1. Structure of DNA Nucleic acid Subunits = nucleotides In DNA
5 carbon sugar = deoxyribose
Phosphate group
Nitrogenous base
Adenine, guanine, cytosine, thymine
Bonds between sugar and phosphate group - backbone

2. Double-helix model
Antiparallel strands
Run in opposite directions
Allows bases to touch
Hydrogen bonds
Weak
Between specific bases
Base pairing
Only certain bases bond
A to T
C to G
Together 2 bases = base pair

3. What does DNA do? Makes more DNA Makes RNA Makes proteins
Building blocks of life

4. RNA DNA 5-carbon sugar – ribose 5-carbon sugar – deoxyribose
Phosphate group
Bases: A, C, G, U
Single-stranded
“Blueprints”
Made in nucleus, but used in cytoplasm
DNA
5-carbon sugar – deoxyribose
Phosphate group
Bases: A, C, G, T
Double-stranded
“Master plan”
Stays in nucleus

5. Role of RNA Disposable copy of DNA Makes proteins from amino acids
Types
Messenger (mRNA)
Instructions for assembly
Brings info. from nucleus to rest of cell
Ribosomal (rRNA)
Several with proteins make ribosomes
Where proteins are assembled
Transfer (tRNA)
Carries amino acids to ribosomes
Specific for an amino acid

6. RNA Synthesis Transcription DNA made into RNA Occurs in nucleus
RNA polymerase
Binds to a promotor region
Specific base sequence on DNA
Separates DNA strands
Uses one strand as a template
Attaches complementary bases
Except no T
Until it reaches a “stop” sequence
Creates pre-mRNA

7. RNA Editing
A lot of “useless” bases in our DNA that ends up in the RNA
Introns
Enzymes cut these sections out
Recent research
Leaves exons
Information used
Creates mRNA
Leaves the nucleus

8. Genetic Code Bases are read in sets of 3 = codon
Represents a specific amino acid
Some amino acids have more than one codon
Start and stop codons
“Punctuation”
Start = AUG = methionine
3 different stop codons
No amino acid, just stops

10. Translation mRNA leaves nucleus Attaches to a ribosome “Reads” codons
tRNA
Has anticodon sequence
Complementary to codon sequence
Brings in specific amino acid
Ribosome moves to next codon
New tRNA comes in
Amino acids bond
Old tRNA leaves
Ribosome moves to next codon….

11. Keeps adding amino acids
Forming polypeptide bonds
Reaches stop codon
No amino acid added
Translation stops
Polypeptide chain released
Further folding to form protein
Other products recycled and reused

14. Central Dogma – How do Genes Work?
DNA (genes)  RNA  proteins
Viruses different
RNA  DNA
Genetic code is universal
Same bases
Read as codons
Codons = same amino acids

15. Mutations Mistakes Often caught/fixed by enzymes
Occasionally “slip” through
Passed on to offspring of that cell
Point mutations
Substitution
Frameshift mutations
Insertion
Deletion
THE FAT CAT ATE HIS HAT
THE SFA TCA TAT EHI SHA
THE FAT ATA THE ISH

16. Chromosomal Mutations
Change number of structure of chromosomes
More DNA/genes involved
Deletion
Duplication
Inversion
Translocation

17. Cause Mutations Random Accumulate over time Mutagens Chemical Physical
Interfere with base-pairing
Weaken DNA

18. Helpful vs. Harmful Most are neutral Create genetic variation Harmful
Change protein structure
Change gene activity
Disrupt normal activities
Examples
Cancers
Sickle cell disease
Beneficial
New trait is helpful for survival
Pesticide resistance
Increase human bone strength and density
Resistance to HIV
Polyploidy
Larger, stronger, seedless plants