DNA AND PROTEIN SYSNTHESIS

DNA AND PROTEIN SYSNTHESIS

DNA AND PROTEIN SYSNTHESIS DNA PROTEIN

What structures are found in the nucleus?

What is a gene? Gene: a portion of DNA that contains the codes (instructions) for one protein.

A gene is a sequence of nucleotides that has the code (instructions) for making a specific protein The average gene is 3000 bases Total number of genes is 30,000 to 35,000 GENE

Protein Synthesis The building of proteins from amino acids

Why are proteins important? Make up important structures like muscles and cell membranes. Substances like enzymes, antibodies and hormones are made of proteins Traits like hair and eye color are the results of proteins

RIBOSOME

Where is DNA? ribosome

AMINO ACIDS Proteins are long chains of amino acids There are 20 different amino acids

Where are proteins synthesized (made)? By the ribosomes In the cytoplasm.

CODON Codon a set of three nitrogenous bases that represents an amino acid Codon

The instructions for making proteins (the order of the amino acids in a particular protein) are encoded in the DNA (the code)

The bases are arranged in threes called codons. A G G - C T C - A A G - T C C - T A G T C C - G A G - T T C - A G G - A T C

Protein Synthesis takes place in 2 stages transcription translation

RNA Ribonucleic acid RNA is similar to DNA but is single stranded RNA contains the sugar ribose (not deoxyribose) The nitrogen base uracil replaces thymine RNA

Messenger RNA (mrna) Is formed in the nucleus Three Types of RNA Carries the instructions from the DNA in the nucleus to the ribosomes in the cytoplasm The Messenger

CODON Order of nitrogen bases in mrna that determines the type and order of amino acids in a protein mrna has the CODON!

There are 64 possible codons, but only 20 amino acids to code for

Transfer RNA (trna) Carries amino acids from the cytoplasm to the ribosome. Has the anticodon TRANSFER RNA The Worker

RIBOSOMAL RNA (rrna) The ribosome is made of rrna.

During the production of proteins the blueprints (instructions) are located in the nucleus, in a code in the DNA DNA acts as a template for making messenger RNA Transcription

Complementary base pairing DNA Base G C A T Complementary RNA Base C G U A

mrna picks up the triplet code from the DNA m RNA leaves the nucleus. Transcription

The instructions (codon) are then carried to the cytoplasm A ribosome attaches to the mrna. The instructions carried by the mrna will be used to assemble the amino acids in the proper order

Translation The amino acids are brought to the ribosomes by the trna molecules to be assembled into a protein (translation) The order of the amino acids is determined by the codon on the mrna

The trna anticodon pairs with the mrna codon The trna releases the amino acid which bonds to the other AA s forming a chain = protein Protein Synthesis

http://www.learnerstv.com/animation/biology /Proteinsynthesis.swf Go to the website above and view the animation.

MUTATIONS

Mutations If DNA is not copied exactly, proteins made from its instructions could be made INCORRECTLY Mutation: any permanent change in the DNA sequence in a gene or chromosome. Factors that cause mutations: X rays, sunlight, and some chemicals

Results of a Mutation Genes control the traits you inherit. Without correctly coded proteins, an organism can t grow, repair, or maintain itself. A change in a gene or chromosome can change the traits of an organism.

Results of a Mutation If the mutation occurs in a body cell, it might not be life threatening to the organism. If a mutation occurs in a sex cell, then all the cells that are formed from that sex cell will have that mutation.

Results of a Mutation Many mutations are harmful to organisms, often causing their death. Some mutations do not have any effect on the organism. Some mutations can be helpful and give the organism a better chance of surviving.

DNA and Mutations Lets looks at different mutations THE DOG BIT THE CAT

Mutations - Substitution THE DOG BIT THE CAT Substitution - Replace just one letter: THE DOG BIT THE CAR

Deletion THE DOG BIT THE CAT Deletion: Delete just one letter (T): THE DOG BIT HEC AT

Insertions THE DOG BIT THE CAT Insertion - Add just one letter (E): THE DOE GBI TTH ECA T Cells have proof reading proteins that constantly check the DNA and fix errors, so most are corrected