1. DNA Replication and Protein Synthesis

2. Biology B-Day 1/3/18 Bellringer What are the 3 parts of a nucleotide?
What is the base-pair rule?
Agenda
Bellringer
RNA and Protein Synthesis Notes
Transcription and Translation Practice

3. Biology B-Day 1/3/18 Bellringer What are the 3 parts of a nucleotide?
Sugar, Phosphate, Nitrogen Base
What is the base-pair rule?
A-T and C-G
Agenda
Bellringer
RNA and Protein Synthesis Notes
Transcription and Translation Practice

4. I. DNA – Deoxyribonucleic Acid
Genetic Code – Way that cells store info (in nucleus) to be passed to the next generation.

5. II. DNA Structure DNA is a macromolecule made up of nucleotides.
Each nucleotide molecule has 3 subunits:
Phosphate Group
5-carbon sugar
Nitrogen base

6. Four Possible Nitrogen Bases:
Adenine
Guanine
Thymine
Cytosine
A & G: purines
T & C: pyrimidines

7. Nucleotides are joined to form DNA molecules.
NOTE: The sugars and phosphates make up the backbone of DNA. (“siderails” of a ladder)

9. Chargaff
Discovered “Base Pairing Rules.”
Adenine always pairs with Thymine (2 H bonds)
Cytosine and Guanine always pair (3 H bonds)
ALWAYS pyrimidine + purine

10. DNA RECAP: DNA is located in the nucleus
The proteins DNA codes for must be made by ribosomes outside the nucleus
Therefore, a messenger is sent outside the nucleus to carry the code to the ribosomes.

11. 3 Types of RNA
Messenger RNA (mRNA) – made when DNA is transcribed into RNA
Transfer RNA (tRNA) – reads the mRNA during translation, translates it into amino acids.
Ribosomal RNA (rRNA) – RNA found in ribosomes

12. Structure of RNA RNA molecules are chains of nucleotides. RNA vs. DNA
Sugar in RNA is ribose, DNA is deoxyribose.
It is single-stranded.
4 Nitrogen bases are:
Adenine
Guanine
Cytosine
Uracil replaces Thymine

13. Gene expression: turning genes into specific traits, done by RNA.
IV. Introduction to RNA
Gene expression: turning genes into specific traits, done by RNA.
1st step: copy part of the DNA sequence into RNA (Ribonucleic Acid).  TRANSCRIPTION

14. 2nd: information in RNA is used to make a specific protein  TRANSLATION

15. NOTE! All base-pair rules are followed:
C = G
A = U, since T is gone

16. Transcription: RNA Synthesis
Copies DNA into mRNA
The RNA molecule will be COMPLEMENTARY to the DNA molecule, NOT identical –b/c it is in “RNA” language.
Carried out by RNA polymerase

17. Steps of Trans. 1. DNA “unzips”. Enzyme: DNA helicase
2. One strand is used as a pattern, or template, for RNA nucleotides.
3. mRNA nucleotides attach to one strand of DNA. Enzyme: Polymerase
4. Newly formed mRNA strand “peels” off and leaves nucleus.
5. DNA molecule “zips” back together

18. Only certain sections of the DNA code are transcribed into RNA
These sections are called genes. Only about 1.5% of DNA is transcribed

19. Transcription Practice!
DNA = A-T-C-T-G-T-T-A
RNA = ?

21. Translation – Process of using the info in mRNA to put together amino acids and make proteins. - Occurs in a series of steps, involves, 3 kinds of RNA, and results in a polypeptide.

22. In Translation:
mRNA leaves the nucleus and attaches to a ribosome in the cytoplasm
Every 3 letters, or bases, equals one codon
Each codon codes for one amino acid (building block of protein)

23. II. Nature of the Genetic Code
Genes are “directions” that help make proteins (made up of a.a.)
Each combination of 3 nucleotides on a strand of mRNA is called a CODON, or 3-letter code word.

24. Ex. C-U-G, A-C-U are both codons.
DNA and mRNA contain information as a sequence of nucleotides
The “words” of this language are all 3 nucleotide sequences called codons

25. Translation Continued:
4. Some codons code for instructions, like STOP. 5. tRNA picks up the correct amino acid in the cytoplasm. 6. Amino Acids attach to anticodons (reverse of codons) on tRNA. 7. tRNA brings the correct amino acid to the ribosome to be added to a growing chain that will become a protein.

26. Protein Synthesis
Protein synthesis is the forming of proteins according to the DNA code
Proteins determine traits
Central dogma: DNA  RNA  Proteins

27. Mutations: What are mutations? Mistakes or changes in DNA code
One single change in a base, or letter can completely change the meaning of the code.
Example: Sickle cell anemia results from a one-letter difference (point mutation) in the code for the red blood cell shape.

28. Mutations Continued:
Germ cell/sex cell mutations: May not show up in the parent, but can be passed onto offspring
Sperm or egg cells
Somatic Mutations:
Where do they occur? In all other cells except germ cells
Cannot be passed to offspring.

29. Mutagens:
Substances that cause alteration by a cell, such as UV light, x-rays, smoking, some drugs and other chemicals.
Most mutations are harmful, a few are beneficial and many are neutral.
Changes in the genetic code can lead to changes in the entire population of species.
To what can this lead? Cancer