Bacteria Structure and Function Flashcards
Give 6 key differences between prokaryotes and eukaryotes?
Size: Pro: 0.2-2.0µ, Euk: 10-100µ diameter
Nucleus: Pro: No, Euk: yes
Organelles: Pro: No, Euk: yes- golgi, mitochondria, endoplasmic reticulum
Cell wall: Pro: Yes(peptidoglycan), Euk: No
Ribosome: Pro: small(70S), Euk: Larger (80S)
DNA: Pro: single cirular chromosome- no histones, Euk: multiple linear chromosomes with histones
give a short description for binary fission? what kind of reproduction is it?
Asexual reproduction
Circular DNA strand replicated, using a signal –> DNA attachment and cell growth—>Pinching of cell mem—>Division of the cells—-> two Daughter cells formed.
What is bacteria growth limited by?
Bacterial growth is only limited by their concentration in the medium, and not by the available surface area.
What are the different agar media?
Nutrient agar
Blood agar
BHI-Brain heart infusion
What are the pro and cons of liquid medias?
Pros: Bacteria grows quicker, can be helped with different manipulations, can grow lots and lots of different bacteria in the tube
Cons: Cant really tell the difference between the bacteria growing unless they have a different colour change.
What are the variables affected by?
Temperature
Time
Type of bacteria
The nutrient amount/type
What measurement is used to measure the bacteria growth?
Optical density/cell density
What are the 4 phases of bacterial growth?
Lag
Log
Stationary
Death
Why does the death phase rarely touch 0?
Because dead bacteria will still absorb the light giving a result.
How can you see the death phase more clearly?
Use both the liquid media to see the other phases and then use the agar media to see the death phase.
What are the 3 main bacteria temperature groups? give there names and optimal temperature
Psychrophiles: 15 or below
Mesophiles: 25-40 42( for avian fl becuase they have higher body temperature)
Thermophiles 50-60 or below, can go even over 100 in underwater vents!
What are the 3 main bacteria pH groups? give there names and optimal pH
Acidophile: less than 5.4
Neutrophiles: 5.4-8.5pH
Alkaliphiles: 7-12pH
Why do bacteria need potassium, magnesium, calcium and other cofactors?
For proper enzyme function
Do strict anarobes like or dislike highly oxygenated cells?
Dislike will have mechanisms to limit the oxygen intake in the cells
What is the difference between Gram negative and positive?
Gram negative: thin peptidoglycan sandwiched between 2 membranes
Gram positive: Thick peptidoglycan on the outside and then you have the plasma membrane
What are the 3 main functions of the cell membrane?
Defence
Resist stress (osmotic stress)
barrier for ultraviolet going into cell also helps against stress.
How would you distiguish Gram negative and positive from each other?
Gram positive: Purple
Gram negative: Pink
What is the main fucntion of peptidogylcan?
Peptidoglycan stabilises the cytoplasmic membrane enabling it to withstand high internal osmotic pressures
What are LPS used for on the membrane?
Biofilm formation
For defence
Virulence
What are some of the advantages of having a capsule as a bacteria?
Covers the membrane in polysaccharide like matri which can help in evading the immune response of the host/ cant bind to receptors
Can evade both adaptive and innate immune responses
Can give rise to antimicrobial resistance as the antibiotic is not able to penetrate the capsule and attack the bacteria
Can help in adhereance
What are the 3 main bacterail tails and what are their functions?
Fimbriae: cell adhesion (attachment)
Pili: genetic exchange, adhesion
Flagella: motility (movement)
