1. Biology Week 18
Mendel, Heredity, and Genetics
Chapter 10.1 Pg. 253
Explain why
• some brown eyed
parents may have blue
eyed children, while
• other brown eyed
parents cannot
Gregor Mendel
(1822-1884)
The Father of Genetics

2. Eye color is a trait –
a characteristic
Different forms of the same
that can be trait (gene) are called alleles.
What are two alleles for eye color?
inherited
 Traits are coded for by
sections of DNA called
genes
which make up
chromosomes in the nucleus

3. Heredity Genetics
 The passing on of
 the branch of
characteristics from
parents to offspring biology that
studies heredity
Write observations for each generation.

4. Trait
 Characteristics that are inherited

5. Gamete
A male or female sex cell,
has 1 set of chromosomes,
half of the amount of a normal body cell
A human male A human female A human body
gamete has + gamete has = cell has
1 set of 1 set of 2 sets of
23 chromosomes 23 chromosomes 23 chromosomes
for a total of 46 chromosomes

6. Fertilization
 When the male gamete unites with the
female gamete
The first cell is called a
zygote

7. Zygote
 The cell which results from the fusing of
male and female gametes, which will
develop into a seed Female gamete
Male gamete

8. Pollination
 The transfer of
pollen grains in a
plant from a male
reproductive organ
to a female
reproductive organ

9. Hybrid
 The offspring of parents that have
different forms of a trait, such as yellow
or green – which below is a hybrid?

10. Allele
 Different gene forms,
ex. for eye color B (brown) or b (blue)

11. Dominant Recessive
 Traits that  traits that don’t always
appear, can be masked
always appear, by dominant alleles,
CAPITAL LETTER  lower case

13. Human Traits: autosomal
 1. Shape of face (probably polygenic) Oval dominant, square recessive
 2. Cleft in chin No cleft dominant, cleft recessive
 3. Hair curl (probably polygenic)
Assume incomplete dominance
Curly: homozygous
Wavy: heterozygous
Straight: homozygous
 4. Hairline Widow peak dominant, straight hairline recessive
 5. Eyebrow size Broad dominant, slender recessive
 6. Eyebrow shape Separated dominant, joined recessive
 7. Eyelash length Long dominant, short recessive
 8. Dimples Dimples dominant, no dimples recessive
 9. Earlobes Free lobe dominant, attached recessive
 10. Eye shape Almond dominant, round recessive
 11. Freckles Freckles dominant, no freckles recessive
 12. Tongue rolling Roller dominant, nonroller recessive
 13. Tongue folding Inability dominant, ability recessive
 14. Finger mid-digital hair Hair dominant, no hair recessive
 15. Hitch-hiker's thumb Straight thumb dominant, hitch-hiker thumb recessive
 16. Bent little finger Bent dominant, straight recessive
 17. Interlaced fingers Left thumb over right dominant, right over left recessive
 18. Hair on back of hand Hair dominant, no hair recessive
 19. Tendons of Palmar MuscleTwo tendons dominant, three tendons recessive

14. Law of Segregation
 States that every individual has two
alleles of each gene (ex. TT, Tt, or tt) and
when gametes are produced, each gamete
receives one of these alleles

15. Phenotype Genotype
 The way an  The alleles that
organism looks and an organism has
behaves

16. Homozygous
 An organism that has the same two alleles
for a trait, like TT or tt

17. Heterozygous
 An organism that has different alleles for
a trait, like Tt

18. Law of Independent Assortment
 States that
genes for
different traits
are inherited
independently
of each other

19. Punnett Square
 Predicts the proportion of genotypes in
the offspring produced by a cross
Aa aa
Aa aa

20. Monohybrid
Dihybrid Cross
Cross
 (mono-, "one, single"):  (di-, "two"): a cross
a cross involving one involving two
set of alleles, different alleles
 ex. Aa x Aa RrYy x RrYy

21. Mahalo!