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370 Cards in this Set
- Front
- Back
What does the term prokaryote come from?
|
the Greek words meaning prenucleus
--pro=pre --karyote=nucleus |
|
What does the term eukaryote come from?
|
the Greek words meaning true nucleus
--eu--true --karyote==nucleus |
|
Do viruses have a plasma membrane?
|
NO!
|
|
What is the defining structure of a cell?
|
the plasma membrane
|
|
What does the group prokaryote include?
|
bacteria and archaea
|
|
How are species of bacteria differentiated?
|
1. morphology (shape)
2. chemical composition (staining reactions) 3. nutritional requirements 4. biochemical activities 5. source of energy (sunlight or chemicals) |
|
Most bacteria range from ____1___ to ___2____ in diameter and from ___3_____ to ____4_____ in length.
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1. 0.2 micrometers
2. 2.0 micrometers 3. 2 micrometers 4. 8 micrometers |
|
What are the basic shapes of bacteria?
|
1. spherical coccus
2. rod-shaped bacillus 3. spiral |
|
Cocci are usually rounded but can be ___1_____, ____2_____, or ______3_________.
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1. oval
2. elongated 3. flattened on one side |
|
What happens when cocci divide to reproduce?
|
the cells can remain attached to one another
|
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Cocci that remain in pairs after dividing are called _________.
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diplococci
|
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Cocci that divide and remain attached in chainlike patterns are called _____________.
|
streptococci
|
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Cocci that divide in two planes and remain in groups of four are known as ____________.
|
tetrads
|
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Cocci that divide in three planes and remain attached in cubelike groups of eight are called _____________.
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sarcinae
|
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Cocci that divide in multiple planes and form grapelike clusters or broad sheets are called ___________.
|
staphylococci
|
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Bacilli that appear as _________ after dividing.
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single rods
|
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Bacilli that appear in pairs after division are called __________.
|
diplobacilli
|
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Baccili that appear in chains after division are called __________.
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streptobacilli
|
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Bacilli that appear oval and look like cocci after division are called ___________.
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coccobacilli
|
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What is the plasma (cytoplasmic) membrane?
|
a thin structure lying inside the cell wall and enclosing the cytoplasm of the cell
|
|
What does the plasma membrane of most prokaryotes consist of?
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primarily of PHOSPHOLIPIDS, which are the most abundant chemicals in the membrane, and PROTEINS
|
|
What does the plasma membrane of most eukaryotes consist of?
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phospholipids, proteins, carbohydrates, and sterols
|
|
What is an example of a sterol?
|
cholesterol
|
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Why are prokaryotic plasma membranes less rigid than eukaryotic plasma membranes?
|
because prokaryotic plasma membranes LACK sterols
|
|
What prokaryote does NOT have a cell wall?
|
Mycoplasma
|
|
The phospholipid molecules of the plasma membrane are are arranged in two parallel rows, called a ___________.
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lipid bilayer
|
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Is the outer membrane of a prokaryotic cell a plasma membrane?
|
NO! The plasma membrane is inside of the cell wall which is inside an outer membrane. The outer membrane is called an outer membrane because it has some features similar to the plasma membrane.
|
|
All cells contain what kind of protein?
|
peripheral proteins
|
|
What are peripheral proteins?
|
proteins that may function as: enzymes that catalyze chemical reactions, as a "scaffold" for support, and as mediators of changes in membrane shape during movement
|
|
What are integral proteins (also called transmembrane proteins)?
|
1. penetrate the membrane completely
2. channels that have a pore through which substances enter and exit the cell |
|
The space outside the cell membrane is called the ___________.
|
environment
|
|
Where does life end?
|
outside the cell membrane. Life is inside the cell membrane.
|
|
When does a cell die?
|
when it cannot maintain the cell membrane
|
|
What are glycoproteins?
|
proteins that are attached to carbohydrates
|
|
What are glycolipids?
|
lipids that are attached to carbohydrates
|
|
What function do glycoproteins and glycolipids serve?
|
both help protect and lubricate the cell and are involved in cell-to-cell interactions.
|
|
Each phospholipid molecule contains a _____1______, composed of a ____2______ and ______3_____ that is _______4_______ and ______5_____ in water, and ______6_____, composed of _____7_____ that are _______8_______ and ______9______ in water.
|
1. polar head
2. phosphate group 3. glycerol 4. hydrophilic (water-loving) 5. soluble 6. nonpolar tails 7. fatty acids 8. hydrophobic (water-fearing) 9. insoluble |
|
Where are the polar heads located in the lipid bilayer?
|
on the two surfaces of the lipid bilayer
|
|
Where are the nonpolar tails located in the lipid bilayer?
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in the interior of the bilayer
|
|
Draw a glycerol molecule.
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H-CH(OH)-CH(OH)-CH2(OH)
|
|
What groups o the glycerol molecule are the most reactive?
|
the hydroxyl groups
|
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What kind of acid is a fatty acid?
|
a carboxylic acid
|
|
What constitutes a fatty acid?
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a carboxyl group plus oil (fat)
|
|
Draw a fatty acid.
|
O=C(OH)-CH2(13)-CH3
|
|
What constitutes a triglyceride molecule?
|
3 fatty acids + 1 glycerol
|
|
What type of chemical reaction will form a glyceride molecule?
|
a dehydration reaction
|
|
How many fatty acids does it take to from a triglyceride molecule?
|
three
|
|
What are saturated fats?
|
where the carbons are at their full bond potential (4), there are NO double bonds.
|
|
What are saturated fats at room temperature?
|
solids
|
|
What are unsaturated fats?
|
fats that are not at their full bond potential, have at least one double bond
|
|
What are unsaturated fats at room temperature?
|
liquids
|
|
What are some examples of saturated fats?
