1. Bellringer What does Protein do?
Protein has a large number of important functions in an organism – in fact, the human body is about 45% protein. Without it, our bodies would be unable to repair, regulate or protect itself.
Think about the different jobs of proteins in your body. List as many types of proteins or functions of proteins as you can.

2. Objective Describe the structure and function of DNA.
Describe the relationship between DNA, genes, chromosomes, and proteins

3. HOMEWORK: Read section 12-2 in the textbook and
Answer the following questions on pp. 111 – 112 in the workbook:
1, 7, 8, 12, 13, 16, 17, 18

4. DNA, RNA, and protein synthesis
You are what you eat!

5. DNA – What is it? Deoxyribonucleic Acid
Long, double-stranded chain of nucleotides
Contains genetic code
Instructions for making
the proteins that control
cell function and physical
traits of an organism.

6. Structure of DNA Physical Double helix (twisted ladder)
Tightly coiled DNA + histones (proteins) = chromatin
Before cell division, chromatin coils more tightly into chromosomes

7. More DNA Structure Chemical 5-carbon sugar (deoxyribose)
Made up of nucleotides:
5-carbon sugar (deoxyribose)
Phosphate group
Nitrogen base

8. What’s a Nitrogen Base? Introducing the nitrogen bases of DNA~~~
The part of a nucleotide that bonds with a partner to make up the “rungs of the ladder” in a double helix
Introducing the nitrogen bases of DNA~~~
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
A – T always pair and C – G always pair – these are the rungs of the ladder

9. What is the job of DNA? Stores all the information, “genetic code”
The code is used to make proteins, which control almost everything that happens in your body
A gene is a specific sequence of DNA that codes for a specific protein
Replication – when the strands of DNA unwind and an exact copy of the entire length of DNA forms during cell division. This is important so that the new cell has the exact same info as the other cell.

10. Where in the cell is your DNA?
Nucleus
DNA is the master plan for a cell, and the cell wants to keep it safe. So the DNA stays inside the nucleus of the cell

11. RNA (DNA’s distant cousin)
What is it?
Ribonucleic Acid
Long chain of nucleotides, with 5- carbon sugar, phosphate group, and nitrogen base (similar to DNA)
Since the all-important DNA has to stay safely tucked away in the nucleus, we need RNA to make a copy of the code to travel to other parts of the cell, where the action happens…

12. What’s the difference? How is RNA different than DNA???
5-carbon sugar is Ribose
(instead of Deoxyribose)
Nitrogen base Uracil (instead of Thymine). The others (Adenine, Cytosine, and Guanine) are the same as DNA.
A – U pair and C – G pair
Single-stranded
It does not stay in the nucleus.

13. Bellringer
Work on the DNA – RNA comparison chart -- #1 on today’s handout.
Hint: Not every box should be filled in. If something is the same in both DNA and RNA, put it in the “Both” column. If there is something different about DNA and RNA, put it in the appropriate column.
Get out your homework assignment from the workbook and your notes from this week.

14. DNA
Both
RNA
What is it?
Nucleic Acid (made up of nucleotides)
Nucleotides contain:
Deoxyribose
5-C sugar
Phosphate group
Nitrogen base
Ribose
Nitrogen bases
Thymine (T)
Adenine (A)
Cytosine (C)
Guanine (G)
Uracil (U)
How many strands?
Double stranded
Single stranded
Where in the cell?
Nucleus only
Nucleus, cytoplasm and ribosome
How many types? 1
3: mRNA, tRNA, rRNA

15. There are 3 types of RNA Messenger RNA (mRNA) Ribosomal RNA (rRNA)
Carries the genetic code from the DNA in the nucleus in the nucleus through the cytoplasm to the ribosome, so it can get translated into a protein
Ribosomal RNA (rRNA)
Becomes part of the structure of a ribosome
Transfer RNA (tRNA)
Carries the specific amino acids to the mRNA on the ribosome.

16. Hey Hey Hey, RNA… What are you going to do today?
I’m going to take that DNA code and turn it into a protein!
How?
First, I copy DNA’s code.
(DNA -> RNA =Transcription)
Then, I use that code to stick
certain amino acids together.
The string of amino acids forms a protein
(RNA -> protein = Translation)

17. Breaking the code! RNA is read 3 bases at a time (codon) (why?)
AUG = start
UAA = stop
UAG = stop
UGA = stop

18. Protein Synthesis
The process of “translating” the RNA code into a chain of amino acids that form a protein is called Translation
Where in the cell?
Protein synthesis occurs on the ribosome.

19. Making proteins
1. DNA unwinds and a matching copy of mRNA forms (Transcription). 2. Messenger RNA carries the code from the nucleus into the cytoplasm to the ribosome (the site of protein synthesis) 3.The genetic code on the mRNA is read 3 letters at a time (codon). Each 3-letter code matches up with a specific amino acid (the building blocks of proteins).

20. Making proteins (continued)
Transfer RNA carries the amino acid to the specific codon on the mRNA. (Translation)
5. The amino acids bond together into a long chain, which forms a protein.

21. What’s the point of all this?
When you eat protein, it gets
broken down in your digestive
system, into amino acids. Your
body uses those amino acids as building blocks
to build the proteins you need!
(you are what you eat…)
Proteins control almost everything in a cell.
Proteins define what the cell looks like, how it functions, how it grows, and how it passes the information on
Ex. Enzymes, hormones, transport, motion, protection, support, and regulation

22. How does the study of DNA, RNA and proteins affect our society today?
DNA “fingerprinting”
Human Genome Project
Medical research
Disease detection and cures
Genetically modified food
Cloning

23. Bellringer
What are some ways scientists use the study of DNA today, and how has it affected our society?