DNA

What is DNA?

DNA stands for deoxyribonucleic acidIt 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 basesThere are only 4 found in DNA

Complementary base pairingA-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 phosphatesWeak 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 sugar P = 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 Pathway to Making a ProteinProtein

DNADNA

mRNAmRNA

tRNA (ribosomes)tRNA (ribosomes)

ProteinProtein

DNADNA RNARNA ProteinProtein

Nuclearmembrane

TranscriptionTranscription

RNA ProcessingRNA Processing

TranslationTranslation

DNA

Pre-mRNA

mRNA

Ribosome

Protein

EukaryotEukaryotic Cellic Cell

Transcription

DNA RNA

What is RNA?

Ribonucleic acidIts 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

DNA RNA

Deoxyribose sugar Ribose SugarNucleotide Nucleotide

Thymine UracilDouble Helix Single Strand

Let’s repeat!

. Three Types of RNAThree Types of RNA

Messenger RNA (mRNA)Messenger RNA (mRNA) copies copies DNA’s code & carries the genetic DNA’s code & carries the genetic information to the ribosomesinformation to the ribosomes

Ribosomal RNA (rRNA)Ribosomal RNA (rRNA), along , along with protein, makes up the with protein, makes up the ribosomesribosomes

Transfer RNA (tRNA)Transfer RNA (tRNA) transfers transfers amino acids to the ribosomes amino acids to the ribosomes where proteins are synthesizedwhere proteins are synthesized

Messenger RNA

Long Straight chain of NucleotidesMade in the NucleusCopies DNA & leaves through nuclear poresContains the Nitrogen Bases A, G, C, U ( no T )

Let’s create some RNA!!

White boards PLEASE!!......

TranscriptionTranscription

The DNA uncoils and copied.mRNA copies the template strand of DNA with the enzyme RNA PolymeraseRNA 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

http://www-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. AUGThe 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 ribosomeElongation-tRNA bring specific amino acids that match with mRNA building the polypeptide chainTermination-mRNA detaches from ribosome and protein is finishes assembling.

http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a3.html