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Biology CP-Mr.Willets
Proteins/DNA
Proteins-
1) Proteins can be structural, enzymes or other types. Each cell can make as many as 2000 different proteins. What an organism is like and how it functions depends on its cells making all the correct proteins.
2) Proteins are made by attaching amino acids together. A chain of amino acids is called a polypeptide. Polypeptides then join and twist into certain shapes to form the protein.
3) The primary structure of the protein is determined by the order of amino acids along the polypeptide chains. The secondary and tertiary structures of the protein are determined by how these chains join and twist.
4) There are about 20 different amino acids. Plants can make all of them. Animals must eat them. There are 10 amino acids you must have in your diet. These are called the essential amino acids. If you eat these, your cells can re-arrange them to make the other 10. Any protein that contains all 10 essential amino acids is called a high quality protein or a complete protein.
5) The complicated and important task of making sure the cell produces all of its proteins correctly is controlled by DNA. DNA is what chromatin is mostly made of. Chromatin threads are thin strands found in the nucleus of cells. During cell division, they thicken and are called chromosomes.
DNA- Deoxyribonucleic Acid
1) Structure discovered in 1953- Watson, Crick, Wilkins
2) DNA is a macro-molecule made of several different smaller molecules joined in a specific pattern.
These smaller molecules are: Deoxyribose sugar, phosphate, and 4 nitrogen bases: adenine, guanine, cytosine and thymine. (we will abbreviate these as A, G, C & T)
These molecules are put together in groups called nucleotides- a nucleotide consists of a sugar molecule, a phosphate and one of the 4 nitrogen bases.
Nucleotides then join to form DNA . The DNA molecule is in the shape of a twisted ladder. This shape is like a spiral staircase and is called a double helix. The sides of the "ladder" are alternating molecules of sugar and phosphate. The rungs of the ladder are pairs of nitrogen bases. (see the other sheet)
The pairs of nitrogen bases that can join are either: guanine with cytosine or adenine with thymine. These bases pair up this way because of the size of the molecules and the places that they can bond (join).
In other words, the members of a base pair are complementary
3) DNA can make exact copies of itself. This process is called replication. Without replication, reproduction could not occur.
4) DNA replicates making only one error per billion nucleotides. Special enzymes correct these errors and repair any damage done to the DNA by normal wear and tear. There is a theory that aging is a result of the DNA wearing out and not being repaired.
5) DNA molecules have thousands of nucleotides. The order of these along the molecule is different for each piece of DNA. This order of nucleotides has the chemical information about making proteins. It is called the genetic code.
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