Chapter 4: Cards 21-30 Organelles Part II

Question 1

There are three components of the cytoskeleton. What are each of these?

1) Thick and hollow, composed of tubulin dimers. Responsible for moving DNA during cell division, cell movement, shape and support the cell
2) Thin filaments composed of actin. Play an important role in muscle contraction and cell movement (cytokinesis).
3) In between the other two components in terms of size. Composed mostly of Keratin. Help make cells rigid.

Answer 1

1) Microtubules
2) Microfilaments
3) Intermediate filaments

Question 2

What structural and functional differences exist between cilia and flagella?

Answer 2

Cilia are short, found in large numbers, and beat rhythmically in a back-and-forth pattern.

Flagella are longer, with only a few found per cell at the most, and beat more slowly but powerfully to propel the cell in a certain direction.

In eukaryotes, both cilia and flagella consist of 9 microtubule pairs arranged in a circle surrounding 2 single microtubules.

Question 3

Which cell types are encased in a cell wall?

Answer 3

Plant cells (cellulose)

Bacterial cells

Question 4

In animal cells, where is most cholesterol found?

Answer 4

Cholesterol is found in the cell (plasma) membrane and confers rigidity to the membrane.

Question 5

Define Endocytosis

Answer 5

Endocytosis is a form of transport in which a material is engulfed by the cell membrane, then enters the cell in a vesicle. Endocytosis requires the expenditure of energy.

Phagocytosis (cell eating) and pinocytosis (cell drinking) are both subtypes of endocytosis.

Question 6

Define exocytosis

Answer 6

Exocytosis is a form of transport in which a material is packaged into a vesicle which then fuses with the cell membrane. This process, which requires energy, allows the material to be exported from the cell.

Waste products and secreted hormones often leave a cell via exocytosis.

Question 7

There are three types of junctions between cells. I’ve given the definition, you provide the term:

Forms an impermeable seal between cells.

Composed of small channels between cells for communication

Anchor sheets of cells together. Think of as rivets of keratin protein.

Answer 7

Tight junction: impermeable seal between cells.

Gap junction: small channels between cells for communication

Desmosomes: anchor sheets of cells together. Think of as rivets of keratin protein.

Question 8

What are peroxisomes, and what cellular function do they perform?

Answer 8

Primarily involved in detoxification of alcohol and other toxic drugs by removing H+’s and adding them to oxygen to form H₂O₂ (peroxide). Peroxide is then converted to H₂0 because H₂O₂ is toxic.

Question 9

Study the attached image of a chloroplast and describe each component listed.

Answer 9

DNA - used for chloroplast reproduction

Stroma - like cytoplasm of animal cell

Lipids and Starch - energy storage molecule

Thylakoid - site of light energy capture to produce glucose

Granum - stacks of Thylakoids

Ribosomes - site of protein production

Lamella - the membrane of Thylakoids

Question 10

What is a motor protein?

Answer 10

Proteins involved in moving material about the cell. “Walk” (really a conformation change of protein) along the cytoskeleton.

How cool are these proteins?!