BIO211 - CELLULAR AND ORGANISMAL BIOLOGY

Lecture Outline for March 9, 2005

 

Topics: Transcription

Chapter 13 sections 13.1, 13.2

Figures used in lecture: 13.1, 13.2, 13.6, 13.7, 13.9,

Additional Resources

Central Dogma includes descriptions of the 3 types of RNA

One-gene-one-polypeptide Beadle and Tatum and Neurospora

Transcription in more detail

Transcription: making an RNA copy of a DNA sequence

 

One Gene One Enzyme (Polypeptide) Hypothesis

The function of a gene is to control the production of a single, specific polypeptide.

This hypothesis is supported by the work of Beadle and Tatum on nutritional mutants of Neurospora crassa.

Define/explain: prototroph, auxotroph, mutant

You should understand and be able to explain the work of Beadle and Tatum (pages 221-222, Figure 11.5)

 

DNA, RNA, Flow of Information

Nucleic Acid

Function

Sugar

Bases

No. of strands

Stability

DNA

Info storage

deoxyribose

A, T, C, G

Double stranded

More stable

RNA

Info transfer

ribose

A, U, C, G

Single stranded

Less stable

 

Central Dogma: DNA codes for the production of RNA (transcription), RNA codes for the production of protein (translation), and proteins do not codes for the production of DNA, RNA, or protein

 

DNA gene genotype

transcription

RNA

translation

 

protein enzyme phenotype

 

 

Transcription

Define: messenger RNA (mRNA), template strand, RNA polymerase, promoter, termination signal

You should be able to

1. Explain the purpose of transcription within the framework of the Central Dogma.

2. Describe the steps of transcription including the functions of RNA polymerase.

3. Explain how the RNA polymerase "knows" what parts of the chromosome to transcribe.

 

Three kinds of RNA:

Messenger RNA (mRNA)

 

Ribosomal RNA (rRNA)

 

Transfer RNA (tRNA)

 

 

Transcription -

-

 

base-pair complimentarity:

DNA base RNA base

C G

G C

T A

A U

 

RNA polymerase -

- enzyme that synthesizes RNA from a DNA template

- new RNA is synthesized in the 5 to 3 direction

- new RNA nucleotides are added to the free 3-OH on the last sugar