1. What is a genome?
The complete set of genetic instructions (DNA sequence) of a species

2. DNA (deoxyribonucleic acid)
Molecule that carries genetic information for all living things
Chromosomes and genes are made of DNA
DNA is in the shape of a double helix (twisted ladder)
Made up of small units called nucleotides
DNA double helix shape

3. Structure of a Nucleotide (3 main parts)
Nitrogenous base (A,T,G,C)
Phosphate group
DEOXYRIBOSE (sugar)

4. Structure of DNA
Nucleotides are linked together by phosphate groups and deoxyribose sugars (sides of molecule)
The 4 nitrogenous bases make up the inner part of the molecule:
Adenine (A), Thymine (T),
Guanine (G), Cytosine (C)

5. Chargoff’s Rules for Complementary Base-pairing
Hydrogen
bonds hold
both strands
together G C
* Adenine pairs with Thymine
* Guanine pairs with Cytosine

6. What does DNA have to do before a cell divides in mitosis?
Make a copy of itself
Make a copy of itself
DNA replication

7. DNA Replication
Process by which DNA copies itself before cell division
Molecule is split in half by enzymes called helicases
DNA polymerase enzymes copy each strand to make 2 new identical DNA molecules
Overview of DNA replication

8. Original
Strand
DNA Polymerase
New Strand
Replication fork

9. The Genetic Code
From Genes to Proteins

10. Instructions
to make proteins
are here
DNA
(cytoplasm)
(nucleus)
ribosomes
Proteins are
made here

11. RNA (ribonucleic acid)
Brings genetic instructions from nucleus to the ribosomes
Is single stranded
Had uracil (U) instead of thymine (T) - all other bases are same as DNA
Has ribose sugar instead of deoxyribose
There are 3 types of RNA:

12. Types of RNA
mRNA (messenger) - carries genetic instructions from nucleus to the ribosomes
tRNA (transfer) - brings amino acids to the ribosome to help construct the protein
rRNA (ribosomal) - makes up part of the ribosomes

13. Transcription
Process by which RNA (specifically mRNA) is made from DNA
Happens in the nucleus
RNA polymerase enzymes make RNA using DNA
A pairs with U, and G pairs with C
RNA can leave the nucleus after it is made

14. Transcription (continued)
- process by which mRNA is made from DNA
(DNA)
ATTGAACG
Leaves
nucleus
(RNA)
UAACUUGC
*C pairs with G, U pairs with A

15. Transcription mRNA (has copy DNA of DNA’s message ribosomes
Translation
(protein synthesis)
protein

16. Translation mRNA code is used to make a protein
Happens at the ribosome
Ribosome reads the mRNA sequence 3 bases at a time (every 3 bases is a codon)
Each codon represents a particular amino acid
tRNA molecules bring the correct amino acid that the codon specifies
The ribosome puts the amino acids together to make a protein

17. Translation (continued)
The decoding of mRNA to make a
protein
codon
A U G G G A C A C U U A G A C
mRNA
ribosome
Codon - sequence of 3 bases which stands for a particular
amino acid
AUG = START CODON - Translation of a protein begins with the start codon

18. mutation A change in the genetic code DNA RNA PROTEIN
Flow of genetic information in a cell:
DNA
RNA
PROTEIN
Mutated
DNA
Mutated
RNA
Defective
protein