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
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
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
Which of the following particles could diffuse easily through a cell membrane? sodium ion hydrogen ion glucose oxygen
oxygen
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
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
When talking about endocytosis and exocytosis, Both exocytosis and endocytosis:
require cellular energy; and transported substance never physically across the plasma membrane
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
A white blood cell engulfing a bacterium is an example of _____.
phagocytosis
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
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 phospholipid also has two "tails" made up of two ______________ molecules, which consist of a carboxyl group with a long hydrocarbon chain tail
fatty acid
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
