I need HELP with BIOLOGY?

Question

I need to answer these two questions:
1.) How does the structure of DNA account for the tremendous variability in all living things?
2.) The 46 human chromosomes from one human cell contain about 3 billion base pairs. Explain how this information is copied, seldom making any mistakes.
Thank You!!! you can answer just ONE or ALL

Answer 1

1. DNA is very long coded strands of genetic material. Because it is so long, there is a lot of variability within the structure. For example, if a stand of DNA was only 10 base pairs long, you could only have a few different peices of DNA. With the human gemone being 3 billion and other organisms having comparable DNA, there is a huge change for variation.
2. DNA polymerase is mostly repsonsible for replication. It 'unzips' the hydrogen bonds of DNA, replicates, and with the actions of other chemicals, rezips the old stands of DNA into 2 new strands. Because it has a correct templateand only base pairs can bond it is effective in preventing mistakes.

Answer 2

All DNA consists of a double coil called a helix, which is like taking a ladder and twisting it. When DNA is copied, it unwinds, and then it is split down the middle, along the region where bases on each side of that "ladder" pair up. The unwinding, splitting, and then the formation of new base pairs with a substance called messenger RNA all take place through various proteins and enzymes (not all enzymes are proteins, but most are). The interesting thing about DNA is that 3 base pairs form a codon (there are 4 different kinds of bases, adenosine, thymine, cytosine and guanine, and for RNA uracil in place of thymine).
This gives rise to a large number of possible codons. In fact, there are 64 different codons. See for yourself by finding out how many three-letter combinations of the letters A,T,G,C you can make:

AAA
AGG
AGC
ACC
AGT
etc

There are 64 in all because for each position there are 4 possible bases, so 4x4x4=64.

This is vital because codons code for amino acids. Amino acids are the building blocks of proteins, and we have about 20 amino acids in all. But notice we have 64 possible codons (for amino acids) and 20 or so amino acids. So we have an abundance of codons (about 40 more than we may need, 64-20). No problem however, because there is a lot of redundancy, meaning more than one codon type codes for the same amino acid.

When we transcribe DNA ("transcription"), the messenger RNA is basically a "complement" of each "parent" DNA strand. That is, since bases pair with each other in a specific fashion:
A with T
G with C
Then if you have one strand that has an "A" as the base, its complement is a "T" and vice-versa, and the one for a "G" is a "C" and vice versa. RNA is very similar to DNA, but it uses uracil in place of Thymine. Otherwise the rules for matching are the same.

Chromosomes- the places where DNA reside- have billions of different three-letter codons, and different combinations of codons make different types of amino acids and proteins. Essentially, there is almost an unlimited number and variety of combinations of codons to form what we know as a "gene", which codes for an entire protein.

For making amino acids, the process involves, as mentioned, the uncoiling of the DNA, the formation of messenger RNA (mRNA)from each parent strand (there are two). This first process is known as transcription. Then the mRNA is processed and it exits the nucleus into the cytoplasm, where it joins up with an organele called a ribosome. At the ribosome another type of RNA,called transfer RNA, brings attached amino acids that correspond to each different codon on the mRNA. Enzymes are required to help attach the correct amino acids in the sequence described by the mRNA. The process of forming a chain of amino acids is called translation.

Replication is what is known as a "semi-conservative" process because the resulting two strands (since we double the original number) contains one "old" strand and one "new" strand. In some ways, there are similarities here with the process of transcription, where we form mRNA, but instead of using an enzyme called mRNA polymerase, we have one for DNA called DNA polymerase. Like transcription, the DNA "ladder" uncoils, and we have two strands. Onto each of these strands, DNA polymerase adds the appropriate complements. The resulting two strands are identical to the parent, but notice that each has 1/2 of the ladder from the parent strand, and the other 1/2 from the new bases that were paired. DNA polymerase has an interesting feature that allows it to base pair both parent strands at the same time, so that you don't have a huge unwound coil of DNA but rather it looks kind of like unwinding a small segment of a zipper and pairing it back up as you go along.

Mistakes do happen, but the enzymes in our bodies catch mistakes almost 99.999% of the time. In many cases, an incorrect codon will simply signal the process to stop (called a nonsense mutation). Other times, however, a base pair may be substituted for another, giving instructions for an incorrect amino acid (missense mutation). Worst of all, imagine you have the sequence AATGCCT and for some reason the "G" is removed, leaving AATCCT. We may have a complete shift in the reading, giving the codons "AAT" and "CCT" instead of the original and correct "AAT" "GCC". This is known as a frameshift mutation and it can have devastating effects if the wrong aminoo acids are coded. (Many times the organism is "lucky" when one base is substituted for another and the codon codes for the same amino acid. Recall that there is a lot of redundancy and that more than one triplet codon codes for each amino acid). But most importantly, our DNA codes for enzymes whose function is to correct these mistakes, and almost always they are caught and corrected.

Answer 3

For number one, look up the mathematical calculation for permutation. Apply that to DNA.

For number 2, you are being asked to explain how RNA works.

Hey Mailboy.... Nice Avatar!

Answer 4

Biology sucks big time, I think number 1 is because it has everything the body needs and wants...at least you'll have an answer

Answer 5

poor dylan

Answer 6

I failed Biology

Answer 7

i droped biology!D