Cell organelles

Question 1

Characteristics of prokaryotic cells

Answer 1

Single-celled
Lack of organelles
DNA is a nucleoid, no separation from rest of cell
Rigid cell wall
Functional structures suspended in the cytoplasm

Question 2

Eukaryotic cell characteristics

Answer 2

Single and multicellular
Contain organelles
DNA organised into chromosomes within the nucleus
Nucleus is surrounded by cytoplasm containing the organelles

Question 3

What is sub-cellular fractionation

Answer 3

Disruption of the plasma membrane
By ultracentrifugation
Cell components separate on the basis of size and density
Further density-gradient centrifugations can separate individual components from each fraction

Question 4

What is the cell membrane

Answer 4

Phospholipid bilayer
Physical isolation
Regulation of exchange with the environment
Communication between the cell and its environment
Structural support

Question 5

What is the cytoplasm

Answer 5

Semi fluid material surrounding the organelles
Site of many cellular reactions
Offers support to the cell
Medium for transport inside the cell

Question 6

What is the nucleus

Answer 6

Cells control centre
Regulates all cellular activity
Contains DNA

Question 7

Two critical functions of the nucleus

Answer 7

Contains the cells hereditary information

Co-ordinates and controls cellular metabolic activity

Question 8

What is the function of nucleolus

Answer 8

Transcribes and assembles rRNA

Question 9

What are the functions of nuclear pores

Answer 9

Facilitates communication between the nucleus and cytosol
ions and small molecules pass freely
allow the cell to restrict DNA to the nucleus

Question 10

What is the endoplasmic reticulum

Answer 10

System of folded, interconnected membranous vesicles
contain large flattened sac-like structures called cisternae
Internal space called the lumen

Question 11

Where are the proteins synthesised in the rough ER transported to

Answer 11

Lumen where modifications take place

Question 12

What happens in the smooth ER

Answer 12

Biosynthetic and biotransformational activities

In liver and kidney, inactivating and detoxifying xenobiotics

Question 13

What is the Golgi apparatus involved in

Answer 13

Packaging and distribution of cell product for internal and external use
Vesicles budding off ER and are accepted by Golgi
Vesicles budding off Golgi travel to the cell surface or other organelles

Question 14

Function of vacuoles

Answer 14

Help to maintain internal hydrostatic pressure
Store nutrients and waste
Increase cell size during growth

Question 15

Characteristics of lysosomes

Answer 15

Bud from the Golgi
Approx. 0.5-1 micrometre in diameter, single membrane
Contain aggregates of digestive enzymes
Lumen has a low pH
Acid hydrolases

Question 16

What is the autophagy

Answer 16

Breakdown of redundant cellular components

Question 17

what prevents lysosome membrane from self-destruction

Answer 17

special carbohydrate coating

Question 18

Characteristics of Peroxisomes

Answer 18

Derived from the ER
Smaller than lysosomes
Contain the enzymes oxidase and catalase
Abundant in the liver
Detoxify and decompose harmful substances

Question 19

Function of transport vesicles

Answer 19

Move molecules within the cell

recognise and fuse only with the target membrane

Question 20

What are the fucntions of secretaory vesicles

Answer 20

Removal of waste

release of chemical signals

Question 21

two types of vesicle fusion

Answer 21

full fusion

kiss-and-run