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butter, crisco, lard, coconut oil, etc.
|
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What are some examples of unsaturated fats?
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corn oil, canola oil, olive oil, etc.
|
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What are polyunsaturated fats?
|
fats that have more than one double bond
|
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The lipid molecules of a saturated fatty acid are __________ packed.
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closely
|
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The lipid molecules of an unsaturated fatty acid are ____________ packed.
|
loosely
|
|
What separates fatty acid chains?
|
sterol molecules such as cholesterol
|
|
What is the fluid mosaic model?
|
the dynamic arrangement of phospholipids and proteins in the lipid bilayer
|
|
What does amphipathic mean (referring to phospholipids)?
|
composed of BOTH polar and nonpolar regions
|
|
Are phospholipids in the lipid bilayer static (ie. can't move)?
|
NO! They can rotate and move laterally but CANNOT flip from one side of the membrane to the other.
|
|
The plasma membrane is a viscous as ____________.
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olive oil
|
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What is the most important function of the plasma membrane?
|
To serve as a selective barrier through which materials enter and exit the cell.
|
|
Define selective permeability.
|
this term indicates that certain molecules and ions pass through the membrane, but others are prevented from passing through it.
|
|
What is the inside of the cell mostly composed of?
|
WATER
|
|
Do eukaryotes have enzymes for ATP production in their plasma membranes?
|
NO! Only prokaryotes have the enzymes for ATP production located in their plasma membranes.
|
|
In some bacteria, pigments and enzymes involved in photosynthesis are found in infoldings of the plasma membrane that extend into the cytoplasm. What are these membranous structures called?
|
chromatophores or thylakoids
|
|
What are mesosomes?
|
one or more large, irregular folds in the plasma membrane of bacterial cells
|
|
What can damage a cell membrane?
|
alcohols, quaternary ammonium (detergents) and polymyxin antibiotics
|
|
Leakage of cell contents is defined as __________.
|
cell death
|
|
___________ happens when the cell can no longer control its internal environment.
|
Cell death
|
|
Which two processes does material move across both prokaryotic and eukaryotic cells?
|
1. passive processes
2. active processes |
|
Define passive processes.
|
a process in which substances cross the membrane from an area of high concentration to an area of low concentration WITHOUT any expenditure of energy (ATP).
|
|
Define active processes.
|
a process in which substances move from areas of low concentration to areas of high concentration WITH expenditure of energy (ATP).
|
|
List passive processes.
|
1. simple diffusion
2. facilitated diffusion 3. osmosis |
|
When are particles continuously in motion?
|
when the temperature is ABOVE absolute zero
|
|
What does motion and entropy lead to?
|
MIXING
|
|
Define osmosis.
|
the NET movement of solvent (water) molecules across a selectively permeable membrane from an area with a high concentration of solvent molecules (water) to an area of low concentration of solvent molecules (water).
|
|
Define osmotic pressure.
|
the pressure required to prevent the movement of pure water (water with NO solutes) into a solution containing some solutes. In other words, it is the pressure needed to STOP the flow of water across a selectively permeable membrane.
|
|
What happens when water molecules enter and leave the membrane at the same rate?
|
equilibrium is reached
|
|
Define tonicity.
|
the root term used in comparative evaluations of the solute (NOT water) concentration of solutions.
|
|
What are the prefixes used with the root tonicity?
|
1. hyper
2. hypo 3. iso |
|
What is an isotonic solution?
|
a medium in which the overall concentration of solutes equals that found inside the cell
|
|
What is a hypotonic solution?
|
the solute concentration in the medium OUTSIDE the cell is lower than that inside the cell (ie. more sugar, etc. is inside the cell)
|
|
What is a hypertonic solution?
|
the solute concentration in the medium OUTSIDE the cell is higher than that inside the cell (ie. more sugar, etc. is outside the cell)
|
|
Why are sugar molecules invisible when they are mixed with water?
|
because they are less than half the wavelength of light
|
|
Why is water cloudy when you mix in clay?
|
because the clay molecules are MORE than half the wavelength of light
|
|
Why type of solution is an ideal living space for cells?
|
an isotonic solution
|
|
What problems will a cell encounter in a hypertonic environment?
|
since the solute concentration outside the cell is higher than inside the cell, water will move OUT of the cell and the cell will shrivel up (plasmolysis)
|
|
What problems will a cell encounter in a hypotonic environment?
|
Since the solute concentration INSIDE the cell is higher than outside the cell, water will move into the cell and the cell will burst (lyse).
|
|
Is the cell wall considered alive?
|
No, because it is outside the cell membrane
|
|
What is the cell wall of bacteria made of?
|
peptidoglycan (MUREIN)
|
|
How does the cell wall prevent osmotic lysis?
|
by resisting osmotic pressure
|
|
What is the cell wall (in regards to a bacterial cell)?
|
a complex, semirigid structure responsible for the shape of the cell
|
|
What do almost all prokaryotic cells have?
|
cell walls
|
|
What is the major function of the cell wall in bacterial cells?
|
to prevent bacterial cells from rupturing when the water pressure inside the cell is greater than outside the cell
|
|
How is the cell wall of bacterial cells important clinically?
|
it contributes to the ability of some species to cause disease and is the site of action of some antibiotics.
|
|
What is the chemical composition of the cell wall used for?
|
to differentiate major types of bacteria
|
|
What does peptidoglycan consist of?
