Mendel's principle of inheritance

1. THE PRINCIPLE OF UNIT CHARACTER – HEREDITARY CHARACTERISTICS ARE CONTROLLED BY A PAIR FACTORS ( GENES IN PAIR)

2. THE PRINCIPLE OF DOMINANCE AND RECESSIVENESS – ONE FACTOR IN A PAIR (DOMINANT) PREVENTS THE EXPRESSION OF THE OTHER TRAIT( RECESSIVE)

3. THE PRINCIPLE OF SEGRAGATION – ONE AND ONLY ONE MEMBER OF A PAIR OF FACTORS GOES TO A GAMETE.

MENDEL’S PRINCIPLE OF INHERITANCE

A A x a a = Aa x Aa

MONOHYBRID INHERITANCE with the

use of PUNNET SQUARE – a diagram

named after REGINALD C. PUNNET w/c helps in

predicting the outcome of a given cross w/ ease.

THE PUNNET SQUARE OR CHECKER BOARD METHOD

ROUND

R R

WRINKLED

r rR r R r

R r R r

GENOTYPE 100% Rr

PHENOTYPE

100% ROUND

CHECKPOINTS: BLACK COAT COLOR IN A PIG IS DOMINANT OVER WHITE COLOR . A HOMOZYGOUS BLACK PIG IS MATED WITH A HYBRID BLACK PIG.

1. GIVE THE GENOTYPES OF THE PARENTS.

2. LIST DOWN THE PROBABLE GAMETES THAT THE TWO PARENTS WILL REPRODUCE.

3. FIND THEIR OFFSPRINGS USING A PUNNET SQUARE AND GIVE THE PHENOTYPE/ GENOTYPE.

DIHYBRID INHERITANCE:

2 traits are crossed at a time.Ex. Smooth and yellow seed is crossed with constricted and

green seeds pea plant. ( SSYY- ssyy respectively)

SS YY x ss yy ( smooth,yellow –

constricted,green) S Y s y Ss Yy (self fertilized

SsYy x SsYy

S Y S Y s y s y

S

Y

S

Y

sy

s y

ovum

sperm

Checkpoints: Complete the table below.

Phenotype =

Genotype =

CATTLEP₁ rr x ww --- rw ( roan) F₁ (red) ( white)

P₂ rw x rw --- ( red, Roan, white) F₂GUMAMELA FLOWERP₁ RR x WW --- RW ( PINK) F₁

P₂ RW x RW –---- RR, RW, WW (RED, PINK, WHITE) F₂

INCOMPLETE DOMINANCE

In a radish, long and round shapes are both dominant. Find the genotypic ratio and phenotypic ratio of the cross between ;

1. Long and round radish2. oval and long radish3. oval and round radish

ANALYZE AND SOLVE:

WHAT IS A CHROMOSOME?

A long strand of DNA (deoxyribonucleic acid).

The stuff in your body that carries information that makes you” you”.

The long strand of DNA gets coiled in your body cell that during cell division, it ends up coiling by forming 2 sisters chromatid joined together by A centromere Known as theChromosome.

The long strand of DNA in all our body cells, when unwrapped, it could make us travel3000 times from the earth to the moon.

However, only 2 to 3 % of all the DNA actually codes for the traits inside our bodies. Those important parts are the GENES.

gene

gene

GENES – a DNASegment sequencesThat code for manyDifferent traits.

junk

A DNA has a thousands of GENES.

An average gene has 10,000 to 15,000Pairs of bases.

chromosome

CENTROMERE

CHROMATID

CHROMATID

adenine

Cytosine

Guanine

Thymine

BASES OF NUCLEOTIDES (4 NITROGENOUS)

Purine group

Pyramidine group

Double helix strand DNA

TA

NUCLEOTIDE – simplest unit of DNA

Nitrogen base

sugar

sugar

Nitrogen base

phophate

phophate

During cell division, exact duplicates of the chromosomes are made so that the genetic information in the chromosomes are passed to the chromosomes of the succeeding cells.DNA REPLICATION

Provides the blueprint of all forms of life

Which is responsible in synthesizing

the complimentary strand?

RNA (RIBONUCLEIC ACID)

Gets direction in making protein from the DNA

Messenger RNA – containsthe sequence of 3 unpaired bases that compliment

those in the DNA code. Transfer RNA – moves the

codeFrom the nucleus to the

cytoplasmand attaches it to an amino acid

and combines it with another for a

certain protein depending on the GENETIC CODE.

Difference between RNA and DNAFound in the nucleus,

cytoplasm and ribosomes

Sugar component is ribose

Single strandNitrogen base-

ADENINE,GUANINE,CYTOSINE and URACIL

Involved in protein synthesis

Found in the nucleusDeoxyribose for the

sugar componentDouble – strandedBases – ADENINE,

GUANINE, CYTOSINE and THYMINE

Directs protein synthesis

Checkpoints :

Adenine

Cytosine

Guanine

Thymine

Double helix strand DNA

RNA

Nucleus, cytoplasm and

Ribosome

?Single strand?Involved in protein

synthesis

?Deoxyribose- sugar

component?Thymine – base?

DNA

NUCLEUS

RIBOSE

DOUBLE STRAND

URACIL

DIRECTS PROTEIN SYNTHESIS