Cell structure and organisation

Question 1

Define a eukaryotic cell

Answer 1

• A cell with a nucleus and membrane bound organelles.

Question 2

Describe the structure of a nucleus

Answer 2

• It has a nuclear envelope with a double bilayer and pores to allow RNA and ribosomes to leave.
• It contains a nucleolus which is densely packed with DNA and proteins
• It has a nucleoplasm

Question 3

Describe the function of the nucleus

Answer 3

• Contains DNA wrapped around histones (Chromatin)
• Co-ordinates cellular activities.
• rRNA (Constituent of ribosomes) is made in the nucleolus.

Question 4

Describe the structure of a mitochondrion

Answer 4

• Double membrane
• Inner membrane is folded to form cristae
• Matrix contains DNA, enzymes, lipids and protein.
• Has 70s Ribosomes

Question 5

What is the function of a mitochondrion?

Answer 5

• Site of aerobic respiration to form ATP

- This occurs the inner mitochondrial membrane or the matrix

Question 6

Describe the structure of the Endoplasmic reticulum

Answer 6

• A system of double membranes making flattened discs
• Two types Rough and Smooth ER
• Rough = Ribosomes

Question 7

Describe the function of the Smooth Endoplasmic Reticulum

Answer 7

• Synthesis and transport of lipids

Question 8

Describe the function of the rough endoplasmic reticulum.

Answer 8

• Protein synthesis and transport

Question 9

Describe the structure of ribosomes

Answer 9

• Made from rRNA and protein.

- Attached to RER or or free in cytoplasm

Question 10

Describe the function of ribosomes

Answer 10

Translation of proteins

• Large subunit joins amino acids
• Small subunit reads tRNA

Question 11

Describe the structure of the Golgi body

Answer 11

• Stack of membrane bound flattened sacs.

- Vesicles can be ripped from the Golgi body to transport materials out of the cell.

Question 12

Describe the function of the Golgi body

Answer 12

• Modifies and packages proteins for transport out the cell
• Synthesises and transports glycoprotein.
• Transport of lipids
• Forms lysosomes

Question 13

Describe the structure and function of lysosomes

Answer 13

• Fluid-filled vesicles containing enzymes; single membrane

- Phagocytosis; break down and recycle old organelles

Question 14

Describe the structure of centrioles.

Answer 14

• Cylindrical shape

- Made up of 9 bundles of microtubules = 9 x 3 microtubules.

Question 15

What is the function of centrioles?

Answer 15

• Moves to opposite poles of the cell to organise the spindle fibres.

Question 16

Describe the structure of the chloroplast

Answer 16

• Disk shaped surrounded by double membrane
• Thylakoids = flattened discs to form grana
• Lamellae connect thylakoids in adjacent grana
• Stroma = fluid filled area in the chloroplast.
• Starch grains appear dark under microscope

Question 17

What is the function of the chloroplasts?

Answer 17

• Site of light dependent reactions in photosynthesis

Question 18

Describe the structure of the vacuole in plants

Answer 18

• Surrounded by the tonoplast; single membrane

- Contains cell sap ( minerals dissolved in water)

Question 19

Describe the function of the vacuole in plants

Answer 19

• Controls turgor pressure
• maintains PH
• isolates harmful waste products
• water storage

Question 20

Define plasmodesmata

Answer 20

• Extensions of the cytoplasm which creates channels between plants cells to facilitate symplastic transport.

Question 21

Define a prokaryotic cell

Answer 21

• A cell WITHOUT a nucleus and membrane bound organelles.

Question 22

How is genetic information stored in prokaryotes

Answer 22

• In plasmids which are small rings of DNA

- Loop of DNA - Circular DNA stored in the nucleoid section of the cell

Question 23

Describe the structure and function of flagella

Answer 23

• Long, whip-like tail

- Rotates to propel the organism

Question 24

Describe the function of the capsule in prokaryotes?

Answer 24

• Protective slimy layer

-