|
a repeating disaccharide attached to polypeptides to form a lattice that surrounds and protects the entire cell.
|
|
What is the dissacharide portion of peptidoglycan made up of?
|
monosaccharides called N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
|
|
Alternating NAM and NAG molecules are linked in rows of _______________ to form a carbohydrate backbone (the glycan portion of peptidoglycan).
|
10 to 65 sugars
|
|
Adjacent rows of peptidoglycan are linked by _______________ (the peptide portion of peptidoglycan).
|
polypeptides
|
|
Although the structure of the polypeptide link varies, it always includes ______1______, which consis of ______2__________ attached to ____3________ in the backbone.
|
1. tetrapeptide side chains
2. four amino acids 3. NAMs |
|
The four amino acids of the tetrapeptide side chains occur in an alternating pattern of ___1____ and ___2_____ forms.
|
1. D
2. L |
|
Peptides contain UNIQUE amino acids. What are they?
|
D amino acids
|
|
_________ bonds join sugars, peptides, and amino acids.
|
Glycosidic
|
|
Parallel tetrapeptide side chains may directly bonded to each other or linked by a ________________, consisting of a short chain of amino acids.
|
peptide cross-bridge
|
|
How does penicillin do its work on bacterial cells?
|
interferes with the final linking of the peptidoglycan rows by peptide cross-bridges which results in cell lysis
|
|
How are peptidoglycan molecules cross-linked?
|
by polypeptides attached to NAG
|
|
What is a peptide?
|
a polymer whose subunits are amino acids
|
|
Amino acids are hooked together by what kind of reactions?
|
dehydration
|
|
The peptides of peptidoglycan are attached to ______.
|
NAM
|
|
All organic molecules come in two versions. What are they?
|
1. Right (Dextro)
2. Left (Levo) |
|
True or False. Almost all sugars are dextro sugars.
|
TRUE
|
|
True or False. All amino acids are levo.
|
TRUE, except for the D amino acids in the peptide chains of the peptidoglycan of bacterial cell walls
|
|
Gram positive cell walls
|
1. thick layer of peptidoglycan
2. polypeptide chain reaches to the polysaccharides on the side, below, and above |
|
Gram negative cell walls
|
1. thin layer of peptidoglycan
2. the peptide chain only reaches out to the polysaccharide side 3. Has two layers of membrane: the plasma membrane and the outer membrane |
|
Is the outer membrane of a gram negative cell wall alive?
|
No
|
|
What are the differences between gram negative and gram positive cell walls?
|
1. gram+ cell walls are thick (up to 60nm) and gram- cell walls are thin (up to 2nm)
2. gram+ cell walls contain teichoic acids and gram- cell walls do not |
|
In acid-fast cells, what is present?
|
MYCOLIC acid
|
|
What do teichoic acids consist of?
|
an alcohol (such as glycerol or ribitol) and phosphate
|
|
What are the two classes of teichoic acid?
|
1. lipoteichoic acid, which spans the peptidoglycan layter and is linked to the plasma membrane
2. wall teichoic acid, which is linked to the peptidoglycan layer |
|
What functions do teichoic acids perform?
|
1. Because of their negative charge, they may bind and regulate the movement of cations into and out of the cell
2. they may also assume a role in cell growth, preventing extensive wall breakdown and possible cell lysis 3. provide much of the cell wall's antigenic specificity and thus make it possible to identify bacteria in certain laboratory tests |
|
What provides the antigenic function of the cell wall?
|
polysaccharides
|
|
What is the periplasm?
|
a gel-like fluid between the outer membrane and the plasma membrane
|
|
What is in the periplasm?
|
high concentrations of degradative enzymes and transport proteins
|
|
Why are the cell walls of gram negative bacteria more susceptible to mechanical damage?
|
because they contain only a small amount of peptidoglycan
|
|
What does the outer membrane of Gr- cell walls consist of?
|
1. lipopolysaccharides (LPS)
2. lipoproteins 3. phospholipids |
|
What are the functions of the outer membrane of Gr- cell walls?
|
1. its strong negative charge is an important factor in evading phagocytosis and the actions of complement (lyses cells and promotes phagocytosis)
2. provides a barrier to certain antibiotics (e.g. penicillin), digestive enzymes such as lysosomes, detergents, heavy metals, bile salts, and certain dyes. |
|
Part of the permeability of the outer membrane is due to proteins in the membrane called __________, that form channels.
|
porins
|
|
What do porins do?
|
permit the passage of molecules such as nucleotides, disaccharides, peptides, amino acids, vitamin B12, and iron
|
|
What are the two most important characteristics of the LPS portion of the outer membrane of the Gr- bacterial cell?
|
1. the polysaccharide portion is composed of sugars, called O polysaccharides
2. the lipid portion of the LPS, called lipid A, is an endotoxin |
|
What is the function of O polysaccharides portion of the LPS?
|
function as antigens and are useful for distinguishing species of Gr- bacteria
|
|
What is the function of the lipid A portion of the LPS?
|
it is an endotoxin that is toxicin the host's bloodstream or GI tract. It causes fever and shock.
|
|
What is an antigen?
|
a substance that stimulates an immune response, especially the production of antibodies.
--a better definition would be: a complex, non-self molecule |
|
If you are inside a Gr- cell and you were leaving, what layers would you pass through (in order)?
|
phospholipid layer of the plasma membrane, peptidoglycan (cell wall), phospholipid layer of the outer membrane, lipopolysaccharide layer of the outer membrane
|
|
What are the two major sugars that make up the structure of the cell wall?
|
1. NAM
2. NAG |
|
Which organisms have atypical cell walls?
|
1. members of the genus Mycoplasma
2. archaea |
|
Do mycoplasmas have cell walls?
|
NO!
|
|
What is unique about the plasma membrane of Mycoplamas?
|
they have lipids called sterols, which are thought to help protect them from lysis
|
|
Do members of the domain Archaea have cell walls?
|
some lack cell walls and some have unusual cell walls composed of polysaccharides and proteins but not peptidoglycan
|
|
If Archaeans have walls, what substance do they contain?
|
contain a substance similar to peptidoglycan called pseudomurein.
|
|
What does psuedomurein contain?
|
contains N-acetyltalosaminuronic acid INSTEAD of NAM and lacks the D-amino acids found in bacterial cell walls.
|
|
How does lysozymes damage Gr+ bacterial cells?
|
catalizes hydrolysis of the bonds between the sugars in the repeating disaccharide "backbone" of peptidoglycan
|
|
How does penicillin damage Gr+ bacterial cells?
|
by preventing the transport of new units of peptidoglycan and the formation of AA cross-links by transpeptidase
|
|
What is a protoplast?
|
the wall-less cell that remains after the cell wall is destroyed
|
|
Example of a wall-less cell.
|
Mycoplasma
|
|
What is a spheroplast?
|
a wall-less Gr- cell
|
|
When organisms lose their cell walls, they may swell into irregularly shaped cells called ________________.
|
L forms
|
|
Protoplasts and spheroplasts burst in pure water or very dilute salt or sugar solutions because the water molecules from the surrounding fluid rapidly move into and enlarge the cell, which has a much lower internal concentration of water. This rupturing is called _____________.
|
osmotic lysis
|
|
In _________ processes, substances cross the membrane from an area of high concentration to an area of low concentration, without any expenditure of energy (ATP) by the cell.
|
Passive
|
|
In _________ processes, the cell must use energy (ATP) to move substances from areas of low concentration to areas of high concentration (against the concentration gradient).
|
Active
|
|
What is simple diffusion?
|
the net movement of molecules or ions from an area of high concentration to an area of low concentration until it reaches equilibrium
|
|
What is equilibrium?
|
the point of even distribution
|
|
What is facilitated diffusion?
|
the substance to be transported combines with a plasma membrane protein called a transporter (sometimes called a permease).
|
|
Does the cell need to use ATP for facilitated diffusion?
|
NO
|
|
What is active transport?
|
the cell uses energy in the form of ATP to move substances across the plasma membrane
|
|
Does active transport depend on transporter proteins?
|
YES
|
|
What is group translation?
|
a special form of active transport that occurs exclusively in prokaryotes in which the substance is chemically altered during transport across the membrane.
|
|
Group translocation of substances requires a ________1________ and ________2______.
|
1. transporter protein
2. phosphoenolpyruvate (PEP) |
|
What is the average size of prokaryotic cells?
|
0.2-1.0 micrometers by 2-8 micrometers
|
|
What are the six shapes of bacterial cells?
|
1.coccus
2. bacillus 3. spirochete 4. spirillum 5. vibrio 6. pleomorph |
|
Coccus
|
sphere
|
|
Bacillus
|
rod-shaped
|
|
Spirochete
|
flexible helix
|
|
Spirillum
|
rigid helix
|
|
Vibrio
|
comma-shaped
|
|
Pleomorph
|
irregular-shaped
|
|
What do some spirochetes cause?
|
1. syphilis
2. lyme disease |
|
What do some vibrios cause?
|
1. cholera (vibrio cholera)
|
|
What is an example of an irregulary shaped bacteria?
|
nitrogen-fixing bacteria on the roots of some plants
|
|
What are some unusual shapes of bacteria?
|
1. star-shaped
2. square |
|
Star-shaped bacteria
|
Stella
|
|
Square shaped bacteria
|
Haloarcula-Arcula
|
|
Most bacteria are __________ (in regards to shape).
|
monomorphic
|
|
Only a few are ___________ (in regards to shape).
|
pleomorphic
|
|
What types of arrangements can some bacterial cells have?
|
1. pairs
2. clusters 3. chains |
|
If all divisions of a bacterial cell are in parallel planes, what are they called?
|
STREPTO or PALLISADE
|
|
What are three mutually perpendicular planes called?
|
SARCINA
|
|
What are irregular planes of division called?
|
STAPHYLO
|
|
How do cells "REMEMBER" previous planes of division???
|
It is not known.
What is known is that cells mess up--they lose the ability to remember |
|
Many prokaryotes secrete on their surface a substance called _____________.
|
Glycocalyx
|
|
What is the bacterial glycocalyx?
|
a viscous (sticky), gelatinous polymer that is external to the cell wall and composed of polysaccharide, polypeptide, or both.
|
|
Where is glycocalyx made?
|
made inside the cell and secreted to the cell surface
|
|
If the substance is organized and is firmly attached to the cell wall, the glycocalyx is described as a _____________.
|
capsule
|
|
If the substance is unorganized and only loosely attached to the cell wall, the glycocalyx is described as a ________________.
|
slime layer
|
|
How do capsules protect pathogenic bacteria?
|
interfere with or slow the process of phagocytosis by the cells of the host
|
|
A glycocalyx made of sugars is called an ____________________.
|
extracellular polysaccharide (EPS)
|
|
What does extracellular polysaccharides do?
|
enables a bacterium to survive by attaching to various surfaces in its natural environment in order to survive.
|
|
What are flagella?
|
long filamentous appendages that propel bacteria
|
|
Bacteria that lack flagella are referred to as ___________.
|
atrichous
|
|
Bacteria that have a single polar flagellum are called ___________.
|
monotrichous
|
|
Bacteria that have a tuft of flagella at each end of the cell are called _______________.
|
amphitrichous
|
|
Bacteria that have two or more flagella at one or both ends of the cell are called ____________.
|
lophotrichous
|
|
Bacteria that have flagella distributed over the entire cell are called _______________.
|
peritrichous
|
|
What are the three basic parts of a flagellum?
|
1. filament
2. hook 3. basal body |
|
What is the filament of a flagellum?
|
the long outermost region that is constant in diameter and contains the globular protein flagellin arranged in several chains that intertwine and form a helix around a hollow core
|
|
In most bacteria, filaments are not covered by a ____1_____ or ___2_____, as in eukaryotic cels.
|
1. membrane
2. sheath |
|
What is the filament of the flagellum attached to?
|
a hook consisting of different proteins
|
|
What anchors the flagellum to the cell wall and plasma membrane?
|
the basal body
|
|
What is the basal body of a flagellum composed of?
|
a small central rod inserted into a series of rings
|
|
How many rings of the basal body of a flagellum does Gr- bacteria contain?
|
two pairs of rings: the outer pair or rings is anchored to various portions of the cell wall, and the inner pair of rings is anchored to the plasma membrane
|
|
How many rings of the basal body of a flagellum does Gr+ bacteria contain?
|
have only an inner pair
|
|
Each prokaryotic flagellum is a _____1______ structure that moves the cell by ________2__________.
|
1. semirigid, helical
2. rotating from the basal body |
|
The rotation of a flagellum is either ______1_______ or ______2_______ around its long axis.
|
1. clockwise
2. counterclockwise |
|
What does flagellar rotation depend on?
|
the cell's continuous generation of energy
|
|
What is motility?
|
the ability of an organism to move by itself
|
|
Motile bacteria rotate their flagella to ___1____ or __2_____.
|
1. run
2. tumble |
|
When a bacterium moves in one direction for a length of time, the movement is called a _____1_____ or ____2______.
|
1. "run"
2. "swim" |
|
"Runs" are interrupted by periodic, abrupt, random changes in direction called ______________.
|
"tumbles"
|
|
What is an advantage of motility of a cell?
|
it enables a bacterium to move toward a favorable environment or away from an adverse one
|
|
The movement of a bacterium toward or away from a particular stimulus is called _________.
|
taxis
|
|
What are chemical stimuli called?
|
chemotaxis
|
|
What are light stimuli called?
|
phototaxis
|
|
In reponse to a stimuli, information is passed to the _____1_____. If the chemotactic signal is positive, called an ____2_____, the bacteria _________3__________. If the chemotactic signal is negative, called a ____4_____, the bacteria _____5______.
|
1. flagella
2. attractant 3. move toward the stimulus 4. repellent 5. move away from the stimulus |
|
The flagellar protein ____1_____ is useful for distinguishing among ____2_____, or variations within a species, of gram-negative bacteria.
|
1. H antigen
2. serovars |
|
ANTIGENS:
K= ? O= ? H= ? |
K= polysaccharide of capsule
O= lipopolysaccharide of outer membrane H= proteins of flagella |
|
What kind of bacteria cells have outer membranes?
|
gram-negative
|
|
What kind of bacteria cells have O polysaccharides?
|
gram-negative
|
|
If you scrape away the capsule of a gram-positive cell, what do you see?
|
peptidoglycan
|
|
Spirochetes move by means of ______1_______, or ______2______.
|
1. axial filaments
2. endoflagella |
|
What are endoflagella?
|
bundles of fibrils that arise at the ends of the cell beneath the sheath and spiral around the cell
|
|
How are axial filaments anchored?
|
they are anchored at one end of the cell
|
|
What does the rotation of axial filaments produce?
|
a movement of the outer sheath that propels the spirochetes in a spiral motion
|
|
What types of appendages do gram-negative bacteria have?
|
1. fimbriae
2. pili |
|
What does fimbriae enable a cell to do?
|
enable the cell to adhere to surfaces, including the surfaces of other cells.
|
|
When fimbriae are absent, what happens?
|
the cells cannot colonize and no disease ensues
|
|
How many fimbriae can a cell have?
|
a few to a hundred
|
|
How many pili can a cell have?
|
only one or two per cell
|
|
What do pili do?
|
join bacterial cells in preparation for the transfer of DNA fro one cell to another, a process called conjugation
|
|
What is the difference between the chromosomes of prokaryotic and eukaryotic cells?
|
1. prokaryotes have one circular chromosome that is not enclosed in a membrane
2. eukaryotes have paired chromosomes that are enclosed by a nuclear membrane |
|
What is the difference between the histones of prokaryotic and eukaryotic cells?
|
1. prokaryotes do NOT have histones
2. eukaryotes have histones that organize DNA |
|
What is the difference between the organelles of prokaryotes and eukaryotes?
|
1. prokaryotes have NO membrane-bound organelles
2. eukaryotes have membrane-bound organelles |
|
What is the difference in the cell walls of prokaryotes and eukaryotes?
|
1. the cell walls of prokaryotes contain peptidoglycan
2. the cell walls of eukaryotes, when present, contains polysaccharides |
|
What is the difference between cell division of prokaryotes and eukaryotes?
|
1. cell division of prokaryotes is by binary fission
2. cell division of eukaryotes invovles a mitotic spindle (MTOC) |
|
For a prokaryotic cell, what does the term cytoplasm refer to?
|
the substance inside the plasma membrane
|
|
What constitutes the cytoplasm?
|
1. 80% water
2. proteins (enzymes) 3. carbohydrates 4. lipids 5. inorganic ions 6. many low-molecular-weight proteins |
|
What are the major structures in the cytoplasm of prokaryotes?
|
1. nuclear area (containing DNA)
2. ribosomes 3. reserve deposits called inclusions |
|
What features of eukaryotic cytoplasm is absent in prokaryotic cytoplasm?
|
cytoskeletons and cytoplasmic streamin
|
|
What is the nuclear area of a bacterial cell called?
|
a nucleoid
|
|
What does the nucleoid of a bacterial cell contain?
|
a single long, continuous, and frequently circularly arranged thread of double-stranded DNA
|
|
What is the DNA of a bacterial cell called?
|
the bacterial chromosome
|
|
What is the difference between a prokaryotic and eukaryotic chromosome?
|
bacterial chromosomes are NOT surrounded by a nuclear envelope (membrane) and do NOT include histones
|
|
Approxmately how long is the chromosome of a bacterial cell?
|
~1 mm long
|
|
How much longer is the bacterial DNA than the bacterial cell?
|
500 times longer than the cell
|
|
What are plasmids?
|
extrachromosomal genetic elements NOT connected to the main bacterial chromosome
|
|
How many genes do plasmids have?
|
from 5 to 100
|
|
What are ribosomes?
|
sites of protein synthesis
|
|
What are the two subunits of ribosomes?
|
1. protein
2. ribosomal RNA (rRNA) |
|
How do prokaryotic and eukaryotic ribosomes differ?
|
1. differ in the number of proteins and rRNA molecules they contain
2. prokaryotic ribosomes are somewhat smaller and less dense |
|
What are prokaryotic ribosomes called?
|
70 S
|
|
What are eukaryotic ribosomes called?
|
80 S
|
|
What are the subunits of a 70 S ribosome?
|
a small 30 S and a large 50 S
|
|
What are the subunits of an 80 S ribosome?
|
a small 40 S and a large 60 S
|
|
What does the S in 70 S and 80 S ribosomes refer to?
|
refers to Svedberg Units, which indicate the relative rate of sedimentation during ultra-high-speed centrifugation.
|
|
What do ribosomes do?
|
1. make proteins
2. translation 3. read mRNA and synthesize appropriate proteins |
|
Cytoplasmic ribosomes vary with ___________.
|
cell type
|
|
Why can microbial cells be killed by an antibiotic while the eukaryotic cell host remains unaffected?
|
because of differences in prokaryotic and eukaryotic ribosomes.
|
|
Within the cytoplasm of prokaryotic cells are several kinds of reserve deposits, known as ________________.
|
inclusions
|
|
True or False. Bacterial cells have all inclusions.
|
False
|
|
What are metachromatic granules?
|
large inclusions that take their name from the fact that they sometimes stain red with certain blue dyes such as methylene blue.
|
|
Collectively, what are metchromatic granules referred to as?
|
volutin
|
|
What is volutin?
|
represents a reserve of inorganic phosphate (polyphosphate) that can be used to synthesize ATP.
|
|
What do inclusions known as polysaccharide granules typically consist of?
|
glycogen and starch
|
|
What type of reserve are polysaccharide granules?
|
energy reserve
|
|
In the presence of _________, glycogen granules appear _________ and starch granules appear __________.
|
1. iodine
2. reddish brown 3. blue |
|
What are lipid inclusions?
|
energy reserves
(fat droplet) |
|
What is a common lipid-storage material unique to bacteria?
|
the polymer poly-B-hydroxybutyric acid
|
|
How are lipid inclusions revealed in bacteria?
|
by staining cells with fat-soluble dyes, such as Sudan dyes
|
|
What function do sulfur granules serve?
|
energy reserves/wastes
(yellow) |
|
What are carboxysomes?
|
inclusions that contain the enzyme ribulose 1,5-diphosphate carboxylase for CO2 fixation
|
|
Which inclusion is a collection of enzymes so big they almost approach the size of ribosomes?
|
carboxysomes
|
|
What are gas vacuoles?
|
hollow cavities found in many aquatic prokaryotes
|
|
What is the structure of a gas vacuole?
|
each vacuole consists of rows of several individual gas vesicles, which are hollow cylinders covered by protein
|
|
What is the function of gas vacuoles?
|
maintain buoyancy so that the cells can remain at the depth of water appropriate for them to receive sufficient amounts of oxygen, light, and nutrients
|
|
In the presence of _________, glycogen granules appear _________ and starch granules appear __________.
|
1. iodine
2. reddish brown 3. blue |
|
What are lipid inclusions?
|
energy reserves
(fat droplet) |
|
What is a common lipid-storage material unique to bacteria?
|
the polymer poly-B-hydroxybutyric acid
|
|
How are lipid inclusions revealed in bacteria?
|
by staining cells with fat-soluble dyes, such as Sudan dyes
|
|
What function do sulfur granules serve?
|
energy reserves/wastes
(yellow) |
|
What are carboxysomes?
|
inclusions that contain the enzyme ribulose 1,5-diphosphate carboxylase for CO2 fixation
|
|
Which inclusion is a collection of enzymes so big they almost approach the size of ribosomes?
|
carboxysomes
|
|
What are gas vacuoles?
|
hollow cavities found in many aquatic prokaryotes
|
|
What is the structure of a gas vacuole?
|
each vacuole consists of rows of several individual gas vesicles, which are hollow cylinders covered by protein
|
|
What is the function of gas vacuoles?
|
maintain buoyancy so that the cells can remain at the depth of water appropriate for them to receive sufficient amounts of oxygen, light, and nutrients
|
|
In the presence of _________, glycogen granules appear _________ and starch granules appear __________.
|
1. iodine
2. reddish brown 3. blue |
|
What are lipid inclusions?
|
energy reserves
(fat droplet) |
|
What is a common lipid-storage material unique to bacteria?
|
the polymer poly-B-hydroxybutyric acid
|
|
How are lipid inclusions revealed in bacteria?
|
by staining cells with fat-soluble dyes, such as Sudan dyes
|
|
What function do sulfur granules serve?
|
energy reserves/wastes
(yellow) |
|
What are carboxysomes?
|
inclusions that contain the enzyme ribulose 1,5-diphosphate carboxylase for CO2 fixation
|
|
Which inclusion is a collection of enzymes so big they almost approach the size of ribosomes?
|
carboxysomes
|
|
What are gas vacuoles?
|
hollow cavities found in many aquatic prokaryotes
|
|
What is the structure of a gas vacuole?
|
each vacuole consists of rows of several individual gas vesicles, which are hollow cylinders covered by protein
|
|
What is the function of gas vacuoles?
|
maintain buoyancy so that the cells can remain at the depth of water appropriate for them to receive sufficient amounts of oxygen, light, and nutrients
|
|
What are magnetosomes?
|
inclusions of iron oxide (Fe3O4), formed by several gram-negative bacteria such as Magnetospirillum magnetotacticum, that act like magnets.
|
|
What is the function(s) of magnetosomes?
|
1.use to move downward untile they reach a suitable attachement site.
2. in vitro they can decompose hydrogen peroxide, which forms in cells in the presence of oxygen. 3. may protect the cell against hydrogen peroxide accumulation 4. Used to find direction--North and cell |
|
Structure of a magnetosome.
|
line of 5 to 8 in a bacterial cell
|
|
What type of bacterial cells produce endospores?
|
Gram positive
|
|
What are endospores?
|
"resting" cells that are formed when essential nutrients are depleted.
|
|
Examples of bacteria that produce endospores.
|
Bacillus and Clostridium
|
|
What is sporulation/sporogenesis?
|
the process of endospore formation within a vegetative (parent) cell
*it can take several hours |
|
Endospores are resistant to __________, ____________, and ________________.
|
1. dessication
2. extreme heat 3. toxic chemicals |
|
What is the one gram negative bacteria that can form endospores?
|
Coxiella burnetii, the cause of Q fever
|
|
What is a spore septum?
|
an ingrowth of the plasma membrane that isolates a newly replicated bacterial chromosome and a small portion of cytoplasm
|
|
The spore septum becomes a double-layered membrane that surrounds the chromosome and cytoplasm. This structure, entirely enclosed within the original cell, is called a ____________. (in regards to endospore formation)
|
forespore
|
|
Thick layers of peptidoglycan are laid down between the two membrane layers. Then a thick _____________ of protein forms around the outside of the membrane. (in regards to endospore formation)
|
spore coat
|
|
What is the spore coat responsible for?
|
the resistance of endospores to many harsh chemicals
|
|
How is the endospore released?
|
by the degradation fo the original cell
|
|
Depending on the species, the endospore might be located _____________, _____________, or _____________.
|
1. terminally (at one end)
2. subterminally (near one end) 3. centrally |
|
When the endospore matures what happens to the vegetative cell?
|
the vegetative cell wall ruptures (lyses), killing the cell, and the endospore is freed.
|
|
How does an endospore return to its vegetative state?
|
by a process called germination
|
|
How does an endospore know when it is in a suitable environment to grow?
|
triggers from physical or chemical damage to the endospore coat
|
|
What are microtubules?
|
long, hollow tubes made up of a protein called tubulin
|
|
What is the difference between a bacterial flagellum and a eukaryotic undulapodium?
|
1. Undulapodiums are powered by mitochondria, flagella are powered by a proton motive force
2. flagella rotate, undulapodia wave from side to side 3. undulapodia are made from different kinds of proteins, flagella are made from flagellin protein molecules 4. undulapodia are surrounded by cell membrane, flagella are not |
|
How are undulapodia arranged?
|
nine pairs of microtubles (doublets) arranged in a ring, plus another two microtubules in the center of the ring, an arrangement called a 9 + 2 array.
|
|
Do bacterial cells perform endocytosis?
|
NO! Only eukaryotic cells do this!
|
|
What is phagocytosis?
|
pseudopods extend and engulf large particles
|
|
What is pinocytosis?
|
membrane folds inward bringing in fluid and small dissolved substances.
