Protein Synthesis

QUIZ1. Where does DNA synthesis occur ? (what

organelle?)2. Pick one…. What does Helicase do? Or what

does DNA polymerase do?3. What is the purpose of DNA synthesis? 4. Explain in your own words what DNA

synthesis is5. Write down this DNA’s complimentary

strand1. G A T A C A

I. RNA vs. DNA StructureRNA DNASingle strandedNucleotide monomersRibose sugarAdenineUracilGuanine Cytosine

Double strandedNucleotide monomersDeoxyribose sugarAdenineThymineCytosineGuanine

There are 3 types of RNA mRNA; tRNA; rRNA

RNAmRNA- is transcribed or re-

written in the nucleus then enters the cytoplasmWhy use RNA?

tRNA- Transfer RNA, has complimentary base pair and brings the amino acid (or mini protein) to the ribosome

rRNA- ribosomal RNA

II. TranscriptionA. The first step in creating a

polypeptide chain (a protein.)B. One gene, ( or a sequence of

DNA nucleotides), codes for ONE PROTEIN.

A. ***1 gene= one sequence of DNA= 1 protein molecule***

III. Steps of TranscriptionA. DNA strands are “unzipped” so

nucleotides are UNPAIRED.B. Free mRNA nucleotides (A, U, C, G)

are brought to the exposed DNA and paired up using the base pair rule.

C. Transcription continues until the end site called the terminator is reached.

D. The finished mRNA chain leaves the nucleus to begin its journey to the ribosome.

A. What does the ribosome do?...

RecapWe have our mRNA which is a compliment to

our DNALets say our DNA says ATGCCTAGC

Our mRNA would read ____________________

This sequence will now leave the nucleus and travel to the ribosome to make…..

IV. TranslationA. The 2nd step in creating a protein.B. Translation happens at the ribosome. Here,

the mRNA is “decoded” into amino acids.C. Each 3 nucleotides on mRNA is called a

“Codon” and was transcribed from complementary DNA “Triplets.”

D. 1 triplet = 1 Codon = 1 amino acidE. The right amino acid is brought to the

ribosome and put into the right spot using tRNA, which contains complementary anti-codons.

Let’s Practice!DNA: TAC CCG GTA TGC CAT ACT

mRNA Transcript:

Polypeptide chain:

V. Protein ProductionA. Because the DNA in the cell

determines the proteins that are made, all cells will make different proteins.

B. If a tissue is damaged, the cells around the tissue will be triggered to go through mitosis or increase protein production to repair the injury.

C. Sometimes, a cell becomes injured or mutated and it begins an overproduction of proteins or rapid uncontrolled cell division possibly leading to cancer.

http://video.pbs.org/video/1675008673/