1.  We know that DNA is the genetic material and its sequence of nucleotide bases carry some sort of code. This code holds instructions that tell a cell how to build proteins, which in turn help to determine an organism’s characteristics.  But how does a cell understand and read this code to make proteins?

2. RNA Chapter 13

3. What is RNA?  Ribonucleic acid  Can be thought of as a disposable copy of a piece of DNA  What is RNA’s job?  To make proteins (Protein Synthesis)

4. Recall that…  Segments of genes in our DNA contain a code for proteins that determine our traits  DNA is confined to the nucleus  Protein synthesis takes place in the ribosomes  Proteins are made up of amino acids

5. Why RNA?  RNA can travel outside of the nucleus (via the nuclear membrane’s pores) and carry DNA’s code to the ribosomes  Ribosomes piece together amino acids based on the RNA code to build the proteins  The DNA stays safe inside the nucleus and the RNA can travel to do the rest of the work!

6.  DNA- Contains the “master plan” with all information needed to build a protein.  RNA- The “builder”, who works from a blueprint, or disposable copy, of the master plan.  The cell uses the DNA’s “master plan” to prepare RNA “blueprints”.

7. Structure of RNA  Single stranded  Ribose Sugar  Phosphate group  Adenine, Uracil, Cytosine, Guanine

8. Types of RNA  Three main types  Messenger RNA (mRNA) – Carries DNA code to ribosomes for translation.  Ribosomal RNA (rRNA) – Ribosomes are made of rRNA and protein.  Transfer RNA (tRNA) – brings amino acids to ribosomes for protein synthesis.

9. rRNA - Structure of ribosomes tRNA - Carries amino acids to ribosomes mRNA -Carries message to ribosomes - Made during transcription

10. Transcription (RNA Synthesis)  Segments of DNA serve as templates to produce complementary RNA molecules  1. RNA Polymerase binds to DNA at the promoter site  Promotor: Region of DNA that shows enzymes where to attach.

11.  2. RNA polymerase separates DNA strands by breaking hydrogen bonds  3. One strand of DNA is used as a template to form a strand of RNA  DNA’s Adenine pairs with RNA’s Uracil  DNA’s Thymine pairs with RNA’s Adenine  Guanine and Cytosine pair normally

12.  4. RNA polymerase eventually reaches a terminator signaling it to stop transcription  5. mRNA strand un-attaches, and travels through nuclear membrane’s pores to the ribosome  The ribosome will read this code and make proteins from it- a process known as translation (which we will get to later on)

13. RNA strands are edited before they’re translated  Some parts are removed and others are expressed  Introns - Portions cut out and discarded  Exons- Expressed genes  Why?  Makes it possible for a single gene to produce many different forms of RNA  Evolution- Small changes in sequences cause dramatic effects on the cellular functioning of genes

14. Transcription Video

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