Beyond DNA

In order for DNA to be useful, it must do what 2 things In order for DNA to be useful, it must do what 2 things? (hint, this was a homework question before break) Store genetic information Be able to be copied CORRECTLY & QUICKLY We’ve already seen how it does the first … …nucleotides. Now let’s look at how it does the second.

RNA – DNA’s cousin (similar but different) DNA RNA Deoxyribose Ribose G,C,A,T G,C,A, U double strand single strand nucleus throughout cell (nuc/cyt/rib) 1 type 3 types

rRNA Ribosomal RNA Makes up ribosomes Types of RNA rRNA Ribosomal RNA Makes up ribosomes

Types of RNA mRNA Messenger RNA Carries DNA directions out of the nucleus (like a copied blueprint) Shown as a chain of Nitrogen bases

Types of RNA tRNA Transfer RNA Transfers amino acids to the ribosome Shown as amino acid, RNA molecule, and 3 Nitrogen bases

Uses information from DNA to make proteins. SO WHAT DOES RNA DO? Welcome to the UN of the cellular world!! (at least that’s my analogy!) Uses information from DNA to make proteins.

Two languages: Nucleotides and Amino Acids/Proteins WHAT DOES RNA DO? Two languages: Nucleotides and Amino Acids/Proteins DNA uses the language of NUCLEOTIDES (Nitrogen bases) Ribosomes use the language of AMINO ACIDS Amino acids go together to make PROTEINS

TRANSCRIPTION Comes from the word SCRIBE. What does a scribe do? Occurs in the nucleus DNA is transcribed into mRNA (same language = nucleotides = C,G,T,A, and U) RNA polymerase “reads” DNA nucleotides and makes a chain (mRNA) of nitrogen bases

Example (don’t forget to change T to U!) DNA strand: C G A C G T A C G A T C mRNA strand: can now leave the nucleus and the DNA is still kept “safe” for future use G C U G C A U G C U A G

Try another DNA strand: A G C T A T C G A A T C mRNA strand: Good job! You have TRANSCRIBED – direct copied, same language two strands of DNA into mRNA!!! U C G A U A G C U U A G

Now… mRNA can leave the nucleus mRNA is carrying a copy of the DNA mRNA goes to the ribosomes, which are the site of protein synthesis.

TRANSLATION What does a translator do? Occurs in the ribosome. mRNA (language = nucleotides) is translated into new language strings of amino acids A protein is a chain of amino acids

TRANSLATION HOW????? Ribosome “reads” mRNA in groups of 3 bases called codons. Ribosome “pulls” tRNA molecule that has matching 3 bases called “anticodons” Ribosome connects the amino acids on the other end of the tRNA molecule into long chains tRNA molecules released to go get new amino acid & repeat

TRY ONE Look back at Example #1- DNA: C G A C G T A C G A T C mRNA: G C U G C A U G C U A G Codons: G C U / G C A / U G C / U A G amino acids: Alanine-Alanine-Cystine-Stop

TRY ANOTHER Look at Example #2- DNA: A G C T A T C G A A T C mRNA: U C G A U A G C U U A G Codons: U C G / A U A / G C U / U A G amino acids: Cys-Isoluec-Ala-Stop

THEN WHAT? A protein has been made by connecting a long chain of amino acids. The protein is sent to the Golgi Apparatus where it is modified and packaged for export. Proteins go on to: Build muscle and bone Regulate cell processes Transport substances in/out of cells Fight disease