Topic 3A

Question 1

What are the two broad types of cells?

Answer 1

Answer: Eukaryotic and prokaryotic cells

Question 2

What is the difference in size between eukaryotic and prokaryotic cells?

Answer 2

Answer: Eukaryotic cells range from 10-100 μm in diameter, while prokaryotic cells range from 0.1-5 μm.+

Question 2

What is ultrastructure?

Answer 2

Answer: Ultrastructure refers to the internal structure of cells.

Question 2

What is the main difference between eukaryotic and prokaryotic cells?

Answer 2

Answer: Eukaryotic cells have a more complex internal structure, including membrane-bound organelles, while prokaryotic cells do not.

Question 3

What is a key feature of eukaryotic cells?

Answer 3

Answer: Eukaryotic cells have membrane-bound organelles, including a nucleus.

Question 4

What is the function of the cell surface membrane?

Answer 4

Answer: The cell surface membrane controls the exchange of materials between the internal cell environment and the external environment.

Question 5

What is the structure of the cell surface membrane?

Answer 5

Answer: It is formed from a phospholipid bilayer with a diameter of around 10 nm.

Question 6

What does the nucleus contain?

Answer 6

Answer: The nucleus contains chromatin, which is made up of linear DNA tightly wound around proteins called histones.

Question 7

What are nuclear pores and why are they important?

Answer 7

Answer: Nuclear pores are channels that allow mRNA and ribosomes to travel out of the nucleus, and enzymes and signaling molecules to travel in

Question 8

What is the nucleolus and its function?

Answer 8

Answer: The nucleolus is a darkly stained region of the nucleus that is the site of ribosome production.

Question 9

What is the function of mitochondria?

Answer 9

Answer: Mitochondria are the site of aerobic respiration, which produces ATP.

Question 10

What structures are found in mitochondria?

Answer 10

Answer: Mitochondria have a double membrane, with the inner membrane folded to form cristae. They also contain mitochondrial DNA and ribosomes.

Question 11

What is the function of ribosomes?

Answer 11

Answer: Ribosomes are the site of protein translation, where mRNA is used to synthesise proteins.

Question 12

What is the difference between 80S and 70S ribosomes?

Answer 12

Answer: 80S ribosomes are found in eukaryotic cells, while 70S ribosomes are found in prokaryotes, mitochondria, and chloroplasts.

Question 13

What is the function of the rough endoplasmic reticulum (RER)?

Answer 13

Answer: The RER processes proteins made on the ribosomes.

Question 14

What is the role of the smooth endoplasmic reticulum (SER)?

Answer 14

Answer: The SER is involved in the production, processing, and storage of lipids, carbohydrates, and steroids.

Question 15

What is the role of the Golgi apparatus?

Answer 15

Answer: The Golgi apparatus modifies proteins and lipids before packaging them into vesicles for transport to their destinations.

Question 16

What is the function of lysosomes?

Answer 16

Answer: Lysosomes contain hydrolytic enzymes that break down waste materials, worn-out organelles, and are involved in apoptosis (programmed cell death).

Question 17

What are centrioles and their function?

Answer 17

Answer: Centrioles are structures made of microtubules that organize spindle fibers during cell division. They are not found in plant and fungal cells.

Question 18

What is the role of microvilli in animal cells?

Answer 18

Answer: Microvilli are folded regions of the cell surface that increase surface area for absorption, such as in the small intestine.

Question 19

What are the key differences between plant and animal cells?

Answer 19

Answer: Animal cells contain centrioles, and some have microvilli, while plant cells have a cellulose cell wall, large permanent vacuoles, and chloroplasts.

Question 20

Ribosomes

Answer 20

• All cells include ribosomes as free organelles, and eukaryotic cells also have them as a component of the rough endoplasmic reticulum.
• There is no membrane around them.
• Each ribosome is made up of a combination of proteins and ribosomal RNA (rRNA).
• There are 80s ribosomes in eukaryotic cells.
• Prokaryotes, mitochondria, and chloroplasts have 70s ribosomes.
• Ribosomes are the site of translation.

Question 21

Rough Endoplasmic Reticulum (RER)

Answer 21

Folds of membrane that are continuous with the nuclear envelope make up the RER.
Ribosomes coat the RER’s surface.
The RER’s function is to process proteins produced by ribosomes.

Question 22

Smooth Endoplasmic Reticulum (SER)

Answer 22

The SER is similarly made up of membrane folds, but unlike the RER, it serves a different purpose by being involved in the synthesis, processing, and storage of lipids, carbohydrates, and steroids.
Ribosomes are not present on the surface of SER.

Question 23

Define Membrane-bound compartments

Answer 23

These are enclosed structures within a cell that are surrounded by a membrane.
These compartments are typically organelles like the nucleus, mitochondria, and the endoplasmic reticulum.
The membrane helps separate the internal environment of the compartment from the cytoplasm of the cell, allowing for specialised functions to take place.

Question 24

Protoplasm

Answer 24

Protoplasm is the living substance inside a cell, consisting of the cytoplasm and the nucleus. It includes the cell’s organelles, cytosol (the liquid part of the cytoplasm), and other components that carry out the cell’s functions. The protoplasm is the site of most cellular activities like metabolism, growth, and reproduction.

Question 25

List the several key components of a mitochondrion.

Answer 25

• Outer membrane
• Inner membrane
• Matrix
• Intermembrane space
• Mitochondrial DNA
• Ribosomes