A STEP INTO GENETICS

First since we are now entering the genetics lets first pay our gratitude to the father of genetics,i.e., Sir Gregor Johann Mendel. *bows* okay so let's first know a bit about the experiments of mendel which led to the discovery of a whole knew subject, genetics. Well Mendel chose Pisum Sativum (garden pea) for his experiments reason bieng :
1. They have a short life span
2. They are easy to grow.
3. Control breeding is possible
4. It shows 7 pair of contrasting character or traits. for example:
+ Tall or Short plant
+ Violet or White flowers
+Yellow or Green seed
+ Round or Wrinkled seed
Mendel first took a pure tall and pure short pea plant. now pure means it contains a pair of genes which are simlar to each other (remember XX and XY) so pure are XX(lets say). He made a cross considering a pair of contrasting characters characters. this cross is known as monohybrid cross (since mono-one and one pair of characters was considered). When he raised first generation (by making breed the pure tall and pure short) he found all of them are tall. so he made the hybrid to self pollinate and found in seconf genration that some of them are tall. Now lets learn how he made the cross.

RULES TO MAKE A CROSS

(I) The dominant trait  (i.e, Violet, Tall, Yellow, and round) are denoted by the capital alphabets such a V,T,Y and R.

(II) the recessive trait (i..e., White, Short, Green and Wrinkled) are denoted by small alphabets which are used by the dominant trait such as v,t,y and r.

A CROSS BETWEEN PURE TALL AND PURE SHORT

 PARENT                       TT (Pure tall)      X                  tt (pure                                                                                                   short)

 GAMETE                          T                      x                       t

F1 GENERATION                                    Tt    x Tt                  (self                                                                                             pollinate)

F2 GENERATION                        TT     Tt     tT       tt

(i) Dominant trait is the trait which the plant shows in first generation for example (Tt) in above example which is tall. with the presence of dominant trait in the pair that trait is shown like in (Tt) there is a recessive gene t but due to the presence of T its charachters are overshadowed. 

(ii) Recessive trait is the trait which is shown in F2 generation 

(iii) the resultant ratio of F2 generation in monohybrid cross will always be 3:1 

for example TT Tt tT ARE THREE TALL WHILE tt IS THE ONLY ONE IS SHORT 

 for a better understanding since this is the base of the genetics do the following question:

Q- Do a cross between a pure round and pure wrinkled seed? if you want to get it checked, then put your answer in the comment box below and i will be there to check it xD