CH 5, SEC 4 GENES, DNA, & PROTEINS

http://www.youtube.com/watch?v=suN-sV0cT6c

http://www.dnalc.org/view/15501-Translation-RNA-to-protein-3D-animation-with-basic-narration.html

The main function of genes - control production of proteins in cells

DNA contains 4 nitrogen bases- thymine - adenine- guanine - cytosine

Single gene on chromosome contains from several hundred to a million or more base pairs

Each gene is located at specific place on chromosome

*The order of the nitrogen bases creates a genetic code that is specific for what protein will be made

Proteins are long-chain molecules made of individual amino acids

A group of 3 DNA bases code for one specific amino acid

Chromosomes & DNA

How cells make proteins

- * During protein synthesis, cell uses info from gene to make a specific protein - protein synth. takes place on the ribosomes in the cytoplasm - So how does the info get from the inside of the nucleus to the cytoplasm of the cell?

- Messenger RNA makes a copy of the DNA inside the nucleus, and carries it out to the ribosome in the cytoplasm

- Transfer RNA grabs the amino acids and adds them to the growing protein on the ribosome

Translating the code1. DNA molecule unzipped, base pair of RNA strand is made CAT AAG TCT DNA

GUA UUC ACA RNA (No

Thymine)2. Messenger RNA leaves nucleus, enters cytoplasm, attaches to ribosome

3. As ribosome is reading the code from messenger RNA, transfer RNA brings in the matching amino acid and the protein is built

4. The protein chain grows as the transfer RNA brings in the amino acid. Once complete it is folded and taken where needed in the cell

Mutation (latin origin – “change”)- change in a gene or chromosome- *can cause cell to produce incorrect protein during synthesis; causing organism’s traits or phenotype to be different- if occurs in body cell, not passed on to offspring- if occurs in sex cell, can be passed to offspring

Types of Mutations- during DNA replication, base may be substituted for another, or section removed - during meiosis when chromosomes don’t separate correctly, extra segments of chromosomes in cell

Effects of Mutations - harmful; if it reduces organism’s chance for survival & reproduction- sometimes can be helpful; improve organism’s chance of survival

Would a mutation in bacteria improving it’s ability to survive & reproduce be good or bad? Why?