Cell Membrane

Question 1

What is the purpose of the plasma membrane?

Answer 1

To surround and separates the cell from the environment.

Question 2

What are the key features of plasma membrane?

Answer 2

• Composed of mostly lipids and proteins
• Controls movement in + out of the cell
• Provides structural support
• Interacts with the environment
• Separates fluids into separate compartments (Extracellular fluid + intracellular fluid)

Question 3

ECF

Answer 3

Extracellular Fluid:
Composed of water and dissolved chemicals outside of the cell
Blood, lymph & interstitial fluid

high in Na+, Ca++, Cl- (salt, calcium, chlorine)

Question 4

ICF

Answer 4

Intracellular Fluid= fluid inside cells –> Cytosol
- high in K+ (potassium), amino acids + nucleic acids

usually negative in charge to ECT

Question 5

What is the Endomembrane system?

Answer 5

ECF + ICF
Membranes within the cell to separate it into different parts.

Question 6

Components of Plasma Membrane

Phospholipid Bilayer

brief summary

Answer 6

• 2 layers of phospholipids
• 40% of the biological membrane
  Most important structural part

Is amphilic

Question 7

Components of Plasma Membrane

Amphilic

definition, components, placement

Answer 7

=hydrophillic + hydrophobic
1 hydrophillic head w/ phosphorus
- inside layer sticks in to tough water inside the cell
- outside layer sticks out to touch water ouside the cell
2 hydrophobic tails
- attracts hydrophonoc
- faces towards the other layers hydrophobic tails
- between the 2 bilayers

Question 8

Components of Plasma Membrane

Cholesterol facts

Answer 8

=Steroid
* 10% of the plasma membrane
* % varries between cells
* +makes the membrane more rigid, - makes it less permeable to water

Question 9

Components of Plasma Membrane

Pollysaccarides

Types of them.

What is it?

Answer 9

Pollysaccarides stick out of cells acting as a signal to other cells for indentification.
1. Glycolipids
2. Glycoproteins
3. Glycolax

Question 10

Components of Plasma Membrane

Glycolipids

Answer 10

• pollysaccharide
• lipids bound to carbs

Question 11

Components of Plasma Membrane

Glycoproteins

Answer 11

• pollysaccaride
• proteins bound to carbs

Question 12

Components of Plasma Membrane

Glycolax

Answer 12

A layer of pollysaccharides on the outside of the cell

Question 13

Components of Plasma Membrane

Proteins

Name the proteins in the plasma membrane

Answer 13

1. peripherial membrane proteins
2. integral membrane proteins
3. transmembrane proteins
4. receptor proteins
5. structural proteins

Proteins in the plasma membrane make up 50%

Question 14

Peripherial Membrane Proteins

Answer 14

Not in the phospholipid bilayer - Attached to the edge

Question 15

Integral Membrane Proteins

Answer 15

Partially penetrate or span across

Question 16

Transmembrane Proteins

Answer 16

Touches the ECF + ICF by going through the membrane

extracellular fluid + intracellular fluid

Question 17

Receptor Proteins

Answer 17

Direct elements outside the cell

Question 18

Transport Proteins

Answer 18

Move things between the ECT + ICF

Question 19

Structural Proteins

Answer 19

Connects to the cytoskeleton inside the cell + extracellular matrix inside the cell

Question 20

Diffusion

What is it? What does it do?

Answer 20

Diffusion moves solutes from high to low concentrations
* doesn’t need energy - actually releases
* happens naturally + spontaneously
* leads to equillibrium
* solutes move with gradient

Question 21

Solute

Answer 21

chemical disolved in water

Question 22

Concentration

Answer 22

amount of solute disolved in a given amount of water

Question 23

Dilute

Answer 23

Lower concentration

Question 24

Concentration Gradient

definition + attributes

Answer 24

The concentration between inside and outside of the cell
* happens across the plasma membrane
* has energy
* bigger difference in solutes leads to more energy

Question 25

Homeostasis | definition + attributes

Answer 25

Homeosasis maintains the difference in concentration between the inside + outside of the cell * NOT equilibrium = death for living cells * Requires energy

Question 26

What affects the rate of diffusion in the plasma membrane? | and how do they affect the membrane?

