Protein Synthesis (Gene Expression) Notes DNA RNA Protein Trait Protein Synthesis (Gene Expression) Notes Proteins (Review) Proteins make up all living materials

Proteins are composed of amino acids – there are 20 different amino acids Different proteins are made by combining these 20 amino acids in different combinations

Proteins are manufactured (made) by the ribosomes

Function of proteins: Help fight disease Build new body tissue Enzymes used for digestion and other chemical reactions are proteins (Enzymes speed up the rate of a reaction) Component of all cell membranes Answer the first 4 questions on your protein synthesis flow chart.

Genes Genes are the instruction manuals for our bodies. They are the directions for building all the proteins that make our body function. Genes are made of DNA.

Gene Expression Not all genes are active or expressed at the same time. Why: Because the cell would produce molecules it did NOT need – waste of energy and raw materials

Gene expression (protein synthesis) is when the Gene expression (protein synthesis) is when the product of a gene, or a specific protein is being produced by a cell. some genes are – rarely expressed – adrenaline some genes are – constantly expressed – hair growth, blood pressure some genes are expressed sometimes and turned off others – estrogen.

Making a Protein—Transcription First Step: Copying of genetic information from DNA to RNA called Transcription Why? DNA has the genetic code for the protein that needs to be made, but proteins are made by the ribosomes—ribosomes are outside the nucleus in the cytoplasm. DNA is too large to leave the nucleus (double stranded), but RNA can leave the nucleus (single stranded).

Nucleus

Part of DNA temporarily unzips and is used as a template to assemble complementary nucleotides into messenger RNA (mRNA).

Nucleus mRNA DNA DNA A U A T U A G C C

mRNA then goes through the pores of the nucleus with the DNA code and attaches to the ribosome.

Nucleus Original DNA mRNA Ribosome

Making a Protein—Translation Second Step: Decoding of mRNA into a protein is called Translation. Transfer RNA (tRNA) carries amino acids from the cytoplasm to the ribosome.

These amino acids come from the food we eat These amino acids come from the food we eat. Proteins we eat are broken down into individual amino acids and then simply rearranged into new proteins according to the needs and directions of our DNA.

A series of three adjacent bases in an mRNA molecule codes for a specific amino acid—called a codon. A triplet of nucleotides in tRNA that is complementary to the codon in mRNA—called an anticodon. Each tRNA codes for a different amino acid. Amino acid Anticodon

mRNA carrying the DNA instructions and tRNA carrying amino acids meet in the ribosomes.

Amino acids are joined together to make a protein. Polypeptide = Protein

CAC/CCA/UGG/UGA AUG/AAC/GAC/UAA Use one of the codon charts on the next page to find the amino acid sequence coded for by the following mRNA strands. CAC/CCA/UGG/UGA ___________/___________/___________/____________ AUG/AAC/GAC/UAA

___________/___________/___________/____________ Histidine Proline CAC/CCA/UGG/UGA ___________/___________/___________/____________ Histidine Proline Tryptophan Stop 1st Base 2nd Base 3rd Base

AUG/AAC/GAC/UAA ___________/___________/___________/____________ Methionine Asparagine Aspartic Acid Stop

Protein Synthesis

Movie about translation at bottom of webpage Movie about translation at bottom of webpage. Click on hyperlink in picture above.

VIDEO – yea…its pretty AWESOME! http://www.youtube.com/watch?v=D3fOXt4MrOM

MUTATIONS A sequence of a gene can be changed in several ways. These changes or mutations can cause no effect to the individual (They could code for the exact same protein even with the new base) OR they can cause large effects to the individual .

Point Mutation  SUBSTITUTION 3 examples of gene mutations that happen at a certain point (called point mutations): 1. __substitution___ a mutation in which 1 nucleotide is exchanged for another.

Mutation -- INSERTION 2. __insertion___ a mutation in which 1 or more _extra nucleotides is added to DNA. G C

3. __deletion___ a mutation in which 1 nucleotide Mutation - Deletion 3. __deletion___ a mutation in which 1 nucleotide is taken out or deleted. G

Gene Mutation Example Table 1: Single-Base Mutation Associated with Sickle-Cell Anemia Sequence for Wild-Type Hemoglobin ATG GTG CAC CTG ACT CCT GAG AAG TCT GCC GTT Start Val His Leu Thr Pro Glu Lys Ser Ala Sequence for Mutant (Sickle-Cell) Hemoglobin

http://learn.genetics.utah.edu/content/molecules/transcribe/ https://www.youtube.com/watch?v=h5mJbP23Buo