MENDELIAN GENETICS

THE NECESSARY VOCABULARY & OTHER FACTS

GREGOR MENDEL – THE FATHER OF GENETICS

AUSTRIAN MONK RESEARCHED HOW TRAITS ARE PASSED

FROM GENERATION TO GENERATION BY CONDUCTING EXPERIMENTS WITH PEA PLANTS

MENDEL

THE STUDY OF HEREDITY

GENETICS

Seed Shape

Flower Position

Seed CoatColor

Seed Color

Pod Color

Plant Height

PodShape

Round

Wrinkled

Round

Yellow

Green

Gray

White

Smooth

Constricted

Green

Yellow

Axial

Terminal

Tall

Short

Yellow Gray Smooth Green Axial Tall

Section 11-1

Figure 11-3 Mendel’s Seven F1 Crosses on Pea Plants

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PLANTS, THAT IF ALLOWED TO SELF-POLLINATE, WILL PRODUCE OFFSPRING IDENTICAL TO THEMSELVES.

THE BASIS OF MENDELIAN GENETICS WERE THE TRUE-BREEDING PLANTS

TRUE-BREEDING

A SPECIFIC CHARACTERISTIC EXAMPLE:

◦ SEED COLOR◦ PLANT HEIGHT

TRAIT

THE ORIGINAL PAIR OF ORGANISMS CROSSED;

PARENT GENERATION (P GENERATION)

(FIRST FILIAL) THE FIRST GENERATION THAT IS PRODUCED BY THE PARENT GENERATION

F 1 GENERATION

THE SECOND GENERATION PRODUCED BY CROSSES BETWEEN THE F 1

GENERATION

F 2 GENERATION

P Generation F1 Generation F2 Generation

Tall Short Tall TallTall Tall Tall Short

Section 11-1

Principles of Dominance

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THE CHEMICAL FACTORS THAT DETERMINE TRAITS

A REGION OF DNA THAT CONTROLS A HEREDITARY CHARACTERISTIC.

A GENE CARRIES BIOLOGICAL INFORMATION IN A FORM THAT MUST BE COPIED AND TRANSMITTED FROM EACH CELL TO ALL OF THE NEW DAUGHTER CELLS.

(MENDEL DID NOT KNOW WHAT GENES WERE – HE REFERRED TO THEM AS FACTORS)

GENES

THE DIFFERENT FORMS OF A GENE

EXAMPLE: THE GENE FOR HEIGHT HAS TWO ALLELES◦TALL ALLELE◦SHORT ALLELE

ALLELES

AN ORGANISM WITH A RECESSIVE ALLELE FOR A PARTICULAR FORM OF A TRAIT WILL HAVE THAT FORM ONLY WHEN THE DOMINANT ALLELE FOR THE TRAIT IS NOT PRESENT.

REPRESENTED BY LOWER-CASE LETTERS

EX. tt = short

RECESSIVE TRAIT

AN ORGANISM WITH A DOMINANT ALLELE FOR A PARTICULAR TRAIT WILL ALWAYS EXPRESS THAT TRAIT.

ALWAYS REPRESENTED BY CAPITAL LETTERS

EX. TT = TALL

DOMINANT TRAIT

SOME ALLELES ARE DOMINANT AND SOME ALLELES ARE RECESSIVE

PRINCIPLE OF DOMINANCE

FOR ANY PARTICULAR TRAIT, THE PAIR OF ALLELES OF EACH PARENT SEPARATE AND ONLY ONE ALLELE PASSES FROM EACH PARENT ON TO AN OFFSPRING

SEGREGATION

A DIAGRAM THAT DETERMINES THE GENE COMBINATIONS THAT CAN RESULT FROM A GENETIC CROSS.

PUNNETT SQUARES

Section 11-2

Tt X Tt Cross

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ORGANISMS THAT HAVE TWO IDENTICAL ALLELES FOR A PARTICULAR TRAIT.

HOMOZOYGOUS ORGANISMS ARE TRUE-BREEDING FOR A PARTICULAR TRAIT.

EX. TT OR tt

HOMOZYGOUS

ORGANISMS THAT HAVE TWO DIFFERENT ALLELES FOR A PARTICULAR TRAIT

HETEROZYGOUS ORGANISMS ARE HYBRID FOR A PARTICULAR TRAIT.

EX. Tt

HETEROZYGOUS

THE PHYSICAL CHARACTERISTICS OF AN ORGANISM THAT ARE EXPRESSED.

EXAMPLE:◦HEIGHT◦HAIR COLOR◦EYE COLOR◦SEED SHAPE◦SEED COLOR

PHENOTYPE

THE RATIO OF THE POSSIBLE PHENOTYPES PRODUCED FROM A CROSS;

EX: TWO TALL : TWO SHORT

PHENOTYPIC RATIO

THE GENETIC MAKEUP OF AN ORGANISM

ALL OF THE GENES THAT ARE PRESENT IN AN ORGANISM

EXAMPLE:◦TT; Tt; Rryy; RRYy;

GENOTYPE

THE RATIO OF THE POSSIBLE GENOTYPES FROM EACH CROSS;

EX: 2 TT: 1Tt: 1tt

GENOTYPIC RATIO

THE LIKELIHOOD THAT A PARTICULAR EVENT WILL OCCUR

PROBABILITIES PREDICT THE AVERAGE OUTCOME OF A LARGE NUMBER OF EVENTS.

PROBABILITY CANNOT PREDICT THE PRECISE OUTCOME OF AN INDIVIDUAL EVENT.

THE PRINCIPLE OF PROBABILITY CAN BE USED TO PREDICT THE POSSIBLE OUTCOME OF GENETIC CROSSES.

PROBABILITY

EACH TRAIT HAS ONE PAIR OF TWO CONTRASTING CHARACTERISTICS

EXAMPLE:◦ TALL AND SHORT (Tt)◦ GREEN AND YELLOW (Yy)◦ Tt x tt

MONOHYBRID CROSSES

TWO-FACTOR CROSS EACH TRAIT HAS TWO PAIR OF TWO

CONTRASTING TRAITS EXAMPLE:

◦ ROUND YELLOW PEAS (RRYY)◦ WRINKLED GREEN PEAS (rryy)◦ RRYY x rryy

DIHYBRID CROSSES

Section 11-3

Figure 11-10 Independent Assortment in Peas

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EACH PAIR OF ALLELES SEGREGATES INTO GAMETES INDEPENDENTLY OF THE PAIR OF ALLELES FOR ANY OTHER GENE

THE PRINCIPLE OF INDEPENDENT ASSORTMENT

States that diploid organisms inherit two genes per trait, and each gene segregates from the other during meiosis such that each gamete will receive only one gene per trait.

MENDELIAN THEORY OF SEGREGATION

1subscribe

concluded that

which is called the

which is called the

GregorMendel

Law ofDominance

Law ofSegregation

Peaplants

“Factors”determinetraits

Some alleles are dominant, and some alleles are recessive

Alleles are separated during gamete formation

Section 11-3

Concept Map

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experimented with