Answer 26

* +concentration gradient = +rate * +membrane thickness = -rate * +surface area = +rate * +temp = +rate * +molecules = -rate * +permeability = +rate

Question 27

Osmosis

Answer 27

How water moves across membranes following salt. * diffusion of water * only way the body can move water across membranes * the body uses energy to move salt from one side of membrane

Question 29

Semipermiable membrane

Answer 29

Membrane that allows *some* chemicals to pass. - solutes that can pass will diffuse

Question 30

Tonicity

Answer 30

The total concentration of solutes that *can't* diffuse.

Question 30

Hypotonic

Answer 30

Occurs when there are fewer solutes outside than inside the cell. water moves in --> cell swells (could explode) | hypo = water loving

Question 31

Hypertonic

Answer 31

Occurs where there's more solutes outside than inside the cell. Water leaves the cell --> cell shrinks | hyper = out

Question 31

Isotonic

Answer 31

Occurs when the same solutes are in and outside the cell - no water movement | Iso = still

Question 32

Passive Transport

Answer 32

Occurs when solutes move / diffuse from high to low concentration. * requires *no* energy

Question 33

Active Transport

Answer 33

Occurs when solutes move from low to high concentrations. *Requires E*

Question 34

Simple Diffusion | What is it? What does it diffuse? What doesn't diffuse?

Answer 34

Occurs when solutes move through the phospholipid bilayer. Hydrophobic molecules that can pass: * lipids + steroids * gas - oxygen + carbon monoxide * small polar molecules: water + ethanol (moves slowly) Molecules that can't pass: * ions * sugars * amino acids * proteins

Question 35

Facilitated Diffusion

Answer 35

Occurs when solutes move though a transport protein passively.

Question 36

Transport Proteins | Definition + types

Answer 36

Transmembrane proteins that chemicals can pass through - pumps 1. Channel Proteins 2. Carrier Proteins

Question 37

Channel Proteins

Answer 37

Transmembrane proteins (pumps) that only do facilitated diffusion.

Question 38

Pumps

Answer 38

A general form of carrier proteins that do facilitated diffusion.

Question 39

Carrier Proteins | Definition

Answer 39

Responsible for transporting protins though ficilitated diffusion and active transport. Need to change in shape when moving something

Question 40

Carrier Proteins: Process

Answer 40

bind chain on one side --> push through membrane --> release on the other side 1. Form (active transport) a hole in the plasma membrane for certain chemicals to diffuse 2. Facilitated diffusion occurs in the pumps

Question 41

Glucose Transporter (GLUT)

Answer 41

Type of carrier protein that does facilitated diffusion of glucose in and out of the cell.

Question 42

Uniport

Answer 42

Involves 1 protein channel

Question 43

Cotrasport

Answer 43

Process of moving 2 chemicals across the membrane.

Question 44

Symport

Answer 44

Process of moving 2 chemicals in the same direction.

Question 45

Antiporter

Answer 45

Process of moving chemicals in the opposite direction.

Question 46

Aquaporin

Answer 46

Protein channel that allows water to pass.

Question 47

Ion Channels

Answer 47

Channels for ions to pass, specific to the type of ion.

Question 48

Channel Proteins | Types + responsibilities

Answer 48

* Leak channels - always open + leaking chemicals * gated channels - only respond to stimulus (Chemical, mechanical force, voltage change)

Question 49

Primary Active Transport | Definition + users

Answer 49

When carriers to use ATP as energy and can only be done by pumps. 1. Proton pump - ATP moves from H+ from low to high 2. Sodium Potassium (Na+K+) Pump - ATP moves 3 Na+ out of the cell, 2 K+ in. * extracellular fluid moves Na+, intracellular fluid moves K+

Question 50

Secondary Active Transport | Definition + Process

Answer 50

When energy is aquired to allow Na+ to diffuse into the cell 1. Primary active transport created Na+ gradient (Energy is present) 2. Let Na+ diffuse into the cell and uses energy to move another chemical from low to high concentration (Energy is released)

Question 51

Sodium Glucose Transporter (SGLT) ## Footnote What does it do?

