1. RNA and Protein Synthesis

2. The Plan…
How does DNA control cell activities if it can’t leave the nucleus?
It sends a messenger! - messenger RNA (mRNA for short)
Remember, DNA contains the code for making proteins.
DNA can’t leave the nucleus, so RNA has to help out and actually make the proteins on the ribosomes.

3. 
Ribonucleic Acid
Ribonucleic acid (RNA) - molecule that controls the production of proteins for cells.
A strand of RNA is made of repeating units (monomers) called nucleotides (like DNA)
What makes up a nucleotide?

4. RNA vs. DNA Three differences between RNA and DNA: Single-stranded
Ribose instead of Deoxyribose
Uracil instead of Thymine

5. Checkpoint: RNA vs. DNA DNA RNA  Double strand Deoxyribose
Contains Thymine
Stays in nucleus
Single Strand
Ribose
Contains Uracil
Leaves nucleus

6. Types of RNA  Messenger RNA (mRNA) Transfer RNA (tRNA)
single, uncoiled strand
serves as pattern for assembly of amino acids
Transfer RNA (tRNA)
carries amino acids to the ribosome
single stranded
Ribosomal RNA (rRNA)
globular form
makes up the structure of the ribosome

7. Transcription  Process of making mRNA from a single–strand of DNA.
The nitrogen bases in RNA always bond to their complement on the DNA strand
ADENINE binds to URACIL
GUANINE binds to CYTOSINE

8. Steps in Transcription
Steps in Transcription
The enzyme RNA polymerase “unzips” the complementary strands of DNA into two single strands.
RNA nucleotides bond to a single strand of DNA
The finished mRNA is released and the two DNA strands “re-zip”

9. Steps in Transcription
RNA
DNA
RNA polymerase
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
Transcription animation

10. mRNA Processing A U G G G C A U U A G C C U A 
Enzymes remove (cut out) introns because they interrupt the coding sequence
INTRONS INTERRUPT … INTRONS OUT !!!
Exons are left behind to be “expressed” (translated) as needed proteins

11. unit of transcription in a DNA strand
Again...
unit of transcription in a DNA strand
exon
intron
exon
intron
exon
transcription into pre-mRNA
snipped out
snipped out
mature mRNA transcript

12. Checkpoint!  Transcribe the DNA strand into RNA:
TAC TCG TCC ATA GGC ATC
AUG AGC UGG UAU CCG UAG

13. 
Protein Synthesis
Bases in mRNA code for the amino acids which will make a functioning protein.
A group of three sequential bases on an mRNA strand is a CODON.

14. Lab – Part 1 Read the introduction and highlight 5 important facts
Transcribe the two DNA sequences.
Complete the Codon activity

15. 
The Genetic Code
There are a possible 64 CODONS that code for 20 AMINO ACIDS and a START/STOP SIGNAL.
The genetic code is universal among all organisms.

16. The Genetic Code mRNA strand – G C A A C G U U G C U A C U G
Amino Acids –
Alanine -
Threonine -
Leucine -
Leucine -
Leucine -

17. 
Steps in Translation
Process of using RNA to assemble amino acids into proteins.
mRNA moves out of the nucleus and attaches to ribosome.
tRNA transports amino acids to the ribosome.

18. Steps in Translation

19. 
Steps in Translation
The anticodon on tRNA bonds to the complementary codon on mRNA.
Amino acids form peptide bonds and form a strand – a polypeptide.
The stop codon on mRNA ends the process and the new protein is released.

20. Steps in Translation
Translation animation

21. Your Turn! Be A Ribosome …
Translate your codons
into amino acids:
A U G C A U A G C C U A
Met
His
Ser
Leu
Protein Synthesis Video

22. Lab – Part 2
Now it’s your turn to be RNA!

23. Concept Mapping for RNA
Translation Anti-codon
Peptide bond Amino Acids
Uracil RNA
Challenge: mRNA -----tRNA rRNA