Cells and Organelles

Question 1

Name organelles in a typical human cell (11)

Answer 1

Nucleus, ER, Golgi, Mitochondria, Plasma membrane, Peroxisomes, Lysosomes, Cytoskeleton, Microfilaments, Microtubules, Intermediate filaments

Question 2

Describe organelles

Answer 2

sub cellular compartments featured in eukaryotic cells, usually membrane bound (except ribosomes), specialised for unique functions

Question 3

4 components of nucleus

Answer 3

nuclear membrane, nuclear lamina, chromatin, nucleolus

Question 4

5 components of the plasma membrane

Answer 4

phospholipid bilayer, cholesterol, carbohydrates, proteins, lipid/membrane rafts

Question 5

4 compartments of mitochondria

Answer 5

outer membrane, inter membrane space, inner membrane (cristae), matrix

Question 6

detailed functions of mitochondria (2)

Answer 6

ATP production: TCA (krebs cycle), electron transport chain (needs cytochrome C on inner membrane), oxidative phosphorylation
Apoptosis (release of cytochrome C from mitochondria to cytosine initiates apoptosis)

Question 7

Name ER definition and functions of rER and sER

Answer 7

Definition: complex set of membranes continuous with nuclear membrane
rER: associated with ribosomes, protein synthesis/folding/modifications
sER: no ribosomes, lipid synthesis, calcium storage

Question 8

Name Golgi apparatus definition and functions

Answer 8

Definition: stack of flattened membrane bound discs (cisternae) and vesicles
Functions: received proteins from ER, modifies them and sorts them for eventual destination in or out of cell

Question 9

Function of lysosomes and characteristics

Answer 9

degrade unwanted molecules, approx. 50 degenerative enzymes (acid hydrolyses), optimum pH 5

Question 10

Peroxisome definition and function

Answer 10

definition - membrane bound organelle performing large numbers of biochemical reactions
functions - contains oxidative enzymes such as catalase, break down of fatty acids (b-oxidation)

Question 11

functions of cytoskeleton (6)

Answer 11

organises cell structure, maintains correct cell shape, supports fragile plasma membrane, provides mechanical linkages allowing cell/tissue to bear stress, facilitates organelle movement, allows cells to adopt specific behaviours (growth, division, motility)

Question 12

3 types of cytoskeleton

Answer 12

microtubules, microfilaments, intermediate filaments

Question 13

intermediate filament function and 3 types of different filaments found in different cell types

Answer 13

function - structural role, provides mechanical strength
keratin - skin epithelial cells
vimentin- fibroblasts
lamins - nuclei of eukaryotic cells

Question 14

intermediate filament function in nucleus

Answer 14

in nuclear lamina (composed of lamins), nuclear organisation, nuclear membrane support, chromatin organisation

Question 15

microtubules function and polymers

Answer 15

function - dynamic structures: cell movement, intracellular support of organelles, mitotic spindle
polymers of a and b tubulin

Question 16

microtubules role in intracellular organelle support

Answer 16

kinesins move cargo away from centrosome
dyneins vice versa

Question 17

what is the cytoskeleton component of cilia and flagella? what are they composed of?

Answer 17

axonemes, allow for bending, primarily composed of microtubules and dynein

Question 18

microfilaments function and polymers of…

Answer 18

function - dynamic processes like cell shape change, cell motility and cell structure
polymers of actin

Question 19

what do cells do in tissues and organs, what structure makes this possible?

Answer 19

work together as aggregates to cooperatively perform a given function, possible through cell junctions

Question 20

cell junction definition and function

Answer 20

definition - transmembrane protein complexes
function - connects plasma membrane to adjacent cells, the basement membrane and the cytoskeleton

Question 21

what anchoring junctions are cell-cell, and what is their cytoskeleton made of?

Answer 21

adherens (actin) and desmosomes (intermediate filaments)

Question 22

what anchoring junctions are cell-extra cellular matrix, and what is their cytoskeleton made of?

Answer 22

focal adhesions (actin) and hemidesmosomes (intermediate filaments)

Question 23

tight junction functions

Answer 23

function as ‘gates’ and ‘fences’
gates control regulation of paracellular permeability
fences form apical and basolateral intramembrane diffusion barriers

Question 24

name of channel forming junctions, type of contact, composition and function

Answer 24

GAP junction, cell-cell contact, composed of hexamers and connexins, allows passage of small molecules

Question 25

which cell had no nucleus, describe it

Answer 25

red blood cell (erythrocyte), biconcave shape, anucleate, lives for 120 days and functions to carry oxygen to tissues

Question 26

name 2 examples of a cell with enriched rER and golgi organelles to carry out their specific functions

Answer 26

plasma cells - produce large amounts of antibodies
fibroblasts - forms connective tissues

Question 27

name 3 cells enriched with sER for their specific function

Answer 27

hepatocytes - lipid biosynthesis
leydig cells - steroid hormone biosynthesis
muscle cells - calcium store needed

Question 28

name condition caused by defective hemidesmosome components, and effects of condition

Answer 28

epidermolysis bullosa, very fragile skin prone to blistering, skin tears easily upon touch and is painful

Question 29

name 3 cells where defective cilia may cause problems in cellular functions

Answer 29

respiratory epithelial cells - mucus clearance from airways
brain ependymal cells - circulation of CSF
epithelial cells lining fallopian tubes - help ovum to move to uterus

Question 30

name the process of defects in microtubules and the disease it can cause

Answer 30

Tau protein dissociates from microtubules in alzheimer’s disease, resulting in microtubules disassembly

Question 31

name the disease caused as a result of lysosome storage disorders, and the process of defection

Answer 31

Tay-Sachs disease, accumulation of gangliosides (type of lipid with a carbohydrate protein) in brain and spinal cord

Question 32

what defective cellular structure can cause cancer, and how?

Answer 32

adherens junctions - epithelial tumours lose e-cadherin (forms part of adherens junction)