Cell Structure

Question 1

Describe the structure of the nucleus.

Answer 1

• nuclear envelope (double membrane)
• nuclear pores
• nucleoplasm (granular, jelly-like material)
• chromosomes (protein-bound, linear DNA)
• nucleolus (site of rRNA production + makes ribosomes)

Question 2

What is the function of the nucleus?

Answer 2

• site of DNA replication + transcription (making mRNA)
• contains genetic code for each cell

Question 3

Describe the structure of the rough + smooth endoplasmic reticulum.

Answer 3

• rough + smooth ER both have folded membranes called cristernae
• rough ER has ribosomes on cristernae

Question 4

What is the function of the smooth + rough endoplasmic reticulum?

Answer 4

• RER: site of protein synthesis
• SER: synthesises + stores lipids + carbohydrates

Question 5

Describe the structure of the Golgi apparatus + Golgi vesicles.

Answer 5

• folded membranes making cisternae
• secretary vesicles pinch off from cisternae

Question 6

What is the function of the Golgi apparatus + Golgi vesicles?

Answer 6

• add carbs to proteins to form glycoproteins
• produce secretory enzymes
• transport, modify + store lipids
• form lysosomes
• Golgi vesicles transport finished products to cell surface + fuse w membrane, releasing contents

Question 7

Describe the structure of lysosomes.

Answer 7

• membrane bound organelles containing hydrolytic enzymes (can contain 50 diff. enzymes)

Question 8

What is the function of lysosomes?

Answer 8

• hydrolyse phagocytic cells
• completely break down dead cells (autolysis)
• release enzymes to outside cell, to destroy material, via exocytosis
• digest worn out organelles for reuse of materials

Question 9

Describe the structure of the cell surface membrane.

Answer 9

• phospholipid bilayer, embedded w proteins, carbs, cholesterol, which are also attached to outside

Question 10

What is the function of the cell surface membrane?

Answer 10

• controls molecules that enter + exit cell
• compartmentalises diff structures within cell
• separates internal envi. from external envi.

Question 11

Describe the structure of the cell wall.

Answer 11

• in plants: made of microfibrils of cellulose polymer
• in fungi: made of chitin (a nitrogen containing polysaccharide)

Question 12

What is the function of the cell wall?

Answer 12

• to provide structural strength to cell

Question 13

Describe the structure of the cell vacuole.

Answer 13

• filled w fluid + is surrounded by a single membrane called a tonoplast

Question 14

What is the function of the vacuole?

Answer 14

• to make cells turgid, + so provide support to plant
• temporarily stores sugar + AAs
• pigments may colour petals to attract - to make cells turgid, + so provide support to plant
• temporarily stores sugar + AAs
• pigments may colour petals to attract pollinators

Question 15

Describe how prokaryotic cells differ from eukaryotic cells.

Answer 15

• cells are much smaller
• cytoplasm lacks membrane-bound organelles
• smaller ribosomes
• no nucleus (have a singular circular DNA molecule, that’s free in cytoplasm + isn’t associated w proteins)
• cell wall made of murein (a glycoprotein)

Question 16

What other features do prokaryotic cells have that eukaryotic cells don’t?

Answer 16

• 1 or more plasmids (small loops of DNA, which only carry a few genes)
• a capsule surrounding cell (prevents bacteria from drying out + protects it against host’s immune system)
• 1 or more flagella (rotates to enable bacteria to move)

Question 17

What are viruses?

Answer 17

• acellular, non-living particles

Question 18

Describe the structure of a virus particle.

Answer 18

• contain genetic material, capsid + attachment proteins