FUNDAMENTALS OF BIOLOGY - LECTURE OUTLINES - CHAPTER 14 - FROM DNA TO PROTEINS

One gene - one polypeptide

All DNA is composed of the same 4 bases

Gene = linear stretch

Genes ---> Proteins

1. Transcription

 

2. Translation

RNA

- single-stranded

- ribose

- bases

3 Kinds of RNA

Messenger RNA

Ribosomal RNA

Transfer RNA

Transcription is like replication in that:

Transcription differs from replication in that:

- only one region

- RNA polymerase

- RNA single

- Uracil

TRANSCRIPTION

- produces

- begins when

mRNA

- newly formed mRNA is unfinished

1. 5 prime

2. poly-A tail

3. introns (non-coding sequences)

 

What is the Genetic Code?

- both DNA and RNA transcript are

- every 3 bases specifies

- complete set of triplets =

 

- Codon =

- 61 triplets

- 3 "stop"

- 1 "start"

Roles of tRNA and rRNA

- each tRNA has anticodon

 

- each tRNA also carries a specific amino acid

 

- rRNA combines with proteins to form

- mRNA arrives in cytoplasm

- anticodon on tRNA

- correct amino acid

- First two bases of anticodon must pair with codon

Translation

- occurs in

1. Initiation

- initiator tRNA

- AUG

 

2. Elongation

- start codon on mRNA defines reading frame

- series of tRNA's deliver

- codons match

- enzymes help form

- tRNA's released

 

3. Termination

- stop codon

- there is no tRNA

- release factors

- enzymes detach

 

 

Three steps repeated

Polysome =

Gene Mutations

- change in one or several

- happens every 1 in

- bases (A,T,C,G)

- may be corrected

 

- chance events

Spontaneous mutations

Frameshift mutations

Review

Review questions 1-8

Self quiz 1-7

Critical thinking 1