1. RNA
Another Nucleic Acid

2. RNA Structure RNA is the second type of nucleic acid found in a cell.
There are 3 different types of RNA
Structure of RNA:
Long chain of nucleotides
5-carbon sugar called ribose
Phosphate
Nitrogen bases- Adenine, Guanine,
Cytosine and Uracil (instead of
Thymine)
Just a single strand

3. Function of RNA
The function of RNA is to carry the code from DNA in the nucleus to the ribosomes in the cytoplasm (where the code will be used to make proteins).

4. Quick Check Compare the details of DNA to RNA Feature DNA RNA
# of strands 2 1
Type of sugar
Deoxyribose
Ribose
Nitrogen bases
A, T, G, C
A, U, G, C
Location in cell
Nucleus
Nucleus → Ribosome in cytoplasm
Number of forms 3
Job description
Carries genetic information
Take info from DNA to the ribosomes to make proteins

5. Types of RNA
Messenger RNA (mRNA)- this is the piece of RNA that takes the code (“message”) from the DNA to the ribosome.
Transfer RNA (tRNA)- this RNA brings (“transfers”) amino acids from the cytoplasm to the ribosome/ mRNA.
Ribosomal RNA (rRNA)- this is the structural part of a ribosome (a ribosome is only protein and RNA)

6. Types of RNA

7. Transcription
Transcription is the process in which a part (gene) of the DNA is copied into mRNA.
Players
Piece of DNA
Nucleotides
Enzyme- RNA polymerase

8. Transcription What happens:
RNA polymerase finds a sequence called the promoter, binds to the DNA and unzips the strands
RNA polymerase “reads” one strand of the DNA and adds the appropriate complementary RNA nucleotides
The product= a single strand of mRNA

9. Quick Check
tRNA
1. The three types of RNA are _______ , _______ and ______ .
2. The process of making RNA from DNA is called ________________.
3. mRNA has to be made from DNA because the DNA cannot leave the _________ and the proteins coded for by the DNA are made by the ____________ which are found in the _____________.
4. If the sequence of DNA is AGTAGGTCA, what is the mRNA made from it? __________________
mRNA
rRNA
transcription
nucleus
ribosomes
cytoplasm
UCAUCCAGU

10. The Genetic Code
Proteins are continuously made by linking together amino acids.
There are 32 different amino acids.
The sequence of nitrogen bases in DNA and mRNA determine the order of amino acids in protein.
Codon= the sequence of 3 nucleotides that codes for a specific amino acid.
Anti-codon= the complementary sequence to the codon; it is found on the tRNA

11. Codon Chart

12. Quick Check
Use your amino acid chart to identify the amino acid that goes with each codon.
1. AUG ___________________
2. UGA ___________________
3. AAA ___________________
4. GAG ___________________
5. UCA ___________________
6. UCC ___________________
Methionine (start)
Stop
Lysine
Glutamate
Serine
Serine

13. Translation
The sequence of nucleotides in mRNA provides the instructions to the ribosomes for putting together a protein.
Translation- the decoding of an mRNA message into an amino acid chain (protein).
Parts involved:
mRNA
Ribosome
tRNA
Amino acids

14. Translation How it’s done:
mRNA attaches to a ribosome in the cytoplasm
The codon on the mRNA is “read” by the ribosome.
The ribosome brings in the correct anti-codon with an amino acid attached.
The anti-codon of the tRNA matches up with the codon on the mRNA.

15. Translation
The second codon is “read” and the ribosome brings in the next tRNA.
A peptide bond forms between the amino acids on the 2 tRNA’s in the ribosome.
The first tRNA loses its amino acid and it leaves the ribosome.
The ribosome slides along continuing the process until a STOP codon is reached.

16. Quick Check
Complete the remaining Quick Check in your notes. We will go over the answers in 15 minutes.