Exam 1: Lecture 4 Flashcards
Anaerobic Respiration (Fermentation)
- Partial breakdown of organics that occurs without O2
2. Yields 2 ATP
Aerobic Respiration
- Complete breakdown of organics with O2
2. Yields 36 - 38 ATP
Comparison of Aerobic Respiration & Fermentation
Both use Glycolysis (Glucose -> pyruvate)
Have different final e- acceptors (O2 vs pyruvate/acetaldehyde)
36/38 ATP vs 2 ATP
Obligate aerobes
Require an ample oxygen source to perform respiration
Microaerophilic/microaerobic
Requires small amounts of oxygen
Capnophilic
Microbes require low oxygen and high carbon dioxide conc
Facultative Anaerobes
Organisms that perform anaerobic glycolysis in the absence of oxygen but can perform aerobic respiration in the presence of oxygen
Obligate anaerobes
Die in presence of oxygen because they lack chemistry to produce organic compounds via reduction of oxygen
3 Main mechanisms bacteria use to adapt to changing environments
Mutation
Gene Transfer
Regulation of gene expression
Types of Mutations in bacteria
Base substitutions
Removal or addition of nucleotides
Transposable elements
Types of Gene Transfer in bacteria
Transformation
Transduction
Conjugation
Base substitutions
Most common
occurs when one base pair is changed (point mutations)
Silent mutation
single base sub in 3rd base nucleotide of codon.
results in NO change in amino acid, 1st 2 letters of genetic code are most critical
Missense mutation
single base sub in 1st/2nd base position
results in changed amino acid
Nonsense mutation
single base sub that yield stop codon
3 nonsense codons in genetic code
Frameshift mutation
genetic mutation caused by insertions or deletions of a number of nucleotides in DNA sequence that is not divisible by 3
Transposable Elements
Special segments of DNA that move spontaneously from 1 gene to a different gene
Transposons may disrupt the integrity of the gene and render its protein product nonfunctional
Gene Transfer
Widespread among bacterial cells
intercellular transfer = genetic material passes from donor cell to recipient cell
Leads to genetic diversity
Transformation
Recipient cell directly takes up naked DNA released from the donor cell altering its genotype
It can occur in the medium
Natural transformation can also occur
Frederick Griffith (Griffiths Experiment) showed 1st demonstration of transformation
Transduction
process by which DNA is transferred from one bacterium to another by a virus
Conjugation
suitable donor cell (male) comes near a recipient cell (female), established direct cell to cell contact and transfers genetic material
Plasmids most frequently transferred by conjugation
Sex pilus responsible or attachment of donor (F*) to recipient (F)
Transfer of antibiotic resistance can occur by conjugation
Operon info
Group of genes that are transcribed at the same time
usually control important biochemical process
Only found in prokaryotes
Genes are turned on/off via operons
Operon Structure
Promoter + operator + structural genes
Repressor binds to operation = transcription prevented
Lac operon
consists of 3 genes each involved in processing the sugar = lactose
One of them is the gene for enzyme B-galactosidase (lactase)
This enzyme hydrolyses lactose into glucose and galactose
Symptoms of Lactose intolerance
Bloating Pain or cramps in lower belly Gurgling sounds Gas Loose stools Diarrhea
Possible nappy rash
When Lactose Gene is turned off….
there s no lactose to inhibit the repressor, so repressor binds to the operator, which obstructs the RNA polymerase from binding to the promoter and making lactose
When Lactose Gene is turned on….
Lactose is inhibiting the repressor, allowing RNA polymerase to bind with the promoter, and express the genes, which synthesize lactose.
Eventually, lactase will digest all of the lactose, until there is none to bind to the repressor.
The repressor will then bind to the operator, stopping the manufacture of lactose
Gram + color of stain
Purple
Gram - color of stain
pink
Structure of Gram +
Peptidoglycan (thicker than Gram -) - outer
Membrane - inner
Structure of Gram -
Outer membrane - outer
Peptidoglycan - middle
Membrane - inner
Phases of Microbial Growth
Lag
Log
Stationary
Death
Lag phase
- occurs after microbes have been added and represents the period of time the organisms need to adapt to new environment
pop growth at this time is slight, very close to 0
Log phase
- represents period of optimal population growth
microbes approach carrying capacity (K), if pass it then run out of nutrients/space and can crash
Stationary phase
- populations levels and growth nears 0
2. can last for a long time
Death phase
- waste and dead cells begin to accumulate
2. pop declines, but doesn’t crash
Infection
invasion of an organisms body tissues by disease-causing agents, there multiplication and the reaction of host tissues to these organisms and the toxins they produce
Infectious disease
known as transmissible disease or communicable disease
illness resulting from an infection
