Ion Channels + Cellular Homeostasis

Question 1

What is a cell?

Answer 1

Basic structural + functional unit of living organism

Question 2

What is a tissue?

Answer 2

Group of cells with similar structures, working together to perform a shared function

Question 3

What is an organ?

Answer 3

Structure made up of group tissues, working together to perform specific functions

Question 4

What is an organ system?

Answer 4

Group of organs with related functions, working together to perform body functions

Question 5

What is organism?

Answer 5

Living thing performing all 7 life processes

Question 6

What is cytoplasm?

Answer 6

Consists of contents of the cell, enclosed within cell membrane
Includes cytosol + organelles

Question 7

What is cytoplasm mainly composed of?

Answer 7

H2O

Question 8

What is cytoskeleton?

Answer 8

Network of fibres that maintain cell’s shape + give it support

Question 9

What is nuclear envelop?

Answer 9

Double membrane that separates nucleus contents from cytoplasm

Question 10

What is function of nuclear envelop?

Answer 10

Maintains shape of nucleus + regulates in + out of nuclear pores

Question 11

What is nucleolus?

Answer 11

Place where ribosomes synthesised

Question 12

What is the chromosomal DNA in form of?

Answer 12

Chromatin

Question 13

How is proteins produced at ER?

Answer 13

Ribosomes attached to cytoplasmic side 
mRNA translated into protein
Enters ER lumen
Passes through SER
Post translational modification

Question 14

What is ER major reserve of?

Answer 14

Ca2+

Question 15

What are the sacs in golgi?

Answer 15

Cisternae

Question 16

What happens in golgi?

Answer 16

Molecules move between cisternae by budding
Vesicle formation
Proteins packaged in vesicles + “shipped” to other sacs

Question 17

What does size of mitochondria depend on?

Answer 17

Metabolism required

Question 18

What does lysosomes contain?

Answer 18

Hydrolytic enzymes = digest cellular macromolecules

Question 19

What is lysosomes main function?

Answer 19

Degraded newly synthesised proteins

Question 20

What is autophagy?

Answer 20

Intracellular structures + proteins engulfed by lysosomes for degradation

Question 21

What is structure of centriole?

Answer 21

Made up of 9 sets of triplet microtubules

Question 22

How many centrioles does each cell contain?

Answer 22

2

Question 23

Where are centrioles found?

Answer 23

In centrosome (near nucleus)

Question 24

What is function of centrioles?

Answer 24

Provide framework for membranes of ER + golgi

Important in cell division

Question 25

What is function of physical barrier of plasma membrane?

Answer 25

Establishes boundary, protects + supports structure too

Question 26

What is function of selective permeability of plasma membrane?

Answer 26

Regulates entry + exit

Question 27

What is function of electrochemical gradient of plasma membrane?

Answer 27

Maintains electrical charge difference

Question 28

What is function of communication of plasma membrane?

Answer 28

Contains receptors that recognise + respond to molecular signals

Question 29

What does plasma membrane form?

Answer 29

Forms lipid bilayer-fluid + dynamic structure with proteins floating through lipid

Question 30

Where are globular proteins embedded?

Answer 30

Bilayer

Question 31

Where are helical proteins embedded?

Answer 31

Span membrane

Question 32

Where does hydrophilic face?

Answer 32

OUTWARDS

Question 33

Where does hydrophobic face?

Answer 33

INWARDS

Question 34

What is structural protein?

Answer 34

Cell support + shape

Question 35

What is receptor protein?

Answer 35

Help communicate with external environment

Question 36

What is channel protein?

Answer 36

Allow H2O, ions + proteins flow positively through bilayer

Question 37

What is transport protein?

Answer 37

Transport molecules cross cell membrane

Question 38

What are glycoproteins?

Answer 38

Carbohydrate chain attached to protein | Embedded into cell membrane + help cell communication + adhesion

Question 39

How do hydrophobic molecules pass through membrane?

Answer 39

Passive diffusion

Question 40

How do hydrophilic molecules pass through membrane?

Answer 40

Need protein carriers

Question 41

How does H2O cross the membrane?

Answer 41

Diffuses | Aquaporin provide membrane pores

Question 42

What is osmosis?

Answer 42

The diffusion of H2O from less concentrated to more concentrated solution through selectively permeable membrane

Question 43

What is hypotonic?

Answer 43

Swells | H2O moves in

Question 44

What is hypertonic?

Answer 44

Shrinks | H2O moves out

Question 45

How is permeability determined?

Answer 45

No. of ion channels

Question 46

What does Na-K pump do?

Answer 46

2K+ in | 3Na+ out

Question 47

How can Na-K pump be inhibited?

Answer 47

Cell swells

Question 48

How does Na+ move in the cell?

Answer 48

Na-K pump establishes + maintains conc gradient for Na+ Na+ go down conc gradient = inwardly-directed , chemical driving force on Na+ -70mV Inside slightly more negative Na+ = positive = attracted inwards = inward-directed electrical driving force Na+ co-transport = cells take up sugars + amino acids Electrochemical gradient maintains Na-K pump

Question 49

How does K+ move in the cell?

Answer 49

Na+ pump maintains high internal K+ = chemical driving force outwardly directed Electrical still inward = K+ positive Net electrochemical force on K+ = outwardly directed

Question 50

How does Ca2+ move in the cell?

Answer 50

``` Ca 2+ extruded by Ca2+ pump Active transport by ATP Ca2+ binds to proteins in cytoplasm [Ca2+] low in cytoplasm = chemical + electrical gradient Membrane impermeable to Ca2+ ```

Question 51

What do drugs do?

Answer 51

Activate ion channels = allow ions to flow down conc gradient = evoke cellular response

Question 52

What does activation of nicotinic receptors allow?

Answer 52

Na+/Ca2+ to cross membrane + enter cell

Question 53

What are ionotropic receptors?

Answer 53

Ones that allow ions to cross + enter membrane when activated