1. NUCLEIC ACIDS & PROTEINS
HL BIOLOGY
Van Roekel
11/6/14

2. BILL
Draw and label a simplified structure of DNA.

3. Enzyme Lab Lab Report Due – Friday, November 14.
If data is not completed, schedule time with me to complete it.
Be sure to graph processed data and figure our averages and standard deviations.
Print copy off, no google docs!

4. Nucleic Acids
Nucleic Acids are organic compounds that code for protein sequences.
REMEMBER:
DNA 
RNA
Protein

5. DNA Structure Two antiparallel strands in the shape of a double helix.
Each strand is a chain of nucleotides bonded together
Nucleotides are composed of phosphate group, deoxyribose sugar, and one of four nitrogenous bases.

6. Nucleotide O O=P-O N CH2 O C1 C4 C3 C2 Phosphate Group 5
Nitrogenous base
(A, G, C, or T)
CH2 O C1 C4 C3 C2 5
Sugar
(deoxyribose)

7. DNA Structure-Nucleotide
For HL (IB BIO II) you need to be familiar with the numbering of carbon atom in sugar

8. DNA Structure- Backbone
DNA backbone is composed of alternating deoxyribose sugar and phosphate groups
Held together by covalent bonds called a phosphodiester bond.
Phosphate—oxygen—carbon

10. DNA Structure-Backbone
Condensation reactions occur between the phosphate group of the 5’ carbon and the hydroxyl group on the 3’ carbon.
Nucleotides are always added to the 3’ side of chain.
DNA strands always have a free 5’ carbon end with a phosphate group and a free 3’ carbon end with a hydroxyl group attached

11. Nucleotides are bonded together by condensation reactions

13. DNA Structure-Base Pairing
Nitrogenous bases are held together by hydrogen bonds
Purines always pair with Pyrimidines
Adenine pairs with Thymine via two hydrogen bonds
Guanine pairs with Cytosine via three hydrogen bonds

14. DNA Structure-Base Pairing
Purines
Pyrimidines
Double ring structures
Single ring structures

15. 2 minute convo
Summarize how nucleic acids are formed.

16. DNA vs RNA DNA 1- Deoxyribose sugar
2- Bases: Adenine, Thymine, Cytosine, Guanine
3- Double-stranded helix arrangement
RNA
1- Ribose sugar
2- Bases: Adenine, Uracil, Cytosine, Guanine
3- Single stranded

18. BILL - Compare DNA and RNA
Deoxyribose Sugar
Thymine as a base
Double stranded
Ribose Sugar
Uracil as a base
Single Stranded

19. DNA Packaging
DNA is paired with a type of protein called a histone to form a nucleosome
Nucleosome: the basic unit of DNA packaging
DNA wrapped around two protein molecules, each of which has 4 different histones
Negatively charged DNA is attracted to Positively charged histones

20. DNA packaging-Nucleosome

21. DNA Packaging-Nucleosome
When DNA is wrapped around histones, it is inaccessible to transcription enzymes
Packaging thus controls transcription process, only allowing certain areas to be involved in protein synthesis
Nucleosomes are essential to the “supercoiling” of DNA molecules to form chromosomes-tightly packs all genetic material into condensed chromosomes.

23. DNA Sequencing Protein-Coding Sequences
Single copy genes with coding functions.
Provide base sequences essential to produce proteins at cell ribosomes.
2% of human genome codes for proteins
Determined by Human Genome Project: began in 1970s, completed in 2001

24. DNA Sequencing Protein-Coding Sequences
Genes are made of numerous fragments of protein encoding information, and non-encoding fragments.
Protein encoding fragments are exons
Non-protein encoding fragments are introns

26. DNA Sequencing Highly repetitive sequences
5-45% of human genome
Composed of base pairs per repetition
Up to 100,000 replications
….GTTACGTTACGTTACGTTACGTTACGTTAC….
Satellite DNA: clusters of repetitive DNA in discrete areas
Repetitive DNA does not code for proteins

27. DNA Sequencing-Structural
Structural DNA is highly coiled DNA that does not have a coding function.
Generally located around centromere and on ends of chromosomes.
A.K.A “Pseudogenes” which have no function

28. Review Questions
Draw the two strands of a DNA molecule representing their antiparallel relationship and complementary base pairing.
Explain how nucleosomes would contribute to transcription control.
Would exons or would introns be more likely to contain highly repetitive sequences? Why?