(cellular "drinking") |
|
What is endocytosis?
|
a segment of the plasma membrane surrounds a particle or large molecule, encloses it, and brings it into the cell
|
|
What are the two types of endocytosis?
|
1. phagocytosis
2. pinocytosis |
|
What types of cells perform phagocytosis?
|
white blood cells--destroy bacteria
|
|
What is one way that a virus can enter an animal cell?
|
when the eukaryotic cell is performing pinocytosis
|
|
Endosymbiotic Theory
|
a model for the evolution of eukaryotes which states that organelles arose from prokaryotic cells living inside a host prokaryote.
|
|
Who developed the endosymbiotic theory?
|
Lynn Margulis
|
|
What is LUCA?
|
Last Known Common Ancestor
|
|
Studies comparing prokaryotic and eukaryotic cells provide evidence for the endosymbiotic theory. Give an example, focus on chloroplasts and mitochondria)
|
1. both mitochondria and chloroplasts resemble bacteria in size and shape
2. these organelles contain circular DNA 3. can reproduce independently of their host cell 4. ribosomes resemble those of prokaryotes and their mechanism of protein synthesis is more similar to that found in bacteria than eukaryotes 5. the same antibiotics that inhibit protein synthesis on ribosomes in bacteria also inhibit protein synthesis on ribosomes in mitochondria and chloroplasts |
|
What are catalysts?
|
substances that can speed up a chemical reaction without being permanently altered themselves
|
|
What serves as biological catalysts in living cells?
|
enzymes
|
|
True or False. As catalysts, enzymes are specific.
|
TRUE!
|
|
What is a substrate?
|
a specific substance that an enzymes acts upon
|
|
True or False. Each enzyme catalyzes only one reaction.
|
TRUE!
|
|
What do enzymes do to chemical reactions?
|
speeds them up
|
|
What is an active site?
|
a region that will interact with a specific chemical substance
|
|
What is an enzyme-substrate complex?
|
a complex formed by the temporary binding of enzyme and reactants that enables the collisions to be more effective and lowers the activation of energy of the reaction
|
|
What is the crucial function of enzymes?
|
to speed up biochemical reactions at a temperature that is compatible with the normal functioning of the cell
|
|
What is the turnover number for enzymes?
|
between 1 and 10,000 and can be as high as 500,000.
|
|
What do enzymes consist of?
|
1. a protein portion called an apoenzyme
2. a nonprotein component called a cofactor |
|
If a cofactor is an organic molecule, it is called a _____________.
|
coenzyme
|
|
Apoenzymes are inactive by themselves. What activates them?
|
cofactors
|
|
What is a haloenzyme
|
the apoenzyme + the cofactor
|
|
How do coenzymes assist the enzyme?
|
1. accepting atoms removed from the substrate or by donating atoms required by the substrate
2. may act as electron carriers, removing electrons from the substrate and donating them to other molecules in subsequent reactions |
|
Many coenzymes are dervied from vitamins. What are the two most important coenzymes in cellular metabolism?
|
1. nicotinamide adenine dinucleotide (NAD+)
2. nicotinamide adenine dinucleotide phosphate (NADP+) |
|
NAD+ and NADP+ contain derivatives of the B vitamin _________, and both function as ______________.
|
1. niacin
2. electron carriers |
|
Why type of reactions is NAD+ involved in?
|
catabolic (energy-yielding) reactions
|
|
What type of reactions is NADP+ primarily involved in?
|
anabolic (energy-requiring) reactions
|
|
What coenzyme contains a derivative of the B vitamin riboflavin?
|
Flavin adenine dinucleotide (FAD+)
|
|
What is the function of FAD+?
|
electron carrier
|
|
Coenzyme A (CoA) contains a derivative of _____________, another B vitamin.
|
pantothenic acid
|
|
What is the function of Coenzyme A (CoA)?
|
plays an important role in the synthesis and breakdown of fats and in a series of oxidizing reactions called the Krebs Cycle.
|
|
What was the first coenzyme discovered?
|
Coenzyme A
|
|
What molecule is at the end of a Coenzyme A coenzyme?
|
-SH
|
|
Why do enzymes have specificity?
|
because the 3-D shape of the active site fits the substrate somewhat as a lock fits with its key
|
|
What are 99% of enzymes?
|
proteins
|
|
Oxidoreductase
|
oxidation-reduction in which oxygen and hydrogen are gained or lost
|
|
Transferase
|
transfer of functional groups, such as an amino group, acetyl group, or phosphate group
|
|
Hydrolase
|
Hydrolysis (addition of water)
|
|
Lyase
|
Removal of groups of atoms without hydrolysis
|
|
Isomerase
|
Rearrangement of atoms within a molecule
|
|
Ligase
|
Joining of two molecules (using energy usually derived from the breakdown of ATP)
|
|
Oxidation-Reduction reactions. What is oxidation?
|
1. addition of oxygen
2. removal of electrons 3. removal of hydrogen atoms |
|
Oxidation-Reduction reactions. What is reduction?
|
1. removal of oxygen
2. addition of electrons 3. addition of hydrogen atoms |
|
What factors influence enzymatic activity?
|
1. temperature
2. pH 3. substrate concentration 4. inhibitors |
|
As temperature increases, the rate of chemical reactions _____________.
|
increases
|
|
Do enzymatic reactions increase as temperature increases?
|
No, elevation beyond a certain temperature drastically reduces the rate of reaction
|
|
Why does the reaction rate of enzymatic reactions decrease as the temperature rises above the optimal temperature?
|
because of the enzymes denaturation, the loss of its characteristic 3-D structure
|
|
How do acids alter the enzyme proteins 3-D structure?
|
because the H+ (and OH-) compete with hydrogen and ionic bonds on an enzyme, resulting in the enzymes denaturation
|
|
What are competitive inhibitors?
|
inhibitors that fill the active site of an enzyme and compete with the normal substrate for the active site
|
|
What are noncompetitive inhibitors?
|
inhibitors that do not compete with the substrate at the active site; instead, they interact with another part of the enzyme.
|
|
What is allosteric inhibition?
|
the inhibitor binds to a site on the enzyme other than the substrate's binding site, called the allosteric site.
|
|
What does allosteric inhibition cause?
|
causes the active site of the enzyme to change its shape, making it nonfunctional
|