Students can go through AP Inter 2nd Year Zoology Notes 6th Lesson Genetics will help students in revising the entire concepts quickly.
AP Inter 2nd Year Zoology Notes 6th Lesson Genetics
→ Genetics is the science of heredity and hereditary variations in living organisms.-
→ Gregoij Mendel – father of genetics.
→ Genetics term coined by W.Bateson.
→ Pleiotropy – A single gene often influence the more than one phenotypic trait.
→ Allele – Alternative forms of a gene.
→ When more than two alletic forms occur at the same locus on the homologous chromosome of an organism, are called multiple alleles.
Eg.: ABO Blood grouping.
→ ABO blood group system was proposed by Karl Landsteiner.
→ A, B, AB and O types are characterized by the presence (or) absence of antigens on the plasma membrane of the RBC.
→ Persons with AB+ group blood are called universal recipients.
→ Persons with O- group blood are Called universal donors.
→ Erythroblastosis foetalis is an alloimmune condition that develops in an Rh positive foetus whose father is Rh positive and mother is Rh negative.
→ Polygenic Inheritance – cumulative effect of two (or), more genes on a single phenotypic character.
Eg : Skin colour.
→ According to chromosomal theory of sex determination, allosomes are responsible for the determination of sex.
→ The Genic balance theory of determination of sex was proposed by bridges.
→ According to genic theory sex of an individual is determined hy the ratio of number of its x-chromosomes and that of its autosomes sets.
→ Genes that are present on the X (or) Y – chromosomes are called sex-linked genes.
→ The genes located on the X-chromosome, whose alleles are absent on the Y – chromosome are called X-linked genes.
→ The genes located on the Y-chromosome, whose alleles are absent on the X- chromosome are called Y-linked genes (or) holandric genes.
→ Pedigree is a chart showing the record of inheritance of certain traits over two (or) more ancestral generations of a person in the form of a diagram of family tree.
→ A number of disorders in human beings are inheritance called Mendelian disorders.
→ Chromosomal disorders are caused by errors in the number (or) structure of chromosomes.
→ Human genome project is a mega project, coordinated by U.S. Department of Energy and the National Institute of Health.
→ Human genome consist of 3164.7 million nucleotides.
→ Human genome contains nearly 30,000 genes.
→ The average gene consist of 3000 nucleotides.
→ Less than 2% of the genome Codes for proteins.
→ DNA finger printing is a method for identifying the individuals by the particular structure of their DNA.
→ Variable number tandem repeats are useful as genetic markers.
→ DNA finger printing is used for many purposes, particularly, peternity/maternity testing and for forensil science.
→ Genetics is a branch of biology that deals with the study of heredity and variations.
→ Heredity is the study of transmission of characters from parents to offsprings.
→ Variation may be defined as the differences in characteristics shown by the individuals or a species and also by the offsprings or siblings of the same parents.
→ Gene is the inherited factor that determine the biological character of an organism.
→ A pair of contrasting characters in a Gene is called allele.
→ Genes are responsible for body structure and for various other characters.
→ ABO blood types: The blood types A, B, AB and O types are characterised by the presence or absence of ‘antigens’ on the plasma membrane of the RBCs.
→ Sex chromosomes: A pair of chromosomes called allosomes or sex chromosomes is responsible for the determination of sex. Non-sex chromosomes are called autosomes.
→ Male Heterogametic method: In this type, the female has two ‘X’ chromosomes and the male has only a single ‘X’ chromosome. This is of two types: (i) XX-XO (ii) XX-XY.
→ Female heterogametic Method: In this type, female produces two types of ova and male produces only-one type of sperms. This of two types: (i) ZO-ZZ type (ii) ZW-ZZ type. [IPE]
→ A disease caused by an autosomal primary non-disjunction is Down’s syndrome. [NEET-2017]
→ The term ‘linkage’ was coined by T.H.Morgan [NEET-2015]
→ A pleiotropic gene controls multiple traits in an individual. [NEET-2015]
→ Multiple alleles are present at the same locus of the chromosome. [NEET-2015]
→ Alleles are different molecular forms of a gene. [NEET-2015]
→ A human female with Turner’s syndrome has 45 chromosomes with XO. [NEET-2014]
→ ESTs (Expressed Sequence Tags) refers to genes expressed as RNA. [NEET-2019]
→ Variations caused by mutation as proposed by Hugo de Vries are random and directionless. [NEET-2019]
→ The genetic disorder in which an individual has an overall masculine development gynaecomastia and is sterlie is Klinefelter’s syndrome. [NEET-2019]
→ Experimental verification of the chromosomal theory of inheritance was done by Morgan. [NEET-2020]