Gene Structure and Function 1

Gene and How They WorkChapter 15

Topics you are not responsible for:SRP-RNADetailed structure of bacterial and

eukaryotic RNA polymerases, and tRNAs, ribosomes, and spliceosomes

specific promoter sequencesAlternative splicing

End of Chapter questions: Understand: all Apply: all Synthesize: 1 - 3Do all mQuiz questions

Gene Structure and Function 2

How is genetic information used?

“Transcription” of code from DNA to RNA

“Translation” of code from RNA into A.A. sequence

Gene Structure and Function 3

How are genes arranged on DNA?

Template strand vs complementary strand

What are the functional regions of a gene?

Gene Structure and Function 4

How does RNA transcription occur?

How does RNA polymerase ‘know’ where to begin?

Promoters-- RNA polymerase binding site… and gene regulation

How does RNA polymerase ‘know’ where to end?

Gene Structure and Function 5

How does transcriptionproceed?

Binding to promoter

Opening of helix

Complementary base-pairing

Concurrent transcription

Transcription - 2Transcription

Gene Structure and Function 6

What are the functions of RNA?mRNA

tRNA

rRNA

(other types, e.g. snRNA, iRNA)

In eukaryotes,

How is mRNA modified before existing the nucleus?

Stabilizing the transcript5’ capping3’ poly-A tail

Removal of introns

Review Differencesin RNA and DNA

Structures (Chapter 3)

Gene Structure and Function 7

How are introns removed?

“RNA processing”

Introns & Exons

“snRNPs” & spliceosomes

Can be many introns

Gene Structure and Function 8

Where does translation occur?

Export to the cytosol

What is the Genetic code?

Codons specify AAs

How many codons?

How many AAs?-- Redundancy

Starting position

Ending position

Gene Structure and Function 9

Where is translation initiated and terminated?

Start Codons & Stop Codons

What is the “Reading Frame”?

Gene Structure and Function 10

What is the structureof ribosomes?

Large and small subunits

rRNA and protein constituents

tRNA binding sites

Model

Gene Structure and Function 11

What is the structure of tRNA?

Anticodons

Model

‘Charging’ of tRNAs -- aminoacyl tRNA synthestases

Translation video

Gene Structure and Function 12

What are the 3 stages of translation?

Initiation-- formyl methionine-- ‘fMet’

Elongation-- elongation factors

Termination-- release factor

Initiation

Virtual cell animation

Gene Structure and Function 13

How does the peptide pass between tRNAs during translation?

New t-RNA entersat the A-site

Peptide chain ontRNA in P-site is

passed new t-RNA

Ribosome translocates1 codon, and t-RNA

exists from E-site

Gene Structure and Function 14

What happens during translation termination stage?

Termination

Gene Structure and Function 15

What are effects of different types of mutations on gene function - I?

What is a “Missense” mutation?

What is a “Nonsense” mutation?

Gene Structure and Function 16

What are effects of different types of mutations on gene function – II ?

What causes a “Frameshift” mutation?

What is a “Silent” mutation?