Prokaryotic Cell Structure and Function.txt
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Prokaryotic Cell Structure and Function.txt
structures and functions
What does the bacteria plasma membrane consist of in bacteria?
Phospholipid and protein bilayer
No sterols (cholestrol) but hapnoids to stablize membrane.
What do the hapnoids do?
Stabilize the membrane.
What is the main function of the plasma membrane?
To serve as a selective permeable barrier for materials entering and exiting the cell (semi-permeable).
What are the other functions of the plasma membrane of a bacteria?
Retains the cytoplasm
Serves as the transport system for nutrient uptake, waste excretion, and protein secretion
What are the passive processes for transport?
simple and facilitated diffusion and osmosis.
What are the active processes of transport?
Active transport and group translocation.
Does metabolic processes take place in the plasma membrane of a bacteria such as respiration, photosynthesis, lipid, and cell wall synthesis?
What do the receptor molecules do in the plasma membrane?
they respond and detect chemicals signals from the organism's surroundings.
In archaea, is there a single or a phospholipid bilayer in the cytoplasm? How are the molecules linked?
single layer and it has ether-linked molecules (glycerol)
Where is the cytoplasm located?
inside the plasma membrane.
What percentage is water of the cytoplasm?
What is the cytoplasm packed with?
proteins in the form of enzymes
low molecular weight compounds
is the cytoplasm a highly organized protein location?
What are the major structures of the cytoplasm?
As of 2001, what does the cytoplasm of prokaryotes known to possess?
What does the cytoskeleton have?
homologs to proteins found in eukaryotes
What does the matrix serve as?
As scaffolding for cytoplasmic components
What does the cytoskeleton do?
helps bacteria maintain its shape and aids in division
In eukaryotes, what are the types of eukaryotic protein fibers?
Microfilaments (comprised of actin)
What are the actin homologs in Bacteria and Archaea?
What are the Tubulin homologue found in Bacteria and Archaea?
What is the intermediate filament homologue?
Crescentin (Caulobacter crescentus)
Where are the ribosome located at?
Cytoplasmic matrix and attached to the plasma membrane
Do the ribosomes in the matrix that are synthesized, remain in the cell or no?
The ribosomes that are synthesized in the matrix remain in the cell.
Do the ribosomes that are attached to the plasma membrane synthesize proteins for transport outside the cell?
yes ribosomes do synthesize proteins for transport outside the cell.
What is the ribosomal Rna (5s, 16s, and 23s) of bacteria similar to?
18s rRna of eukaryotes
What is found in the nucleoid?
the Bacterial chromosomes, it is the region that contains the Dna.
In most prokaryotes, there is a single chromosome, what does it look like?
Circular, double- stranded
some have linear chromosome such as in Borrelia and Branched are rare
What is supercoiling?
Supercoiling in when the Bacterial Dna is wound up into a smaller unit, it is twisted in the opposite direction from the right-handed double helix.
What do Condensin and Rna help with in regards to supercoiling?
help in supercoiling
What do prokaryotic chromosomes not have?
What are the two types of supercoiling?
Positive supercoiling and negative supercoiling
What is positive supercoiling?
Is what results when additional turns are introduced and left-handed supercoiling, overwinding, is introduced
What is negative supercoiling?
Results when additional turns are removed and right-handed supercoiling, underwinding is made.
In the Dna structure of bacteria cupercoiling, there are two types of enzymes what are they?
Type 1 Topoisomerase 1 and topoisomerase 2
and Dna gyrase is in topoisomerase 2
What does the type 1/ Topoisomerase 1 do?
cuts one strand of the Dna and reanneals the strand, relaxes the helix, and is used to reduce some of the torsional strain produced by the unwinding of dna.
What does Type 2/ Dna Gyrase do?
Cuts both strands of dna, reanneals them both, allows unbroken strands of dna to pass through, and it is used to introduce supercoils, knots; important for catenation.
what are knots
important for catenation.
How is supercoiling accomplished in Archaea?
By the use of histone proteins.
What is the Archaeal nucleosome made of?
Achaeal histones + Dna
Supercoiling in eukaryotes
Histones help to supercoil the dna.
Supercoiling forms eukaryotic nucleosomes.
: H1: h2: H2b, h3, and h4
eight molecules form the nucleosome but from h1
OriC is the site of what?
What does the oriC use?
a multi-enzyme replication complex which binds to the origin of replication and initiates unwinding and separation of the two dna strands
What are the types of enzymes that are used in the replication process of the OriC?
dna gyrase (topoisomerase type 2)
single stranded binding proteins (ssBps)
What is the replication method of the bacterial chromosome?
Replication of a bacterial plasmid is performed by what kind of a method?
rolling circle from the 5' to 3'.
What are plasmids?
Plasmids are small circular double stranded dna molecules independent of the chromosome (extra chromosomal) and do not carry genes essential for survival.
Are plasmids self replicating?
Yes, and they exist and they replicated independently of the bacterial chromosome.
Plasmids have three characteristics what are they?
They are small double stranded molecules independent of the chromosomes, self-replicating, and are inheritable in where they can be ingerited from parent cell to daughter cell.
How are plasmid transferred from one organism to another?
