RNA 13.1 p. 362-365

1.What does RNA stand for?•Ribonucleic acid (unlike DNA, which

stands for…)

2. 3 major differences between DNA and RNA•1. Sugar in RNA is ribose not deoxyribose•2. Single-stranded (vs. double-stranded)•3. Contains the nitrogenous base uracil

vs. thymine

3. Roles of DNA vs. RNA•Kind of like a construction site•DNA is the “master plan” •Used to prepare the “blueprints” which is

the RNA•DNA molecule stays safely in the cells

nucleus •RNA molecules go to proteins building

sites in the cytoplasm called the ribosome

•4.RNA controls the assembly of amino acids into proteins!

•Proteins direct/ control a lot of cellular functions…that’s one of the reasons RNA is so important!

•Each of the 3 main types of RNA has a different job when it comes to protein synthesis:

•Messenger RNA (mRNA)•Ribosomal RNA (rRNA)•Transfer RNA (tRNA)

5. mRNA•RNA that carries instructions for

polypeptide synthesis from nucleus to ribosomes in the cytoplasm!

5.rRNA•Forms an important part of both subunits

of the ribosome

5.tRNA•Carries amino acids to the ribosome and

then matches them to the coded mRNA message

RNA SynthesisHow does the cell make RNA?

Transcription•1.Most of the work of making RNA takes

place during transcription▫2. In transcription, segments of DNA serve

as templates to produce complementary RNA molecules

Where does transcription happen?•3. Prokaryotes

▫RNA synthesis+ protein synthesis in the cytoplasm

•4.Eukaryotes▫RNA synthesis is in cell’s nucleus▫Protein synthesis is in cytoplasm

5.RNA polymerase•Works much like DNA polymerase•6. RNA polymerase binds to DNA during

transcription then separates the DNA strands

•Uses one strand of DNA as a template from which to assemble nucleotides into a complementary strand of RNA

7. How does RNA know where to bind and start making RNA???•8.Promoter region of DNA that signals

RNA polymerase exactly where to begin making RNA

•*Similar signals in DNA cause transcription to stop when a new RNA molecule is completed

9-10 RNA editing•RNA needs to be edited before it can be

read!

•Introns= portions that are cut out and discarded

•Exons= left over portions that are then pushed back together to form the final mRNA strand

Watch!•Transcription!

Photo credits•http://images.tutorvista.com/cms/images/

101/rna.png•http://www.lhsc.on.ca/_images/Genetics/tr

anscription.jpg•http://upload.wikimedia.org/wikipedia/co

mmons/3/3e/Eukaryotic_Cell_%28animal%29.jpg

•http://classes.midlandstech.edu/carterp/Courses/bio101/labquiz2/prokaryote.jpg

•http://www.odec.ca/projects/2004/mcgo4s0/public_html/t3/mRNA%20to%20protein.gif