Can You Please HELP me with these science questions!!!?

Question

What possible effects can a mutation have on an organism?

Where in a cell does protein synthesis take place?

Why are mutations that occur in an organism's body cells not passed on to its offspring?

Any help wpuld be appreciated.

Answer 1

Generally, by mutation we mean a change in the DNA sequence (structure). These events happen during DNA synthesis (S phase of the cell cycle) because the enzyme charged of making the DNA replica, i.e. the polymerase, is not always precise. If the mutation is not repaired, the gene made from the portion of mutated DNA will be mutated, and as a consequence will give a mutated RNA during transcription and a mutated protein during Protein Synthesis. Mutated proteins are often no longer functional or can drive the cell to proliferate without control - which generates a "tumour" clone.

The protein synthesis takes place in the RER, or rough endoplamstic reticulum and is "performed" by the ribosomes. A ribosome is composed of 2 subunits; these subunits bind togheter onto the mRNA (messanger RNA), are able to "read" the message that the RNA molecule is encoding and, by the use of the tRNA, link the aminoacids in the appropriate sequence to make the required protein.

Most mutations are immediately corrected by the polymerase itself which exerts "proof-reading" functions, i.e. it goes back onto the bit of DNA only just replicated and "checks" that it was correctly copied. If some mutations escape this mechanism, there are complexes in the nucleus colled mismatch repair proteins which recognize the "mismatches", chop them off and new correct DNA is synthesized. These mechanisms of defense are normally enough to repair a mutation.

It is still possible, though, that some replication errors "survive" all this and give origin to a cell with mutated proteins. Sometimes these mutations are lethal, so they can't be passed on to the daugther cells. Other times, the cell undergo a process calle "cell cycle checkpoint" which blocks it from dividing into 2 cells if there are "problems", e.g. muations.

This is why cancer is, all in all, still a rare event

Answer 2

What possible effects can a mutation have on an organism?
-Effects can be advantageous, deleterious or null. They can cause cancer or other nasty problems, they can kill the cell or the whole organism, or they could have no effect at all.

Where in a cell does protein synthesis take place?
-It occurs on the ribosome, either in the cytosol or stuck to the endoplasmic reticulum.

Why are mutations that occur in an organism's body cells not passed on to its offspring?
-The mutation would have to be in the gametes in order to be passed on. If a skin cell becomes mutated, there is no way for that information to be passed on to the offspring.

Answer 3

hearing defects, mental reardation, blindness, blood clotting..
2. ribosome
3.because they die