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370 Cards in this Set

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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.
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_________.
1. oval
2. elongated
3. flattened on one side
What happens when cocci divide to reproduce?
the cells can remain attached to one another
Cocci that remain in pairs after dividing are called _________.
diplococci
Cocci that divide and remain attached in chainlike patterns are called _____________.
streptococci
Cocci that divide in two planes and remain in groups of four are known as ____________.
tetrads
Cocci that divide in three planes and remain attached in cubelike groups of eight are called _____________.
sarcinae
Cocci that divide in multiple planes and form grapelike clusters or broad sheets are called ___________.
staphylococci
Bacilli that appear as _________ after dividing.
single rods
Bacilli that appear in pairs after division are called __________.
diplobacilli
Baccili that appear in chains after division are called __________.
streptobacilli
Bacilli that appear oval and look like cocci after division are called ___________.
coccobacilli
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?
primarily of PHOSPHOLIPIDS, which are the most abundant chemicals in the membrane, and PROTEINS
What does the plasma membrane of most eukaryotes consist of?
phospholipids, proteins, carbohydrates, and sterols
What is an example of a sterol?
cholesterol
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 ___________.
lipid bilayer
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?
in the interior of the bilayer
Draw a glycerol molecule.
H-CH(OH)-CH(OH)-CH2(OH)
What groups o the glycerol molecule are the most reactive?
the hydroxyl groups
What kind of acid is a fatty acid?
a carboxylic acid
What constitutes a fatty acid?
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?
butter, crisco, lard, coconut oil, etc.
What are some examples of unsaturated fats?
corn oil, canola oil, olive oil, etc.
What are polyunsaturated fats?
fats that have more than one double bond
The lipid molecules of a saturated fatty acid are __________ packed.
closely
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 ____________.
olive oil
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