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How Genes Work
14.1 Translation
What is translation?
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Conversion of code to polypeptide
Happens in cytoplasm
Players
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tRNA
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Anticodon
mRNA
Ribosomes
What does the ribosome do?
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Two parts to ribosome
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60S, 40S subunits (eukaryotes)
50S, 30S subunits (prokaryotes)
Polyribosomes
What are the three steps of translation?
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Initiation
Elongation
Termination
What happens in initiation?
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Small subunit attaches at start codon
First tRNA arrives at P site
Large subunit attaches
What happens in elongation?
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Second tRNA arrives at A site
P site tRNA transfers amino acids to A site
Ribosome shifts to open A site

“old” tRNA released at E site
What happens in termination?
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Ribosome reaches
stop codon
Release factor
attaches
Subunits detach
How Genes Work
14.2 Mutations
What is a mutation?
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Permanent change in DNA
sequence
Can cause cancer
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Carcinogenesis
Carcinogens vs. mutagens
Two types of mutations
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Point
Frameshift
What is a point mutation?
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Substitution of wrong nucleotide
What is a frameshift mutation?

Original:
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Point mutation:
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THE BIG FLY HAD ONE RED EYE.
THE BIT FLY HAD ONE RED EYE.
Frame shift mutation:
Addition:

Deletion:
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THE BIT GFL YHA DON ERE DEY E.
THE BIF LYH ADO NER EDE YE.
Which is more dangerous?