a

Frameshift mutation

so all right guys let's talk about

frameshift mutation so that was the

gateway of silent mutation we have

already talked about that we have talked

about silent mutation missense mutation

nonsense mutation so I will encourage

you to go back to the videos and watch

those videos because it will be helpful

for you now in this video I am going to

talk about the frame shift mutation

frame shift mutation so in the frame

shift mutation what we want to say is

again we will take the simple example of

let us say CAT stretch of CAT

nucleotides present okay so stretch of C

80 nucleotides and the C 80 nucleotide

CT is a codon you know so for

understanding frame shift mutation you

need to understand understanding of

genetic code and codon so codon means

three nucleotide sequence which acts as

a signal to add a particular

corresponding amino acid during the

protein synthesis for example during

protein synthesis what happens this is

the mRNA so mRNA contains all those say

for example you in mRNA

so all those structures here all those

nucleotides and there is an ribosome

sitting on to that and there are T RNAs

which will detect the presence of each

codon so codon means three nucleotide

for example CA you see a these are the

codon so there is a tRNA which also have

an anticodon loop exactly to bind with

CA you right so it should have you know

G you if so this tRNA with GU a can

actually pair with ca you which is in

the codon present in the mRNA so that

tRNA will go and attach there so here is

the tRNA attaching here and that tRNA is

corresponding to there is

site for amino acid binding in tRNA and

that tRNA will bind to a specific amino

acid corresponding to this CAU codon and

here the amino acid is no histidine

right so histidine corresponding to CA

you will attach with this tRNA histidine

specific tRNA because there are specific

amino acyl tRNA s present in cell so

that tyranny will bring histidine to the

place so on depending upon different

codons different T RNAs will bring

corresponding amino acids and they will

join the amino acid and produce the

proteins that is the simple way of

protein synthesis explanation now so

once we know this concept of codons for

three there will be a particular defined

tRNA with define and in acid so for C 80

all these cases we should put histidine

histidine history

so we are having a kind of track here

kind of three tracks here five amino

acid track all of them will be history

right now what happens in frameshift

mutation this each codon during the

transcription and during the translation

process the protein synthesis process

are acting as a open reading frame they

are called as open reading frame or ORF

so each one if consists of one codon and

one codon means three nucleotide

sequence which is here CA T so this open

reading frame kind of fixed for example

for normal case it is ca t CA TCA T and

each open reading frame will insert one

histidine together ultimately they will

add five histidine by translating this

DN I am translating this mRNA which is

produced okay

now during this process for example if

by any means of error during the DNA

replication or transcription they add an

extra nucleotide in somewhere here or

they delete one nucleotide

from here so let okay so now this is the

reading frame this five reading frames

are there now let us say during the

process they insert a new nucleotide

which should not be placed here but they

during the DNA replication or

transcription of mRNA they produce the

and a nucleotide there for example they

place all these reading frames firmly

but here a place one extra add a mean in

this place right so that is added here

so once this thing is added what it does

actually it increases the number of

nucleotides previously there was 15

nucleotides but now it is one extra

nucleotide which is a added now remember

the difference between this frame shift

with the Miss sense and nonsense

mutation because in those mutations we

never see any addition or deletion we've

seen the substitution for example

instead of a there is C as the T there

is G is placed but here what we see a

new nucleotide is placed so during this

part as a result of this addition of new

nucleotide arraigning here it disrupts

this open reading frame how let us look

at here so previously there are five

stretch of histidine that should be

produced but now this will stand for

histidine again next C stand for

histidine next C instead of a C 80 it

becomes a see a c 18 serum AC so reading

frame kind of change instead of C 80 it

becomes TC again completely different

instead of C 80 it is TCA again right

and then it will go on like that in the

future okay

so that thing happens so from this level

you know from the first two things

histidine and histidine are placed but

after that a C stands for adding Fionan

so they will actually TCA stands for

setting they will add setting and again

another seven

so you know in previously they should

produce five histidines and they will

produce proteins with this five is

studying chain but now they produce to

history in Syrian serene setting so

there is a remarkable different

structure of the protein will be

observed due to this frame shift

mutation so it is not one particular

change now I should compare this with

silent mutation you can see in silent or

in missiles or non sense whatever it is

there is a change in a particular

nucleotide it will change that one only

but rest of the nucleotide will remain

same but in case of silence it never

does so next why it remains the same but

in case of missense or nonsense there

will be the change in the nucleotide and

what it does it will change that

nucleotide only dag amino acid only and

rest of the amino acid frame remains the

same but in this case by adding one

nucleotide extra it will disrupt the

whole open reading frame and it it

produce a complete different type of

completely different type of proteins so

that is why frame shift mutation is much

more dangerous it can produce much more

variety of proteins inside the cell

right this thing may happen also if we

delete a nucleotide from that position

if we delete something from their

position it can also leads to the

disruption of the reading frame until

that deletion everything will be the

same but whenever it is addition or

division from the nucleotide rest of the

downstream nucleotide sequence will be

changed right so that is the frame shift

mutation so I hope you like this if you

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