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See all the wonderful things sangeetha vel has made

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genetics
heredity
variation
mendels laws of inheritance- law of dominance, law of segregation
contrasting characters 7 - seed colour, seed shape, flower colour, pod shape, pod colour, height and flower position
monohybrid cross- geno - 1:2:1 and pheno- 3:1
dihybrid cross
phenotype
genotype
heterozygous
homozygous
factor/gene
locus
allele
incomplete dominance
co dominance
pleotropic genes
autosomes
sex determination
xx-xo
xx-xy
zw-zz

linkage
crossing over
mutation
somatic variation
germinal variation
chromosomal aberrations

euploid:
monoploid, polyploidy,

aneuploidy:
hyperploidy, trisomic,tetrasomy, hypoploidy,monosomy,

purine- adenine and guanine
pyramidine- cytosine and thymine
transition- purine replaced by purine Vice versa
transvertion: purine replaced by pyramidine vice versa
substitution mutation
frameshift mutation
pedigree
disorders:
autosomal: sickle-cell, phenylketonuria, thalassaemia,
sex chromosome linked disorders: colour blindness, Down syndrome, klinfelters syndrome, turnsers syndrome.

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- Mendelian Genetics

- Genetics-Branch of life science dealing with the study of heredity and variation

-Heredity-transmission of characters from parents to offspring

-Variation-difference among offspring of same parents

-Hereditary variation-genetical ,inheritable

-Environmental variation-Acquired ,not inheritable

-Gregor Johann Mendel- Austrian monk, Father of genetics, Published his work in "Translation of the characters

Three scientists rediscovered his work:
-Hugo de Vries
-Carl Correns
-Erich Tschermak

Mendel used pea plants in his experiment.
Monohybrid cross ratio in F2 generation-
Genotypic ration-1:2:1,TT:Tt:tt
Phenotypic ration-3:1,Tall:Dwarf

Factor or gene:
Functional unit of heredity responsible for the expression of character in the progeny

Locus:
Position of a gene on the chromosome

Allele:
The alternative form of gene for a contrasting character.

Phenotype:
External appearance of an organism due to the influence of genes and the environment.

Genotype:
The genetic make up of an organism responsible for the phenotype.

Phenotypic ratio
Genotypic Ratio

Homozygous:
Individual having identical genes in an allelic pair for character

Heterozygous:
Having unidentical genes in an allelic pair.

Dominant gene:
Gene that expresses its character in heterozygous condition

Recessive gene:
Gene that does not express its character in heterozygous condition

Hybrid
Progeny after crossing over 2 parents of different characters

Back cross
Cross between F 1 hybrid and one of its parents

Test cross
Cross between hybrid and its homozygous recessive parent. Used to identify genotype of hybrid.

Homologous chromosome:
Pair of chromosomes having same gene sequence each derived from one parent

Autosomes
Body characters

Allosomes
Sex chromosomes

Why did Mendel select the pea plant?

Reasons for his success

1st law of Mendel
When 2 factors are brought together in a hybrid union ,one member of a pair dominates over the other in a heterozygous condition, the factor expressed is dominant while the other is recessive.

2nd law
When a pair of factors for a character are brought together in a hybrid ,they segregate during the formation of gametes.

Incomplete dominance
Inheritance in which allele for a specific character is not completely dominant over other allele.

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genetics-deals with heredity and variations
variations - degree of difference
heredity-transmission of characters
Gregor Mendel - father of genetics
Mendel's laws - law of of dominance and law of segregation
Mendel -  studied 14 traits in Pisum sativum.
reasons for pea plant -
*distinctive traits
*self-pollination =  pure breeding
*short life cycle
*easy artificial pollination=fertile hybrids
gene - unit of heredity responsible for expression of character
allele- alternative form of gene
homologous chromosomes-pair containing same gene sequence
genotype
phenotype
heterozygous gene-unidentical gene in an allelic pair (individual)
homozygous gene-identical gene in an allelic pair (individual)
dominant-gene expressed in heterozygous condition
recessive-gene suppressed in heterozygous condition
test cross - cross between hybrid and recessive parent
pleiotropy
polygenic inheritance
co-dominance-
incomplete dominance-
dihybrid cross-

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Heredity/ Inheritance
Genetics - study of heredity/ inh
Father of genetics - G. Mendel
Mendel - worked on pea plant
Re discovery - Carl Correns, Hugo DeVries, Erich Von Tschermak
7 contrasting characters of pea plant
Monohybrid cross (G - 1:2:1, P - 3:1)
Law of Dominance
Law of segregation(purity of gametes)
Basic terms like Gene, Locus, Allele, Phenotype, Genotype, Phenotypic ratio, Genotypic ratio, Homozygous, Heterozygous, Homologous chromosome, Dominant, Recessive, Hybrid, Back cross, Test cross( Mono-1:1 , Di-1:1:1:1
Reasons for selection of pea plant
Reasons for success
Dihybrid cross (G - (1:2:1:2:4:2:1:2:1, P - 9:3:3:1)

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Mendelian genetics
Hereditary
monohybrid cause
Dihybrid cross
incomplete dominance
Co- dominance
Genotype and phenotype
Pleiotropic genes
Sex determination
Crossing over
Mutations:
-Chromosomal Aberrations
-Point mutations
Pedigree chart
Mendelian disorders:
Sickle cell anemia
Phenylketorunia
Thalassaemia
Haemophilia
Down's syndrome
Klinefelter's syndrome
Turner's syndrome

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Pranaiya

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Mendelian genetics

Genetics:
-branch of life science that deals with the study of heredity and variation

