Download Structure and Function of DNA

Structure and Function of DNA
DNA Replication and Protein Synthesis
DNA Structure
 Double Helix in Shape- two stands wound around one
another.
 Composed of subunits called nucleotides
 Parts of a Nucleotide
 5 Carbon Sugar- Deoxyribose
 Phosphate Group
 Nitrogen Base (4 Flavors)
 Adenine, guanine, cytosine, and thymine (A,T,C,G)
Nucleotides of a DNA Molecule
Watson and Crick
 Credited with Double Helix
Model
 Spiral staircase or twisted
ladder
 Maurice Williams and Rosalind
Franklin worked with them
also.
Base Paring
 Chargoff’s Rule
 A,C,T, G always bind in a certain way
 Adenine- Thymine
 Cytosine- Guanine
 Hydrogen Bonds Hold Them Together
Function of DNA
 DNA stores all of the genetic information for the cell.
 If it located in the nucleus but can also be found in the
mitochondria and the chloroplast.
 Serves as the blueprint for making proteins.
DNA Replication
 Copying DNA to make an exact copy (in nucleus)
 DNA strand unwinds and separates
 Enzymes help new DNA chains form by using
nucleotides floating around the nucleus.
 Produces two new exact copies of the original DNA
strand.
 Occurs during S phase if interphase
 Remember A-T and C-G !!!
Replication Practice
 1. CTC GGG ATA CTG GGG CGT
 2. ATG GCG CGT CGT CAT TAC
 3. GTG CGT CAT CCC AAA TTT
 4. TAC CAT ATC GTA CGT GTA
 5. AAT TTA TAT CTC GTG CCC
Part II: RNA
 Ribonucleic Acid
 Structure of RNA





Made of nucleotides
Sugar-Ribose
Uracil Replaces Thymine and Pairs with Adenine
Single Strand not double
Smaller than DNA
Types of RNA
 mRNA- messenger RNA
 Carries RNA info from nucleus to cytoplasm
 tRNA- transfer RNA
 Picks up amino acids
 rRNA- ribosomal RNA
 Makes up the ribosomes where proteins are made.
DNA VS. RNA
Transcription
 DNA RNA
 Occurs in the nucleus
 When the cell needs a protein is transcribes a certain
part of DNA into RNA.
 RNA is then the directions to make the proteins.
Transcription Practice
 1. TAC GGC TAT ATC CTG CGC TAT ACG ATT
 2. TAC CCG GAT CCG TTC ATA CGT ACT ATC
 3. TAC GTA AAA AGT GGG CCC TAT GAT ATT
 4. TAC GTA CGT CAT GAT TAG AGT TCT ATC
 5. TAC GTA CTA GTA CCC GTA ATA AGA ATC
The Genetic Code
 RNA is read in sets of 3
bases called codons.
 Each codon CODES for
a specific amino acid.
 Start Codon –AUG
 Stop Codons- UAA,
UAG, UGA
Translation
 Making proteins from the mRNA code.
 mRNA leaves the nucleus and moves to the
cytoplasm.
 Goes to the ribosome where it is read is sets of 3
bases called a CODON.
 tRNA picks up amino acids needed to make specific
proteins
Protein Synthesis
 Structure of Proteins
 Polymers made of amino acids bonded by peptide
bonds.
 Specific sequence of amino acids makes each protein.
 There are 20 different amino acids used to make
proteins.

Protein Assembly
 Once at the ribosome, the amino acids brought by the
tRNA are bonded together by peptide bonds.
 Bonded by peptide bonds.
 MAKES A PROTEIN.
SUMMARY
PROCESS
REPLICATION
TRANSCRIPTION
TRANSLATION
MOLECULES
LOCATION
Translation Practice
 Transcribe and Translate the following sequences.
1. DNA- TAC GGT ACT TAG AGA TTT AAA ATT
RNA
AA
2. DNA- TAC GTG GGG TTT ACT TCA CAT TTC GAG
RNA
AA