Chapter 7 (Membrane Structure and Funtion)

Question 1

Properties of membrane (5)

Answer 1

1. Flexible2. Self-healing3. Fluid4. Can fuse with each other5. Selectively permeable

Question 2

What’s the direction of the phospholipids movements in the membrane?

Answer 2

Lateral ➡️ Sideways

Question 3

What does the selective permeability of membrane help with?

Answer 3

Maintaining homeostasis

Question 4

What are membrane permeable to? (3)

Answer 4

• hydrophobic molecules (lipids because they are heterogeneous)- non-polar molecules- gas and steroids

Question 5

What are membrane impermeable to?

Answer 5

• hydrophilic molecules- polar/charged- ions, water, sugars, macromolecules

Question 6

What are integrins?

Answer 6

Membrane associated proteins in the CM that attaches cells to their surroundings [Image]

Question 7

What does integral proteins mean?

Answer 7

proteins found in the CM

Question 8

Functions of membrane proteins (6)

Answer 8

ATRCR1. Attachment and anchoring (integrins)2. Transport3. Enzymes4. Receptors5. Cell connections6. Recognition

Question 9

Name the 5 small molecules that are transported across the membrane:

Answer 9

ions, aa, sugars, water, gases

Question 10

What are the 2 factors that affect transport?

Answer 10

1. Concentration of solutes2. Size and polarity

Question 11

Simple diffusion: (2)

Answer 11

1. [hi] ➡️ [low]2. non-polar molecules (lipid soluble) ➡️ gases and steroids

Question 12

Water movement across membrane: (3)

Answer 12

1. Osmosis by aquaporins2. [low] ➡️ [hi] (solute)3. Hypo ➡️ Hyper

Question 13

Facilitated diffusion:

Answer 13

• [hi] ➡️ [low]- hydrophilic molecules1️⃣ channels- ions and water- fast- donut form (always open)2️⃣ transporters- large and polar (sugars and aa)- slow- changes shape

Question 14

Name the 3 type of passive mechanics

Answer 14

1. Simple diffusion2. Osmosis3. Facilitated diffusion

Question 15

What does passive transport mean?

Answer 15

doesn’trequire energy

Question 16

Why type of solution do animal and plants cells prefer?

Answer 16

Plant: Hypotonic (less water inside so that water form outside of the cell comes inside) ➡️ TurgidAnimal: Isotonic ➡️ no net movement of water

Question 17

Explain the 3 stages of solutions for both animal and plant cells and give the names of each one:

Answer 17

1. Hypertonic ➡️ water leaves the cell, cell shrinks- animal: crenation- plant: plasmolysis2. Isotonic ➡️ No net mvt of water- animal: normal- plant: flaccid3. Hypotonia ➡️ Water comes into cell, brusting- animal: Lysed (hemolysis)- plant: trugid

Question 18

List the 2 subgroups of active mechanism:

Answer 18

1. Active transport2. Bulk transport

Question 19

what does active transport imply?

Answer 19

requires energy

Question 20

Active transport (3)

Answer 20

1. Against gradient: [low] ➡️ [hi]2. Pumps (sodium/Potassium Pump) ➡️ Requires hydrolysis of ATP3. Co-transporters

Question 21

Electrogenic pumps

Answer 21

creates membrane potential/charge separation

Question 22

Co-transport

Answer 22

transport solute against gradient with help of co-transport ion down gradient

Question 23

briefly explain the sodium potassium pump

Answer 23

1. The charge outside the cell is more positive than inside the cell2. To be activated and moved the pump needs an ATP (energy currency)3. Then 3Na2+ from inside the cell gets transported outside the cell where [Na] is higher4. Then 2 K+ will come from outside and transported inside the cell where its concentration is higher

Question 24

Bulk transport means ________

Answer 24

transport of large molecules like proteins in and out of cell

Question 25

What are the two types of bulky transport?

Answer 25

1. Exocytosis (vesicle fuses with PM)2. Endocytosis (formation of vesicles)

Question 26

What are the 3 types of endocytosis?

Answer 26

1. Phagocytosis (cell eating) ➡️ large food molecules/bacteria 2. Pinocytosis (cell drinking) ➡️ dissolved material3. Receptor-mediated endocytosis (uptake of cholesterol) ➡️ Picky only specific molecule of receptor can be brought inside

Question 27

True or false: The number of phospholipid with saturated fatty acid tails increases the plasma membranes fluidity

Answer 27

❌ False!by increasing the number of saturated fatty acid tails, the more rigid the cell membrane becomes because the straighter details are so there are more packed together, however on the other hand unsaturated fatty acid tails are bent therefore it creates space to let fluid flow [Image]

Question 28

True or False: An integral, transmembrane protein has a hydrophobic middle region that interacts with the lipid bilayer and hydrophilic ends that face the inside and outside of the cell

Answer 28

✅ True 🧲 Hydrophobic middle → Stays inside the membrane, avoiding water💧 Hydrophilic ends → Face the watery inside & outside of the cell [Image]