protein synthesis

RNA stands for

Ribonucleic acid

RNA is a ____ strand

single

Components of RNA

1. Sugar: ribose

2. Nitrogen bases: A G C U

3. phosphate

RNA carries

• a portion of genetic code

____ # nucleotides code for ____

1. 3

2. Amino acid

What are the three types of RNA

1. messenger RNA

2. ribosomal RNA

3. transport RNA

What is the central dogma?

• Process of making protein

What are the steps of making protein?

1. Transcription - transcribe using DNA to make an mRNA copy

2. Translation - Use mRNA as a template to translate into a protein

One gene code for one____

• polypeptide

• One gene - one polypeptide hypothesis

What is the Genetic Code problem?

• there are 4 nucleotides and 20 amino acids

• 1 and 2 letter codes are not enough

What did Marshall Nirenberg discover in 1961?

• 3 letter codons are most likely to occur

• all 64 codons were eventually identified

• same codons specify the same amino acids in nearly all species

What happens during transcription?

Synthesis of mRNA

1. template strand acts as template for transcription

2. RNA polymerase binds to promoter region (just before the desired starting point)

3. RNA polymerase unwinds and unzips DNA helix

4. synthesis of mRNA occurs (5’ - 3’)

5. RNA polymerase brings in complementary RNA nucleotides

6. terminator region signals the ends and RNA polymerase detaches and DNA recoils

What happens during post transcription modifications in eukaryotes

• addition of 5’ cap and poly-A (adenine) tail

Role of 5’ cap

• protect mRNA from degradation

Role of poly-Adenine tail

• promotes export of mRNA from nucleus to cytoplasm