BIO 3014 Lecture Notes - Lecture 4: Lipid Bilayer, Hydrophile

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ceruleanweasel284

10 Feb 2019

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Document Summary

Diffusion means the movement of molecules from one location to another across a membrane. Result of their random thermal motion. (random movement of a particle associated with the particle"s thermal energy) Direction- net flux always proceeds from higher to lower concentration. (moves high to low: magnitude of diffusion. Rate of diffusion obeys fick"s law (diffusion rate = ds * a. Ex: if the diffusion area increases then the size of the concentration gradient increases. Rate of diffusion depends on many factors: size of concentration gradient(dc/dx, size of the molecule used to calculate the diffusion coefficient (ds, diffusion area (a, diffusion through membranes. 10^3 to 10^6 times slower than the diffusion rates of the same molecules. Membranes act as barriers slowing down diffusion of molecules across their surfaces. Hydrophobic (water-fearing particle) interior of its lipid bilayer is the major factor limiting diffusion across a membrane.

Related Questions

1. Microscopic cells or particles suspended in water exhibit atype of movement known as

_______________________________________________________________________.

2. The yeast cells in suspension appear to jiggle back and forthbecause they are bombarded

by the ______________ energy of water molecules which are inconstant, rapid, random

motion.

3. The movement of the molecules of a gas, liquid, or solid froma region of higher

concentration of that substance to a region of lesserconcentration is termed

____________________________.

4. What are 2 factors that influence the rate of diffusion?

5. ______________ is the diffusion of a solvent across aselectively permeable membrane.

6. In ______________________, water moves out of a plant cell byosmosis causing the

protoplast to shrivel up.

7. In __________________, water moves into an animal cell byosmosis causing the cell to

swell and burst.

8. The process of ________________ can be used in treatingkidney patients to separate

urea (small molecules) from proteins (large molecules) using aselectively permeable

membrane.

9. Which type of solution (hypotonic or hypertonic) is formed inthe soil environment

around root cells when a lawn is over fertilized? Would the rootcells lose or gain water?

10. Why is it common practice to place lettuce and celery inwater before serving them?

orchidbear657

I have this questions for my homework i need help with them look please it is important i need help so please give me the correct answers for each question and also please be clear to understand and aslo be correct it is very important becuase i need them so i really need the right answers. please help me and on Questions 6 and 9 please help me with it hope you can help me with the correct answers please

Question 5

At a constant temperature, if you increase the number of unsaturated fatty acid chains in the phospholipid, the membrane will become......

less fluid

more fluid

fluidity will be unchanged

Question 6

Bacteria in a hot spring at 80 degrees celsius would be expected to have ______________ in their cell membrane

high proportions of saturated phospholipids

high proportions of unsaturated phospholipids

an equal ratio of saturated to unsaturated phospholipid

Question 7

Membrane proteins have an important role in membrane fluidity

True

False

Question 8

The HIV virus can't attach to cells that have a mutation in the CCR5 gene and so such individuals are resistant to HIV. What population of people have a higher incidence of the mutant CCR5 gene and why?

europeans because their ancestors survived the bubonic plague

North Americans because their ancestors survived small pox

europeans because they have a longer evolutionary past with HIV

Africans because they have a longer evolutionary past with HIV

Question 9

Nematode trapping fungi have ______________ molecules called ______________ that recognize specific carbohydrates on the surface of the nematode worms. This is how a fungus can recognize that its prey, the nematode worm, has wriggled into the loop. Write two words on lowercase separated by a space with no other syntax

Question 10

Diffusion requires energy

True

False

Question 11

The net direction of molecule movement when molecules diffuse is

down their concentration gradient

random directions

Question 12

In osmosis, water molecules from a solution of higher solute concentration cross a semi-permeable membrane into a solution of lower solute concentration?

True

False

Question 13

Which best defines osmosis?

In osmosis, water from a solution of lower solute concentration move across a semi-permeable membrane into a solution of higher solute concentration?

In osmosis, water from a solution of higher solute concentration move across a semi-permeable membrane into a solution of lower solute concentration?

Question 14

Animal cells placed into a hypotonic solution would most likely?

lyse (burst)

shrink

remain unchanged in size

Question 15

Glucose and amino acids move into cells via carrier proteins, the same protein can move glucose or amino acids

True

False

Question 16

ATP powered pumps move substances into and out of cells by diffusion?

True

False

Question 17

For every 3 Na ions moved out, 2 K ions are moved into a cell by one cycle of the sodium-potassium pump.

True

False

Question 18

Bulk transport of fluid and any of the substances within that fluid is called

pinocytosis

phagocytosis

receptor-mediated endocytosis

exocytosis

Question 5

At a constant temperature, if you increase the number of unsaturated fatty acid chains in the phospholipid, the membrane will become......

less fluid

more fluid

fluidity will be unchanged

Question 6

Bacteria in a hot spring at 80 degrees celsius would be expected to have ______________ in their cell membrane

high proportions of saturated phospholipids

high proportions of unsaturated phospholipids

an equal ratio of saturated to unsaturated phospholipid

Question 7

Membrane proteins have an important role in membrane fluidity

True

False

Question 8

europeans because their ancestors survived the bubonic plague

North Americans because their ancestors survived small pox

europeans because they have a longer evolutionary past with HIV

Africans because they have a longer evolutionary past with HIV

Question 9

Question 10

Diffusion requires energy

True

False

Question 11

The net direction of molecule movement when molecules diffuse is

down their concentration gradient

random directions

Question 12

In osmosis, water molecules from a solution of higher solute concentration cross a semi-permeable membrane into a solution of lower solute concentration?

True

False

Question 13

Which best defines osmosis?

In osmosis, water from a solution of lower solute concentration move across a semi-permeable membrane into a solution of higher solute concentration?

In osmosis, water from a solution of higher solute concentration move across a semi-permeable membrane into a solution of lower solute concentration?

Question 14

Animal cells placed into a hypotonic solution would most likely?

lyse (burst)

shrink

remain unchanged in size

Question 15