DNA, RNA and Protein Synthesis Chapter 11

DNA Structure DNA is a chain of Nucleotides 3 parts of a Nucleotide: sugar (deoxyribose) Phosphate nitrogen base - 4 possible bases: Adenine Guanine Thymine Cytosine

DNA Structure (continued) The DOUBLE HELIX Double Stranded– 2 sugar/ phosphate backbones rungs = nitrogen base pairs Base-pairing rules A-T C-G The number and sequence of the nitrogen bases determines the CODE of the genes in the DNA!

DNA Replication DNA making copies of itself is called replication DNA replication is controlled by enzymes. 2 of the main enzymes are: Helicase: untwists the DNA DNA polymerase: adds new nucleotides and connects them

RNA Structure of RNA nucleotide sugar= ribose phosphate nitrogen base (instead of thymine, RNA has Uracil). Uracil is complementary to Adenine (it replaces Thymine) Single stranded

RNA Function of RNA accomplish protein synthesis Why?--DNA is trapped in the nucleus but protein synthesis happens at ribosomes located in cytoplasm SO… Messenger RNA (mRNA) is used to take the message from DNA to the ribosome Ribosomal RNA (rRNA) attaches to mRNA and helps assemble proteins Transfer RNA (tRNA) transfers (brings) amino acids to mRNA so that they can be attached to make a protein

Protein Synthesis 11.2 From DNA to PROTEIN I. The Purpose of DNA: DNA is used to make RNA which is used to make proteins!! (DNA--> RNA--> Proteins) A. One DNA molecule has many GENES on it! B. Gene—segment of DNA molecule that codes a specific protein.

Protein Synthesis Step 1: Transcription A. Transcription is the synthesis of mRNA using the code of a gene (DNA) as a template (pattern).

Protein Synthesis Step 2: Translation Translation (Converting the “language” of mRNA to the language of proteins.) Codon= triplet of nitrogen bases on mRNA Each codon codes for one specific amino acid Note: amino acids are the building blocks of proteins This code is universal- it applies to all organisms!

Translation continued… The order of codons determines the order of amino acids found in the protein. mRNA from nucleus is ‘read’ along its codons this occurs at the ribosome The protein is assembled cool video

Check for Understanding DNA is a chain of ________ nucleotides The three parts of a nucleotide are sugar, phosphate, nitrogen base The four possible DNA nitrogen bases are A, T, C, G What are the base paring rules? A-T, C-G

Check for Understanding