Cell Structure & Organisation (D)

Question 1

What is the structure and function of cell surface/plasma membrane?

Answer 1

• These control the exchange of materials between the internal and external environments
• The membrane is partially permeable, some substances can pass through the membrane
• There is a phospholipid bilayer

Question 2

What is the structure and function of the nucleus?

Answer 2

• Separated from the cytoplasm by the nuclear envelope
• Nuclear envelope: pores to allow mRNA and ribosomes out and enzymes in
• Chromatin: this is linear DNA that makes chromatin
• Histones: chromatin is wound around proteins called histones

Question 3

Explain the structure and function of nucleolus?

Answer 3

A dark area of the nucleus, it is involved in the synthesis of ribosomal RNA and formation of ribosomes

Question 4

Explain the structure and function of ribosomes?

Answer 4

• Very small
• Can be found in cytoplasm or attached to the rER,
• Site of protein synthesis

Question 5

Explain the structure and function of the rough endoplasmic reticulum (rER)

Answer 5

• Folds of the membrane that are continuous with nuclear envelope,
• Surface is covered in ribosomes and its role is to process proteins and glycoproteins
• It is then taken to the Golgi apparatus to be secreted

Question 6

Explain the structure and function of smooth endoplasmic reticulum (sER)

Answer 6

• Made from the folds of the membrane that are continuous with the nuclear envelope
• It plays an important role in producing cholesterol and lipids

Question 7

Explain the structure and function of mitochondria

Answer 7

• Site of aerobic respiration
• Double membrane, 2nd membrane folds for form cristae
• Matrix of mitochondria has enzymes, producing ATP (in respiration) and circular DNA

Question 8

Explain the structure and function of the Golgi apparatus

Answer 8

• Stacked, flattened sacs of membrane
• Modifies proteins and lipids
• Forms secretory vesicles to transport proteins and lipids to their required destination
• forms lysosymes

Question 9

Explain the structure and function of Lysosome

Answer 9

• Specialist vesicles containing hydrolytic enzymes to break down waste materials

Question 10

Explain the structure and function of Centrioles

Answer 10

• Made of hollow fibres known as microtubules
• Microtubules are filaments of protein that can be used to move substances inside a cell and support the cell shape

Question 11

How do the rER and Golgi apparatus transport proteins?

Answer 11

• Proteins made on the rER are transported and secreted (unlike proteins processed from free ribosomes in cytoplasm)
• rER proteins are transported to the Golgi apparatus in vesicles
• Proteins are modified at the Golgi apparatus to be secreted at the cell membrane

Question 12

P: Explain the structure and function of plasmids?

Answer 12

• Small loops of DNA

Question 13

P: Explain the structure and function of capsule?

Answer 13

• A slimy outer layer
• Stops bacteria drying out
• Protects from cells of the immune system

Question 14

P: Explain the structure and function of flagellum?

Answer 14

Hair-like structure that rotates enabling the cell to move

Question 15

P: Explain the structure and function of pili?

Answer 15

Hair-like structures that extend from the bacteria surface to enable the bacteria to attach to other cells and surfaces

Question 16

P: Explain the structure and function of mesosomes?

Answer 16

Folded regions of the membrane that are involved in aerobic respiration, cell division, DNA replication

Question 17

P: Explain the structure and function of ribosomes?

Answer 17

• Site of protein synthesis
• Smaller than eukaryotic ribosomes

Question 18

P: Explain the structure and function of circular DNA

Answer 18

• A single circular strand
• No nuclear membrane