Inner cell

Question 1

what is the structure of the endomembrane system

Answer 1

collection of membranes inside and surrounding eukaryotic cells

Question 2

functions of the endomembrane system

Answer 2

• storage and trafficking
• metabolism
• detoxification

Question 3

what is the SER

Answer 3

smooth endoplasmic reticulum - surface lacks ribosomes
extensively developed in many cells: muscles, kidneys, steroid producing endocrine cells

Question 4

what is the RER

Answer 4

rough endoplasmic reticulum - surface covered in ribosomes
carries out protein synthesis due to ribosomes

Question 5

what is the TER

Answer 5

transitional endoplasmic reticulum - exit/entry site
site of exit from ER and entry into the secretory pathway

Question 6

what is the structure of the Golgi apparatus

Answer 6

flattened membranous sacs called cisternae - arranged in orderly stack-like pancakes

Question 7

describe the function of the Golgi apparatus

Answer 7

• receives newly synthesised proteins from ER and modifies them by proteolysis, amino acid modification, modifying their carbohydrate chains
• sorts and ships materials into transport vesicles

Question 8

what is the overall role of the ER and Golgi apparatus

Answer 8

metabolism and trafficking within the cells

Question 9

what are lysosomes

Answer 9

digestive compartments found in animal cells

Question 10

what is the structure of lysosomes

Answer 10

membranous sac of hydrolytic enzymes that can digest macromolecules

Question 11

what is the function of lysosomes

Answer 11

involved in phagocytosis and autophagy

Question 12

define phagocytosis

Answer 12

the process by which a cell engulfs a particle and digests it

Question 13

define autophagy

Answer 13

degrades unwanted proteins and organelles and recycles their components

Question 14

how do cells protect themselves from ‘self-digestion’

Answer 14

via pH controlled mechanisms and bulky protective structure of lysosomal components

Question 15

what is the structure of a vacuole

Answer 15

large vesicles derived from the ER and Golgi apparatus

Question 16

what is the function of a vacuole

Answer 16

varies across different cells
* food vacuoles are formed by phagocytosis in animal cells
* contractile vacuoles pump excess water out of cells
* central vacuoles in plants contain sap
* digestive vacuoles in plants act as plant lysosomes
* storage vacuoles in plants act as reserves

Question 17

what is a peroxisome

Answer 17

oxidative organelles
specialised metabolic compartments bounded by a single membrane

Question 18

what is the structure of peroxisomes

Answer 18

contain enzymes that remove hydrogen atoms from various substances and transfer them to oxygen, forming hydrogen peroxide, which is decomposed by catalase to form water

Question 19

what is the function of a cells compartmentalisation

Answer 19

allows dangerous reactions to occur in the protected environment of lysosomes, vacuoles and peroxisomes

Question 20

what is the structure of the cytoskeleton

Answer 20

network of fibres extending through the cytoplasm
4 components:
* microtubules
* microfilaments
* intermediate filaments
* accessory proteins

Question 21

what is the function of the cytoskeleton

Answer 21

‘muscle and skeleton’ of the cell
- cell shape maintenance and change
- cell organisation
- cell motility
- organelles motility

Question 22

what is the function of microtubules

Answer 22

• shaping the cell
• guiding movement of organelles
• separating chromosomes during cell division

Question 23

what are cilia and flagella

Answer 23

microtubule containing extensions that project from some cells

Question 24

what is the difference between cilia and flagella

Answer 24

they differ in their beating patterns
flagella undulates, cilia back and forth

Question 25

which are more numerous, cilia or flagella

Answer 25

motile cilia are found in large numbers on cell surface flagella are limited to one or a few per cell

Question 26

what is the structure of cilia and flagella

Answer 26

a group of microtubules sheathed in an extension of the plasma membrane a basal body that anchors the cilium or flagellum a motor protein called dynein which drives the bending movements of a cilium or flagellum

Question 27

what is dynein

Answer 27

a motor protein which drives the bending movements of a cilium or flagellum

Question 28

what is the structure of microfilaments

Answer 28

solid rods built as a twisted double chain of actin subunits

Question 29

function of microfilaments

Answer 29

- Microfilaments that function in muscle contraction contain the protein myosin in addition to actin - In ameboid movement, cells crawl along a surface by extending pseudopodia (cellular extensions) and moving toward them - Cytoplasmic streaming, in plant cells, is a circular flow of cytoplasm within cells, driven by actin-protein interactions

Question 30

structure of intermediate filaments

Answer 30

rope like fibres, made up of intermediate filament proteins (e.g. lamins, vimentin, keratin) depending on the cell type

Question 31

function of intermediate filaments

Answer 31

- provide cells with mechanical stability - important at cell-cell contact sites - cell motility - organelles anchorage

Question 32

what is the most diverse family of intermediate filament proteins

Answer 32

keratins - over 50 members

Question 33

what is the purpose of accessory proteins

Answer 33

essential for controlled assembly of cytoskeletal filaments

Question 34

what is the overall role of the microtubule cytoskeleton

Answer 34

maintaining cellular architecture and events through its dynamic properties and regulation

Question 35

what is the overall role of the actin cytoskeleton

Answer 35

its coordinated regulation allows cells to rapidly adapt and move in response to external stimuli