CELLS

Question 1

What is a cell?

Answer 1

• the cell is the basic structural and function unit of living organisms
• the basis of life- all living things are made of one or more cells

Question 2

what are three basic components of eukaryotic cells?

Answer 2

1. plasma membrane
2. cytoplasm
3. nucleus

Question 3

why is it important that the plasma membrane is fluid?

Answer 3

fluid membrane provides for and allows

• cell movement, growth, division
• self-sealing if torn or punctured

Question 4

describe the basic composition of the lipid bilayer

Answer 4

1. phospholipids(75%)
2. cholesterol (20%)
3. Glycolipids (5%)

Question 5

amphipathic

Answer 5

lipids have both polar and nonpolar components

1. phosphate head (polar)
2. fatty acid tails (nonpolar)

Question 6

what function does cholesterol serve in the lipid bilayer? how does it accomplish this?

Answer 6

cholesterol mediates membrane fluidity

1. makes lipid bilayer less fluid at normal body temperature
2. increases membrane fluidity at lower body temperature

Question 7

what are the two types of membrane protein classifications?

Answer 7

1. integral proteins

2. peripheral proteins (not part of the bilayer)

Question 8

describe integral proteins

Answer 8

proteins that extend through or well into the bilayer

they are amphipathic

Question 9

what are transmembrane proteins? What functions do they serve?

Answer 9

proteins that go all the way through the bilayer
they form ion channels (channel proteins)
and they are also transporters (carrier proteins)

Question 10

Name the different types of membrane protein functions

Answer 10

1. ion channels (pores)
2. carriers (selective movement of materials)
3. receptors for specific ligands
4. enzymatic
5. linkers (link membranes of adjacent cells)
6. cell identity markers (glycoproteins or glycolipids)

Question 11

how do carrier proteins function? provide an example

Answer 11

transport specific substances across membrane by changing shape
Amino acids enter body cells via carriers

Question 12

what is a receptor protein? provide an example

Answer 12

recognizes a specific ligand and alters the cells function in some way
ADH binds to receptors in the kidneys and changes the water permeability of plasma membranes

Question 13

provide an example of an enzymatic protein

Answer 13

these catalyze a reaction inside or outside the cell.

Lactase enzyme from epithelial cells in the small intestine splits the lactose from dairy products

Question 14

give an example of a cell identity marker

Answer 14

glycoprotein (self vs nonself)

Major histocompatibility complexes (MHCs)

Question 15

What is a glycocalyx in eukaryotes?

Answer 15

1. sugars that are attached to either proteins (to form gylcoproteins)
2. lipids (to form glycolipids)

Question 16

what is the function of eukaryotic glycocalyx?

Answer 16

1. protect cells from enzymatic action
2. cell adhesion
3. cell recognition (ABO blood groups) (liver phagocytizes aging RBCs because they have fewer sugars in their glycocalyx)

Question 17

The lipid bilayer is permeable to what type of molecules?

Answer 17

nonpolar uncharged molecules (oxygen, carbon dioxide and steroids)

Question 18

the lipid bilayer is impermeable to what type of molecules?

Answer 18

ions and large uncharged polar molecules (glucose)

Question 19

the inner surface of the plasma membrane are usually postively or negatively charged?

Answer 19

negatively

Question 20

the outter surface of the cell is typically positively or negatively charged?

Answer 20

positively

Question 21

name the types of passive movement through a bilayer

Answer 21

1. simple diffusion
2. osmosis
3. facilitated fission

Question 22

what are the types of active transport?

Answer 22

1. primary active transport

2. secondary active transport

Question 23

what are the types of bulk transport?

Answer 23

also known as vesicular transport

1. exocytosis
2. endocytosis
3. transcytosis

Question 24

what factors influence the diffusion rate and time?

Answer 24

1. steepness of gradient
2. temp
3. surface area of membrane
4. diffusion distance
5. Mass of the diffusing substance (larger mass slower diffusion)
6. size
7. density of diffusing substance
   8 charge
   9 diffusion medium
8. shape
9. permeability of a membrane
10. lipid solubility (lipid soluble molecules can move through bilayer)

Question 25

define isotonic solution

Answer 25

equal concentration of osmotically active solution

Question 26

define hypotonic solution

Answer 26

lower conc than the cell (water moves into the cell)

Question 27

define hypertonic solution

Answer 27

higher concentration of cell (cell creneates and water moves out of the cell)

Question 28

describe molecules that passive diffuse through the lipid bilayer?

Answer 28

1. lipid soluble
2. small (water, urea)
3. assisted by carriers

Question 29

names the substances that can move in and out of the cell through simple diffusion

Answer 29

1. oxygen
2. CO2
3. Fats
4. Alcohol
5. fat soluble vitamins (A, D, E, and K)

Question 30

two polar substances that can diffuse across the membrane?

Answer 30

water and urea

Question 31

what solutes move by facilitated diffusion?

Answer 31

1. fructose
2. glucose
3. galactose
4. some vitamins

Question 32

allosteric

Answer 32

the protein changes shape due to binding of an effector

Question 33

describe the concentration of K+ and NA+ inside and outside the cell

Answer 33

K+- is high inside the cell

NA+ is low inside the cell