Ch.7 - The MembraneSee all chapters
All Chapters
Ch.1 - Introduction to Biology
Ch.2 - Chemistry
Ch.3 - Water
Ch.4 - Carbon
Ch.5 - Biological Molecules
Ch.6 - Cells
Ch.7 - The Membrane
Ch.8 - Energy and Metabolism
Ch.9 - Respiration
Ch.10 - Photosynthesis
Ch.11 - Cell Signaling
Ch.12 - Cell Division
Ch.13 - Meiosis
Ch.14 - Mendelian Genetics
Ch.15 - Chromosomal Theory of Inheritance
Ch.16 - DNA Synthesis
Ch.17 - Gene Expression
Ch.18 - Regulation of Expression
Ch.19 - Viruses
Ch.20 - Biotechnology
Ch.21 - Genomics
Ch.22 - Development
Ch.23 - Evolution by Natural Selection
Ch.24 - Evolution of Populations
Ch.25 - Speciation
Ch.26 - History of Life on Earth
Ch.27 - Phylogeny
Ch.28 - Prokaryotes
Ch.29 - Protists
Ch.30 - Plants
Ch.31 - Fungi
Ch.32 - Overview of Animals
Ch.33 - Invertebrates
Ch.34 - Vertebrates
Ch.35 - Plant Anatomy
Ch.36 - Vascular Plant Transport
Ch.37 - Soil
Ch.38 - Plant Reproduction
Ch.39 - Plant Sensation and Response
Ch.40 - Animal Form and Function
Ch.41 - Digestive System
Ch.42 - Circulatory System
Ch.43 - Immune System
Ch.44 - Osmoregulation and Excretion
Ch.45 - Endocrine System
Ch.46 - Animal Reproduction
Ch.47 - Nervous System
Ch.48 - Sensory Systems
Ch.49 - Muscle Systems
Ch.50 - Ecology
Ch.51 - Animal Behavior
Ch.52 - Population Ecology
Ch.53 - Community Ecology
Ch.54 - Ecosystems
Ch.55 - Conservation Biology

Fluid Mosaic Model

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Sections
Fluid Mosaic Model
Osmosis and Diffusion
Facilitated Diffusion
Active Transport
Bulk Transport

Concept #1: The Fluid Mosaic

Concept #2: Spontaneous Assembly

Concept #3: Membrane Proteins Structure and Function

Concept #4: Membrane Proteins Function

Concept #5: Mosaic Structure Fits Function

Practice: Proteins in the plasma membrane are involved with all of the following except:

Practice: Which of the following does not influence membrane fluidity?

