{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

prelim 1 outline - NS 3200 Human Biochemistry Prelim 1...

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

View Full Document Right Arrow Icon
NS 3200- Human Biochemistry Prelim 1: Study Guide- Replication: DNA replication involves 3 steps: A. Initiation B. Elongation C. Excision-ligation (proofreading, patch up) Transcription: DNA to RNA Translation: mRNA to protein Base Nucleotides: Purines- A,G: Pyrimidines C,T (no T in RNA, U instead) Purines are larger than Pyrimidines If there is a pentose sugar attached to the nucleotide, its called a nucleoside Bases are hydrophobic G-C bond has 3 hydrogen bonds compared to A-T, which has 2. This requires a higher temperature to ‘melt’ the C-G base pair Chargaff’s rule: concentration of A=T, C=G Read DNA from 5’ to 3’ Always add nucleotides directionally through the 3’ hydroxyl end Dominant form of DNA is B-conformation. (A-conformation is overwound) Modification of bases: methylation can regulate or turn off gene expression Chromosomes and Chromatin: Components of Chromatin: made up of DNA, protein, and a small amount of RNA Euchromatin- transcribed chromatin; Heterochromatin is not transcribed (condensed) Chromatin becomes highly condensed to form chromosomes Basic Elements of Chromosome: autonomously replicating sequence (ARS); the centromere (spindle attachement site during nuclear division); and the telomeres(ends), which are involved in completion of DNA replication Composition of a Nucleosome: a nucleosome core contains two molecules of each histone (2A, 2B, 3, and 4) with DNA wrapped around the histones. Histone 1occupies the linker region between nucleosomes Acetylation of DNA packing: acetylation on the lysine reduces the positive charge and this weakens the electrostatic attraction between histones and the DNA. In general, acetylation of histones leads to activation of gene expression and deacetylation reverses the effect. Only eukaryotes contain chromatin. Prokaryotes do not have chromatin, histones, nuclear membrane and cell organelles 1
Image of page 1

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

View Full Document Right Arrow Icon
Basic Elements of a Gene: Gene: a gene consists of all the DNA sequences necessary to produce a single polypeptide or RNA product. Thus, the gene may not consist of contiguous sequences and need not code for a protein. Only one DNA strand codes for the protein, this is called the sense strand. The other strand does not code for the protein and is referred to as the anti-sense strand. A gene has both. Defining regions of a gene: Promoter : sites at which RNA polymerases and other regulatory proteins bind to DNA. Cis-acting elements: Specific sequences that bind trans-acting factors that influence gene expression. Transcriptional start site: Site on the DNA at which mRNA synthesis begins Translational start codon: consists of the three nucleotides “ATG” Introns: Intervening sequences in a gene that do not code for protein sequence and are removed during mRNA maturation Exons: DNA sequence that code for protein Termination codon: the end of the coding region of a gene Polyadenylation site: DNA sequence at the 3’ end of a gene that signal for adenosine nucleotide addition in the mRNA Transcriptional termination site: Signals present in DNA to terminate transcription
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern