Intro to Cell Membrane Transport

Question 1

How many neurons are present in the human brain?

Answer 1

86 billion neurons

Question 2

which animals have the highest to lowest number of neurons?

Answer 2

elephant, humans, gorilla, chimpanzee

Question 3

What is a cell membrane?

Answer 3

A thin elastic structure, 7 to 10 nanometers thick

Question 4

What are the 3 components of the cell membrane?

Answer 4

lipid barrier, proteins, carbohydrates

Question 5

what is the neuron membrane composed of?

Answer 5

A lipid-bilayer

Question 6

What is the lipid bilayer impermeable and permeable to?

Answer 6

it is IMpermeable to water/ water-soluble substances (glucose, ions, urea)
it is permeable to lipid-soluble substances (oxygen, nitrogen, carbon dioxide, alcohol)

Question 7

What do membrane proteins transport across the cell membrane?

Answer 7

water-soluble substances

Question 8

What do integral proteins act as?

Answer 8

Pores, channels and substance carriers

Question 9

What do peripheral proteins act as?

Answer 9

Enzymes, controller of transport through channels

Question 10

What are peripheral proteins often attached to?

Answer 10

Integral proteins

Question 11

Define the two basic processes of transport

Answer 11

Diffusion: Passive transport, simple (lipid bilayer or channel proteins), facilitated (carrier proteins)
Active Transport: Energy required, carrier proteins

Question 12

What do molecules move through in simple diffusion?

Answer 12

interstices of lipid bilayer, proteins channels

Question 13

What characteristics do proteins channels have for molecules passing through?

Answer 13

Diameter of channel, shape of channel, diameter of the substance, nature of electrical charges along the SURFACE of the channel

Question 14

Which gates can open or close protein channels and how?

Answer 14

Voltage gating channels: responds to electrical potential and participates in the generation of action potentials

Chemical (ligand-gated) gating channels: responds to binding of another molecule with the channel, participates in synaptic transmission

Question 15

What are the steps of facilitated-diffusion?

Answer 15

Molecules diffuses by using a specific carrier protein; molecule enters the pore and binds to the binding point of protein; a conformational change occurs so that the pore opens to the opposite side; the molecule is released

Question 16

what are two examples of large molecules?

Answer 16

Glucose and amino acids

Question 17

What is the diffusion rate proportional to in simple diffusion?

Answer 17

To the concentration of the transported substance

Question 18

What is the diffusion rate NOT proportional to in facilitated diffusion?

Answer 18

To the concentration of the transported substance

Question 19

What factors affect the Net Rate of Diffusion?

Answer 19

Concentration difference (high concentration to low concentration; concentration gradient), Electrical potential difference

Question 20

How do molecules or ions move across the membrane in active transport and what do they move through?

Answer 20

against their concentration gradient/ electrical gradient and they move through a carrier protein

Question 21

What is required to move substances against their concentration gradient?

Answer 21

An additional source of energy

Question 22

Name the substances that are transported though the membrane via active transport

Answer 22

Na+, K+, Ca2+, H+, Cl-, urate ions, sugars and amino acids

Question 23

Name the two types of active transport and what differentiates them

Answer 23

Primary Active Transport: Energy is directly driven from ATP
Secondary active transport: 2 substances are transported, energy is driven from concentration gradient of ONE of the two substances

Question 24

what is the sodium potassium pump used for?

Answer 24

To transport Na+ and K+ against their concentration gradients

Question 25

After an action potential, where is there more sodium and where does it move?

Answer 25

More sodium inside the cell, it gets pumped out o the cell for the cell to return to its negative charge

Question 26

What is the ratio of Na+ an K+ that is pumped in/out of the cell?

Answer 26

3 Na+ pumped OUT of the cell and 2 K+ pumped INTO the cell

Question 27

At resting state, what charge does the cell have?

Answer 27

Always negative

Question 28

What causes a conformational change in primary active transport for the sodium-potassium pump?

Answer 28

Enzymatic ATPase

Question 29

Where does the additional source of energy come from in secondary active transport?

Answer 29

From the concentration gradient of the principal transported substance

Question 30

Define symport and antiport

Answer 30

Symport: The two substances move in the SAME direction
Antiport: the two substances move in OPPOSITE directions

Question 31

What is the main goal of secondary active transport?

Answer 31

To maintain homeostasis in the cell

Question 32

Between sodium and glucose in a symport, which is the principal substance and which is the co-transported substance?

Answer 32

Sodium is the principal substance and glucose is the co-transported substance

Question 33

Where are the principal an co-transported substances located on the membrane?

Answer 33

On opposite sides of the membrane

Question 34

What type of changes occurs in a symport secondary active transport situation?

Answer 34

A conformational change

Question 35

Where is the Na+ H+ counter-transport especially important?

Answer 35

In the proximal tubules of the kidneys