Plasma Membrane Recap

Question 1

what 3 molecules does the plasma membrane have embedded in it

Answer 1

proteins, carbs and cholesterol

Question 2

what do the embedded proteins of the plasma membrane assist in

Answer 2

cell signalling and act as receptors

Question 3

plasma membrane is

Answer 3

selectively permeable
- separates intracellular and extracellular environments
- helps the cell maintain homeostasis
- ensures optimal function of organelles ( they require specific concentrations
of proteins, small molecules, and ions.)

Question 4

main component of plasma membrane and how are they arranged

Answer 4

phospholipids
phospholipid bilayer

Question 5

what do phospholipids contain and which is hydrophilic / hydrophobic

Answer 5

phosphate head (hydrophilic) and fatty acid tail (hydrophobic)

Question 6

what is the function of proteins in plasma membrane

Answer 6

controlling what enters and exits the
cell
- speeding up chemical reactions
- communicating and receiving signals
via the cytoskeleton
- adhesion by
sticking to other cells, the extracellular
matrix, or the cytoskeleton.

Question 7

what is the structure of proteins found in PM

Answer 7

integral - permanently anchored - called transmembrane proteins if they span the entire membrane
peripheral - temporarily anchored

Question 8

function of carbs in PM

Answer 8

adhesion by
sticking to other cells, the extracellular
matrix, or the cytoskeleton.

Question 9

structure of carbs in PM

Answer 9

Usually in chains that extend outside
the cell, rooted in the membrane
to lipids (glycolipids) or proteins
(glycoproteins).

Question 10

function of cholesterol in PM

Answer 10

Regulates the fluidity of the membrane.
At higher temperatures, cholesterol keeps phospholipids bound together.
At lower temperatures, cholesterol
disrupts the fatty acid tails, stopping phospholipids from becoming a solid
boundary.

Question 11

structure of cholesterol in PM

Answer 11

A lipid steroid that embeds itself between the fatty acid tails of the
phospholipid bilayer in animal cells.

Question 12

glycolipid

Answer 12

a phospholipid bound
to a carbohydrate

Question 13

glycoprotein

Answer 13

a protein bound to a
carbohydrate

Question 14

which factors affect if and how a molecule passes through the PM

Answer 14

molecule in qs
size and shape
polarity
concentration gradient

Question 15

what are the 2 and then 2 of each type of transport

Answer 15

passive - diffusion and osmosis
active - active transport and bulk transport

Question 16

diffusion

Answer 16

the passive movement
of molecules from areas of
high concentration to areas of low concentration (down the concentration gradient)

Question 17

what is the cause of diffusion

Answer 17

occurs as a result of the kinetic energy stored inside each molecule,
which causes them to randomly move around and bounce off each other. Over time,
this random movement leads to an even dispersion of particles in an area

Question 18

explain the relation of polarity with passing through PM

Answer 18

Nonpolar or hydrophobic molecules can easily pass through the plasma membrane because its interior, made of fatty acid tails, is also hydrophobic.

Nonpolar molecules are attracted to each other, allowing them to move freely across the membrane.
Examples include oxygen (O₂), hydrogen (H₂), carbon dioxide (CO₂), and lipids.

Question 19

explain the relation of size with passing through PM

Answer 19

Small molecules like water can pass through the phospholipid bilayer by slipping between the lipids, allowing them to diffuse freely.
However, highly charged molecules, like ions (e.g., H⁺, K⁺, Cl⁻), cannot cross the membrane this way. They need special protein channels to help them move across.

Question 20

osmosis

Answer 20

the passive movement
of water from a region of high concentration of water molecules
to a region of lower concentration
of water molecules through a cell’s
semipermeable membrane

Question 21

tonicity

Answer 21

 a measure of the relative
concentration of solutes on either side of a semipermeable
membrane,

Question 22

hypertonic

Answer 22

describes a solution
with a higher solute concentration
when compared to another
solution

Question 23

isotonic

Answer 23

 describes a solution with
the same solute concentration as
another solution

Question 24

hypotonic

Answer 24

describes a solution
with a lower solute concentration
when compared to another
solution

Question 25

turgid

Answer 25

describes plant cells that
are swollen and firm from water
uptake

Question 26

plasmolysed

Answer 26

describes plant cells
with weak and sagging plasma
membranes from water loss

Question 27

lyse

Answer 27

 to cause a cell membrane to burst or break

Question 28

facilitated diffusion

Answer 28

a type of
passive transport where molecules move through a phospholipid bilayer with the aid of a membrane
protein

Question 29

protein channel

Answer 29

transmembrane protein embedded in the phospholipid bilayer that selectively allows large or polar molecules to pass through the membrane.

Question 30

carrier protein

Answer 30

membrane-based protein that changes shape (undergoes a conformational change) to transport molecules across the membrane.

Question 31

active transport

Answer 31

moving molecules against their concentration gradient from a region of low concentration of that molecule to a
region of high concentration. This process requires both energy and the assistance of protein pumps.

Question 32

protein mediated active transport

Answer 32

a type of active
transport which involves using
membrane proteins to move
molecules across a membrane
against their concentration
gradient.

Question 33

bulk transport

Answer 33

 a type of active
transport that uses vesicles to move large molecules or groups of molecules into or out of the cell.
Also known as cytosis

Question 34

exocytosis

Answer 34

Exocytosis is the process by which large molecules or large groups of molecules are
released from cells via vesicles.

Question 35

endocytosis

Answer 35

transporting large molecules or large groups of molecules into the
cell.