the surface antigen A and the
surface antigen B, respectively. The antibodies in your blood
plasma do not recognize the surface antigens on your erythrocytes.
21-14 Slide 15 15 Slide 16 16 Slide 17 Rh blood type Based on
another surface antigen Called either Rh or D Rh positive (Rh + ):
has the antigen Rh negative (Rh - ): does not have the antigen
21-17 Slide 18 1-Mid-digital hair: Some people have hair on the
back of the middle segment of some fingers. Individuals with hair
on the middle segment of at least one finger are considered to have
the trait mid-digital hair (H); other people have no mid-digital
hair (N). Mid-digital hair is often used to illustrate basic
genetics; the myth is that the presence or absence of mid-digital
hair is controlled by a single gene with two alleles, and the
allele for H is dominant. Slide 19 2- Tongue rolling: Some people
can roll their tongue into a tube, and some people can't. This is
one of the most common traits that biology teachers use to
demonstrate basic genetic principles. Alfred Sturtevant (one of the
pioneers of Drosophila genetics) described tongue rolling as a
simple two-allele character, with the allele for rolling (usually
given the symbol T or R) being dominant over the allele for non-
rolling (t or r) (Sturtevant 1940).pioneers of Drosophila genetics
Slide 20 3- widow's peak Some people have a prominent V-shaped
point at the front of their hairline, called a widow's peak, while
other people have a hairline that goes straight across. Widow's
peak is sometimes used to illustrate basic genetics; the myth is
that it is controlled by one gene with two alleles, and the allele
for widow's peak is dominant over the allele for straight hairline.
Slide 21 4- Earlobe Attachment Some people have earlobes that curve
up between the lowest point of the earlobe and the point where the
ear joins the head; these are known as "free" or "unattached"
earlobes, as shown in the upper picture below. Other people have
earlobes that blend in with the side of the head, known as
"attached" or "adherent" earlobes, as shown in the lower picture.
Slide 22 5- Hitchhiker's thumb: Some people have "hitchhiker's
thumbs," which bend backwards with a large angle between the two
segments (phalanges). The myth is that there are just two kinds of
thumbs, straight thumbs (S) and hitchhiker's thumbs (H), and the
trait is controlled by a single gene with two alleles, with the
allele for S being dominant. Slide 23 6- Relative finger Length
Some people have an index finger that is longer than their ring
finger; we'll call this long index finger, or L. Others have an
index finger that is shorter than their ring finger (S). This is
said to be a sex- influenced trait. In males, the allele for S is
said to be dominant, while the allele for L is said to be dominant
in females. Thus SS and SL males will have short index fingers and
only LL males will have long index fingers, while SS females have
short index fingers and SL and LL females have long index fingers.
Slide 24 Terms used in Modern Genetics: Genes Diploid Mutation
Alleles Hybrid Heterozygous Homozygous Dominant Recessive Gene
expression Genotype phenotype
