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