13.1 RNA

Warm-Up What are the 3 parts of a nucleotide? Which Bases pair up during replication? What does DNA stand for?

Daily Info Objective: -Contrast RNA and DNA. -Explain the process of transcription. Essential Question: How do we actually use DNA? Agenda: 13.1 Notes Amoeba Sisters RNA video w/ handout RNA vocab Homework: Questions pg. 310

The Role of DNA RNA, like DNA, is a nucleic acid that consists of a long chain of nucleotides. RNA stands for RiboNucleic Acid, while DNA stands for DeoxyriboNucleic Acid. RNA uses the base sequence copied from DNA to direct the production of proteins.

Comparing RNA and DNA - Each nucleotide in both DNA and RNA is made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base. - There are three important differences between RNA and DNA: (1) The sugar in RNA is ribose instead of deoxyribose. (2) RNA is generally single-stranded and not double-stranded. (3) RNA contains uracil in place of thymine.

Functions of RNA RNA is like a disposable copy piece of DNA It is a working copy of a single gene Most RNA makes proteins – Protein synthesis RNA controls how amino acids join together to make proteins

3 Types of RNA 1. Messenger RNA (mRNA) – carries copies of genes with instructions for assembling amino acids into proteins from the nucleus to ribosomes 2. Ribosomal RNA (rRNA) – Proteins are put together on the ribosomes. - Ribosomes have 2 subunits made of rRNA and proteins 3. Transfer RNA (tRNA) – Carries amino acids to the ribosome and matches them to the coded mRNA message.

RNA Synthesis - Transcription Segments of DNA serve as templates to make complimentary strands of RNA In Eukaryotes RNA is produced in the nucleus then moves out to the cytoplasm In Prokaryotes everything is in the cytoplasm Enzyme – RNA Polymerase (like DNA polymerase) binds to DNA where one strand is used as a pattern to create the RNA.

RNA Synthesis - Promoters Promoter – a region of DNA that have specific base sequences. Signals in the DNA that tells RNA polymerase where to start making a strand of RNA. Other signals in the DNA tell it where to stop.

Steps of transcription: Step 1 RNA polymerase binds to the gene’s promoter. The two DNA strands unwind and separate. Step 2 Complementary RNA nucleotides are added. (Match up bases to one side of a gene in DNA) Step 3 mRNA detaches from the DNA mRNA moves out of the nucleus and into the cytoplasm

RNA Editing RNA molecules sometimes require bits and pieces to be cut out of them. Introns - “junk DNA” - The portions that are cut out and discarded. Exons - The remaining pieces are then spliced back together to form the final mRNA.

Amoeba Sisters - RNA