L3: CELL STRUCTURE AND FUNCTION

Question 1

What is the plasma membrane made of?

Answer 1

The plasma membrane is a semipermeable phospholipid bilayer that defines the boundary of a cell.

Question 2

What factors affect the permeability of the plasma membrane?

Answer 2

The permeability depends on the proteins embedded in the membrane, which have hydrophobic regions.

Question 3

What does the “fluid mosaic model” describe?

Answer 3

The “fluid mosaic model” describes the lateral movement of membrane components (proteins and lipids).

Question 4

Can water diffuse through the plasma membrane?

Answer 4

Yes, water can diffuse through the membrane because it is small, even though it is polar.

Question 5

Can oxygen diffuse through the plasma membrane?

Answer 5

Yes, oxygen can diffuse through because it is non-polar.

Question 6

Can amino acids diffuse through the plasma membrane?

Answer 6

No, amino acids are large and polar, so they cannot diffuse through easily.

Question 7

Can glucose diffuse through the plasma membrane?

Answer 7

No, glucose is large and polar, so it cannot diffuse through the plasma membrane.

Question 8

Can ions diffuse through the plasma membrane?

Answer 8

No, ions are charged and cannot diffuse through the plasma membrane.

Question 9

What do prokaryotic cells lack?

Answer 9

Prokaryotic cells lack internal membrane-bound organelles.

Question 10

What covers the plasma membrane of prokaryotic cells?

Answer 10

The plasma membrane of prokaryotic cells is covered by a cell wall.

Question 11

What does the cytosol in prokaryotic cells contain?

Answer 11

The cytosol contains proteins and nucleic acids in prokaryotic cells.

Question 12

How do prokaryotic cells compare in size to eukaryotic cells?

Answer 12

Prokaryotic cells are much smaller than eukaryotic cells.

Question 13

What is the difference between cytoplasm and cytosol?

Answer 13

The cytoplasm includes all the contents of the cell minus the nucleus, while the cytosol is the part of the cell minus all organelles.

Question 14

What is contained in the nucleus of a cell?

Answer 14

The nucleus contains the cell’s DNA, which holds genetic information.

Question 15

What is the nuclear envelope?

Answer 15

The nuclear envelope is a double membrane surrounding the nucleus, containing nuclear pores.

Question 16

What is the role of nuclear pores?

Answer 16

Nuclear pores allow molecules to move in and out of the nucleus.

Question 17

How is DNA in the nucleus packaged?

Answer 17

DNA in the nucleus is packaged with proteins to conserve physical space.

Question 18

What is the function of the ER?

Answer 18

The ER is where proteins and lipids are made.

Question 19

How is the ER connected to the nucleus?

Answer 19

The ER has a single membrane connected to the nuclear envelope.

Question 20

What is the internal space of the ER called?

Answer 20

The internal space of the ER is called the lumen.

Question 21

What is unique about the rough ER?

Answer 21

The rough ER has ribosomes studding its surface, which synthesize proteins to be transported around the cell.

Question 22

What do free-floating ribosomes do?

Answer 22

Free-floating ribosomes make proteins that remain in the cytosol.

Question 23

How is the smooth ER different from the rough ER?

Answer 23

The smooth ER lacks ribosomes and is involved in marking portions where vesicles bud off to transport proteins and lipids.

Question 24

What is the function of the Golgi apparatus?

Answer 24

The Golgi apparatus directs proteins and lipids produced by the ER to their final destinations and adds chemical groups to them.

Question 25

How does the Golgi apparatus look?

Answer 25

The Golgi apparatus consists of a series of flattened membrane sacs surrounded by many small vesicles.

Question 26

How are proteins transported between the ER and Golgi?

Answer 26

Vesicles transport proteins from the ER to the Golgi and between the sacs of the Golgi.

Question 27

What are lysosomes?

Answer 27

Lysosomes are vesicles that contain enzymes used to break down sugars, proteins, and fats.

Question 28

What is the pH of the lumen of lysosomes?

Answer 28

The lumen of lysosomes is acidic, with a pH of about 5.

Question 29

How do molecules reach lysosomes?

Answer 29

Molecules are delivered to lysosomes by vesicles.

Question 30

What is the function of vacuoles?

Answer 30

Vacuoles are organelles found in plants and fungi, and they can store water and nutrients or perform functions similar to lysosomes.

Question 31

What is the function of mitochondria?

Answer 31

Mitochondria are the “power plants” of the cell; they use chemical reactions to break down sugar and produce ATP (cellular respiration).

Question 32

How are mitochondria structured?

Answer 32

Mitochondria are pod-shaped organelles surrounded by a double membrane.

Question 33

What is the function of chloroplasts?

Answer 33

Chloroplasts capture energy from the sun to produce sugar through photosynthesis, using CO2 and water. Oxygen is a waste product.

Question 34

How are chloroplasts structured?

Answer 34

Chloroplasts have a double membrane, and thylakoids inside contain chlorophyll.

Question 35

What is the function of the cytoskeleton?

Answer 35

The cytoskeleton provides dynamic support to the cell, maintaining cell shape and helping with organelle distribution.

Question 36

What are microtubules?

Answer 36

Microtubules are polymers of the protein tubulin that can grow or shrink in length by adding or losing tubulin units.

Question 37

What are actin filaments?

Answer 37

Actin filaments are polymers of actin that can change length by adding or removing actin units.

Question 38

What do actin filaments do?

Answer 38

Actin filaments are involved in cell movement and form networks that help cells move, such as in pseudopodia