Cell Membrane

Question 1

Generalized functions of the cell membrane

Answer 1

• Holds cell together
• Allows the cell to recognize and be recognized
• Binds to other cells and molecules
• a site for biochemical reactions
• selectivly pearmeble

Question 2

Describe the drawing of a single phospholipid

Answer 2

• Circle on top(phosphate)(hydrophilic, polar)
• glycerol- separates the fatty acid from the phosphate
• Fatty acids( squiggly line attached to the glycerol. They are hydrophobic and non polar

Question 3

Phospholipids structure

Answer 3

• fats with two nonpolar fatty acid “tails”
• One polar phosphate “head”
• attached to glycerol

Question 4

Phospholipids in water

Answer 4

Form a stable bilayer aiming their heads out and their tails in

Question 5

What does the hydrophobic interior of the phospholipid offer

Answer 5

an effective barrier to the flow of most
hydrophilic molecules.(AMPHIPATHIC)

Question 6

Fluid mosaic model
parts

Answer 6

Glycoprotein(attached to peripheral protein)(field goal)
glycolipid(attached to head)(feild goal shape)
peripheral protein(small)
Integral Protein(big)
Phospholipid bilayer
Cholesterol
Outside(top)
inside(bottom)

Question 7

In the fluid mosaic model why do lipids and proteins appear to move sideways

Answer 7

In response to functions and surrounding conditions

Question 8

What does cholesterol do for the fluidity of the cell membrane

Answer 8

Helps stabilize at different temps

Question 9

Describe the drawing of the fluid mosaic model

Answer 9

Three sets of circles stacked on top of each other, the bottom circle is the phospholipid, they can go in a row of 3 circles

Next to those circles you have two integral proteins( banana shaped)

Next to those you have more phospholipids same orientation as first explained

A peripheral protein will be in between the circles of the phospholipids

Then you have another integral protein separating another group of phospholipids(only the heads)

Attaching to the tails of the phospholipids you have another set of phospholipids(upside down)

Thicker squiggly lines in the phospholipids are cholestrol

The head is labeled as a glycolipid and a glycoprotein

Whole Phospholipid is labeled bilayer

Question 10

General functions of membrane proteins

Answer 10

Channels for passive transport
◼ Can be glycoproteins
◼ Pumps for active transport
◼. Can be glycoproteins
◼ Electron carriers
◼ Enzymes
◼ Hormone binding sites
– Can be glycoproteins
◼ Cell Adhesion
◼ Cell to Cell Communication

Question 11

Energy not required, transmembrane transport

Answer 11

-diffusion
- osmosis
- facilitated diffusion

Question 12

Energy required, transmembrane transport

Answer 12

Active transport- carrier assisted
Vesicle mediated transport
* Endocytosis
* Pinocytosis
* Phagocytosis
* Exocytosis

Question 13

Phagocytosis

Answer 13

(cell eating large solids)

Question 14

Pinocytosis

Answer 14

(cell drinking fluid/nutrients

Question 15

Molecules that can pass through bilayer

Answer 15

Small non polar(O2)

Small polar(water and CO2)

Lipids

Question 16

Molecules that cannot pass through the bilayer

Answer 16

Large molecules(starch, glucose)

Ions(Na +)(K+

Question 17

Simple Diffusion

Answer 17

the passive movement of small, nonpolar molecules (like oxygen and carbon dioxide) directly across a cell membrane, from a high concentration area to a low concentration area, without needing energy or protein help

Question 18

How do the molecules move in simple diffusion

Answer 18

The molecules move down a concentration gradient.

Question 19

What does equilibrium mean in terms of simple diffusion

Answer 19

This is when there is no net movement
of molecules from either side.

