Protein Synthesis

[Pages:14]Protein Synthesis

? The process of reading the instructions in the DNA to make a protein.

Central Dogma of Genetics

? DNA = instructions and is in the nucleus and can't leave

? But proteins are made in ribosomes ? So protein synthesis takes 2 steps:

DNA RNA transcription translation protein

Remember Proteins??

? Proteins are the most versatile macromolecules in living systems and serve crucial functions in essentially all biological processes such as:

- Function as catalysts - Transport and store other molecules such as oxygen - Provide mechanical support and immune protection - Generate movement - Transmit nerve impulses - Control growth and differentiation.

? #proteinsmatter

Three Essential Types of RNA

? mRNA (messenger): copies instructions in DNA and carries these to the ribosomes in the cytoplasm

? tRNA (transfer): carries amino acids to the ribosome and mRNA

? rRNA (ribosomal): composes the ribosome

TRANSCRIPTION

Purpose: Carry the code/instructions out of the nucleus

(Remember: DNA never leaves the nucleus, and proteins are made in the cytoplasm by ribosomes.)

Location: Nucleus

Starts with: DNA

Ends with: mRNA

TRANSCRIPTION

Process:

1.RNA Polymerase binds to the DNA promoter where transcription is to begin and unzips the gene that needs to be copied. (looks for "TATA box" as a signal)

2.RNA Polymerase uses complementary base-pairing rules to match RNA nucleotides with the exposed DNA nucleotides

(Remember: RNA has uracil instead of thymine, so A binds with U)

3.Release the completed mRNA molecule

4.DNA zips back up and the mRNA leave the nucleus and enters the cytoplasm

Transcription: DNA is copied into a

complementary strand of mRNA

RNA is made in the 5'-3' direction

The DNA template read in the 3'-5' direction

3'

5' 3'

5'

5'

5'

DNA

3' 5'

3'

mRNA DNA

3'

DNA mRNA

Transcription ? Try it!

? DNA sequence (template):

3' TACGCTAGTACGATT 5'

? mRNA sequence:

5' AUGCGAUCAUGCUAA 3'

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