Answer 51

1. Na+K+ pumps create a gradient with high Na+ outside the cell 2. SGLT lets Na+ back into the cell, energy is used to pull glucose in too

Question 52

Membrane Potential ## Footnote Definition + attributes

Answer 52

The difference in charge between two sides of the membrane. 1. membrane potential is maintained by opening and closing ion channels * ions flow in or out of the cell changing the charge on either side * different channels = different effects on membrane

Question 53

Channels that affect the plasma membrane & how

Answer 53

* Open Na+ or Ca++ = Move Na+&Ca++ into the cell = more positive * Open K+ = Move K+ into the cell = more negative * Open Cl- = Move Cl- into the cell = more negative

Question 54

Electrochemical Gradient ## Footnote Definition

Answer 54

The difference in chemical concentrations and electrical charge across the membrane.

Question 55

Effectors of Electochemical Gradient

Answer 55

* ions = charge * ^ cations (+) outside the cell = ouside ECF creates a *positive* charge relative to the outside -- inside the cell will have a *negative* charge relative to outside

Question 56

Voltage ## Footnote Definition

Answer 56

Units used to measure potential

Question 57

Membrane Potential

Answer 57

= inside charge - outside charge * usually negative * at rest

Question 58

Vesicular Transport

Answer 58

Occurs when substances move in + out of the cell with vesicles.

Question 59

Exocytosis ## Footnote What is it? What is the process?

Answer 59

A type of vesicular transport. Occurs when a vesicle goes up to the plasma membrane, merges with the membrane, and releases substances outside the cell.

Question 60

Endocytosis ## Footnote What is it? What is the process?

Answer 60

A type of vesicular transport. Occurs when part of the membrane pinches off and forms a vesicule, this process pulls substances from outside the cell into it.

Question 61

What are the other types of endocytosis occur in cells? ## Footnote List them

Answer 61

1. Pinocytosis 2. Receptor-Mediated Endocytosis 3. Phagocytosis

Question 62

Pinocytosis

Answer 62

A non-specific process that pulls small substances outside of the cell (like taking a sip).

Question 63

Receptor-Mediated Endocytosis

Answer 63

Endocytosis of certain specific chemicals - something specific bonds to a receptor.

Question 64

Phagocytosis

Answer 64

Phago = eat Occurs when a lysome merges with a vesicle and releases what's inside. Ex: large molecules, baterial cells, dead tissue

Question 65

ECM ## Footnote Definition and functions

Answer 65

**Extracellular Matrix** is a mesh of macromolecules and ions outside the cell that gives structure to the tissue. * holds the cell in place * gives tissues their characteristics (stretch, shape, etc.) * has lots of connective tissue * is secreated by the cell * attaches to membrain proteins to hold it in place

Question 66

Cell Junctions

Answer 66

A combination of membrane proteins + other proteins that connect cells to others on the ECM. These connections between cells hold them together, they can be long lasting or transmit/ transient.

Question 67

CAMs

Answer 67

**Cell Adhesion Molecules** are transmember proteins that attach to molecules outside of the cell on the ECM. BUT large protein complexes inside the cell attach to CAMs on the cytoskeleton.

Question 68

Gap Junction

Answer 68

Small membrane channels that are attached to cells for small substances to pass between cells, ions + chemical signals.

Question 69

Tight Junctions

Answer 69

Protein complexes that hold cells closely together so substances can't pass between cells.

Question 70

Desmosomes

Answer 70

Structures where 2 cells are attached inside by intermediate fillaments to create a sheet of cells inside and outside. Substances can still pass between cells.