Section 1 - Intro cell membrane

Question 1

How many neurons are present in the human brain?

a) 6 billion
b) 16 billion
c) 32 billion
d) 86 billion
e) 36 billion

Answer 1

86 billion

Question 2

Where is the reception of the signal in the neuron’s structure?

Answer 2

Dendrites

Question 3

What is the action related to the cell body (soma)?

Answer 3

Treatment

Question 4

Where is the transmission of the signal in the neuron’s structure?

Answer 4

Axon of the neuron

Question 5

Cell membrane is almost entirely composed of _____ and _____

Answer 5

Lipids and proteins

• lipid barrier
• proteins
• carbohydrates

Question 6

How can we describe the lipid bilayer of the membrane?

Answer 6

Impermeable to water and water-soluble substances

Permeable to lipid-soluble substances

Question 7

With what type of proteins do the water-soluble substances get across the cell membrane? (2)

Answer 7

• Integral proteins (pores and channels)

- Peripheral proteins (enzymes)

Question 8

What are the two basic processes of transport?

Answer 8

• Diffusion = passive transport (NO energy) + either simple or facilitated
• Active transport = energy required + through carrier proteins

Question 9

Explain where do lipid-soluble and water-soluble substances move through in the simple diffusion:

Answer 9

Lipid-soluble = interstices of lipid barrier
Water-soluble = protein channels

Question 10

What are the important characteristics of the diffusion through protein channels? (4)

Answer 10

Selectively permeable to one or more specific ions/molecules based on:

• diameter of channel
• diameter of the substance
• shape of channel
• nature of electrical charges along the surface of the channel

Question 11

During the diffusion through protein channels, channels can be opened or closed by 2 types of gates? Name them

Answer 11

Voltage gating channels and chemical gating (ligand-gated) channels

Question 12

What do the voltage gating channels respond to? and it participates in ?

Answer 12

• Respond to electrical potential

- Participate in the generation of an action potential

Question 13

What do the chemical gating (ligand-gated) channels respond to? and it participates in ?

Answer 13

• Respond to binding of another molecule with the channel

- Participate in synaptic transmission (receptors)

Question 14

T or F : facilitated diffusion uses energy

Answer 14

False

Question 15

What is the role of the facilitated diffusion?

Answer 15

Transporting large molecules (ex: glucose and amino acids) see image p.22

Question 16

Explain the difference in the diffusion rate (speed) between simple and facilitated diffusion

Answer 16

Simple = proportional to the concentration of the transported substance ( the higher the concentration, the faster the diffusion)
VS facilitated = not proportional to the concentration of the transported substance ( diffusion rate approaches a max as the concentration of the diffusing substance increases)

Question 17

What are the two factors that affect net rate of diffusion?

Answer 17

Concentration difference (high concentration to low = concentration gradient)
Electrical potential difference (vers le +)

Question 18

T or F: A concentration difference of the
ions will be developed in the opposite
direction to the electrical
potential.

Answer 18

True

Question 19

Do molecules/ions move across the membrane through a carrier protein AGAINST or WITH their concentration and/or electrical gradient?

Answer 19

AGAINST

Question 20

Name the two types of active transport

Answer 20

• Primary active transport

- Secondary active transport

Question 21

What is the transport used to bring ions against their concentration gradient in the cell membrane in the primary active transport?

Answer 21

Sodium-potassium pump (Na+/K+) see p.27-28

Question 22

How do we call the two substances transported in the secondary active transport?

Answer 22

Principal and co-transported

Question 23

What are the two forms of secondary active transport according to the direction of diffusion of the two substances?

Answer 23

1. symport (co-transport) = same direction

2. antiport (counter-transport) = opposite direction

Question 24

What is the main goal?

Answer 24

Homeostasis in the cell

Question 25

Examples of symport and antiport

Answer 25

symport: Na+ as principal and glucose as co-transported
anti-port: Na+ as principal and Ca 2+ as co-transported
see p.31-32

Question 26

T or F: Molecules are constantly kept with equal

concentrations inside and outside of cell.

Answer 26

False = unequal concentrations (see p.33)