micro chapt 3 and 4
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The labratory sythesis of urea disproved what idea
organic chemicals could only come from living organisms
what are two types of prokaryotic organisms
archae and bacteria
what is the typical size range of a eukaryotic cell
what are the characteristics of living organisms
what is only found in eukaryotic cells
sometimes prokaryotic cells are are surrounded by a sticky gelatinous substance which is
which microorganisms show all the characteristics of life
does growth occur in viruses
do viruses reproduce
host cell replicates the virus
what are the ways to reproduce
- Binary fission
do viruses have cell structure
viruses lack cytoplasmic membrane
what is cell theory
everything that is living is composed of a cell or cells
tumble occurs when flagella
Which of the following types of bacterial cells would have only a single flagellum?
Peritrichous bacteria make a run when
the flagella turn counterclockwise and become bundled.
Which of the following types of bacterial cells would have flagella located at only one end of the cell?
Lophotrichous and monotrichous
Which of the following molecules would be blocked by a cell membrane?
Hydrophobic molecules would enter a cell
through integral transport proteins.
What is a hallmark of passive transport across cell membranes?
It occurs along an electrochemical gradient, and may involve the use of transport proteins.
A positively charged sodium ion
would require the use of integral protein channels to pass through a cell membrane.
Which of the following statements regarding active transport is false?
It powers the diffusion of water across the cell membrane.
Which of the following statements about bacterial flagella is true?
Flagella can rotate 360 degrees.
movement towards or away from a stimulus.
Which of the following terms refers to a bacterium moving towards a light source?
As a bacterium approaches a food source, one would expect
runs to become more frequent
Why are receptors on the cell surface necessary for bacterial movement?
The receptors sense the stimulus and send signals to the flagella.
What makes phospholipid membranes good at keeping some molecules out, and allowing others to freely pass?
They have both hydrophilic and hydrophobic regions.
Integral proteins are mostly involved in
How does water enter and exit a cell?
By simple diffusion or by use of an integral transport protein
is a type of peripheral protein above that can be used as a receptor or in enzymatic functions.
What structural part of a bacterial flagellum is composed of flagellin?
How are Gram-positive and Gram-negative flagella different?
A Gram-positive flagellum has only two rings in its basal body; Gram-negatives each have four.
anchor the flagellum to the cell membrane.
The basal body is comprised of which structural component(s) of flagella?
Rod and Rings
can be identified and classified by differences in their flagellar proteins.
Which of the following scenarios is an example of bacterial motility?
A bacterium moving towards a food source
Axial filaments are found on
How do axial filaments differ from regular bacterial flagella?
The axial filament is located between the cell membrane and the outer membrane.
What is the advantage to spirochetes of the corkscrew movement provided by axial filaments?
It allows the cells to move more easily through viscous human tissues and fluids, such as mucus.
Axial filaments are composed of
Which of the following molecules is shared by both Gram-positive and Gram-negative organisms?
Amoxicillin is an antibiotic that inhibits the formation of
peptide cross-links. Amoxicillin, therefore, would most likely inhibit
the growth of __________.
both Gram-positive and Gram-negative organisms
Porins are present in ______________bacteria because, in these
organisms, molecules entering the cell must pass through an extra layer
Why is ATP necessary for active transport?
ATP provides energy to transfer material against its concentration gradient.
Which type of active transport protein moves two molecules into the cell at the same time?
Which transport protein employs transporters that move molecules only in one direction?
Uniport and Symport
Which molecule shown in the animation, the square or the circle, is moving against its concentration gradient?
Both the circle and the square
Which type of active transport protein uses one protein to pump two different molecules?
Antiport and Symport
Which of the active transport types employs diffusion?
What type of transport uses two transport proteins?
Sodium and potassium ions
need to be pumped simultaneously against their concentration gradients.
Which one of the transport proteins would be most effective at this?
Why are ATPases associated with active transport proteins?
They provide transport proteins with the energy needed to pump molecules against their concentration gradients.
Efflux pumps can be used to pump antibiotics out of a cell once they enter to protect the cell. This will be done against the concentration gradient of the antibiotic. Which of the active transports would most likely be used?
How is osmosis different from simple diffusion?
Water movement is driven by the concentration of solutes rather than its own concentration.
allow a variety of molecules to cross the cytoplasmic membrane.
What will happen to a cell
that is placed in a solution containing a high concentration of sugar, a
molecule that cannot pass across the cell membrane?
The cell will lose its interior water, causing it to shrivel up and possibly die.
How is simple diffusion different from other types of passive transport?
Simple diffusion does not require a permease.
Why is no energy required in passive transport?
The concentration gradient drives the movement.
Once equilibrium is reached,
molecules move, but there is no net movement in a particular direction.
Which of the following would not move freely across the cytoplasmic membrane?
