DNA Deoxyribonucleic Acid

“The Blueprint of Life”

A. What is DNA?

1. Organic molecule

2. Nucleic acid

B.Where is it

located?1. Nucleus2. In the Chromosomes

DNA

Chromosomes in Nucleus

C. Structure of DNA

1.Nucleotidesa. Phosphateb. Deoxyribose sugarc. Nitrogenous bases:

Adenine-ThymineGuanine-Cytosine

2. Ladder Shape 3. Double strand, helix

twist

Ladder Shape (Sides & Rungs)

Sides:PhosphateSugarPhosphate

Rungs:A-TT-AG-CC-G

Watson & Crick’s Double helix:

D. What is DNA’s Function?

Hereditary InstructionsChemical code for every trait“Blueprint” for making Proteins

Chromosome DNA Code:

Genes =Segments of DNA Code for a trait

HairColor

EyeColor

DNA Chromosome Code:

A triplet of bases code for an amino acidA series of amino acids code for a proteinThe protein codes for a

Trait

Acid AcidSugar-T-A-SugarAcid AcidSugar-G-C-SugarAcid AcidSugar-C-G-Sugar

DNA Chromosome Code:Like Morse Code: Hair =

*** *- ** *-*Or DNA

A-T

A-T

G-C

C-G

T-A

C-G

DNA ReplicationChromosomes doubleInterphaseS or Synthesis stage 2N

1N

E. Steps for DNA Replication:

1. DNA untwists2. DNA unzips-hydrogen bonds are

broken by enzyme3. Corresponding nucleotides line up and hydrogen bonds form between nitrogen bases 4. 2 strands twist into helix5. Result is 2 chromosomes- part old and part new

IdenticalStrand

A. What is RNA?1.Organic

Molecule2.Nucleic Acid3.Types:mRNA=messengertRNA=transferrRNA=ribosomal

B. Where is RNA located?

1.mRNA in

nucleus & cytoplasm

2.tRNA only in cytoplasm

3.rRNA at the ribosomes

B. What is RNA’s structure?

PhosphateSugar-BasePhosphateSugar-BasePhosphateSugar-BasePhosphateSugar-Base

1.Nucleotides=a. Phosphateb. Ribose sugarc. Nitrogenous

Bases: Adenine-UracilGuanine-Cytocine

2. Single Strand3. No Twisted helix

Comparison of RNA & DNA:

PhosphateSugar-BasePhosphateSugar-BasePhosphateSugar-BasePhosphateSugar-Base

PhosphatePhosphate

Sugar----Bases----Sugar

Phosphate Phosphate

Sugar----Bases----Sugar

Phosphate Phosphate

Sugar----Bases----Sugar

Phosphate Phosphate

RNA DNA Ladder

Deoxy-ribose

Ribose

Double StrandedSingle Stranded

Uracil replaced thymine

D. What are RNA’s functions:

1.mRNA=Copies the DNA codeDeliveries message to RibosomeRibosomes-Protein Factories

Why not send the original DNA code out?

DNA might be damaged!mRNA components are reusedTo copy more messages

Original DNA

mRNA copy

RNA function cont.2. tRNA:

in cytoplasmPicks up an amino acid“Taxis” the aa to the Ribosome protein factories

tRNA

Aminoacid

III. Protein Synthesis

Assembling Proteins from the DNA Instructions

A. Transcription:

1.mRNA is copied off of DNA

2. In nucleus3.Steps:

DNA untwistsDNA unzipsRNA codons line up

Transcription:mRNA has:Ribose sugarUracil instead of thymine basesNuclear membrane allows it to leave!DNA Code

mRNAA

T

C

G

U

A

G

C

Transcription in The nucleus

mRNA copyDNA

B. Translation =Conversion of the message (mRNA Code)Into a proteinBy the ribosome factories

B.Translation

1.mRNA arrives at the Ribosome

2.tRNA picks up an amino acid

3.tRNA delivers the aa to the ribosome

4.aa are assembled into polypeptide proteins

U A G C

GC

U

A

mRNA code

tRNA taxi

• tRNA delivers

amino acid

2. Peptide bond forms

3. tRNA leaves ribosome

4. PolypeptideChain of aminoacids grows

Summary:

DNA Replication:Make duplicate DNAIn nucleusCopy the chromosomesFor Mitosis

Protein Synthesis:

1.Transcrition:Make mRNAFrom DNA

2.Translation:Make proteinOff mRNA codeUsing amino acids