Unit 8 Lesson 2 Notes

Review from Lesson 1

• Protein synthesis is the making of protein using information from DNA.

Let’s Review

• You learned the differences between DNA and RNA.

• You learned tRNA is transfer RNA and it transfers amino acids from the cytoplasm to the ribosomes to form protein chains.

• A nucleic acid is made up of repeating nucleotides. • A nucleotide is a sugar, a phosphate

and a base.• In RNA the sugar is ribose.

http://www.biologyjunction.com/images/nucleotide1.jpg

• RNA contains the base uracil instead of thymine.

• Uracil is represented by the letter U which bonds with Adenine (letter A).

http://www.biologycorner.com/resources/mRNA-colored.gif

• RNA is made during transcription.• Transcription takes place inside the

nucleus of the cell.

http://www.phschool.com/science/biology_place/biocoach/images/transcription/euovrvw.gif

• An analogy for why transcription of DNA must occur:–Encyclopedias must stay in the library

just like DNA must stay in the nucleus.

Transcription

• During transcription, DNA is used as a pattern to create RNA.• Synthesis means to make… so DNA

is used to synthesize, or make, RNA.• Transcription occurs in the nucleus of

a cell.

• In transcription the four bases in RNA are U, A, G and C. • Remember the base that replaces

Thymine in RNA is Uracil.

http://leavingbio.net/HEREDITY-ORDINARY%20LEVEL_files/image038.jpg

RNA Production• In transcription, DNA bases are

paired with RNA bases. • This new single strand of RNA will be

used to create proteins with the same base sequence as the original DNA molecule.

• DNA RNA• A U• T A• C G• G C

http://biology.unm.edu/ccouncil/Biology_124/Images/transcription.gif

The process…

• DNA – TAC ATC GTA CTA • mRNA – AUG UAG CAU GAU

• DNA – TAC CCG GGC AAA• mRNA – AUG GGC CCG UUU

• Notice in this picture that DNA is on the left. We know this because DNA contains the base Thymine (T). RNA is produced on the right… look for the Uracil (U) which is replacing T in DNA.

http://science.halleyhosting.com/sci/ibbio/chem/nucleic/chpt15/transcription.gif

Your turn!

• Now it’s time for you to practice creating proteins by copying DNA to make RNA.