Transcript TRANSCRIPTION TRANSLATION

TRANSCRIPTION
TRANSLATION
IB BIOLOGY
TOPICS 4, 5
TRANSCRIPTION OVERVIEW
1. Initiation
RNA polymeraseII
TATA box
2. Elongation
addition of RNA nucleotides
5`  3` direction
3. Termination
AAUAA
prokaryotes vs. eukaryotes
Prokaryotic Transcription
Eukaryotic Transcription
4 types of RNA
 MESSENGER (mRNA)
Single stranded
Template for aa sequencing during
translation
Codon: 3 consecutive bases coding
for a specific aa
(64 possible codons for 20 aa)
 Transfer (tRNA)
Sequence of anticodons
Link with aa and transfer them to
mRNA transcript
 Ribosomal (rRNA)
building blocks of ribosomes
 Small nuclear RNA (snRNA)
utilized in eukaryotic mRNA
processing
TRANSLATION OVERVIEW
http://www.stolaf.edu/people/giannini/biological%20anamations.html
Translation
 The process of forming peptide bonds
between amino acids in a sequence defined
by mRNA is called translation.
 Involves:
 (i) charging of the tRNA with the specific
amino acids and
 (ii) synthesis of polypeptide chain by the
ribosomes.
tRNA
Anticodon

The middle loop that
sticks out from the
opposite end of the
tRNA contains a triplet
of bases
complementary to the
bases of the
mRNA. This triplet is
referred to as an
anticodon.
Ribosomes page 63
 Ribosomes are huge nucleic acid-protein
complexes, each made of two subunits
(small and large) that come together only
during protein synthesis. Otherwise they
float separately in the cytoplasm.
The Translation Process
 Translation consists of:
– initiation
– elongation
– termination
 Ribosome moves along the mRNA towards
the 3’ end. The start codon is nearer to the
5’ end than the stop codon.
 Animations
An overview of the subject
 Transcription and Translation
 Translation; the Sequence
 http://carbon.cudenver.edu/~bstith/transla.M
OV
 Look over the gene expression in
eukaryotes page 61.
 Regulation of transcription
Animations
Lac operon The lac Operon
Tryp operon Tutorial 13.2 The tryp Operon