Microbiology Exam #1 Part 2
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Microbiology Exam #1 Part 2
Functional Anatomy of Prokaryotic & Eukaryotic Cells
What do prokaryotic cells include?
bacteria & archaea
Cocci? How big are they in diameter?
Round - 1 micrometer
Bacilli? What is the typical length?
Rod-shaped - 2 to 8 micrometers
What are the basic shapes of prokaryotic cells?
Coccus (round), Bacillus (long), Spirillum (curved or spiral)
What does vibrio describe?
curved cells (spirilla, only with a partial turn)
What does coccobacillus describe?
Short bacilli that may appear oval in shape
What does the prefix "strepto" mean? Where can it be added?
It indicates chains - bacillus and or coccus (streptobacillus, streptococcus)
What does pleomorphic indicate?
cells that vary in shape, or have no shape consistency
What is one example of pleomorphic cells?
Are there more shapes and descriptions for cells?
Yes, we just haven't got there yet
What is the prokaryotic cell anatomy?
no membrane-bound organelles
What structures do occur in a prokaryotic cell?
An extracellular layer of polysaccharides
capsule or slime layer
What does a capsule or slime layer allow?
Attachment to surfaces
What do capsules or slime layers prevent?
immune cells from grabbing them
What is an example of something with a capsule or slime layer? What does it cause?
- strep throat
Made of chains of pillin
Fimbriae and Pili
What is pillin?
What is usually produced by gram-negative bacteria?
Fimbriae or Pili
Fimbriae allow what?
Attachment to surfaces
Pili attach to what? What do they play a role in?
Other bacterial cells - transferring DNA from one cell to another
What is an example of Fimbriae or Pili?
Neisseria, E. Coli
Made of chains of flagellin
What is flagellin? What else is it known a?
Protein - H Antigen
This is anchored to the cell wall and cell membrane
These rotate like a propeller to provide cell movement
What is flagella useful for?
finding nutrients (glucose)
finding favorable conditions (light)
evading harm (immune cells)
What is an example of Flagella? What does it do?
Proteus - UTI
Where does H antigen vary?
between strains (subspecies) of bacteria
What is flagellin useful for?
What is prokaryotic flagellalike?
composed of flagellin
outside the cell
rotates 360 like a propeller
What is eukaryotic flagella like?
inside the cell
flap back and forth like a paddle
What are flagella arrangements?
has a single flagella on one end
has a single flagellum on each end
has two or more flagella on one or both ends
has flagella on all sides
Peritrichous cells may have how many flagella?
What does polar indicate?
cell has flagella only at the ends of the cell
Which cells are polar?
Is peritrichous polar?
Axial filaments are also called what?
Where do axial filaments occur?
What are spirochetes?
spiral bactera with axial filaments
Where are axial filaments anchored?
the end of one cell, but still inside like an outer sheath
What does rotation cause with Axial Filaments?
causes cell to move in a spiral motion, like a corkscrew
What is an example of Axial Filaments?
A structure outside the cell membrane that provides strenght and protection for the cell
Contains peptidoglycan (murien)
What is peptidoglycan?
a scaffolding of polysaccharides linked by short polypeptides
What are the two monosaccharides that alternate in peptidoglycan?
N-acetylmuramic acid (NAM)
What affect peptidoglycan? What do they make the cell do?
Lysozome and penicillin - they make the cell vulnerable to physical damage
What is lysozome?
an enzyme produced in tears and saliva, breaks down peptidoglycan
What is penicillin?
antibiotic that inhibits cel formation
What is a gram-positive cell wall? Are there other molecules?
10-20 layers thick of peptidoglycan - yes
What does the thick peptidoglycan do for gram-positive cell walls?
they are more resistant to physical damage than gram-negative bacteria
What is a gram-negative cell wall composed of? How many layers of peptidoglycan?
an outer membrane and a thin layer of peptidoglycan - one
What is the outer layer of a gram-negative cell wall? What does it contain?
A phospholipid bilayer - lipopolysaccharides and porins
What are lipopolysaccharides composed of?
What is O-polysaccharide do in peptidoglycan?
it varies between strains of bacteria and is useful for identifying bacteria
What kind of bacteria does Opolysaccharide identify? How do you know?
E. coli O157:H7 - O157 says it has specific O-poly.
What is lipid A in peptidoglycan? What can it cause?
Toxic - fever in low amounts, shock and death in high amounts
What are porins?
proteins in outer member that allow small molecules like nutrients to pass through
What is the space between the cell membrane and the outer membrane called? What is the fluid in it calle?
periplasmic space - periplasm
Why are gram negative bacteria resistant to chemicals?
their outer membrane acts as a barrier to substances
What is an example of something that has no affect on gram negative cell wall?
penicillin and lysozome, antibiotics
What are gram-negative cells more vulnerable to and why?
Physical damage - they only have a thin layer of peptidoglycan
Which bacteria are more resistant to physical damage? Chemicals?
Bacillus, Clostridium, Lactobacillus, Staphylococcus, Streptococcus - Escherchia, Salmonella, Proteus, Neisseria, Psuedomonas
What do Mycobacterium cell walls have?
