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BIOSC-139 Lecture Notes - Lecture 11: Osmosis, Passive Transport, Lipid Bilayer

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School
Diablo Valley College
Department
Biological Science
Course
BIOSC-139
Professor
hoffman

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Document Summary

Cell junctions: gap junctions: transmembrane proteins form pores (connexons) that allow small molecules to pass from cell to cell, for spread of ions, simple sugars, and other small molecules between cardiac or smooth muscle cells. Membrane transport: plasma membranes selectively permeable, some molecules pass through easily; some do not, two ways substances cross membrane, passive processes, active processes. Types of membrane transport: passive processes, no cellular energy (atp) required, substance moves down its concentration gradient, active processes, energy (atp) required, occurs only in living cell membranes. Passive processes: two types of passive transport, diffusion, simple diffusion, carrier- and channel-mediated facilitated diffusion, osmosis, filtration, usually across capillary walls. Passive processes: diffusion: collisions cause molecules to move down or with their concentration gradient, difference in concentration between two areas, speed influenced by molecule size and temperature. Passive processes: molecule will passively diffuse through membrane if, it is lipid soluble, or, small enough to pass through membrane channels, or, assisted by carrier molecule.

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Related Questions

Question 1

Plasma membranes are selectively permeable. This means that

A.

glucose cannot enter the cell.

B.

the plasma membrane allows some substances to enter or leave a cell more easily than others.

C.

plasma membranes must be very thick.

Question 2

Oxygen molecules O2 crosse a plasma membrane by

A.

passive transport

B.

osmosis

C.

active transport

Question 3

Facilitated diffusion across a biological membrane requires ________ and moves a substance ________ its concentration gradient.

A. energy and channel proteins; against (up)

B. transport proteins that make channels ; down

C. energy ; down

Question 4

When two aqueous solutions that differ in solute concentration are placed on either side of a semipermeable membrane and osmosis is allowed to take place, the water will

A. move to the side with lower water concentration

B.

move to the side with higher water concentration

C.

move to the side with lower solute concentration

Question 5

Kinetic energy differs from chemical energy in that

A.

chemical energy is a particular form of kinetic energy.

B.

kinetic energy is the energy of a moving object, whereas chemical energy is the potential energy of molecules.

C.

kinetic energy is stored energy that has the potential to do work, and chemical energy is the energy of movement.

Question 6

When a cell uses chemical energy to perform work, it uses the energy released from a(n) ________ reaction to drive a(n) ________ reaction.

A.

exergonic; endergonic

B.

endergonic; exergonic

C.

spontaneous; exergonic

Question 7

When an enzyme catalyzes a reaction

A. it raises the activation energy of the reaction.

B. it lowers the activation energy of the reaction.

C. it is used once and discarded.

Question 8

Which of the following statements regarding enzyme function is false?

A. An enzyme's function depends on its three-dimensional shape.

B. Enzymes are very specific for their substrates.

C. Enzymes are used up when they catalyze a chemical reaction so must be synthesized for each new chemical reaction

Fill in the blank assignment

Biological membranes are primarily formed from two types oforganic molecules, (16)______, composed of amino acids and(17)_____, composed of phosphates, glycerol and fatty acids.Membranes are (18)___ ____ to molecules allowing some to freelypass through and restricting or preventing the passage of others.Molecules may cross membranes on their own moving from areas ofhigher to lower concentration, with no expenditure of externalenergy, in a process called (19)____. Protein molecules that spanthe membrane may assist or carry other molecules across themembrane, (20)_____ _____, also from areas of higher to lowerconcentration. (21)____ _____ moves molecules across membranes fromareas of lower to higher concentration with the use of energy inthe form of ATP. As opposed to the process of passive transport,illustrated by answers (19) and (20), molecules move against their(22) ______ _______.

If you compare two situations on either side of a cellularmembrane, they are said to be (23)_____ if their soluteconcentrations are equal. Solutions that have higher soluteconcentrations are (24)_____ when compared to solutions with lowersolute concentrations, (25)______. If molecules or substances aretoo large to pass through membranes on their own or with the use ofprotein carriers, vesicles may help to move these materials in orout of the cell as vesicles fuse with or pinch off membranes. This(26)____ ____ of materials is called (27)____ if materials aremoved into cells. The transport of lage solids or "cell-eating" is(28)_____. Entry of liquids is termed (29)____ or "cell drinking."Movement of materials out of the cell is (30)_____.

Biological membranes are primarily formed from two types oforganic molecules, (16)______, composed of amino acids and(17)_____, composed of phosphates, glycerol and fatty acids.Membranes are (18)___ ____ to molecules allowing some to freelypass through and restricting or preventing the passage of others.Molecules may cross membranes on their own moving from areas ofhigher to lower concentration, with no expenditure of externalenergy, in a process called (19)____. Protein molecules that spanthe membrane may assist or carry other molecules across themembrane, (20)_____ _____, also from areas of higher to lowerconcentration. (21)____ _____ moves molecules across membranes fromareas of lower to higher concentration with the use of energy inthe form of ATP. As opposed to the process of passive transport,illustrated by answers (19) and (20), molecules move against their(22) ______ _______.

If you compare two situations on either side of a cellularmembrane, they are said to be (23)_____ if their soluteconcentrations are equal. Solutions that have higher soluteconcentrations are (24)_____ when compared to solutions with lowersolute concentrations, (25)______. If molecules or substances aretoo large to pass through membranes on their own or with the use ofprotein carriers, vesicles may help to move these materials in orout of the cell as vesicles fuse with or pinch off membranes. This(26)____ ____ of materials is called (27)____ if materials aremoved into cells. The transport of lage solids or "cell-eating" is(28)_____. Entry of liquids is termed (29)____ or "cell drinking."Movement of materials out of the cell is (30)_____.