Molecular Biology

Molecular Biology - Purines: Adenine and Guanine...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Purines: Adenine and Guanine Pyrmidines: Cytosine and Thymine A binds with T, C binds with G The phosphate groups in DNA is what makes it have an overall negative charge - The peptide bonds with a carbon between them are the backbones of proteins. If enzymes decide to bind to a specific sequence of nucleotides in DNA, they will interact with purine/pyrimidine bases, but not with the backbone of the peptide. Nucleotides – linked by phosphodiester bonds. - Between the 3’ hydroxyl group of one deoxyribose and the 5’ phosphate of the next deoxyribose. - The only unique part of a nucleotide is the base (sugar) DNA – a right-handed double helix - Between adenine and thymine, we have two hydrogen bonds - Between cytosine and guanine, we have 3 hydrogen bonds. - DNA is double-stranded, and each strand is antiparallel. Annealing/hybridization – binding of two complementary strands of DNA Melting/denaturation – separation of two complementary strands of DNA Temperature at which 50% of a solution of DNA molecules melts: T m . Bases that have more C-G pairs will have a higher T m than bases with A-T pairs? Why? Because A-T has two hydrogen bonds between them, while C-G has three…thus it takes more to break the C-G bond. In the double-stranded DNA helix, there are van der waals attractions between the bases, which are in the interior of the double helix. Prokaryotic (bacterial) genomes are singular and circular . Viral genomes are linear or circular, and consist of RNA or DNA. DNA gyrase – twists the large circular DNA molecule in prokaryotes to make it compact. - Breaks the DNA and twists both ends. In eukaryotes, DNA is wrapped around histone proteins - Why? Because histidine is a positively-charged amino acid (basic), and DNA is negatively-charged. - Note that lysine is also abundant in histone proteins - DNA wraps around the histones . Nucleosomes – beads on a string - DNA wrapped around 8 histones. Reverse transcriptase – what viruses use to make RNA from DNA
Background image of page 1

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

View Full DocumentRight Arrow Icon
- Understand the terms transcription and translation - Know that the central dogma is DNA RNA protein. DNA mRNA - mRNA then travels out of the nucleus and into the cytoplasm (it needs to be methylated at the 5’ end as a “cap,” and a poly-adenosine tail is added at the 3’ end to protect this molecule from degradation while traveling in the cytosol. Protection is from potential lysozymes or other degradative molecules. - mRNA travels through ribosomes (made from rRNA, synthesized in the nucleolus). Stop codons – also called “nonsense codons” - UAA, UAG, UGA Switching the 3 rd nucleotide in the majority of codons has no effect on the production of the appropriate amino acid - Known as the wobble hypothesis . One codon cannot specify for two amino acids, but several amino acids can be produced by more
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/07/2010 for the course CBN 356 taught by Professor Merill during the Spring '08 term at Rutgers.

Page1 / 6

Molecular Biology - Purines: Adenine and Guanine...

This preview shows document pages 1 - 3. Sign up to view the full document.

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