BIOL Exam 1
Answer the following about polar molecules: hydrophilic or hydrophobic? able to cross lipid bilayer? Transport protein required?
hydrophilic; have difficulty crossing the hydrophobic part of bilayer; transport protein required to cross efficiently
Answer the following about non polar molecules: hydrophilic or hydrophobic? able to cross lipid bilayer? Transport protein required?
hydrophobic; can cross easily; no transport protein required
Will one type of particle only move from one side to the other?
no, never
What happens when a cell is in an isotonic solution?
nothing
When do concentration gradients exist that drive diffusion of two different types of molecules?
only before equilibrium is reached
When is there a net movement of particles from one side of the membrane to the other?
only before equilibrium is reached
What name is given to the process by which water crosses a selectively permeable membrane?
osmosis
If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell?
hypotonic
Endocytosis moves materials _____ a cell via _____.
into....membraneous vesicles
True or false? Molecules always move independently from other types of molecules when passing through a membrane
true
True or false? Osmosis is a type of diffusion
true
True or false? The water-soluble portion of a phospholipid is the polar head, which generally consists of a glycerol molecule linked to a phosphate group.
true
When talking about protein channels and carriers, Only Carriers:
undergo a change in shape to transport solutes across the membrane; and transport primarily small polar organic molecules
A phospholipid has a "head" made up of a glycerol molecule attached to a single ___________, which is attached to another small molecule
phosphate group
When talking about protein channels and carriers, Only Channels:
provide a continuous path way across the membrane; and allow water molecules and small ions to flow quickly across the membrane
Because the phosphate group and its attachments are wither charged or polar, the phospholipid had is _____, which means it has an affinity for water
hydrophilic
Answer the following about ions: hydrophilic or hydrophobic? able to cross lipid bilayer? Transport protein required?
hydrophilic; have difficulty crossing the hydrophobic part of bilayer; transport protein required to cross efficiently
Because the C-H bonds in the fatty acid tails are relatively nonplus, the phospholipid tails are __________, which means they are excluded from water.
hydrophobic
When talking about endocytosis and exocytosis, Only endocytosis:
decreases the surface area of the plasma membrane; and forms vesicles from inward folding of the plasma membrane
A red blood cell placed in a hypertonic solution will shrink in a process called crenation. A red blood cell placed in a hypotonic solution will swell and potentially burst in a process called hemolysis. To prevent crenation or hemolysis, a cell must be placed in an isotonic solution such as 0.9% (m/v) NaCl or 5.0% (m/v) glucose. This does not mean that a cell has a 5.0% (m/v) glucose concentration; it just means that 5.0% (m/v) glucose will exert the same osmotic pressure as the solution inside the cell, which contains several different solutes. A red blood cell is placed into each of the following solutions. Indicate whether crenation, hemolysis, or neither will occur. Solution A: 3.21% (m/v) NaCl Solution B: 1.65% (m/v) glucose Solution C: distilled H2O Solution D: 6.97% (m/v) glucose Solution E: 5.0% (m/v) glucose and 0.9%(m/v) NaCl
Crenation: D; A; E Hemolysis: C; B
What property of dishwashing liquid (detergent) makes it useful to wash grease from pans?
amphipathic nature
When is there no net movement of particles?
at equilibrium
A phospholipid also has two "tails" made up of two ______________ molecules, which consist of a carboxyl group with a long hydrocarbon chain tail
fatty acid
Which of the following molecules can cross the lipid bilayer of a membrane easily, without a transport protein or other mechanism? Select all that apply. water sucrose lipids ions carbon dioxide proteins oxygen
lipids carbon dioxide oxygen
How can a lipid be distinguished from a sugar?
lipids are mostly non polar
Which of the following particles could diffuse easily through a cell membrane? sodium ion hydrogen ion glucose oxygen
oxygen
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis
When talking about protein channels and carriers, Both Channels and Carriers:
provide a hydrophilic path across the membrane; are integral membrane proteins; and transport solutes down a concentration or electrochemical gradient
When talking about endocytosis and exocytosis, Both exocytosis and endocytosis:
require cellular energy; and transported substance never physically across the plasma membrane
When talking about endocytosis and exocytosis, Only exocytosis:
secretes large molecules out of the cell; increases the surface area of the plasma membrane; and requires fusion of vesicles with the plasma membrane
What factors affect the membrane permeability?
temperature; saturation of hydrocarbon tails in membrane phospholipids; amount of cholesterol in the membrane
What happened when a cell is in a hypotonic solution?
the cell swells from an intake of water; the inside of the cell is more concentrated than the outside
What happens when a cell is in a hypertonic solution?
the cells shrivels because of water leaving the cell; the outside of the cell is more concentrated than inside
