Questions - Molecular Basis of Inheritance Video Lecture - NEET

hello friends this video on molecular
basis of inheritance part 38 is brought
to you by exam fear calm no more fear
from exam so with this we have reached
towards the end of this lesson so let us
look at some of the questions just to
check if we got the lesson right
question number one group the following
as nitrogenous bases and nucleosides now
I hope you all remember what a
nitrogenous bases there are just four
nitrogenous bases which exist adenine
thymine guanine and cytosine and add in
in case of RNA there is a uracil so here
you see uracil is a nitrogenous base
thymine is a nitrogenous base adenine is
a nitrogenous base sign Tosun is again a
nitrogenous base so these are the bases
now what about nucleoside the first of
all what is a nucleoside you remember is
going to do that if when you compare the
structure of a nucleotide if it has
three components that is the pentose
sugar the phosphate group and the
nitrogenous base so when the base and
the sugar combines so base and sugar
combine together to form nucleoside and
when the phosphate group combines with
the nucleoside then it forms the
nucleotide so in this case which are the
nucleoside that means a combination of
base and sugar so here you can see site
18 so it is basically a combination of
the cytosine and the pentose sugar so
this is a knife this is a nucleoside so
this is nucleoside geuvânio sin this is
again a combination of guanine and the
pentose sugar so this is also a
nucleoside question number two if a
double-stranded DNA has 20% of cytosin
calculate the percentage of adenine in
the DNA now in DNA there
is the total of four bases that is a T C
and G right now a entity always pair up
with each other and CNG always pair up
with each other so this means that a and
T are present in equal amounts because
every time you have an A you will also
have a team because they pair up only
with each other
similarly every time you have a T there
will be an a that means a and T has to
be present in equal amounts so with any
C and D G also has to be present in
equal amounts now here in this question
we two stole that the cytosin is present
20% so if cytosin is 20% what would be
gladden when it will also be 20% so that
means together cytosine and guanine has
covered 40% so how much is left so left
out is the remaining 60%
so this 60% will get divided among the
remaining two and the remaining two are
adenine and kyuman so what would be
added and shared so I didn't share would
be 30% so therefore the percentage of
adenine present in DNA would be 30% if
the sequence of one strand of DNA is
written as 5 prime to 3 prime and the
sequence which you can see here write
down the sequence of complementary
strand in the five prime three prime
direction okay so now this is the strand
this is one strand of DNA so if this is
one strand of DNA so this strand is
running from 5 prime to 3 prime the
other one will be running from 3 prime
to 5 prime because the two strands of
DNA are and be parallel to each other
so in keep this trend so if you see this
trend will have the sequence T a now as
we know a will always pair up with T and
T will always pair up with a similarly C
will always pair of
G&G will pair up with C so whenever you
have a it will pair up with TT will pair
up with a G will pair up with C C with G
a mix DT with a G with C C with G again
T a see gta2 G T a and so on so this is
how you will have the entire sequence so
now the question says you have to write
down so this is going to be the
complementary strand so the
complementary strand will learn
antiparallel that is from three prime to
five friend but the question asks to
write down the sequence of the ante of
the complementary strand running in five
prime to three prime so if you have to
write down the sequence running from
five prime to three prime how will you
write it you write it just the opposite
way right that means just the opposite
of this not the complementary because
this is going to be the complementary
stand so when you want to write down the
sequence from 5 prime to 3 Prime Evils I
write it in the reverse way that's all
so here you can see this ad GC is
actually repeating itself so they are
also ta GC is repeating itself
e in GC is getting they repeat it right
so if you want to write it in the way
that it is running from 5 prime to 3
Prime how will it be it will be like
this GC 80 again GC 80 again GC 18 and
so on so this is how the complementary
strand sequence will be if you want to
write down the sequence from 5 prime to
3 prime direction so I hope you
understood it the two strands of DNA so
if this strand runs from 5 prime to 3
prime then this strand will run from 3
prime to 5
but in this question the sequence for
this strand is given you have to find
out the sequence of this strand so this
is the sequence of this strand running
from 3 prime to 5 prime so we are
