1. Chapter C4 Unraveling DNA
Section 2 How DNA Works
Chapter C4
Unraveling DNA
DNA is often wound around proteins, coiled into strands, and then bundled up even more.
In a cell that has a nucleus, the strands of DNA and proteins are bundled into chromosomes.
A gene consists of a string of nucleotides that give the cell information about how to make a specific trait.

2. Chapter C4
Section 2 How DNA Works

3. Chapter C4 Genes and Proteins
Section 2 How DNA Works
Chapter C4
Genes and Proteins
Proteins act as chemical triggers for many of the processes within cells. Proteins help determine traits.
Another type of molecule that helps make proteins is called RNA, or ribonucleic acid. RNA is so similar to DNA that RNA can serve as a temporary copy of a DNA sequence.
* The base Thymine is substituted for a Uracil.

4. Genes and Proteins, continued
Section 2 How DNA Works
Chapter C4
Genes and Proteins, continued
The first step in making a protein is to copy one side of the segment of DNA containing a gene. This copy is called messenger RNA (mRNA).
A ribosome is a cell organelle composed of RNA and protein. A ribosome uses mRNA, transfer RNA (tRNA), and amino acids to make proteins.
You can see the steps of protein production on the following two slides.

5. Section 2 How DNA Works
Chapter C4

6. Section 2 How DNA Works
Chapter C4

7. Chapter C4 Changes in Genes
Section 2 How DNA Works
Chapter C4
Changes in Genes
Changes in the number, type, or order of bases on a piece of DNA are known as mutations.
A mutation could be a replacement, addition, or removal of a base pair.

8. Changes in Genes, continued
Section 2 How DNA Works
Chapter C4
Changes in Genes, continued
There are three possible consequences to changes in DNA: an improved trait, no change, or a harmful trait.
Mutations happen regularly because of random errors when DNA is copied. Any physical or chemical agent that can cause a mutation in DNA is called a mutagen.

9. An Example of Substitution
Section 2 How DNA Works
Chapter C4
An Example of Substitution
A mutation, such as a substitution, can be harmful because it may cause a gene to produce the wrong protein.
A simple change in an amino acid can cause a disease such as sickle cell anemia, as shown on the next slide.

10. Section 2 How DNA Works
Chapter C4

11. Uses of Genetic Knowledge
Chapter C4
Section 2 How DNA Works
Uses of Genetic Knowledge
Scientists can manipulate individual genes within organisms. This kind of manipulation is called genetic engineering.
Your DNA is unique, so it can be used like a fingerprint to identify you. DNA fingerprinting identifies the unique patterns in an individual’s DNA.