Post on 17-Jan-2016
transcript
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