Microbiology Chapter 3
Which of the following best describes peripheral membrane proteins? Peripheral proteins are not easy to extract from membranes. Peripheral proteins are not water soluble. Peripheral proteins span the membrane. Peripheral proteins are on the surface of a membrane.
Peripheral proteins are on the surface of a membrane.
The minimum unit of a cell membrane is the _____. nucleotide amino acid glycerol phospholipid
Phospholipid
Which type of lipids compose a cell membrane? Phospholipid Integral protein Rationale: Realize that proteins and lipids are very different compounds. Cholesterol Hopanoid
Phospholipid
Which type of lipids compose a cell membrane? Cholesterol Integral protein Phospholipid Hopanoid
Phospholipid
Which of the following structures is absolutely required for something to be considered a living organism? Nucleus Plasma membrane Capsule Cell wall Flagella
Plasma Membrane
Which of the following structures is found in all living organisms? Nucleus Flagella Plasma membrane Capsule Cell wall
Plasma Membrane
What cellular structure is closely associated with the cell's cytosol? Slime layer Capsule Cell wall Plasma membrane
Plasma membrane
Which of the following terms describes a bacterial cell that is variable in shape and lacks a single characteristic form? Spiral Bacillus Coccus Pleomorphic
Pleomorphic
Drs. Singer and Nicholson proposed a model to describe how lipids behave in a membrane called ___________ _____________ model.
fluid mosaic
Which of the following terms describes the way in which lipids and proteins behave in a membrane? Permeable mosaic model Endosymbiotic hypothesis Rigid mosaic model Fluid mosaic model
fluid mosaic model
Lipids in membranes arrange __________. tails toward the water side heads toward the water side both heads and tails toward the water side (i.e., they lay flat, "side-ways")
head toward the water side
Lipids in membranes arrange __________. tails toward the water side both heads and tails toward the water side (i.e., they lay flat, "side-ways") heads toward the water side
heads toward the water side
Molecules crossing a plasma membrane from a ____ concentration to a ____ concentration without energy use is an example of passive diffusion. low / low high / low high / high low / high
high / low
The lipid composition of a plasma membrane varies with the environmental temperature. The structural changes to the phospholipids occurs in the _____ hopanoids glycerol portion polar hydrophilic head hydrocarbon chains
hydrocarbon chains
The tails of a phospholipid are nonpolar. Their insolubility in water is described by the term _________
hydrophobic
The tails of a phospholipid are nonpolar. Their insolubility in water is described by the term ___________
hydrophobic
Lipids in membranes arrange __________. hydrophilic head to hydrophobic tail hydrophobic tail to hydrophobic tail hydrophilic head to hydrophilic head
hydrophobic tail to hydrophobic tail
A(n) _______ _________ is a layer of lipid macromolecules that surround the cell's cytoplasm.
plasma membrane
Bacterial cells that are variable in shape and lack a single characteristic form are called __________ unavailable correct in shape.
pleomorphic
Which of the following describes how the phospholipid tails interact with water? Hydrophilic Neutral Amphipathic Hydrophobic
Hydrophobic
Which three of the following substances cross a membrane by passive diffusion? Amino acids Oxygen Carbon dioxide Water Sugars
Oxygen Carbon dioxide Water
Which three of the following are macronutrients? Oxygen Zinc Nickel Cobalt Sulfur Carbon
Oxygen, Sulfur, and Carbon
Bacterial membranes are lipid bilayers within which proteins float. What is the relative proportion of these two components? 90% lipid + 10% protein 70% lipid + 30% protein 20% lipid + 80% protein 50% lipid + 50% protein
50% lipid + 50% protein
Which term is used to describe the asymmetric character of the lipids found in membranes? Selectively permeable Amphipathic Hydrophobic Hydrophilic
Amphipathic
What term is used to describe the plasma membrane and all layers external to it? Flagella Outer membrane Capsule Cell envelope Cell wall
Cell envelope
Which of the following describes proteins that aid in the movement of materials across a membrane? Adhesin Flippases Channels and carriers Integrases
Channels and carriers
Which of the transport mechanisms relies only on concentration gradients to provide the "force" to move materials across the plasma membrane? Group translocation transport Secondary transport Primary active transport Facilitated diffusion
Facilitated diffusion
Which of the following terms describes the way in which lipids and proteins behave in a membrane? Fluid mosaic model Permeable mosaic model Rigid mosaic model Endosymbiotic hypothesis
Fluid mosaic model
Which of the following best describes integral membrane proteins? Integral proteins are on the external surface of a membrane. Integral proteins are on the cytoplasmic surface of a membrane. Integral proteins span the membrane. Integral proteins can easily be removed from membranes.
Integral proteins span the membrane.
Which of the following is true regarding macronutrients and micronutrients? Macronutrients are substances that can be synthesized by the cell. Macronutrients are substances needed in large quantities. Micronutrients are substances needed in large quantities. Micronutrients are substances that can be synthesized by the cell.
Macronutrients are substances needed in large quantities.
Which of the following transport mechanisms relies on concentration gradients of one substance to power the translocation of a different substance across a membrane? Secondary transport Primary active transport Facilitated diffusion
Secondary Transport
Which two of the following are differences between spirochetes and spirilla? Spirochetes have one or more flagella at one or both the ends, spirilla have a unique internal flagellar arrangement. Spirochetes have a unique internal flagella arrangement, spirilla have one or more flagella at one or both the ends. Spirochetes are more rigid spiral shaped structures, spirilla are more flexible, spiral shaped structures. Spirochetes are more flexible, spiral shaped structures, spirilla are more rigid spiral shaped structures.
Spirochetes have a unique internal flagella arrangement, spirilla have one or more flagella at one or both the ends. Spirochetes are more flexible, spiral shaped structures, spirilla are more rigid spiral shaped structures.
How many lipid layers are found in a bacterial plasma membrane? (Note: a lipid layer consists of a series of phospholipids arranged side to side with hydrophilic heads all facing one direction and hydrophobic tails facing the other direction) Two Three Four One Varies for bacteria
Two
Which term describes a bacterial cell that is a slightly "bent rod" shape, also called comma-shaped?
Vibrio
The bacterial shape known as bacillus is different from coccus because bacillus is __________. motile smaller larger a rod shape a spherical shape
a rod shape
The _______ ________ is defined as the plasma membrane and all surrounding layers external to it (e.g., cell wall and/or capsule).
cell envelope
The two most common bacterial cell shapes are _____ and _____, both shown here.
cocci, bacilli
Bacteria growing at higher temperatures have phospholipids with _____. more saturated fatty acids shorter hydrocarbon chains longer hydrocarbon chains fewer saturated fatty acids
more saturated fatty acids
Substances like oxygen, carbon dioxide and water move across a bacterial cell membrane by _____. group translocation facilitated transport passive diffusion active transport
passive diffusion
The unaided energy-free movement of molecules across a membrane is called _______. passive diffusion active transport group-translocation transport facilitated diffusion
passive diffusion
The amphipathic character of phospholipids found in plasma membranes implies that ______. the lipid is long the lipid is fluid the lipid is rigid the lipid is asymmetric
the lipid is asymmetric
Plasma membranes are organized by having ______. one lipid layer and a cell wall three lipid layers two lipid layers one lipid layer and a capsule
two lipid layers
Active transport and facilitated diffusion are similar because they both ____. use proteins to move materials across a membrane transport solutes using energy provided by ATP are independent of solute concentration use diffusion to move materials across a membrane
use proteins to move materials across a membrane