Question 20

Factors affecting Diffusion rate

Answer 20

Greater difference in conc

Distance—Shorter distance greater rate vise versa

Area— Larger surface area for diffusion Vise versa

Barriers—Thinker barriers slow rate, pores enhance diffusion

Temp—high temp, more molecules move

Size—larger molecule harder to move

Question 21

Osmosis

Answer 21

Passive transport of water
- From an area of low SOLUTE molecule conc to an area of higher conc of SOLUTE molecule
Across semi permeable membrane

Question 22

Tonicity

Answer 22

• The movement of water in response to the amount of solute on either side of a membrane

Question 23

The rule for osmosis

Answer 23

Water will always move toward the side of the membrane with the most solute

Question 24

3 types of tonicity

Answer 24

Hypertonic—The side the membrane or part with the greater amount of solute

Hypotonic — side/part with the lower amount of solute

Isotonic—Equal solute content

Question 25

Low solute concentration vs high solute concentration

Answer 25

LOW SOLUTE CONCENTRATION HIGH SOLUTE CONCENTRATION HYPOTONIC(L) HYPERTONIC(H) HIGH WATER CONCENTRATION(L) LOW WATER CONCENTRATION(H) LOW OSMOTIC POTENTIAL (L) HIGH OSMOTIC POTENTIAL(H) DILUTE (L) CONCENTRATED(H)

Question 26

In comparing two solutions

Answer 26

–a HYPERTONIC is the solution with the greater solute concentration relative to the HYPOTONIC solution.

Question 27

Osmolarity

Answer 27

Measure of solute concentration. Number os osmotes per liter of solution -- an be estimated by bathing a sample in solution -- Tissue loses water when placed in hypertonic solution -- Tissue gains water when placed in a hypotonic solution

Question 28

How is tissue osmolarity inferred by

Answer 28

IDENTIFYING THE CONCENTRATION OF SOLUTION WHERE THERE IS NO WEIGHT GAIN/LOSS.

Question 29

Isotonic, hypotonic, hypertonic solutions in an animal and a plant cell

Answer 29

Isotonic: Animal Cell—normal. Plant cell—flaccid Hypotonic—Animal cell: Lysing , Plant cell—Turgid Hypertonic animal cell: shriveled, plant cell, shirveled

Question 30

Osmosis & Aquaporins type of cellular transport

Answer 30

water can move in and out of cells freely because despite being hydrophilic and polar, is very small and easily passes through the membrane

Question 31

Aquaporins channel proteins

Answer 31

Specifically allow water to pass through. Found in Kidneys and root hair cells

Question 32

Medial applications of isotonic solutions

Answer 32

Hyper and hypo are bad for cells Isotonic: Used to rinse wounds and abrasions used to keep areas of damaged skin moisted prior to skin grafts eye drops

Question 33

Facilitated diffusion

Answer 33

Passive(no energy required) Ions and charged and/or polar particles diffuse using facilitated diffusion by passing through membrane proteins but with the help of transport proteins (channels or carriers), because they are too large or polar to pass through the lipid bilayer alone, requiring no cellular energy (ATP)

Question 34

Active transport?

Answer 34

Involves the aid of a transport protein or a transport vesicle in moving a solute up a concentration gradient Energy required low to high conc

Question 35

Some molecules moved

Answer 35

Sodium must be removed from cells in order to maintain fluid balance

Question 36

Generate charge gradients

Answer 36

Sodium potasium pump Proton pump

Question 37

How does active transport work

Answer 37

The protein uses energy, typically from the breakdown of ATP, to change its shape. This change in shape allows the protein to move the molecule from one side of the membrane to the other, against its concentration gradient. Release: The molecule is released on the other side of the membrane

Question 38

Vesicle mediated—endo and exocytosis

Answer 38

The cell membrane invaginates (folds inward) to engulf extracellular material, forming a vesicle that buds off into the cytoplasm.(endo) move to the plasma membrane, fuse with it, and release their contents outside the cell.

Question 39

Exocytosis

Answer 39

removes large substances from cell Secretory vesicle fuses with cell membrane secreted: Enzymes, hormones Excreted: waste products

Question 40

Endocytosis

Answer 40

Takes large or bulk substances into cell

Question 41

function of glycoproteins

Answer 41

cell-to-cell recognition and play a role in the immune system.

Question 42

glycoproteins structure

Answer 42

protein with attached sugar chains

Question 43

glycolipids structure

Answer 43

a combination of a lipid and a carbohydrate chain, where the lipid portion is embedded in a cell membrane and the carbohydrate chain extends outwards