What is mycolic acid?
a waxy molecule that makes mycobacteria resistant to chemicals and the immune system
What is one species of bacteria that have mycolic acid in their cell walls?
Mycobacterium that cause tuberculosis and leprosy
what species have no cell walls?
Why do mycoplasma have no cell walls?
sterols stablize their cell membrane, which is very rare in bacteria
What species of mycoplasma has no cell wall?
mycoplasma that call pnuemonia
What are Eukaryotic Cell Walls like?
they do not have peptidoglycan in their cell walls, if they even have cell walls at all
What is the main structural component of algal cell walls?
What is the main structural component of fungal cell walls?
What does the cell membrane in general consist of?
phospholipid bilayer and various embedded proteins (like eukaryotic cells)
The hydrophobic part of the phospholipid point where? Hydrophilic?
points toward the center of membrane - remains on outside in contact with water
What is the hydrophobic part? Hydrophilic?
Side Chains - Phosphate Group
What does the cell membrane have the consistency of? Why?
Olive oil, because it is a fluid
What do proteins in the cell membrane do?
No sterols occur where? Except when...?
bacterial cell membranes - Mycoplasma
Eukaryotic cell membranes often contain sterol like...?
cholesterol (animals) - ergosterol (fungi)
Prokaryotic cells don't have...?
Some prokaryotic cells do what to their membrane?
form folds in their cells membrane, giving the appearance of vesicles in the cell
What do prokaryotic cell folds where?
where specialized functions can take place
How are prokaryotic cell folds named?
different name for different bacteria
Where are prokaryotic cells folds most common?
In photosynthetic bacteria, where do the bacteria form compartments?
where photosynthesis occurs
What is an example of a photosynthetic bacteria that folds?
thylakoids in cyanobacteria
Since the cell membrane is selectively permeable what kinds of things does it let through?
Why is the cell membrane selectively permeable?
the hydrophobic core of the membrane
What kinds of substances passes through the cell membrane?
Oxygen and carbon dioxide
What cannot specifically pass through the cell membrane without help?
ions and large molecules must be carried across by protein transporters
What do ions include?
Salts and minerals
What do large molecules include?
sugars, amino acids, vitamins, etc
What happens to larger molecules like proteins and polysaccharides when they try to go through the cell membrane?
they cannot get through, so they must be broken down into smaller parts by enzymes released by the cell - but, individual amino acids and sugar can pass
Do endocytosis and exocytosis occur in prokaryotic cells? Why?
No - they have no cell membrane-bound organelles, so they dont have vesicles necessary for these processes
What do eukaryotic cell membranes contain?
sterols (like cholesterol and ergosterol)
Do endocytosis and exocytosis occur in eukaryotic cell membranes? Why?
Yes - they have cell membranes and occassionally things needs to be transported to and from the cell that are too big to go through alone
What is the cytoplasm mainly composed of?
What is the consistency of the cytoplasm? Why?
it's thick, gel-like - due to large amounts of materials dissolved in it (like proteins, amino acids, vitamins, sugars, ions, ribosomes, DNA)
What does the cytoplasm NOT contain?
nucleus, membrane-bound organelles, cytoskeleton, cytoplasmic streaming
What is cytoplasmic streaming?
a process done by eukaryotic cells that moves organelles around the cell
How does cytoplasmic streaming benefit cells?
stirring up cell contents, including nutrients
How is the distribution of nutrients in prokaryotic cells done?
Chromosome are what? What about in eukaryotic cells?
usually singular and circular - usually have multiple, linear chromosomes
Chromosomes do NOT have what?
What are histones?
proteins that eukaryotic DNA wraps around that provide support and help control access to DNA
Where is the chromosome located?
anchored to the cell membrane, held near center by proteins
What is the space that DNA occupies in the cell called?
small, non-essential, pieces of dna
What do plasmids contain?
Why are plasmids not considered chromosomes?
they do not contain genes necessary for daily living
What if a plasmid contains essential genes?
then it is a chromosome, and not a plasmid
What genes do plasmids carry
genes for toxins or various resistances (disinfectants, antibiotics)
protein-making structures of the cell
Bacterial ribosomes are smaller or larger than eukaryotic ribosomes?
smaller (70S) compared to (80S)
The difference in prokaryotic and eukaryotic ribosomes are great enough that what can be done?
antibiotics can work by blocking the action of bacterial ribosomes, but have little to no effect on eukaryotic
what are most inclusions?
granules or clumps of nutrients (phosphate, lipids, glycogen, starch, sulfur)
Do inclusions occur randomly? Why?
No, they are genetically controlled
Carboxysomes are granules of what enzyme?
What is rubisco used for?
photosynthetic bacteria to fix carbon dioxide during photosynthesis
What are gas vacuoles?
protein tubes filled with gases
What do aquatic bacteria use gas vacuoles for?
to control their depth and gain more access to nutrients or light
how do aquatic bacteria use their gas vacuoles?
varying the number of gas vacuoles in their cells, depending on their needs
An endospore is what kind of structure?
survival... not reproductive
One cell produces how many endospores?
