BIOL 1201 : Bio Study Guide Final

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azuremammoth471

15 Mar 2019

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Document Summary

Membranes and membrane function (chapter 7 of the textbook) Why are membranes called phospholipid bilayers: plasma membranes consist of 2 layers of phospholipids, each layer contains a hydrophilic head and a hydrophobic tail. What is meant by fluid mosaic: proteins drift laterally in the fluid bilayer of phospholipids. How do the relative amounts of saturated and unsaturated fats change: membrane fluidity is adjusted by the changing ratio of unsaturated to saturated fatty acids. If a membrane has a relatively high amount of saturated fats, it has a higher melting point because the hydrophobic tails of the phospholipids are easily organized into a solid. Why is this an important property: fluidity is the measure of how solid or permeable a membrane is. It is important because a membrane that is too solid will cause enzymatic proteins to become inactive if there activity requires them to move throughout the membrane.

Related Questions

22- 25

22. As the temperature in a cellular membrane cools, the membrane
a. switches from a fluid state to a solid state
b. switches froma solid state to a liquid state
c. remains fluid if it has many phospholipids
d. A and C
e. B and C

23. How does cholestrol affect affect membranes?
a. it restrains the movement of phospholipids at warm temepratures
b. it maintains membrane fluidity by preventing high packing
c. it provides a bridge for molecules of pass into the cell
d. A and B
e. All of the above

24. An amphipathic protein
a. has hydrophilic regions
b. has regions that protude outside of the membrane
c. resides in the bilayer
d. B and C
E. All of the above

25.The major electrogenic pump for animals is
a. The sodium-potassium pump
b. The proton-Pump

The table below shows the percent of each type of phospholipid fatty acid tail found in each type of the grass membranes on Oct. 2 and Dec. 8th. The first column in the table shows the length of the fatty acid tail and the number of double-bonds in the fatty acid. For example the fatty acid â16:0â would be a fatty acid that was 16 carbons long and had 0 double-bonds. The second and third columns show the percent of all phospholipid fatty acids that were of this type. For example, in grass collected on October 2nd, 23.9 % of the phospholipid fatty acids were 16 carbons long and had no double-bonds (16:0 type), and in the grass collected on Dec. 8^th, 21.0 % of the phospholipid fatty acids were 16 carbons long and had no double-bonds (16:0 type).

Fatty Acid composition of Phospholipids	October 2	December 8
Fatty Acid composition of Phospholipids	% of phospholipids	% of phospholipids
16:0	23.9	21.0
16.1	0.4	0.7
18:0	0.8	0.4
18:1	9.6	6.1
18:2	34.4	38.6
18:3	30.2	32.4
20:0	0.7	0.7

A. For each date the grass was collected, calculate the total percent of phospholipid fatty acids that were saturated fatty acids and the total percent of phospholipid fatty acids that were unsaturated fatty acids.

B. Draw a column graph that shows the total percent of phospholipid fatty acids that were saturated for each date that grass was collected and the total percent of phospholipids that were unsaturated for each date that grass were collected.

C. Why are the % of saturated and unsaturated fatty acid tails on the phospholipids of the Oct 2^nd collected grass and the Dec 8^th collected grass not the same? Use your understanding of membrane fluidity to address why these percentages have changed during this time period.

D. During this experiment the concentration of cholesterol found in the membranes of the grass was also measured. On Oct. 2^th the concentration of cholesterol was 1.10 umol/mg and on Dec. 8^th the concentration of cholesterol was 1.22 umol/mg. Why did the concentration of cholesterol change? Use your understanding of membrane fluidity to address why these concentrations have changed during this time period.

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 be correct and clear it is important ok

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