Microbiology 251 Lecture Notes 9/19 to 9/23
Microbiology 251 Lecture Notes 9/19 to 9/23 BMB 251
Popular in Molecular and Cell Biology I
Popular in Microbiology
This 2 page Class Notes was uploaded by Julianna Sickafus on Sunday September 25, 2016. The Class Notes belongs to BMB 251 at Pennsylvania State University taught by SCOTT LINDNER in Fall 2016. Since its upload, it has received 16 views. For similar materials see Molecular and Cell Biology I in Microbiology at Pennsylvania State University.
Reviews for Microbiology 251 Lecture Notes 9/19 to 9/23
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/25/16
Microbiology 251 9/19 – 9/23 DNA Damage and Repair -after replication DNA can still be damaged -mutations in certain genes can affect the enzymes that repair DNA -deaniminated C -G in new strand is replaced with A -depurinated A -A-T pair is deleted -because undamaged DNA can serve as template (for mutated strand), enzymes can replace damaged strand based on undamaged strand -base excision repair: -DNA glycolases -find mismatched bases -cleaves N-glycosidic bond to remove damaged base -AP endonuclease removes deoxyribose -DNA polymerase adds missing nucleotide -DNA ligase seals nick -UV light and chemical mutagens produce “bulky” lesions -UV light breaks carbon-carbon double bond and makes one nucleotide covalently bond to another -UV damage usually to: -C-T, C-C, or T-T -polynucleotide excision repair: -excision nuclease recognizes lesion and introduces flanking nicks -DNA helicase removes polynucleotide between nicks -DNA polymerase adds nucleotides -DNA ligase seals nick -mismatched/damaged bases “flip” out of double helix and are recognized by proteins -requires energy -chromosomes can break -caused by replication errors -can be induced by X-rays and other high energy particles -mitochondria exist in cells as network -have multiple copies of DNA -mutated DNA is more tolerated -have no DNA repair mechanisms 2 major uses of homologous recombination 1) DNA repair (DSBs) 2) General recombination during meiosis (crossing over) -pairing of DNA strands from different DNA molecules is called DNA hybridization and the product is called a DNA heteroduplex How Cells Read the Genome: From DNA to RNA -transcription -usually more DNA made = more proteins made -RNA produced is complementary to template strand -grows from 5’ to 3’ -RNA polymerase synthesizes RNA -unwinds about 12 nucleotides of DNA and sustains an 8 nucleotide RNA/DNA heteroduplex -no helicase needed -no overwinding problem -rezips DNA -needs no primer
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'