Gregor Mendel ~ Father of modern genetics. Mendel was an
Austrian monk and mathematician. One of his assignments in the
monastery was to tend the garden. Pea Plants Traits
Self-pollination ~ purebred Cross-pollination ~ hybrid
Segregation The separation of alleles on different chromosomes
during meiosis. Each allele ends up in a different egg or sperm
cell. Tt TTtt Diploid mother cell Haploid daughter cells
Slide 6
Fertilization Fertilization: The union of an ovum and a sperm
cell. Zygote: The first new diploid cell of an individual made by
fertilization.
Slide 7
Mendels Laws of Heredity Law of Segregation (1 st Law) ~
Alleles for the same gene are separated during meiosis when the
chromosomes separate. Law of Independent Assortment (2 nd Law) ~
Genes on different, nonhomologous chromosomes assort independently
during meiosis. (They are shuffled like cards.) Assortment occurs
during meiosis. Principle of Dominance ~ Some traits are dominant,
and some are recessive. Dominant traits will always be expressed
when they are present.
Slide 8
Punnett Square ~ A device that is used to predict the possible
gene combinations for a trait that two parents can pass to their
offspring. Monohybrid cross ~ A cross of two parents to evaluate
what happens with one set of alleles. In other words, seeing how
one gene will be passed to offspring.
Slide 9
Purebred Parents: TT x TT P 1 Cross TT x tt F 1 Cross Tt x Tt
Phenotypic Ratios: Show the ratio of the different possible
phenotypes of offspring. Genotypic Ratios: Show the ratio of the
different possible genotypes of offspring. Probabilities: Show the
percentages of chance for each type of phenotype or genotype Tall
vs. Short Pea Plants
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Actual vs. Hypothetical A couple has a 50% chance of having a
girl every time they have a baby. They have four children, and all
are girls. What is the hypothetical number of girls and boys? What
is the actual number of girls and boys?
Slide 11
Dihybrid Cross ~ Crossing the genes for two different traits at
the same time. 9:3:3:1 ~ The phenotype ratio if both parents are
heterozygous for both traits. TtYy x TtYy
Slide 12
Build-a-Baby Eyes Cyclops dominant (E) Binocular recessive (e)
Appendages Flippers dominant (A) Legs recessive (a) Color Green
dominant (C) Blue recessive (c) Body Round dominant (B) Pear-shaped
recessive (b) Hair Curly dominant (Z) Bald recessive (z) Heads One
head dominant (H) Two heads recessive (h) Use the penny to decide
the genotype of your baby for each trait. Heads dominant, Tails
recessive. Make a text box showing the different genotypes for your
baby, then draw the baby according to what phenotypes he or she
would show.
Slide 13
Dihybrid Cross ~ Crossing the genes for two different traits at
the same time. 9:3:3:1 ~ The phenotype ratio if both parents are
heterozygous for both traits. Tall, green father: Ttyy Short,
yellow mother: ttYY
Slide 14
Linked Genes ~ Genes for different traits that are on the same
chromosome, so they are passed on to offspring together.
Slide 15
Multiple Alleles There are more than two possible genes that
can be inherited for a trait. Examples Flower color Blood type
Slide 16
Incomplete Dominance ~ Describes genes that are neither
dominant or recessive. The traits show as a mixed phenotype. r ~
red allele y ~ yellow allele w ~ white allele rr ~ red flower yy ~
yellow flower ww ~ white flower ry ~ orange flower rw ~ pink
flower
Slide 17
Co-dominance ~ Traits that have more than one dominant allele.
Some traits have more than one possible dominant or recessive gene.
For instance, blood type! Blood type is determined by proteins on
the surface of your red blood cells.proteins Type ADominant Type
BDominant Type ABCo-Dominant Type ORecessive
Slide 18
Co-dominance
Slide 19
Cows
Slide 20
Dihybrid Cross TYTytYty TYTTYYTTYyTtYy TyTTYyTTyyTtYyTtyy
tYTtYYttYYttYy tyTtyy T = tall pea plant t = short pea plant Y=
yellow pea pods y = green pea pods Fill in the missing offspring
genotypes. What is the phenotype ratio for the offspring? What must
the genotypes of the two parents be?
Slide 21
Bellwork: Do a dihybrid cross for the following, then show the
genotypic and phenotypic ratios for the offspring. Pansy color is
incompletely dominant. Broad leaves are dominant over narrow
leaves. An orange pansy with broad leaves ryBb A red pansy with
broad leaves rrBb Do a dyhbrid cross for a mother who is AB+ and
her husband who is B-. Here are their genotypes: Mother: I A I B
RrFather: I B irr What are the phenotype and genotype ratios for
their potential children?