1. Chapter 13 –RNA and Protein Synthesis
Section 1 - RNA

2. RNA RNA stands for RiboNucleic Acid
RNA is a nucleic acid; therefore, made of nucleotides
RNA works with DNA to make proteins
Proteins are made through a process called protein synthesis
Review: Proteins are made of amino acids
Review: Proteins are made by ribosomes

3. Phosphate
Nitrogen Base
Guanine
Cytosine
Adenine
Thymine (only in DNA)
Uracil (only in RNA)
5 – Carbon Sugar
- Ribose (if RNA)
- Deoxyribose (if DNA)

4. Differences between RNA and DNA
Has the sugar deoxyribose
Double stranded - double helix
Has thymine
RNA
Has the sugar ribose
Single stranded
Has uracil

6. The Nucleotides of RNA

7. DNA has the 5-carbon sugar, deoxyribose.
RNA has the 5-carbon sugar, ribose.
DNA has thymine, adenine,
cytosine and guanine.
RNA has uracil, adenine, cytosine and guanine.
DNA is a double stranded molecule. It has base-pairs with hydrogen bonds between the nitrogen bases. The molecule is anti-parallel.
RNA is a single stranded molecule.

10. 3 types of RNA There are 3 major types of RNA:
Messenger RNA (mRNA) – carries the genetic code from DNA to the ribosome (site of protein synthesis)
Ribosomal RNA (rRNA) – makes the two subunits of ribosomes
Transfer RNA (tRNA) – transports amino acids (monomers of proteins) to the ribosomes

11. 3 types of RNA
Messenger RNA (mRNA) – carries code from DNA to ribosome for protein synthesis
Ribosomal RNA (rRNA) – assembles amino acids brought by tRNA in a specific order from mRNA to make proteins; made of RNA by the nucleolus
Transfer RNA (tRNA) – transports specific amino acid to ribosome for protein synthesis

13. Production of RNA RNA is made through a process called transcription
“trans” – across
“script” – to write
DNA is split and one strand forms a template
A sequence of DNA that codes for a protein is known as a gene
There are portions of DNA that do not code for protein

14. Transcription
DNA template is formed when it untwists and hydrogen bonds between nitrogen bases are broken
RNA polymerase (an enzyme) binds complementary nucleotides to the template
Places Cytosine with Guanine
Places Adenine with Thymine
Places Guanine with Cytosine BUT
Place URACIL with Adenine
RNA DOES NOT HAVE THYMINE!!

15. Transcription

17. Transcription
DNA “unzips”
One side of DNA becomes a template
Free nucleotides of RNA attach to open sites of the template by RNA Polymerase (not shown)
Cytosine attaches to Guanine
Uracil attaches to Adenine
Guanine attaches to Cytosine
Adenine attaches to Thymine
Messenger RNA is produced and released
mRNA is edited
Introns removed
Exons spliced together
mRNA goes to ribosomes for protein synthesis

18. Another look at transcription . . .

20. Transcription (cont’d)
Transcription starts at a location called the promoter
Promoter is a specific sequence of DNA that starts transcription
Pre-RNA is produced
Introns are cut out and thrown out
Exons are spliced together to form mRNA
mRNA is sent to ribosomes to be decoded

22. Editing/Refining Introns and Exons are processed
Introns are removed and exons are placed together
Exons are expressed; introns disappear
Purpose of introns are not known

32. A sequence of nitrogen bases on a segment of DNA of one of its strands that actually carries instructions for the order of amino acids in a protein is called a gene.
When DNA separates, one side becomes the template. Which side is the template? The side that is a code for a protein!
After transcription, a molecule of mRNA with codons is produced.
During translation, each codon of mRNA is matched with an anti-codon on a tRNA molecule with the amino acid it carries.