One gene=one protein

RNA & Protein Synthesis

Genetic Code -UniversalAll living organisms have the same four

nucleotides- A, C, T, & GCentral Dogma:

Information flows from DNA RNA ProteinRNA- Ribonucleic Acid

1 single chain of nucleotidesRNA nucleotide- 3 parts

Sugar- ribosePhosphate groupNitrogen base

Adenine, Guanine, Cytosine, Uracil (instead of thymine)

3 types of RNA- mRNA; tRNA; rRNABase pairing rules: A-U

C-G

Triplet Code:There are 20 amino acids-

4 nucleotides must combine in

groups of three.64 codons- (43)

61 code for amino acids.

3 are “stop codons”There is one start

codon- AUG- methionine

mRNA codon chart

Protein Synthesis- 2 main steps:

1. Transcription- occurs in nucleusmRNA( messenger RNA) is made from

DNA.mRNA leaves the nucleus.DNA stays in the nucleus.

2. Translation- occurs at the ribosomesmRNA codons are translated into

proteins.

Overview protein synthesis steps:

Details, details, details……..Transcription-

DNA molecule separates; one chain serves as a template.

Base pair rules apply- A-U; C-GmRNA (after editing) goes to the ribosomes.

Translation-mRNA is read by the ribosome.Translation begins with the start codon- AUG rRNA (ribosomal RNA) holds the mRNA in the ribosome.tRNA (transfer RNA) brings the correct amino acid.tRNA is T shaped:

At one end- anticodon ( grouping of 3 RNA nucleotides) that matches up with the mRNA. (base pair rules)

Opposite end -correct amino acid.Each tRNA is specific for only one amino acid.

Details continued……..Amino acids combine to form a protein.The ribosome reads the mRNA code until a

“stop” codon.Then the ribosome releases the mRNA and the

protein is released.Very fast process- occurs in less than 1 minute.

3 nucleotide terms: DNA= triplet codemRNA= codontRNA= anticodon

Review: mRNA codon chart to determine the amino acids.

mRNA Codon Chart