Module 3 - Cells

Question 1

permeability of lipid bilayer

Answer 1

• Oxygen, carbon dioxide, fatty acids & some steroid hormones easily pass-through cell membrane
• Not stopped by hydrophobic acid chains
• Special protein channels for water like substances & ions

Question 2

membrane proteins

Answer 2

• Receptors for attachment of chemical hormones & neurotransmitters
• Enzymes to help chemical reactions or breakdown molecules
• Ion channels allowing water like substances into cell
• Membrane transport carriers, transport across membrane
• Cell identity markers

Question 3

mechanisms to cross membranes

Answer 3

• Diffusion
• Active transport
• Osmosis
• Concentration gradients
• Sodium/Potassium pump

Question 4

mechanisms of diffusion

Answer 4

• Movement down concentration gradient
• Area of high concentration to area of low concentration
• Specific protein carriers that change shape (larger molecules)
• Charged molecules (+/-) move to area of opposite charge

Question 5

movement through protein channels

Answer 5

• Saturated system (all carriers are occupied) can’t work any faster
• Change in shape/configuration of carrier
• Specific carriers for specific substances
• Competitively inhibited by molecules of similar shape

Question 6

facilitated diffusion

Answer 6

• Transport of larger substances
• Attach to specific protein carrier
• Protein carrier undergoes change in shape
• Protein channel opens/protein rotates molecule to inner side
• Powered by concentration gradient (no energy required)

Question 7

active transport

Answer 7

• Requires protein carriers that span cell membrane
• Energy is needed to move molecules up concentration gradient
• Transport mechanism can be saturated & show chemical specificity

Question 8

osmosis

Answer 8

• Controls difference of water moving in & out of cell
• Movement of water down concentration gradient
• Water will move to area of high solute concentration (dilution)
• High solute concentration = low water concentration
• Water can only move through semi permeable membrane

Question 9

osmotic pressure

Answer 9

• Pressure applied to side with solution to stop fluid movement
• When semipermeable membrane separates a solution from pure water

Question 10

meaning of isotonic

Answer 10

• Same tonicit compared to cellular fluids
• No ability to cause osmosis
• little or no net movement of water across membrane

Question 11

meaning of hypertonic

Answer 11

• Higher tonicity compared to cellular fluids
• Causes osmosis, cell would shrink
• water moves out of cell

Question 12

meaning of hypotonic

Answer 12

• Lower tonicity compared to cellular fluids
• Causes osmosis, cell would swell
• water moves through membrane into cell

Question 13

equilibrium potentials

Answer 13

• Two ion forces chemical & electrical gradients
• Two forces equal in magnitude & heading in opposite directions
• No net movement, electrochemical equilibrium

Question 14

resting membrane potential

Answer 14

• Equal cations (outside) & anions (inside) cell membrane
• Establishes electrochemical difference (resting membrane potential)
• -70mV polarity
• Negative charge inside is greater that positive charge outside

Question 15

importat equilibrium potentials

Answer 15

• Potassium (K+) -90mV
• Sodium (Na+) +60mV
• Chloride (Cl-) -70mV

Question 16

function of chemical gradient

Answer 16

• Drives ion from area of high to low concentration

Question 17

function of electrical gradient

Answer 17

• Drives ion toward area that has opposite charge

Question 18

sodium/potassium pump

Answer 18

• Balances leakage of ions to maintain membrane potential
• Form of active transport, requires ATP
• 3 sodium ions out, 2 potassium ions in

Question 19

function of golgi apparatus

Answer 19

• packaging proteins

Question 20

function of secretory vesicle

Answer 20

• transport proteins out of cell
• secretion

Question 21

function of free ribosomes

Answer 21

• create proteins from amino acids

Question 22

function of lysosomes

Answer 22

• digestive system cell
• destroy bacteria
• breakdown biomolecules

Question 23

function of mitochondria

Answer 23

• ATP generation
• energy transfer & storage
• self replicate

Question 24

function of endoplasmic reticulum

Answer 24

• protein synthesis
• storage & transport of proteins/lipids

Question 25

function of cell membrane

Answer 25

• regulate passage of substances
• detect chemical signals from other cells

Question 26

function of centriole

Answer 26

• direct movement of DNA during cell division
• cylinder bundles of microtubules

Question 27

function of nucleus

Answer 27

• contains DNA that produces RNA in ribosomes
• within cell nucleus

Question 28

phospholipids

Answer 28

• composed of phosphate (head) & lipid (tail)
• phosphate head is hydrophilic (like water)
• lipid tail is hydrophobic (do not like water)
• when in water they form lipid bilayer (heads face out towards water & tails face in away from water)
• tails are barrier to water/water soluble substances (ions, glucose)
• fat soluble substances can can penetrate easily (oxygen, carbon dioxide)

Question 29

concentration of fluid inside typical human cell

Answer 29

• 300 mOsm/kg water

Question 30

tonicity

Answer 30

• ability of solution cause osmosis across biological cell membrane
• dependent on number of non penetrating solute molecules in a solution

Question 31

solute

Answer 31

• what’s being dissolved

Question 32

solvent

Answer 32

• what’s doing the dissolving (water)

Question 33

solute + solvent

Answer 33

• solution

Question 34

units of osmosis

Answer 34

• osmole
• used to describe number of particle in a solution that causes osmosis
• osmotically active particles (ex. Na+, Cl-, K+, glucose)

Question 35

units of concentration

Answer 35

• number of osmotic particles (osmol/volume of solution)
• omolaity, number of osmoses per kg of water
• osmolarity, number of osmoses per L of solution

Question 36

osmolality calculation
1 molar solution of NaCl is made up of 1 mole of NaCl in 1 kg of water
In water, NaCl will dissociate to 1 mole of Na+ ions and 1 mole of Cl- ions (both are osmotically active particles)

Answer 36

• the number of osmotically active particles is (1 Na+ + 1 Cl- )= 2
• Osmolality = 2 osmol/kg of water