Positively charged hydrogen ions
Peptidoglycan is a polymer of millions of N-acetylglucosamine (NAG) and
N-acetylmuramic acid (NAM) sugars based on glucose molecules linked
together in long chains cross-braced with four amino acids that link
individual polymer chains together in a chain-link fence pattern. Layers
of cross-braced NAG and NAM sheets are stacked vertically and held
together by proteins with lipid anchors attached to the cell’s
cytoplasmic membrane to form a scaffold of sugars and proteins that is
able to hold the bacterial cell’s shape, even in response to extreme
osmotic pressures. How would you expect a microbiology student to be
able to describe the composition of peptidoglycan?What is the composition of the peptidoglycan layers found in the cell wall of bacteria?
short amino acid chains, NAG, NAM, and some lipid proteins
gram postive contains these 3 things
- thick peptidoglycan wall
- single lipid bilayer membrane
- teichoic acid
gram neg contains these 4 things
- thin peptidoglycan wall
- double lipid bilayer membrane
- periplasmic space
At this point in writing your tutorial, you have to find a way to get
across to the students the importance of a cell wall to a bacterium. How
do you convey that the bacterial cell will be at the mercy of its
environment? The cell wall will need to act as a support mechanism to
neutralize the inflow or outflow of water that would alter the shape of
the cell. The cell cannot search out for a better place in the
environment that has more available water; or if there is water that it
has a high enough solute concentration that the cell will not gain
water. Because that's the problem for a bacterial cell, it cannot
control the tonicity due to solute concentrations in the surrounding
water. Water will flow in or out depending on solute concentrations and
the only thing a bacterial cell can do to keep from collapsing due to
water loss or rupturing due to too much water coming in is to have a
strong cell wall that will hold its shape regardless of the osmotic
pressures. The rigidity of the cell wall will maintain a set shape
regardless of water flow. The proteins and lipids that anchor the
cytoplasmic membrane to the cell wall will tether the membrane to the
peptidoglycan layer so that when environmental conditions result in the
loss of water from the cell, the membrane will not collapse in on
itself. Similarly, changes in environmental conditions that would result
in the inflow of water would expand the volume of the cell to the
limits of the cell wall and no more.The composition of the cell wall
allows for the expansion and contraction of the cell wall in response
to the gain or loss of water from the cell. t or f
A cell wall is a requirement for all living bacteria.
Image of a single round bacterium.
Image of a single rodishaped bacterium.
Image of a cluster of round bacteria.
Image of a string of rodishaped bacteria.
Image of a vibrio (commaishaped) bacterium.
Image of a corkscrewishaped spirochete bacterium.
With the description of the
different cell walls, membranes, and associated proteins set in the
students' minds, you now need to introduce them to the idea that the
cell wall can also act as a foundation to build things upon. Bacterial
appendages require a strong foundation that will offer the support
needed to move and function in a dynamic world. For example, flagella
are long, whiplike protein structures that are used by many
Gram-positive and Gram-negative bacteria for locomotion. In order to
function effectively, a flagellum must be firmly anchored to the cell
wall. How will you be able to get across the idea that the peptidoglycan
cell wall is strong enough to support such a mechanism? With a protein
rod that passes through the cell wall and protein rings used to anchor
it in the membranes, these basal bodies are the rudimentary biological
motors that use ATP power to spin the hook and the flagella attached to
it.Bacterial flagella have a biological motor that spins within the
cell wall and is powered by ATP. This allows the flagella to spin in a
whiplike motion to propel the bacterium.
Is this statement True or False? Choose the answer that you think is correct.
Where is the genetic information of the cell stored?
The structural framework in a cell is the
Where in a cell is ATP made?
What carries instructions for making proteins from the nucleus into the cytoplasm?
One of the ways smooth endoplasmic reticulum (ER) differs from rough endoplasmic reticulum is that rough ER is covered by
Which of the following is part of the endomembrane system?
Which of the following organelles breaks down worn-out organelles?
Where are lipids made in the cell?
smooth endoplasmic reticulum
What structure acts as a selective barrier, regulating the traffic of materials into and out of the cell?
Peptidoglycans are composed of sugars and _____.
One chain of alternating NAGs and NAMs is connected to another chain via _____.
One of the main differences
between a Gram-positive and a Gram-negative bacterial cell wall is that
the peptidoglycan portion of a Gram-positive cell wall is _____ as
compared to a Gram-negative cell wall.
Within the peptidoglycan layer, the crossbridges that connect the chains of alternating sugar molecules extend between _____.
two N-acetylmuramic acid molecules
The peptidoglycan cell wall of bacteria is most analogous to _____.
a chain-link fence
What role do the teichoic acids play within the cell wall of Gram-positive bacteria?
They serve to stabilize the cell wall and hold it in place.
The region between the outer
and inner membranes of a Gram-negative bacterial cell is known as the
__________, and it is the location of enzymes that assemble
A patient is infected with
Gram-negative bacteria and is experiencing only mild symptoms. When the
patient is given an antibiotic causing lysis of the bacterial cells, he
suddenly experiences an increase in inflammation and fever, as well as
the formation of blood clots. What explanation best describes what
The lysis of the cells releases lipid A from the lipopolysaccharide layer.
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