Characteristics/traits shared by all individuals of a species

E.g. Presence of eyes, nose, arms etc. Of humans

Characteristics/traits that are unique/distinct to an individual of a species

E.g skin color on humans

Theory of blending inheritance

Traits manifested on ofsspring are a combination of the traits of the parents

Heredity (nature) Environment (nurture)

“Which is a more important factor in how your personality develops – nature or nurture?”

What are the different factors that affect individuality?

How does heredity bring about traits in every individual?

How does environment affect an individual’s traits?

cite specific examples of each of the four types if hereditary characters

explain inheritance based on Mendelian laws

Characters that are controlled by genes

Genes

▪ factors of heredity

▪ transmitted from one generation to the next

Which do you inherit from your parents?, the genes or the characters?

Hereditary Characters

Morphological Physiological Behavioral Sexual

Morphological

Characters that refer to structure or form such as shape, length or color of body parts

E.g. fur color in cats

hitchhiker’s thumb

bent little finger

Physiological

Characters that refer to the functions of parts

e.g. lactose intolerance and diabetes mellitus

Behavioral

externally directed activities in response to stimuli

examples are instincts such as crying and thumb sucking in babies

Sexual

Characters that are associated with being male or female

E.g. moustache

Classify the following and present your answer in tabulated form:

1. Hitchhiker’s thumb 8.Internal and external genitalia2. Cleft chin 9. Spinning of spider’s web3. Bent little finger 10. Pubic hair4. Lactose intolerance 11. Diabetes mellitus5. Fur color in cats 12. Bird migration6. Widow’s peak 13. widening of hips in females7. Polydactyly 14. appearance of Adam’s apples

Morphological

Physiological

Behavioral

Sexual

Morphological Hitchhiker’s thumb, bent little finger, cleft chin, fur color in cats, widow’s peak, polydactyly

Physiological Lactose intolerance, diabetes mellitus

Behavioral Spinning of spider’s web, bird migration

Sexual Pubic hair, internal and external genitalia, widening of hips in females, appearance of Adam’s apples

CLEFT CHIN

BENT LITTLE FINGER

SPINNING OF SPIDERS WEB

Gregor Johann Mendel – Father of Classical Genetics

Austrian monk and a botanist

Joined the Augustinian Monastery of St.Thomasat Brunn, Austria

Spent 10 years in experimenting garden peas (Pisum sativum)

Another 2 years in analyzing the results

The plant has several characters that exhibit two contrasting expressions or traits.

The plant reproduces at a fast rate.

Garden peas can produce enough offspring for study purposes

Garden pea flowers are structurally adapted for self-pollination

Pollination can be controlled in this group of plants with minimum work

1. Mendel studied one character with two contrasting expressions at a time, e.g. seed color, yellow and green.

yellow-seeded plants self-pollination pure-breeding yellow-seeded plantsgreen-seeded plants self-pollination pure-breeding green-seeded plants

2. Mendel cross-pollinated the two pure-breeding plants with contrasting expressions for the same character (seed shape used in the example.)

2. The parents were referred to as the first parental (P1) generation. The offspring produced from the cross is referred to as the first filial (F1) generation.

Law of Dominance – some traits are transmitted to and manifested in offspring more often than others

Dominant traits – traits that are expressedRecessive traits – traits that are hidden or not

expressed

3. Mendel allowed the F1 plants to self-pollinate. He noted that some of the offspring expressed the recessive trait.

When the F1 plants that expressed only the domonant trait were self-pollinated, some of their offspring (f2) expressed the recessive trait.

The ratio of the plants with dominant traits to the plants with recessive traits is almost 3:1

F1 plants have “unit determiners/characters” F1 plants with yellow seed color – two unit

determiners: one for the yellow, one for the green seed color

Mendel unit determiners Walter Sutton (1902) GENES

Seed color

G – yellow

g – green

:: G and g alleles (alternative/different forms of the gene for the seed color)

:: genes appear in pairs

:: yellow-seeded plants – GG

:: green –seeded plants - gg

Phenotype – physical expression of the character

Genotype – set of genes that an organism has

Homozygous – gene pairs that are made up of identical genes

Heterozygous – gene pairs that are made up of dissimilar genes

1. AA 6. SSrr2. Rr 7. GG3. aaBB 8. LLll4. MmNN 9. CCrr5. PpQq 10. Jj