Via horizontal (lateral) transfer.
Do plasmids often exist as copies?
Can plasmids be integrated into the main bacterial chromosome?
What are the two plasmid types?
What are the four ways to increase genetic variation?
What is the function of cell inclusions?
Cell inclusions serve as energy reserve or as reservoirs for structural building blocks.
What are the types of inclusion bodies?
Granules of the lipid, poly-bets-hydroxbutyric acid (pbh) and inorganic phosphate in the form of polyphosphate
Elemental sulfur (appear as globules)
What are the gases in the gas velicles that are spindle-shaped and made of protein?
N, o, co2, co, h2, ar ch4
What are gas vacuoles?
are aggregates of individual gas vesicles
Where are the gas vacuoles found?
in many aquatic planktonic prokaryotes such as cyanobacteria, certain species of purple and green photosynthetic bacteria, and in some species of Archaea.
What is the function of gas vacuoles?
gives buoyancy to cells by decreasing their density so that they can be in correct depth to oxygen and light.
What are biofilms?
Are complex and highly organized microbial communities consisting of layers of microbial cells associated with physical surfaces.
Are biofilms ubiquitous?
Yes. Bacteria can be free-living but most species exist as biofilms and are present everywhere: soil, water, and environmental surfaces.
What are some of the devices that biofilm organisms grow in?
catheters and syringes, dishes, and contact lenses.
What is the layer of slime called that forms across the surface of liquids?
What are pellicles important for?
in clogged drains and sewer systems.
Do Biofilms form on surfaces of living organisms? if so, where?
tongue (results in halitosis)
: dental plaque
What are the benefits of forming a biofilm:
Increased protection from harmful agents.
Incresed access to nutriends and the removal of toxic waste
Increased genetic diveristy
In biofilms, how is increased access to nutrients and the removal of toxic waste important in the benefits of formation of a biofilm?
The wast of one microbe can serve as a source for another.
How is the increase in genetic diversity a benefit from the formation of a biofilm?
The dna from one organism when dies may be taken up by another organism (transformation/ lateral transfer)
What do the cells in a biofilm secrete?
signaling molecules that recruite nearby cells.
Besides the signaling molecules that are secreted from the cells in a biofilm, what else is secreted?
An extracellular matrix that consist of proteins and polysaccharides.
When the cells in a biofilm secrete an extracellular matrix in a biofilm, what do they help with?
Allow for attachment to surfaces and to each other, expopolysaccharide, and surfactin.
What is quorum sensing?
Cell to cell communication that allows a bacterial population to determine the cell density.
Why is it necessary to have a high cell density due to quorum sensing?
Various metabolic responses are initiated when the cell density is high such as spoulation, and antibiotic synthesis.
What is quorum sensing important for?
Microbial processes such as biofilm formation, sporulation, and filamentation.
What are the molecules called in quorum sensing?
By what Gram stain are inducers produced by and what is an example?
Gram negative and an example is Ahl (N-acyl homoserine lactone)
What are the molecules (autoinducers) used in quorum sensing?
(produced by both gram positive and negative)
(produced by gram-positive)
(gamma-butyrolacone)(used for antibiotice synthesis and sporulation)
Where do obligate parasites live?
Obligate parasites can only live in host cells.
Do bacteria make asexual spores to only a limited number of species?
How do fungi make spore? Do all make spores?
All fungi make spores as their taxonomy is based on the type of spores produced and are produced either sexually and asexually.
How do protozoa produce spores?
asexually, very small number of species produce spores, and are collectively called sporozoans.
What are bacterial spores called?
endospres and they develop inside a vegetative bacterial cell.
What are endospres useful for?
Help bacteria survive harsh environmental conditions which are not suitable for growth
What are spores inside a mother cell called?
What is the exosporium?
The outermost, thin covering of the endospore.
What is the spore coat composed of?
Several protein layers that include dipicolinic acid and calcium ions, which may be thick.
What is the cortex of the spore made up of?
peptidoglycan and is located inside the spore coat.
Where is the spore cell wall located?
Inside the cortex surrounding the ribosome and nucleoid and protoplast.
What does the core contain?
Ribosomes and chromosomes.
By what Gram stain ar endospored made?
Gram positive such as Clostridium and Bacillus
Are Myxobacteria called slime bacteria?
What are other spore forming bacteria but not endospore forming bacteria?
Myxobacteria, Actinomyces, and Streptomyces
What does growth under adverse conditions include?
Helminths and eggs
What are the four phases that cells go through during cell growth in a closed environment?
What is the lag phase in the first stage of the closed environment cell growth?
Cells are jsut beginning to grow and slow growht is present due to adjustment, enlargement, and synthesis.
What is the exponential growth/log phase that is the second step of the closed environment of cell growth?
It is the geometrical increase in population size and is the concept of generation; generating time equaling to one complete fission cycle where one cell becomes two.
What happens on the third phase of the closed environment cell growth phase?
The population reaches a maximum capacity and the same number of cells multiply as die and the nutrients are depleted and waste products are excreted in the environment as the density gets high.
What is the death phase that is in the four phases of the closed environment of the cell growth?
It is where more cells die than multiply and the population number decreases drastically.