Heredity:
transmission of characters from the parents to the offspring

Variation:
difference in characters among the offspring and the parent

Factor/Gene
functional unit of heredity responsible for expression of character in the progeny

Locus
position of the gene on the chromosome

Allele
alternative form of gene, for a contrasting character present on the same locus of a specific chromosome

Genotype
genetic constitution of an individual

Phenotype
characters expressed in an individual due to the genetic combination

Homozygous
condition in which an individual has identical genes in an allelic pair for a specific character

Heterozygous
condition in which an individual has unidentical (contrasting) characters

Autosomes
chromosomes that determine the normal body characters

Allosomes
chromosomes that determine the sex of the individual

Mendelian Laws:
First law:
-also called the law of dominance
-for monohybrid gametes
-"When two factors are brought together in a hybrid union, one member of a pair is expressed (dominant character) while the other is suppressed (recessive)"

Second law:
-Law of segregation / Law of purity of gametes
-"When a pair of factors for a character are brought together in a hybrid, they segregate during the formation of gametes"

Third Law:
-Law of independent assortment
-"Factors for different pair of contrasting characters in a hybrid cross are assorted independently during the formation of gametes"

Monohybrid cross:
-cross between two organisms having alleles of the same character

Back cross:
-cross between F1 hybrid and one of its parents

Test cross:
-cross between hybrid and its homozygous recessive parent
-used to identify the genotype of the hybrid

Incomplete/ partial dominance:
-the hybrid does not express wither of the parents' characters and instead expresses a new one (usually a combination of both the characters of the parents)

Pleiotropy:
-phenomenon in which one gene influences many characters
-ex: starch synthesis in pea seed, phenylketonuria

Co-dominance:
-both alleles are dominant and are expressed
-ex: blood group in humans

Polygenic inheritance:
-condition in which many genes influence one specific character
-ex: skin colour in humans

Pedigree:
visual representation of the genetic inheritance of one family

Sex determination:

XX_XO type:
-ex: grasshopper
-the females have24 chromosomes while the males have only 23
-females - (22 + XX)
-males - (22 + XO)

XX-XY type:
-ex: drosophila and mammals
-females and males have the same number of chromosomes
-females are heterozygous (AA + XX)
-males are homozygous (AA + XY)
-exception - birds (males are homozygous and females are heterozygous)

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Mendelian genetics
Hereditary variations - genetical and inheritable
Environmental variations - acquired and non - inheritable
Gene - functional unit of heredity responsible for the extension of character in progeny
Locus - position of the gene of chromosomes
Allele - alternative form of a gene for a contrasting character present on identical locus of homologous chromosomes
Phenotype - External appearance of an organism due to the influence of genes and environmental factors
Genotype - genetic constitution of an individual responsible for phenotype
Homozygous - individual having identical genes in an allelic pair for a character
Homozygous chromosome - same gene sequences, each derived from one parent
Hybrid - progeny obtained by crossing 2 parents that differ in characters
Heterozygous - individual having different genes in an allelic pair for a character
Test cross - cross b/w hybrid and its homozygous recessive parent
Back cross - cross b/w hybrid and one of its parent
Mendel's first law - "when two factors are bought together in a hybrid union, one member of pair dominates over the other in heterozygous condition, the factor expressed is dominant while other is recessive"
Mendel's second law - "when a pair of factors for a character brought together in a hybrid, the segregate during the formation of gametes"
Mendel's third law - "factors for diff. pairs of contrasting characters in a hybrid assorted independently during gamete formation"
Monohybrid cross- cross b/w 2 parents differing in one pair of contrasting character
Co-dominance - both the alleles for a character are dominant and express its full character
Pleiotropy - genetic effect of a single gene on multiple phenotypic traits
Dihybrid cross - cross b/w 2 parents, which differs in 2 pairs of contrasting character
Autosomal dominant inheritance -
trait should not skip generations
equal no.of males and females
an affected person mating with an unaffected person should produce 50% affected offspring
offspring will not be affected if heterozygous parent
Autosomal recessive inheritance - trait often skip generations
equal no.of males and females
both parents are affected, all children are affected

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Genetics - study of heredity and variation
Heredity - transmission of characters
from parents to offspring.
Variation - difference between the offspring.
Hereditary variation - inheritable, genetical
Environmental variation - acquired , not inheritable .
Gregor  Johann Mendel - Father of genetics , Austrian monk,
Mendel 's work  rediscovered by-Hugo de vries ,Carl correns, Erich Tschermak
Gene-  functional unit of heredity ,  responsible for expression of characters
Locus - position of the gene on the chromosome.
Allele - alternative form of gene, for contrasting characters present on the same locus of a  chromosome .
Phenotype - appearance of the organism  influenced by the gene .
Genotype -genetic constitution responsible for the phenotype
Homozygous -Identical gene in an allelic pair for  a character .
Heterozygous -un -identical gene in a allelic pair .
Dominant gene - expressed  character in a gene .
Recessive - gene that fails to express its character
Hybrid
Mendel selected pea plant :
-easy to cultivate
- pure varieties available
-life cycle of plants only few months
- flowers bisexual and  self pollinated
Reasons for success
1st law of mendel -
In a hybrid union  two characters  are brought together and in heterozygous condition one pair dominates while the other remains recessive
2nd law  of Mendel -
Pair of factors brought together in a hybrid  segregate during formation of gametes .
Monohybrid cross - cross between parents differing in one pair of character , inheritance of one gene.
Test cross - cross between hybrid and its homozygous recessive parent
used to identify the genotype of the hybrid
Incomplete dominance - blending of characters from both the parents forming new combination or intermediate character.
Pleiotropy- effect