Microbiology Lecture -3 :Procaryotic Cell Structure and Function
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What does the term amphipathic ?
What do hopanoids do for the plasma membrane ?
It means that there is a hydrophobic and hydrophilic.
What does Archaea have for a phosphlipd bilayer ?
ether-linked , glycerol
Which of the following are passive or Active transport ?
What are the locations for metabolic processes ?
- lipid and cell wall synthesis
What percent of the cytoplasm is water ?
What are the major structures of the cytoplasm ?
DNA, ribosomes and inclusions
Name the three types of Eukaryotic protein fibers ?
- Microfilaments (comprised of actin)
- Intermediate filaments
Where do Ribosomes in the "matrix" send there proteins and where do the "plasma attached" ones go ?
What is the size of the ribosomes in the prokaryote and the eukaryote ?
Matrix stay in the Matrix
Plasma bound ones go outside of the cell
procaryotic ribosomes 70S (Svedberg units), smaller than eucaryotic ribosomes(80S)
What are the two subunits that make the 70S ribosome?
50S and 30S
What are condensins , and how do they function with RNA ?
Does Procaryotic chromosomes have histones?
They supercoil chromosomes
No they don't
Does DNA perfrom negative or positive supercoiling ?
DNA uses negative supercoiling
Explain DNA supercoiling in bacteria Type I and II ?
- Type I/Topoisomerase I: cuts one strand of DNA; reanneals the strand
- -Relaxes the helix
TypeII/DNA gyrase: cuts both strands of DNA; reanneals the strands
What do Archaea supercoiling use ?
Histones + DNA
Where does replication begin , what is the single sites name ?
origin of replication (oriC)
What is the replication method of the bacterial chromosome called ?
How is the replication of a bacterial plasmid usually performed ?
by a rolling circle
How can a plasmid be transferred from one organism to another ?
via horizontal (lateral) transfer
What are Resistance Plasmids Factors ?
What are Fertility Plasmids/Factors?
What are resistance plasmids?
plasmids with genes that code for resistance to antimicrobial drugs
Play a major role in conjugation–Encodes genes for attachment and plasmid transfer
Can have genes that code for resistance to–antibiotics–heavy metals (cadmium, mercury)–disinfectants
1.Explain how bacteria reproduce Asexually ?
2.Under special conditions what type of reproduction does bacteria undergo ?
3. What is it called when bacteria have sexual reproduction ? What fertility letter/symbols are present ?
1.Reproduce by binary fissionincludes snapping division.
2.Some procaryotes will reproduce by budding
3.Sexual Reproduction–Conjugation–Fertility factor; F+/F-
Identify the following ways to increase genetic variation ?
1.Transfer of DNA from one cell to another
2.Taking up DNA from the environment (neighbor dies and DNA material is absorbed)
3.Transposons: mobile genetic elements This can happen between the plasmid and chromosome."Jumping Genes"
4.Bacterial DNA is transfered to the Virus
What are cell inclusions / inclusion bodies ?
Serve as energy reserves or as reservoirs for structural building blocks.
Also called inclusion bodies
Inorganic phosphate in the form of polyphosphate–Glycogen–Elemental sulfur
What are Magnetosomes ?
contain the iron oxide, magnetite (Fe3O4)
• allows bacteria to respond to the earth’s magnetic field–act like magnets and help bacterial cells align on the Earth's geomagnetic field.
–north-seeking bacteria predominate in the northern hemisphere and south seeking bacteria predominate in the southern hemisphere.
What are gas vesicles and vacoules ?
buoyancy–confers buoyancy to cells by decreasing their density–Maintains buoyancy so that cells can remain at the depth of water most appropriate for them to receive sufficient amounts of oxygen, light and nutrients
What are Biofilms ?
Are they ubiquitous ?
•Definition–Complex and highly organized microbial communities consisting of layers of microbial cells associated with physical surfaces
What is the difference between simple and complex biofilms ?
simple is usually one layer of organisms
A complex is multiple organisms , and different ones.
What are some benefits of a Biofilm ?
–Increased protection from harmful agents•E.g. host defenses (antibodies), antibiotics and UV radiation.
–Increased access to nutrients and the removal of toxic waste.•The waste of one microbe can serve as the food source for another.
–Increased genetic diversity.•DNA from one organism when it dies may be taken up by another organism (transformation/lateral transfer)
–Members within a biofilm can cooperatively protect the entire population from antibiotics.
–The structure of biofilms makes it difficult for drugs to reach the intended target.
What is EPS: exopolysaccharide ?
It helps biofilms attach to a surface.
What is Quorum sensing ?
Cell to cell communication that allows a bacterial population to determine cell density.
What are the molecules called that are used in quorum sensing ?
Are they different in Gram negaitve organisms?
- 1. AHL (N-acyl homoserine lactone
What auto inducer is used by both Gram - and Gram + ?
2. AI-2 (autoinducer 2): furonone-Produced by both Gram-negative and G-positive bacteria
What are Oligopeptides ?
- Short peptides produced by Gram-positive bacteria used in quorom sensing
What is aA-factor (gamma-butyrolactone)?
- Produced by filamentous Gram-positive bacteria
Used for antibiotic synthesis and sporulation
What is 4-Hydroxy-alkyl-quinoline ?
Produced by Pseudomonas aeruginosa for virulence and biofilm formation
What does Pathogenic mean ?
What are Obligate parasites ?
Have the ability to cause disease in humans–Can live on the surface of cells, or within cells
Can only live inside host cells
What are sporozoans ?
What type of spores do the following make ?
species of microorganisms that produce spores
- Bacteria- asexual
- Fungi - asexual , sexual
- Protozoa - asexual
What are bacterial spores called ?
What type of organisms tend to make them ?
Endospores-help bacteria survive harsh environmental conditions which are not favorable to growth.–Confers resistance to environmental factors such
Gram + Bacilli
1.What are the following components of the endospore ?
Spore cell wall:
2.What is sporangium ?
1.Exosporium: outermost, thin covering of the endospore
Spore coat: composed of several protein layers (dipicolinic acid, calcium ions), may be thick
Cortex: layer inside spore coat, made of peptidoglycan
Spore cell wall: inside cortex, surrounding protoplast and core
Core: nucleoid and ribosomes
2.Structure of endospore within the mother cell which is called a sporangium–
Place this in order start from the most inner layer ?
Germ cell wall
- Inner membrane
- Germ cell wall
- Cortex membrane
Explain these 4 closed environment stages of a bacterial cell ?
cell are just beginning to grow–slow growth due to adjustment, enlargement, and synthesis
geometrical increase in population size–Concept of generation; generation time•Equals one complete fission cycle where one cell becomes two
population reaches maximum capacity–same number of cells multiply as die–nutrients are depleted and waste products are excreted in the environment, high density
more cells die than multiply–population number decreases drastically
Explain the process of sporulation ,be sure to include germination ?
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