BCH4024 - Exam IV Studyguide

BCH4024 - Exam IV Studyguide - BCH 4024 INTRODUCTION TO...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
BCH 4024 INTRODUCTION TO BIOCHEMISTRY AND MOLECULAR BIOLOGY DR. MAVIS AGBANDJE-McKENNA DNA Review questions LECTURE 45 1. What are the heterocyclic bases found in DNA? In RNA? DNA – Adenine, cytosine, guanine and thymine RNA – Adenine, cytosine, guanine and uracil 2. Which types of bases have a double ring structure? Which have one? Purines (A and G) have double, pyrimidines (C, T and U) have one 3. Which bases form H-bonds to each other? How many H-bonds do they form? 2 bonds - A=T and A=U 3 bonds – C= G 4. What are the components of a nucleoside? A Nucleotide? Nucleoside – heterocyclic base + sugar Nucleotide – heterocyclic base + sugar + phosphate groups 5. What is a glycosidic bond? What is a phosphodiester bond? Glycosidic bonds – links heterocyclic base to sugar Phosphodiester bonds – link nucleotides in DNA and RNA; attaches hydroxyl group on the 5’ C and the 3’ hydroxyl at the other end; Reactive nucleotide phosphates added to growing polynucleotide chain at 3’ end 6. At which atoms are glycosidic bonds formed between bases and sugars in nucleic Pyrimidines: N1 to C1’ Purines: N9 to C1’ 3’C to 5’C 7. What are the main properties of a nucleic acid chain? A. Chain has polarity – 3’ end and 5 end
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
B. Alternating sugar-phosphate backbone (hydrophilic) C. Variable bases: A, G, T, C or U 8. Why are DNA and RNA considered to be acids? Phosphate groups are strongly acidic. DNA and RNA carry strongly negative charge at physiological pH. 9. What are the main forms of DNA? How do they differ? - A form o Right handed o Dehydrated, non-physiological o Major groove deep, minor groove shallow; same width - B form o Right handed o Fully hydrated as in vivo o Major and minor grooves are same depth, but major groove is wider - Z form o Left-handed o G-C rich o High energy form 10. What properties of the DNA helix ensure specific protein-DNA interactions? - N and O atoms at the edges of base pairs can make H-bonds to the side-chains of proteins. - Sequence specific recognition sites – H in cytosine and CH 3 in thymine. - NOTE: Interactions of proteins with the sugar-phosphate backbone are non- specific 11. What properties determine the stability of DNA? 1. Hydrophobic interactions by base stacking 2. H-bonding between N bases, Pu=Py 3. Cations neutralize PO 4 - 4. Divalent cations and polyamines cross-bridge PO 4 - residues Which conditions cause denaturation? - Acid - Alkali - Heat 12. What forms/shape can DNA adopt? A. Linear, ds or ss B. Circular – relaxed or supercoiled LECTURE 46 – Biosynthesis and Degradation of Nucleotides 13. How is PRPP synthesized? ATP + ribose-5-phosphate 5’-phosphoribosal-1-pyrophosphate (PRPP)
Background image of page 2
What are its roles in nucleotide metabolism? De novo
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 17

BCH4024 - Exam IV Studyguide - BCH 4024 INTRODUCTION TO...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online