Micro. Chapter #3
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142 Terms
What is a prokaryotic cell?
a simple single-celled organism that lacks a nucleus and membrane-bound organelles
What are the three basic bacterial shapes?
Coccus, bacillus, and spirillus.
What shape is a coccus?
Spherical
What shape is a bacillus?
Rod-shaped.
What shape is a spirillus?
Spiral-shaped
What are some other bacterial shapes?
Vibrio, spirochete, and pleomorphic.
What determines bacterial groupings?
The planes of cell division and how the cells stick together.
What does "strep-" mean?
Long chains.
What does "staph-" mean?
Irregular clusters.
What is a diplococcus?
Two cocci grouped together.
What is a tetrad?
A cluster of four cells.
What is a streptococcus grouping?
Cocci arranged in long chains.
What is a staphylococcus grouping?
Cocci arranged in irregular clusters.
What is sarcina?
Clusters of 8, 18, 32, or more cells in a perfect cube shape.
What is a diplobacillus?
Two bacilli grouped together.
What is a streptobacillus?
Bacilli arranged in long chains.
What are palisades?
A side-by-side arrangement of bacilli.
What are proteins made of?
Amino acids joined by peptide bonds.
What are examples of proteins?
Enzymes, most hormones, and collagen.
What is the basic structure of carbohydrates?
CH₂O.
What is an example of a simple carbohydrate?
Glucose.
What are examples of complex carbohydrates?
Polysaccharides such as cellulose and chitin.
What is a major characteristic of lipids?
They are hydrophobic.
What do triglycerides and phospholipids contain?
Glycerol and fatty acids.
What are steroids?
Lipids that are variations of a four-carbon-ring structure, such as cholesterol and sex hormones.
What are the three layers of the cell envelope?
Cell membrane, cell wall, and outer gel layer.
What are other names used for the outer gel layer?
Capsule, glycocalyx, and slime layer.
Which group rarely has a gel layer?
Archaea.
What is the approximate composition of the cell membrane?
40% phospholipid bilayer and 60% proteins.
What model describes the cell membrane?
The fluid mosaic model.
What are the two parts of a phospholipid molecule?
Two hydrophobic tails and a hydrophilic head made of glycerol and phosphate.
What kind of tails do Bacteria and Eucarya have?
Fatty acid tails.
What kind of tails do Archaea have?
Isoprene tails with branches.
What are the membrane transport types listed in the slides?
Osmosis, active transport, and facilitated diffusion.
What does selectively permeable mean?
The membrane controls what can pass through it.
What are some functions of membrane proteins?
Membrane transport, secretion, energy transformation, and acting as enzymes.
What do receptor proteins do in Eucarya cell membranes?
They help with cell communication and can recognize foreign cells.
What do sterols do in Eucarya cell membranes?
They give strength to the cell membrane.
What are lipid rafts?
Groups of proteins and lipids.
Where are cell walls found?
In most Bacteria and Archaea.
Which cells lack cell walls?
Animal cells and some protists (protozoa).
What bacterial genus is an exception and lacks a cell wall?
Mycoplasma.
What helps strengthen the cell membrane of Mycoplasma?
Sterols.
What are the functions of the cell wall?
Maintaining cell shape, protecting from the environment, and protecting from osmotic pressure.
What type of solutions do bacteria usually live in?
Hypotonic solutions.
Where is peptidoglycan found?
Only in bacteria.
What are the two major subunits of peptidoglycan?
Alternating glycan molecules and tetrapeptide chains.
What are glycans made of?
A simple sugar (glucose) plus an amino acid, forming amino sugars.
What does NAM stand for?
N-acetylmuramic acid.
What does NAG stand for?
N-acetylglucosamine.
How are NAM and NAG arranged?
They alternate into chains: NAG-NAM-NAG-NAM.
What is a tetrapeptide chain?
A string of four amino acids.
What is the function of tetrapeptide chains?
They link the glycan chains together.
How are tetrapeptide chains connected in Gram-positive bacteria?
By peptide interbridges.
How are tetrapeptide chains connected in Gram-negative bacteria?
By direct connections.
What does peptidoglycan resemble in three dimensions?
A chain-link fence.
Who is associated with the Gram stain, and when?
Hans Christian Joachim Gram, 1882.
How many peptidoglycan layers does a Gram-positive cell wall have?
One thick peptidoglycan layer.
What connects tetrapeptide chains in Gram-positive bacteria?
Peptide interbridges.
What is found in Gram-positive cell walls?
Teichoic acid.
What is the periplasm?
A gel-like substance outside the cell membrane.
What are the two main layers of a Gram-negative cell wall?
A thin peptidoglycan layer in the periplasm and an outer membrane.
What is found in the Gram-negative outer membrane?
Phospholipids, lipopolysaccharides, lipoproteins, and porin proteins.
How do penicillin-type antibiotics affect the cell wall?
They interfere with the synthesis of tetrapeptide linkages.
What does lysozyme do?
It digests glycan.
Why are Gram-negative bacteria less sensitive to antimicrobial medication?
Because of their outer membrane.
Where is the outer gel layer located?
On the outside of the cell wall.
What is a capsule?
A thick, distinct, gelatinous outer layer.
What is a slime layer?
A thin, irregular outer layer.
What is the layer called if it is made of polysaccharides?
Glycocalyx.
What are the functions of the gel layer?
Protection from dehydration, attachment to tissues and other cells, biofilm formation, and protection from white blood cells and phagocytosis.
What are flagella used for?
Locomotion, chemotaxis, and entering a host cell.
How do bacterial flagella move?
They rotate 360°.
What are the three main parts of a bacterial flagellum?
Filament, hook, and basal body.
What is the filament?
A hollow protein tube made of flagellin subunits.
What is the hook of a flagellum?
A curved protein structure.
What is the basal body?
A ringed protein structure that acts as an anchor and motor.
What does monotrichous mean?
One flagellum.
What does amphitrichous mean?
Flagella at both ends.
What does lophotrichous mean?
A tuft (small/soft clump) of flagella.
What does peritrichous mean?
Flagella all around the cell.
What does "trichous" mean?
Hair.
What does "mono" mean?
one
What does "amphi" mean?
both
What does "lopho" mean?
tuft
What does "peri" mean?
around
What structures are involved in Eucarya flagella?
A plasma membrane, basal body, and microtubules made of tubulin protein subunits.
How do Eucarya flagella move?
With a whip-like motion.
What are axial fibrils/endoflagella?
Bundles of flagella in the periplasm of spirochetes.
How can some bacteria glide?
Using polysaccharide slime or surface proteins.
What are pili primarily used for?
Attachment.
What are pili made of?
A long, hollow filament of pilin proteins.
What helps pili attach to specific surfaces?
An adhesive tip.
What do fimbriae do?
They stick to host tissue and allow invasion of the host
What do sex pili do?
What do sex pili do?
What are the two main types of nucleic acids?
DNA and RNA.
What is the monomer of a nucleic acid?
A nucleotide.
What are the three parts of a nucleotide?
A pentose sugar, nucleobase, and phosphate.
What bases are listed in the slides?
A, G, C, T, or U.
What is the structure of DNA?
A double helix with a sugar-phosphate backbone.