Question

Provide a definition of non–random mating, selection and genetic drift.

Describe at least one technique used to localize genes along the chromosomes

How can the expression of genes be monitored using a reporter gene?.

Describe both genetic and non-genetic mechanisms of sex determination.

Explain the difference between sex-linked, sex-influenced and sex-limited traits.

What is a molecular marker? How can molecular markers be used to build a genetic map?

Describe a typical DNA denaturation experiment: What is useful for?

Answer 1

A.Answ:--- )

Definition ------)

Random mating:- It is a type of mating in which coupling between reproductive mates are done randomly , no specific selection procedure follow between population to do intercourse.

Selection :- selection is a process specially in biology refers natural selection where nature select fittest individual to survive based on their useful trait and unfit are eliminated from the nature. Normally selection is a procedure to select or choose something.

Genetic drift :- genetic drift is a process which indicates the modification of allele frequency of a particular existing population over time due to various external factors and chance mutation.

B.answer:- By using insitu hybridization technique genes can be localised along with chromosome.

Steps are------ I. Target sequence is hybridised by using labelled DNA or RNA probe

Ii) antibodies are used to detect DNA or RNA probe

III) probes are used to localised the mRNA or gene of interest.

C. Answer:- expression of gene can be monitored by using reporter gene as reporter gene can induce certain expression in the gene which are easily observable, distinguishable by using a specific probe .

D. Answer:- Genetic mechanism of sex determination:- sex are determined by presence or absence of x chromosome in organism.

For example in human male sex is determined by presence of one X chromosome and Y chromosome i.e XY

In female presence of two X chromosome determine the female sex i .e XX

In XO-XX system of sex determination in grashoper, insect.

Male have only one X chromosome ie XO and female have XX chromosome.

Non genetic sex determination:- in some organism environmental factor such as temperature, light and nutrients availability etc plays role in sex determination which is considered as non genetic sex determination . For eg :- in some reptiles during fertilisation , temperature above 30 degree , egg produce all female while below 25 degree produces male .

E. Answered:- difference between sex linked , sex limited and sex influence trait is ----

In sex linked trait particular trait is linked with X chromosome or a particular gene is present in X chromosome, male are more affected one because they have only one X chromosome.eg- colourblind ness

In sex limited trait , trait are only limited to particular sex , they are confined only particular sex type not both . These are controlled by autosomal gene or sex limited gene .eg:- breast development in female.

In sex influenced trait a particular trait is influenced by sex of a person . Same trait is expressed in different way depending on the sex type of the individual..for eg:- baldness in female vs male

F. Answer:- a molecular marker is an important tool in molecular biology and biotechnology to recognise a particular sequence of DNA from a segment of unknown DNA.