RNA, DNA, and Protein Synthesis

Deoxyribonucleic Acid (DNA)

A double stranded molecule containing genetic material that carries all the information about an organism and is passed from parent to offspring.

Nucleotides (building blocks of DNA)

LllDNA Nucleotide

1. Sugar

2. Phosphate group

3. Nitrogenous base

Nitrogen Bases

The 4 nitrogen bases in DNA are:

adenine, guanine, cytosine, andthymine.

The Structure of DNA

Rosalind FranklinUsed X-Ray crystallography to get information about the structure of DNA.

Structure of DNAUsing Rosalind Franklin’s data, two scientists:James Watson (USA)Francis Crick (GBR)Proposed that DNA was a double-helix.

Watson & Crick along with Maurice Wilkins jointly received the Nobel Prize in physiology or medicine for their work.

The Double-HelixA twisted ladder with two long chains of alternating phosphates and sugars. The nitrogen bases act as the “rungs” joining the two strands.

How long is your DNA?

Chromosome Structure:

Chromosomes are complexes of DNA wound around proteins (called histones) residing in the nucleus of the cell. Genes are sections of DNA that code for a specific protein that determines a particular characteristic.

Ribonucleic Acid (RNA)RNA is similar to DNA in that it is also a nucleic acid composed of 4 nucleotides.

Ways RNA is different from DNA:

1) RNA contains Ribose, a 5-carbon sugar (instead of deoxyribose)

2) Uracil replaces thymine

3) Single-stranded

Messenger RNA (mRNA) Copies a section

of DNA by matching bases.

Contains the instructions (recipe) for producing a specific protein.

TRANSCRIPTION The process of copying

information from a section of DNA into mRNA.

Transcription is like copying down a recipe. In this case it’s a recipe for a specific protein.

TRANSLATION Translation =

reading or “translating” the RNA code to form a chain of amino acids.

Results in protein synthesis

Occurs in the cytoplasm.

Transfer RNA (tRNA)

tRNA acts like a truck to transport an amino acid to the ribosome to make the specific protein coded by the mRNA.

A specific amino acid is attached to one end.

The Genetic Code

The genetic code is responsible for building all the proteins in the body using 20 different amino acids.

Amino acids

Protein molecule

The genetic code is the “language” that translates the sequence of nitrogen bases in DNA (mRNA) into the amino acids of a protein.

Codon = three nucleotides on DNA or mRNA One codon specifies one amino acid Some codons are redundant (code for the

same amino acid) The genetic code is universal to all

organisms

Codon: A three letter “word” (sequence of RNA nucleotides) that specifies an amino acid.

DNA: TAC CTT GTG CAT GGG ATC

mRNA AUG GAA CAC GUA CCC UAG

A.A MET G.A HIS VAL PRO STOP