Transcript RNA and Protein Synthesis

RNA
12.3
What is RNA?
 Macromolecule made of nucleotides from
DNA
 Used to build proteins.
RNA is different from DNA
1.
2.
3.
4.
Single stranded
Uracil replaces Thymine
Ribose instead of deoxyribose
Can leave the nucleus
3 types of RNA
1.) mRNA
 m=messenger
 Long, stringy (like a snake)
 Function - Carries the instructions from the
nucleus to the cytoplasm to initiate translation
 Codons = sequences of 3 bases
 Made during transcription
2.) tRNA
 t= transfer
 Shaped like a “hair pin” or a T
 Responsible for bringing the amino acids for
translation
 Contains “anti-codons” that match up with
mRNA temporarily
3.) rRNA
 rRNA = ribosomal
 Structurally part of the ribosome organelle
 Site of translation
 Globular shaped
 RNA is made through “Transcription”
 RNA is made in the nucleus like DNA
replication
Review the steps
 Transcription




Unzip one gene in DNA
Match up bases to one side of a gene in DNA
mRNA detaches from the DNA
mRNA moves out of the nucleus and into the
cytoplasm
Steps in transcription
 Making of RNA from DNA in the nucleus
1.
2.
3.

Initiation at the promoter site by RNA
polymerase opens up the DNA molecule
Elongation adds new RNA bases, including
Uracil, down the exposed DNA bases
Termination occurs when RNA polymerase
hits the “stop” signal and detaches the new
single strand of RNA
http://207.207.4.198/pub/flash/26/transmenu_s.swf
In RNA: A binds with U
C binds with G
DNA strand: GAG AAC TAG TAC
RNA:
CUC UUG AUC AUG
 Animation 1
 http://www.stolaf.edu/people/giannini/flasha
nimat/molgenetics/transcription.swf
 Animation 2
 http://staff.concord.org/~btinker/workbench_
web/models/eukTranscription.swf