basically writing the sequence like this
but the question is telling give me the
sequence in this direction 5 prime to 3
prime so we have to just reverse the
direction that's on question number 4 if
the sequence of the coding strand in a
transcription unit is written as follows
write down the sequence of mRNA now we
always already know that the DNA will
have 2 strands template strand and
coding strand so the mRNA will be
synthesized based on the template strand
so the mRNA will be complementary to the
template strand and this will be
identical to the coding step so it will
be same as the sequence of coding strand
the only difference will be that the T's
on the coding strand will be replaced
with you in case of mRNA so therefore
the sequence of mRNA would be 5 prime a
u GC
a u GC a u GC and so on till 3 prime so
it will actually remain the same as of
this coding standards that T will get
replaced with a you will get replaced
with you question number 5 depending
upon the chemical nature of the template
of DNA or RNA and the nature of nucleic
acids synthesized from it list the types
of nucleic acid polymer raises now we
have seen that there are two important
types of polymer raises which play a
very important role in the process of
replication and transcription and they
are DNA polymerase and RNA polymerase so
what do DNA polymerase do will
synthesize a new strand of DNA from DNA
template so basically DNA polymer is
play an important role during the
process of D
replication or in a similar way there is
anime polymerase which synthesize a new
strand of RNA from a DNA template strand
so it helps in the process of
transcription now the way both of these
polymerase enzymes work is almost like
their basic concept is the same their
job is to keep on adding free
nucleotides to the three prime hydroxyl
end so they need a free three prime
hydroxyl end and then on that end they
will keep on adding more and more free
nucleotides and that is how they will
allow the polymerization of the
nucleotides to happen question number
six list two essential rules of angles
on during translation ribosomes are the
cell organelles which are popularly
known for known as the site for protein
synthesis so they are the location where
protein synthesis take place so if you
look at this picture which it describes
the entire process of protein synthesis
you see that this is the smaller unit of
ribosome and this is the larger unit of
the ribosome
so if you see the smaller unit of
ribosome helps the mRNA to bind so the
mRNA will bind with the smaller unit and
the larger unit actually helps in the
formation of the polypeptide chain
so polypeptide chain which the where the
amino acids are being carried by the
tRNA so all these things take place in
the larger subunit so that Aiko's owns
is that area where protein synthesis
take place so that is the most important
function of ribosome other than this
also they play a very important role
during the peptide bond formation
between the amino acid so as I was
telling just now that in the larger
subunit when the amino acids are being
carried by the transfer RNAs a peptide
bond formation takes place between them
so they are also ribosome play a very
important role question number seven
explained in one or two lines the
function of the following promoter tRNA
and exons so if you talk about promoter
it is that area of the DNA subscription
unit which initiate the process of trans
how it initiates by allowing RNA
polymerase to brag bind to this portion
so that this promoter plays a very
important role in the process of
transcription tRNA that is transfer RNA
they carry amino acids that is extremely
important for the process of translation
because based on the sequence of mRNA
the amino acids needs to be need to be
sequenced now who does that that is done
by the adapter molecule that is tr in it
so tRNA has this unique property that on
one end it can read the mRNA sequence
and on the other end it can bind to an
amino acid so it makes sure that the
correct amino acid is being bound to the
corresponding mRNA sequence so it helps
in sequencing the amino acids based on
the sequence on the mRNA and that is how
the polypeptide or protein synthesis
happens exons are those regions of the
DNA which actually code for proteins as
I have already mentioned that there are
two parts of DNA's on and introns
introns are like interference between
exons so they do not allow to code for
proteins but exons actually code for
proteins and thus they are extremely
important so with this we have reached
towards the end of this lesson and this
lesson was extremely important important
in terms of understanding the concept of
replication and transcription and
translation so please go through the
lesson well and that I hope this would
have helped you see you all in the next
lesson thank you please visit
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