1. Chapter 4 Section 3
DNA

2. DNA deoxyribonucleic acid
The code of life.
Contains the code for information for an organisms growth and function
When a cell divides, DNA code is copied and passed to new cells.
This is how the new cells receive identical coded information that was in the original cell.

3. DNA Franklin Watson Crick
Three scientists credited with the discovery of DNA
Watson & Crick – developed the model of what DNA looked like

4. DNA Double helix – twisted ladder Made up of three parts
Nitrogen base : ladder rungs
Sugar called deoxyribose: side of the ladder
Phosphate: side of the ladder

5. DNA – Nitrogen bases Adenine Thymine Guanine Cytosine
These bases are always paired
Adenine to Thymine
Guanine to Cytosine

6. DNA Bases 30% Adenine = 30 % Thymine 5% Cytosine = 5% Guanine
The paired amounts must be equal
Each base will only bond with its correct partner.
30% Adenine = 30 % Thymine
5% Cytosine = 5% Guanine

7. Copying DNA Occurs BEFORE mitosis or meiosis Occurs in INTERPHASE
Original DNA
Enzyme separates DNA sides
New bases pair with bases on original DNA
Pair with correct partner ( A-T / C-G)
Two new identical DNA molecules produced

8. GENES Gene – section of a DNA on a chromosome
Genes – have the instructions for the making of your proteins
Each chromosome can have thousands of genes
Amino acids – building blocks for proteins
Genes – determine to order of the amino acids

9. Making proteins Chromosome made up of a long molecule of DNA
DNA is made up of thousands of genes
Gene is made up of nucleotides ( three parts – sugar/base/phosphate)
Nucleotide determines the type of amino acid
Order of amino acids – determines the type of protein.

10. Making of Proteins DNA – stores the code for the protein
DNA – locked in the nucleus
Proteins are made by ribosomes
Ribosomes are outside the nucleus
So the code from the DNA must get out of the nucleus and to a ribosome
How does that happen?

11. Making Proteins Nucleic acid – RNA ( ribose nucleic acid)
RNA will get the code from the nucleus to a ribosome and then find an amino acid and build the protein.

12. Types of RNA
3 types of RNA
Messenger RNA (mRNA)
Ribosomal RNA (rRNA)
Transfer RNA (tRNA)

13. RNA RNA – also made of 3 parts (nucleotide) Sugar ( ribose) Phosphate
Nitrogen base
RNA – singled stranded/ not twisted
like a ladder that has all its rungs sawed in half

14. RNA bases Adenine Uracil Cytosine Guanine
Notice they are the same as DNA EXCEPT RNA makes uracil inplace of thymine

15. Messenger RNA Messenger RNA – made in the nucleus
Messenger RNA carries the DNA code
From the nucleus to a ribosome in the cytoplasm
So messenger RNA is how the code gets out of the nucleus.
This code will direct the order in which amino acids will bond. There by directing the code for a protein

16. Ribosomal RNA
Ribosomal RNA – this is the material that makes a ribosome They allow the messenger RNA carrying the code to attach.

17. Transfer RNA
Transfer RNA are molecules of RNA found in the cytoplasm with certain amino acids attached.
Transfer RNA brings these amino acids to the ribosome.

18. Controlling genes
Cells must be able to control genes by turning some on and some off.
Sometimes mistakes are made when DNA is being copied.
Mutation – any permanent change in the DNA sequence of a gene or chromosome
If DNA is not copied exactly, proteins made from the instructions might not be made correctly.

19. Code Copying DNA: AAT GGG CGG TAT DNA : TTA CCC GCC ATA
mRNA using DNA the top strand
UUA CCC GCC UAU
tRNA – AAU GGG CGG AUA
Notice that tRNA is almost a perfect match for the original DNA ( thymine was replaced by uracil)