Additional Problems
The proteins of the plasma membrane are in large part responsible for the cell's ability to interact with its environment. They act as or are involved in all of the following except a. channel b. recognition c. reception d. transport e. packaging (histones)
The molecules that convert extracellular signals into intracellular ones area.  neurotransmittersb.  peptide hormonesc.  cell surface receptorsd.  growth factor proteinse.  genes
The primary structural component of a cell membrane is:  a. A cholesterol molecule b. A protein molecule c. A phospholipid molecule d. An enzyme e. A sugar molecule attached to a protein
A phospholipid molecule:  a. Has a hydrophilic head that is repelled by water b. Has hydrophilic tails that are repelled by water c. Has a hydrophilic head that is attracted to water d. Has a hydrophobic head that is repelled by water e. Has hydrophobic tails that are attracted to water
A cell membrane is not: a. A fluid structureb. A rigid structurec. A mosaic structured. A bilayered structuree. Composed of phospholipid molecules
When phospholipids are mixed with water their ____ interact with water and their ____ are repelled, forming a lipid bilayer. a. Hydrophobic heads, hydrophilic tailsb. Hydrophobic tails, hydrophilic headsc. Hydrophilic heads, hydrophobic tailsd. Hydrophilic tails, hydrophobic heads
The plasma membrane is a thin sheet of lipid embedded with larger moleculesa. called proteinsb. called polymersc. called nucleotidesd. of sodium and potassium ions
Membrane proteins are not very soluble in water, because they possess long stretches of non-polar amino acids thata. are too long to interact with the water moleculesb. are hydrophobicc. are transmembranald. are hydrophilice. serve as transport channels
Which of the following properties is not true of membrane phospholipids?a.  The hydrophobic tails are oriented towards the interior.b.  The hydrophilic heads are oriented towards the exterior.c.  Once they are incorporated they remain in the membrane permanently.d.   The bilayers made up of them are randomly interspersed with proteins.
The fluid nature of the membranes is attributed to a lateral movement ofa. protein channelsb. phospholipid moleculesc. antigen moleculesd. pumps such as the proton pumpe. the entire lipid bilayer
On the outer surface of the plasma membrane there are marker molecules that identify the cell-type. Often these molecules area. ATPb. amino acidsc. nucleotidesd. carbohydrate chainse. inorganic ions
The following are all functions of a typical plasma membrane excepta. transport of water and bulk materialb. selective transport of certain molecules and materialc. reception of informationd. expression of cellular identitye. be permanent in composition
It is said that ribonucleotides can diffuse through some types of liposomes. It is likely that the lipids present early in chemical evolution had short chains. Would liposomes formed from these types of lipids be more or less permeable to ribonucleotides than if early cells formed from long-chained lipids?A) same permeabilityB) less permeableC) more permeable 
Cholesterol functions in the plasma membrane toa. transport ionsb. serve as an energy moleculec. regulate membrane fluidityd. mediate steroid action 
The Fluid Mosaic Model proposed by Singer and Nicolson in 1972 included thata. The cell membrane was composed of lipids and proteins.b. The cell membrane was composed of a phospholipid bilayer between two layers of globular proteins.c. The cell membrane was composed of a phospholipid bilayer with globular proteins actually inserted into the bilayer. 
Which of the following statements are true? Select all correct answers. a. A plant that produces more monounsaturated fatty acids than polyunsaturated fatty acids in its membranes in winter has an increased resistance to freeze damage. b. Cell membranes in cold-tolerant winter wheat plants have a higher ratio of unsaturated fatty acids to saturated fatty acids than do cold-intolerant wheat varieties. c. Yeast cells that produce more unsaturated fatty acids than saturated fatty acids in response to cold have greater cold tolerance. d. Cell membranes in reindeer legs (near the hooves) are kept flexible because they have a large number of saturated fatty acids. 
When phospholipid molecules are placed into water, microspheres form spontaneously. These microspheres are called: a. protons b. archaebacteria c. eukaryotes d. coacervates
List 2 reasons why it is crucial that the cell membrane exhibit fluidity rather than be rigid.
Yeast strain X has ergosterol in its membranes, while yeast strain Z does not incorporate ergosterol into its membranes. These two yeast strains growing at 30ºC werew shifted to 20ºC. Based upon what you know about the function of cholesterol inanimal cell membranes, you would predict:A. The membrane fluidity of strains X and Z would initially increase at the lower temperature.B. At 20ºC, the membrane fluidity of strain Z would be greater than the membrane fluidity of strain X.C. At 20ºC, the membrane fluidity of strain X would be greater than the membrane fluidity of strain Z.D. A & B are correct.E. A & C are correct.
Why are membranes referred to as Fluid Mosaics? What does this mean at a molecular level?
Among the following, which amino acid is least likely to occur in the membrane crossing segments of a protein.A. leucine (L)B. leucine (L)C. isoleucine (I)D, phenylalanine (F)E. aspartic acid (D)
Which of these is a general feature of the lipid bilayer in all biological membranes?A. Na+ and K+ ions readily diffuse across the bilayer.B. Individual lipid molecules in one face (monolayer) of the bilayer readily diffuse (flip-flop) to the other monolayer.C. Individual lipid molecules are free to diffuse laterally in the surface of the bilayer.D. The bilayer is stabilized by covalent bonds between neighboring phospholipid molecules.E. The polar head groups face inward toward the inside of the bilayer.