One endospore - then the cell dies - that endospore produces another cell later
why aren't endospores considered reproductive?
there is never an increase in population
what are endospores?
dormant mini-cells wrapped by a protein coat
What are endospores resistant to?
desiccation, chemicals, acid, vacuum, radiation, enzymes, and heat
What are some genera that produce endospores?
Bacillus and Clostridium (both are soil bacteria)
Canning time and temperatures are set to destroy what set of endospores?
What is the process of forming endospores called?
the process of re-forming vegetative cells
What are vegetative cells?
What is sporulation stimulated by?
declining levels of nutrients
What are the contents of an endospore?
dna, ribosomes, enzynes and nutrients
What do endospores NOT have? Why?
water - inhibits enzymes and causes cellular processes to cease entirely
Endospores are.... ?
When do endospores begin germinating again?
when conditions return to be ideal - enzymes break down the protein coat, water enters the cell, and metabolism occurs
What are the two things that contribute most to the resistance of endospores?
thick protein coat (protection) - lack of water (prevents metabolism)
Where is ATP found?
cells of all living organisms
What does the removal of a third phosphate group do?
ADP is created
How can ATP be regenerated?
when other reactions provide the energy to add the third phosphate back onto ADP
what are enzymes?
proteins responsible for most metabolic reactions
Why are enzymes catalysts?
they speed chemical reactions in the cell without being changed
What are some factors that alter the shape of the active site?
temperature and pH - both of which have an optimal range for enzymes
enzymes of E. coli work optimally at what temp?
37 degrees Celsius - intestinal tracts of mammals, they grow fast and compete for for space & nutrients
how can factors of enzyme activity be taken advantage of?
cooking, freezing, pasteurization
At lower temps, the available energy for enzyme activity... ? Higher temps...?
decreases, and the enzyme becomes less flexible - increases, so much that weak bonds holding proteins lose 3D shape and denature
At low pH - what happens to enzyme activiy? At high pH?
high H+ interferes with weak bonds holding protein and denature - OH- interferes with bonds and denatures
What happens when enzymes denature?
active site changes shape
When does competitive inhibition occur?
when the inhibitor competes with the substrate for the active site and prevents entry of the substrate
How do inhibitors work?
their shape is close enough to the substrate that it fits in the active site, but different enough that no reaction occurs
When does noncompetitive inhibiton occur?
when the inhibitor bins to a different site on the enzyme and causes the enzyme to change shape enough that the substrate can no longer enter the active site
What else uses competitive and noncompetitive inhibition? Why?
drugs, like antibiotics - they black an enzyme necessary to make folic acid, an essential vitamon
What drug is an example of inhibition?
What is cellular respiration?
a method of ATP production that involves an electron transport chain
What is the most common form of cellular respiration?
the catabolism of glucose to carbon dioxide (and production of ATP)
What does the catabolism of glucose require?
Glycolysis, Krebs cycle, oxidative phosphorylation
What is glycolysis?
series of enzymatic reactions that converts molecules of glucose into 2 molecules of pyruvate
Where does glycolysis occur?
cytoplasm of eukaryotic cells
What is formed during glycolysis?
Where does the pyruvate go during glycolysis? the ATP? the NADH?
used in cell activity that require energy
carries high-energy electrons that will be released during oxidative phosphorylation
What is the Krebs cycle?
series of enzymatic reactions that converts 2 pyruvates to 6 molecules of carbon dioxide
Where does the Krebs cycle occur?
mitochondria of eukaryotic cells (citric acid cycle)
What is formed during the Krebs Cycle?
Where does CO2 go after Krebs cycle? ATP? NADH/FADH2?
waste product - diffuses out of cell
cell reaction requiring energy
carry high-enery electrons to be released during O.P.
What is oxidative phosphorylation?
series of enzymatic reactions that includes an electron transport chain and a process called chemiosmosis
Where does oxidative phosphorylation occur?
the cell membrane (or mitochondria for eukaryotic cells)
Where are the components of the electron transport chain located?
cell membrane - provides a barrier that allows H+ to accumulate on one side
What is chemiosmosis?
the cycling of hydrogen ions by accumulating them outside of the cell membrane and producig ATP as they pass through ATP synthase to the inside
How many ATP can be produced from each molecule of glucose?
34 - 3 ATP per NADH, 2 ATP per FADH2
Why is one less ATP made per FADH2?
it drops off electrons further down the electron transport chain, and fewer hydrogen ions are pumped across cell membrane as a result
How can oxidative phosphorylation be described?
NADH, FADH2 drop off e- at start of electron transport chain (converted to NAD+ and FAD)
As e- are passed, they lose energy. several proteins in transport chain use this energy to pump H+ outside of cell membrane
at the end of transport chain, e- are transferred to oxygen (and H+) to form water
H+ that accumalate outside of the cell return to the cell interior through the enzyme ATP synthase - ATP forms ADP as they pass through
What is the final electron acceptor?