1. Transcription and Translation

2. RNA: Composition and Shape
Ribose (a sugar)
Phosphate group
--N-base: Adenine(A),
Uracil(U),
Cytosine (C), and
Guanine (G)
Shape: single-stranded

3. RNA: Types
mRNA – messenger RNA carries info from DNA in the nucleus to the cytoplasm.
tRNA- transfer RNA takes info from the mRNA and binds to amino acids.
rRNA- ribosomal RNA exists where proteins are made.

5. DNA codes for DNA = REPLICATION
DNA codes for RNA = TRANSCRIPTION
RNA codes for protein = TRANSLATION

6. How do we know what to transcribe?
Promoter
Characteristic region of DNA that signals the start of a gene.
A sequence of letters that signals “gene ahead!”
Start and stop codons ( 3 consecutive nucleotides that specify a single amino acid)

7. Transcription - Step One:
RNA Polymerase unwinds and unzips the DNA double helix.

8. Transcription: Step Two:
RNA polymerase adds on free-floating nucleotides
A, G, C, U
What does each bind with?
Stops at STOP codon
Releases RNA polymerase
releases mRNA
mRNA

9. RNA Editing While still in the nucleus: a. INTRONS are cut out, and
b. EXONS are spliced together
c. before the RNA sequence is sent to the cytoplasm for translation

11. Transcription animation
Transcription animation

12. Translation The mRNA leaves the nucleus  cytoplasm
Message is read at the ribosome
1 Codon (3 letter message) is translated into 1 amino acid
tRNA molecule has one end (anticodon) that matches the mRNA . Each anticodon specifies an amino acid.
The amino acids are bonded together as peptide chains…which fold into proteins

13. The Genetic Code: 3 letters = 1 codon  1 amino acid

14. Animation of translation
Animation of translation

16. Practice with this sequence
DNA: TCGATGTTCCGCCGTACGTCGTAACCG
AGCTACAAGGCGGCATGCAGCATTGGC
Use the bottom strand as the complement to the mRNA. What’s that mean?
Hint: Look for where it starts. How do you know?
Once you’ve found the “reading frame”, write in triplets
mRNA 
Use your genetic code wheel to write the amino acid sequence. How will you know when to stop?

17. Try again without help DNA: CCGTCATGTTCGCGCTACAAATGAAATGA
GGCAGTACAAGCGCGATGTTTACTTTACT
mRNA:
Polypeptide: