Biology 1202B Chapter Notes - Chapter 5: Biological Membrane, Lipid Bilayer, Osmosis

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26 Mar 2017

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Because membranes are primarily hydrophobic, this restricts free movement of many molecules, in and out of the cells from one section to another: 5. 4a passive transport is based on diffusion. Passive transport the transport of substances across cell membranes without expenditure of energy, as in diffusion. Diffusion the net movement of ions or molecules from a region of higher concentration to a region of lower concentration. The diffusion rate is dependent on the difference in concentration across the membrane, or between two areas. Concentration gradient the concentration difference that drives diffusion. A larger gradient results in a faster rate of diffusion. Once equilibrium is reached, molecules are still moving, but at an equal rate: 5. 4b there are two types of passive transport: simple and facilitated. Simple diffusion mechanism by which certain small substances diffuse through the lipid part of the biological membrane. The rate of diffusion is dependent upon lipid solubility and molecular size.

Related Questions

1 Which of the following statements is false?

(a) CO₂ and O₂ can diffuse freely across the cell membranes.

(b) The differences in permeability between artificial lipid bilayers and cell membranes arise from variations in phospholipid content.

(d) Cells expend energy in the form of ATP hydrolysis to maintain ion concentrations that differ from those found outside the cell.

2 Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell?

(a) Na⁺

(b) K⁺

(d) Cl^â

3 Pumps are transporters that are able to harness energy provided by other components in the cells and drive the movement of solutes across membranes, against their concentration gradient. This type of transport is called _____________.

(a) active transport.

(b) free diffusion.

(d) passive transport.

harlequinbuffalo618

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

Ion diffusion across plasma membrane needs

		a concentration gradient across the membrane
		specific transporters
		ATP
		provide extra energy for the transport

2 points

QUESTION 2

There are four types of large biological molecules

2 points

QUESTION 3

Active transporters transport substances across cell membrane against ____________

2 points

QUESTION 4

Which of the following is a nonpolar amino acid?

	1.	Valine
	2.	Serine
	3.	Aspartic acid
	4.	Glutamic acid

2 points

QUESTION 5

Membrane potential of a cell is created by:

	1.	sodium ion concentration difference between inside and outside of the cell
	2.	a difference in protein concentration across the cell membrane
	3.	an electrical potential difference between the intracellular fluid and the surrounding extracellular fluid
	4.	a difference between the potassium concentration inside and outside of the cell

2 points

QUESTION 6

A mutation resulted in a change from a valine to a glutamic acid in a peptide sequence. This mutation will NOT change the protein folding

True

False

2 points

QUESTION 7

Ions can be transported across plasma membrane by

	1.	diffusion
	2.	No need of transporters
	3.	osmosis
	4.	active transport

2 points

QUESTION 8

Phospholipid is composed of

	1.	A glycerol backbone
	2.	One protein group
	3.	One carbohydrate group
	4.	Two fatty acid chains and one phosphate group

2 points

QUESTION 9

Prokaryotic cells and eukaryotic cells are similar in

	1.	Plasma membrane
	2.	nucleus
	3.	mechanism for protein translation
	4.	endoplasmic reticulum

2 points

QUESTION 10

Disulfide bonds are formed between two histidine residues

True

False

Biology 1202B Chapter Notes - Chapter 5: Biological Membrane, Lipid Bilayer, Osmosis

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