DNA

What is DNA? DNA stands for deoxyribonucleic acid It stores all of our genetic information It’s function is to tell the cell what proteins to make and when to make them. Remember: it is the brain of the cell.

Who Discovered It? First identified in 1868 by Friedrich Miescher but he didn’t know what it’s job was. Then in 1953, James Watson and Francis Crick figured out the molecular structure of DNA. The shape was called a double-helix They won the Nobel Prize in 1962

Structure of DNA It has 3 parts making a nucleotide. (sugar, P’s, and N groups) It looks kind of like a ladder. The sides are made of alternating sugar and phosphate groups (P) The steps are made of nitrogen groups that pair together The ladder isn’t straight, it has a twisted shape called a double helix.

Structure of DNA Nitrogen-containing bases There are only 4 found in DNA Complementary base pairing A-T will pair up and C-G will pair up using hydrogen bonding 1 ______2 _____4 ______3 ______

Characteristics of DNA There are very strong bonds between the sugar (deoxyrobse) and the phosphates Weak hydrogen bonds are holding the nitrogen groups (A to T and C to G) So, the rails of the ladder are fairly strong but the steps can be easily separated.

DNA Replication 1.The 2 chains unwind and separate. 2.An enzyme call helicase unzips the chain and move up the chain to help it separate by breaking Hydrogen bonds between the A,T,C and G’s 3.Another enzyme call DNA polymerase binds to the chain and identifies and locates the unpaired A,T,C and G’s to help assemble the new chain. (The Copy)

D = the sugarP = phosphate group

So you end up with 2 copies of the DNA. Then polymerase proofreads the nucleotides for mistakes and cuts any part that is incorrectly matched.

Practice What is the compliment? A T C A T G G C T A G T A C C G

How to Make a Protein?

Pathway to Making a Protein DNAmRNA tRNA (ribosomes) Protein

DNA  RNA  Protein Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein Eukaryotic Cell

Transcription DNA  RNA

What is RNA? Ribonucleic acid Its job is to take information from the DNA and bring it to the ribosomes in the cytoplasm. DNA is the MASTER PLAN RNA is the BLUEPRINT of the Master Plan

DNA vs. RNA DNARNA Deoxyribose sugar Ribose Sugar Nucleotide Thymine Uracil Double Helix Single Strand

Let’s repeat!

. Three Types of RNA Messenger RNA (mRNA) copies DNA’s code & carries the genetic information to the ribosomes Ribosomal RNA (rRNA), along with protein, makes up the ribosomes Transfer RNA (tRNA) transfers amino acids to the ribosomes where proteins are synthesized

Messenger RNA Long Straight chain of Nucleotides Made in the Nucleus Copies DNA & leaves through nuclear pores Contains the Nitrogen Bases A, G, C, U ( no T )

Let’s create some RNA!! White boards PLEASE!!......

Transcription The DNA uncoils and copied. mRNA copies the template strand of DNA with the enzyme RNA Polymerase RNA Polymerase bind to one side of the DNA template at the promoter site. When the enzyme gets to the terminal signal, it comes off of the DNA and transcription has stopped

Template Strand

class.unl.edu/biochem/gp2/m_biology/animation/ gene/gene_a2.html

Practice Question Transcribe the following sequence to show the resulting mRNA. A T G A T T C G T

Translation RNA  Proteins

Protein Synthesis Translation is the process of decoding mRNA into Protein (or polypeptide chains) Proteins are the physical display of your genetic information or DNA.

Ribosomes read mRNA three bases or 1 codon at a time to construct the proteins Start codons= translation to starts (AUG) Stop codons = translation to stop (UAA, UAG, UGA)

Translation The mRNA is attached to the ribosome Finds a start codon. AUG The tRNA brings a specific an amino acid at one end and has an anticodon (complementary to the mRNA) on the other. Each tRNA brings an amino acid that binds together to form a protein.

Translation Translation occurs in 3 parts: Initiation-mRNA attaches to ribosome Elongation-tRNA bring specific amino acids that match with mRNA building the polypeptide chain Termination-mRNA detaches from ribosome and protein is finishes assembling.

class.unl.edu/biochem/gp2/m_biology /animation/gene/gene_a3.html