01:119:115 Lecture Notes - Lecture 2: Electrochemical Gradient, Membrane Transport Protein, Ion Transporter

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15 Mar 2016

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Document Summary

Membrane carbohydrates play a role in cell-cell recognition. Glycolipids membrane carbohydrates covalently bonded to lipids. Glycoproteins membrane carbohydrates covalently bonded to proteins. The plasma membrane controls a cell"s exchange of materials with surroundings. Hydrophobic (non-polar) molecules dissolve in lipid bilayer and pass easily e. g. hydrocarbons, co2, o2. Polar molecules do not cross membrane easily e. g. sugars, h2o. Transport proteins regulates passage of hydrophilic substances e. g. carrier proteins, channel proteins. Passive transport- the diffusion of a substance across membranes with no energy investment. Diffusion- the tendency for molecules to spread out evenly into the available space (high concentration to low concentration) Diffusion of one solute across a permeable membrane. Substances tend to diffuse down their concentration gradient. Rule: substances diffuse from area of more concentration to area of lower concentration. Osmosis is the diffusion of water across a selectively permeable membrane. Water tends to go from low solute concentration to high solute concentration.

Related Questions

1. predict the direction of water movement based on differences in solute concentrations. Use the terms osmotic pressure, hypotonic, isotonic, and hypertonic
2. Why do membranes have to be selectively permeable?

3. What determines whether a particular substance can diffuse (simple or facilitated) through a membrane?

4. What mechanisms drive molecules across membranes? Use the terms concentration gradient, (facilitated) diffusion and active transport.
5. Which parts of the plasma membrane proteins do you expect to be hydrophobic or hydrophilic? Justify your answer.
concise and short answers pls

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

01:119:115 Lecture Notes - Lecture 2: Electrochemical Gradient, Membrane Transport Protein, Ion Transporter

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