BIOL 153 Lecture Notes - Ribose, Pigment, Membrane Protein

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blushmule307

27 May 2012

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The pupil is actually a lack of tissue. Iris (the colourful part of eye) : variable in size, regulates light by contracting and becoming bigger. Eyelashes: top and bottom, there for protection from dust. Fold of eye: at the edges of eye, where eyelids meet: outside edge = lateral cantus. Lacrimal caruncle: drain tear liquids into the sinus. Lacrimal gland: just above the fold, makes tears (tears = salt water), drains flud onto the eye on the lateral side. Water, 0. 9% nacl, other components (fatty acids, modified phospholipid) The fatty acids/modified phospholipids produce an oily film barrier with the water. The heads of the phospholipids face the water, tails face the air. This prevents the evaporation of the water (by keeping it separate from the air) Tears do evaporate but it takes a long time = that"s why we can keep our eyes open.

Related Questions

Phospholipids make up most of the lipid part of the cell membrane. Since water exists on both the outside and inside of a cell, which of the following phospholipid arrangements makes the most sense?

a single layer of phospholipids with the polar heads facing outside the cell

two back-to-back phospholipid layers with the non-polar tails facing out on both sides

a single layer of phospholipids with the polar heads facing inside the cell

two back-to-back phospholipid layers with the polar heads facing out on both sides

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.

3. In an aqueous environment, the phospholipids of a membrane____.

a) are arranged in a single layer

b) are arranged in a bilayer with the polar heads of each layerlocated at the surface

c) are arranged in a bilayer with the fatty acid tails locatedat the surface

d) are arranged in a bilayer but the phospholipids have nospecific orientation

e) dissolve

4. which of the following molecules demonstrate dual solubilitycharacteristics

a) sterols only

b) proteins only

c) phospholipids only

d) sterols and phospholipids

e) sterols, phospholipids, and proteins

5. The "mosaic" part of the fluid mosaic model refers to themembrane ____.

a) proteins

b) phospholipids

c) cholesterol

d) functions

e) layers

9. Transport of a molecule across a cell membrane by facilitateddiffusion ____.

a) does not exhibit specificity for a particular type ofmolecule

b) requires the input of energy

c) depends on a concentration gradient

d) goes against the concentration gradient

e) allows non-polar uncharged molecules to diffuse across amembrane

13. A transport system in which transport of an ion in onedirection provides the energy for active transport in the oppositedirection is known as ____.

a) primary active transport

b) active diffusion

c) secondary active transport

d) cotransport

e) osmosis

14. Cells undergo exocytosis ____.

a) to pump protons down a concentration gradient

b) when replicating

c) to secrete protein and wastes from the cell

d) to ingest nutrients

e) as a means of cellular protection

15. What is the molecular basis of familialhypercholestremia?

a) HDL enters cells using a specific receptor on the cellsurface

b) LDL enters cells using a specific receptor on the cellsurface

c) HDL exits cells using a specific receptor on the cellsurface

d) LDL exits cells using a specific receptor on the cellsurface

e) receptor-mediated exocytosis

16. Carrier molecules are utilized for ____.

a) active transport only

b) passive transport only

c) both active and passive transport

d) osmosis

e) transport of all types of molecules

17. All of the following are functions of integral membraneproteins EXCEPT ____.

a) transport of polar molecules

b) reception of chemical signals form other cells

c) cell division

d) recognition of other cells as being "like"

e) cell-cell binding

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BIOL 153 Lecture Notes - Ribose, Pigment, Membrane Protein

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