1. DNA

2. Characteristics of DNA
Supplies instructions for cell processes, like how to make proteins
Can be copied each time a cell divides
It is the “blueprint of life”, every living thing has DNA

3. DNA Structure Is a nucleic acid that is double stranded
Made up of subunits called nucleotides

4. A nucleotide consists of 3 parts:
Phosphate
Sugar
Nitrogen base:
adenine (A),
guanine (G),
thymine (T),
cytosine (C)

5. Structure of DNA Nucleotide Hydrogen bonds Sugar-phosphate backbone
Section 12-1
Nucleotide
Hydrogen bonds
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)

6. Scientific Contributions
Watson and Crick: made a model of DNA structure in 1953
The “Double Helix” looks like a twisted ladder
Sides of the ladder are alternating sugar and phosphate units
Rungs are the bases held together by hydrogen bonds
A always pairs with T and C always pairs with G

7. DNA Replication
Def: Ability of DNA to make an exact copy or a new strand of DNA from an old one

8. The Steps in Replication
Start with a DNA molecule
Hydrogen bonds break and the strands separate (unzip)
Add matching nucleotides
The result: 2 identical DNA molecules
½ old strand, ½ new strand

9. Drawing DNA Replication: Step 1

10. Drawing DNA Replication: Steps 2 and 3

11. Drawing DNA Replication: Step 4

12. DNA Replication:

13. Chromosomes
Tight coils and supercoils of DNA and protein

14. Section 12-2
Chromosome
Nucleosome
DNA
double
helix
Coils
Supercoils
Histones

15. Protein Synthesis

16. Genes and the Genetic Code
Gene: a segment of DNA on a chromosomes that codes for a specific trait
Genetic Code: formed by the order of nitrogen bases along a gene that specifies what type of protein will be produced

17. How cells make proteins
A cell uses the coded information from a segment of DNA (gene) to make a specific protein
Why make proteins?
Proteins determine your traits, hair color, eye color, tongue rolling ability, etc.
Things that are not traits: athletic ability

18. What Protein Synthesis involves:
DNA found in the nucleus
Ribosome: where the proteins are made
RNA (see below)
Amino acids: these are the building blocks of proteins

19. RNA Similar to DNA Structure of RNA: Sugar is different
Single-stranded
Uracil replaces thymine
Still has cytosine (C), guanine (G), and adenine (A)

20. DNA vs RNA

21. 2 Types of RNA
mRNA: messenger RNA
Copies the coded message from the DNA in the nucleus and carries the message to the ribosome in the cytoplasm
tRNA: transfer RNA
Picks up and transfers amino acids in the cytoplasm to the ribosome and adds them to the growing proteins

22. How Cells Make Proteins
- The DNA Connection
How Cells Make Proteins
During protein synthesis, the cell uses information from a gene on a chromosome to produce a specific protein.

23. Mutations - The DNA Connection
Mutations can cause a cell to produce an incorrect protein during protein synthesis. As a result, the organism’s trait, or phenotype, may be different from what it normally would have been.

24. So, what’s the big deal? most of the time they are fixed by our bodies
Mutations happen all the time
most of the time they are fixed by our bodies

25. If they are not fixed, 3 things could happen:
1. Absolutely nothing:
occurs most of the time
2. A small change:
like having 2 different color eyes
a change that does not effect the way you live

26. has a big effect on how you live
3. A BIG change: (can be good or bad)
like getting a disease or being able to blend in to your environment better
has a big effect on how you live