3.3.3 Cell Walls

Question 1

review

Answer 1

• The cytoskeleton is comprised of microfilaments, intermediate filaments, and microtubules that provide support and enable movement of the cell’s contents. Centrioles have fused triplet microtubules in a 9+0 arrangement. Flagella and cilia have fused paired microtubules in a 9+2 arrangement.

Question 2

basal body

Answer 2

• it is a eukaryotic cell organelle. It is similar in structure to a centriole and directs microtubule assembly in
  cilia and flagella present at the base of every flagellum and cilium, where it serves to direct microtubule assembly. It consists of fused triplet microtubules in a 9+0 arrangement, and so is similar in structure to the centriole.
• During fertilization a sperm cell’s flagella and basal body enter the egg. The basal body turns into a centriole, possibly indicating a close evolutionary relationship between the structures.

Question 3

cell wall

Answer 3

• a structure of support that lies outside of the plasma membrane. The cells of bacteria, fungi, and plants
  possess a cell wall.
• The bacterial cell wall consists of peptidoglycans; polymers of modified sugars cross-linked by short polypeptides.
• The fungal cell wall contains chitin.
• The cell walls are composed of strands of glucose
  connected by beta linkages, causing every other glucose subunit to be oriented upside-down within the chain. The subunits link together to form cellulose.

Question 4

note

Answer 4

• The majority of living plant cells are connected by
  plasmodesmata (singular, plasmodesma). Plasmodesmata are cytoplasmic channels that run through adjacent plant cell walls. They are surrounded by plasma membrane and form a connection between the cytoplasm of one plant cell and another.

Question 5

Primary cell walls are composed of

Answer 5

• carbohydrates

Question 6

True or false?

Plant cells are the only type of cell that has a cell wall.

Answer 6

• false

Question 7

The cell wall

Answer 7

• is a matrix of cellulose and pectin, with cellulose providing structural support and pectin providing the ‘glue’ to join neighboring cells.

Question 8

Cell walls are found in which types of cells?

Answer 8

• bacterial cells

- plant cells

Question 9

The glucose units of cellulose are bonded together by

Answer 9

• beta 1–4 linkages