BIO207 Study Guide - Spring 2018, Comprehensive Midterm Notes - Bacteria, Macrophage, Pathogen
BIO207
MIDTERM EXAM
STUDY GUIDE
Fall 2018
Antibiotics and Control of Pathogen Growth
• How We Control Growth in Bacteria
o Resistant: antibiotics are non-effective
o Sensitive: antibiotics are effective
o Control Mechanisms
▪ Physical
• Heat (steam or dry heat) = autoclave
• Radiation = causes different changes in DNA which leads to
non-viability; in humans you can get skin cancer
▪ Chemical
• Chemotherapies
▪ Mechanical
• Air = by filtering out the air you can sterilize things
• Liquids
▪ Biological
• don’t really use anymore
• people are starting to try phage therapies for certain terminal
illnesses (uses bacteria phages/virus to kill a specific
bacteria)
• double edged sword because phages kill bacteria but could
also become lysogenic
o Germicides: chemical agents that specifically kill pathogens
o Disinfectant: chemical agents that can kill vegetative pathogens, not
endospores
o Antiseptic: agent that prevents sepsis (blood-born infections)
o Antibiotics: agent that kills microorganisms as specifically as possible
(but will damage good bugs)
• Disruption of Functions
o Biological functions that are disrupted by colicins are essential functions
to cell survival
o Proteins and enzymes are the targets of antibiotics because all of the other
molecules don’t have functions
o Changes brought on by mutations can result in death of microbes
• Autoclaves
o Autoclaves: sterilant machines that use a combination of pressure,
steam, and heat to destroy solid and liquid material
o Works by pumping steam into the steam jacket (pressurizes)
o Steam penetrates endospores (makes it a true sterilant; kills everything)
o Expose organisms to 2-5 ATM of pressure and 150 degrees Celcius or
higher temperatures
• Ultraviolet Light
o UV light is often used to sterilize equipment as well
o UV light causes thymine dimers that creates holes in DNA that can be
excised or mutated
find more resources at oneclass.com
find more resources at oneclass.com
o Cancer can be caused when you oversaturate your body’s ability to resolve
mutations; once this happens often, cancer forms
• Antibiotics
o Penicillin was discovered by accident
o We have proteins in our body that act like natural antibiotics
▪ Lysozyme: enzyme that has very distinct active site which binds to
the crosslinking aspects of peptidoglycan and cleaves them
• found in many sebaceous secretions
• through the process of hydrolysis, the lysozyme
breaks/cleaves NAM and NAG
• Lysozyme is a bactericidal enzyme
o Cidal = kills
o Static = no growth (does not kill)
• Beta-Lactams
o Square ring; come in a few types (ex. Penicillin)
o Useful against gram positive infections and can be used for gram negative
infections but aren’t as effective
o Unlike lysozyme which destroys pre-formed peptidoglycan crosslinks, beta
lactams prevent the cross-links from even forming
▪ The proteins that do this job are known as penicillin-binding
proteins
o As a cell divides, it must make new and form new crosslinks between NAM
and NAG in order to maintain osmotic homeostasis
• Antibiotics
o Macrolides: bind to large subunit of ribosome; specifically, to 50s aspect
▪ Prevent the unit from sliding on the mRNA and continuing
translation
o Tetracycline: inhibit protein synthesis
o Amino glycosides: 3 ring structures in vertical arrangement
▪ Distort codon/anticodon matrix
▪ Bind to the 30S rRNA which skews the rRNA complex, which in
turn gives the wrong codon to translate into the wrong amino acid
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Dna-rna-protein: these can be subject to mutations. General: gram-negatives have an lps: can produce a disease without an exotoxin. ); bacteria infect a living organism prior to infecting you: three distinct mechanisms of how you get infected, ingestion: vector borne, inhalation: droplet, airborne, open exposure: contact, vector borne, common vehicle, open wounds and burns. Shiga like toxin (has very specific entrance point: enters through gb3 receptor which is unique to erythrocytes and endothelial cells, meaning shiga like toxin only kills rbcs and blood vessel cells) Shiga toxin travels to kidneys and can destroy kidneys (big reason why people die from this) Can"t treat with antibiotics because more phages will be produced which produces more toxins. Locus of enterocyte (make eukaryotic cell produce receptor for the ligan they use to adhere; make sthe cell go from flat to curved so membrane surrounds the e coli, and the biofilm cannot be taken out)
