RNA

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

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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