Unit 2 - Cells

Question 1

Describe structure and function of cell surface membrane

Answer 1

Hydrophilic phosphate head

Hydrophobic fatty acid tails

Selectively permeable - enables passage of substances

Receptors on surface - allow recognition

Question 2

Describe the function of the rough endoplasmic reticulum (3)

Answer 2

Ribosomes synthesise proteins

Proteins processed inside RER

Proteins packaged into vesicles for transport

Question 3

Describe the function of the smooth endoplasmic reticulum (2)

Answer 3

Synthesises and processes lipids

Eg cholesterol

Question 4

Describe the function of the Golgi body (5)

Answer 4

Apparatus:

Adds carbohydrate to protein- form glycoprotein
Adds carbohydrate to lipids - form glycolipids
Packages proteins and lipids into Golgi vesicle
Produces lysosomes

Vesicl:

Transports proteins and lipids to

Question 5

Describe the structure of mitochondria

Answer 5

Surrounded by double membrane
Matrix contains circular dna
Small 70s ribosomes

Question 6

Compare and contrast the structure of eukaryotic and prokaryotic cells (6)

Answer 6

Eukaryotic cells have membrane bound organelles, prokaryotes do not

Eukaryots have linear DNA contained in nucleus, prokaryotes have circular DNA free in the cytoplasm

Eukaryotic cells are larger overall

Eukaryotic cells have larger (80s) ribosomes
Prokaryotic cells have smaller (70s) ribosomes

Only plant algae and fungal eukaryotes have a cell wall containing cellulose or chitin

Prokaryotes sometimes have plasmids a capsid or a flagellum

Question 7

Transmission electron microscope (5)

Answer 7

2D image

High(er) resolution due to short wavelength of electrons

Internal structures are visible

Specimens must be thin, dead/dehydrated

Black + white image produced

Question 8

How do TEMs work (2)

Answer 8

Electrons focused using electromagnets

Electrons pass through specimen