Cell Structure and Types (4.14, 4.16, 4.17, 4.18, 4.19, 4.20, 4.21 and 4.22)

Question 1

Mitochondria

Answer 1

An organelle in eukaryotic cells where cellular respiration occurs.

Question 2

What is cellular respiration?

Answer 2

A process that converts the chemical energy of food molecules to the chemical energy of ATP.

Question 3

Chloroplasts

Answer 3

An organelle found in plants and algae that absorb sunlight and uses it to drive the synthesis of organic compounds (sugars) from carbon dioxide and water.

Question 4

Which membrane in a chloroplast appears to be the most extensive? Why might this be so?

Answer 4

The thylakoids are the most extensive. The chlorophyll molecules that trap solar energy are embedded in them.

Question 5

Cytoskeleton

Answer 5

A network of protein fibers in the cytoplasm of a eukaryotic cell.

Question 6

Motor Protein

Answer 6

A protein that interacts with the cytoskeleton and other cell components, producing movement of the whole cell or parts of the cell wall.

Question 7

Microtubules

Answer 7

The thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell.

Question 8

Microfilaments

Answer 8

The thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell.

Question 9

Intermediate filament

Answer 9

An intermediate-sized protein fiber is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells.

Question 10

Which component of the cytoskeleton is most important in:

a. holding the nucleus in place within an animal cell
b. guiding transport vesicles from the Golgi to the plasma membrane
c. contracting muscle cells?

Answer 10

a. Intermediate filaments
b. microtubules
c. microfilaments

Question 11

How does the discovery of the cytoskeleton illustrate the idea that advances in scientific knowledge often rely on advances in techniques and tools?

Answer 11

Before electron microscopy and fluorescent dyes, biologists had no evidence that the cytoskeleton existed.

Question 12

Cilia

Answer 12

A short cellular appendage specialized for locomotion or moving fluid past the cell.

Question 13

Primary ciliary dyskinesia (PCD), also known as immotile cilia syndrome, is a fairly rare disease in which cilia and flagella are lacking motor proteins. PCD is characterized by recurrent respiratory tract infections and immotile sperm. How would you explain these seemingly unrelated symptoms?

Answer 13

Without motor proteins, microtubules cannot bend. Thus cilia cannot cleanse the respiratory tract, and sperm cannot swim.

Question 14

Describe the structures that provide support to the plasma membrane.

Answer 14

The membrane is attached through membrane proteins to microfilaments of the cytoskeleton and to connecting glycoproteins and collagen fibers of the ECM.

Question 15

Tight junctions

Answer 15

At tight junctions, the plasma membranes of neighboring cells are knit tightly together by proteins. Tight junctions prevent leakage of fluid across a layer of cells.

Question 16

Anchoring junctions

Answer 16

Anchoring junctions function like rivets, fastening cells together into strong sheets. Intermediate filaments made of sturdy proteins anchor these junctions in the cytoplasm. Anchoring junctions are common in tissues subject to stretching or mechanical stress, such as skin and muscle.

Question 17

Gap junctions

Answer 17

Gap junctions also called communicating junctions, are channels that allow small molecules to flow through protein-lined pores between cells. The flow of ions through gap junctions in the cells of the heart muscle coordinates their contraction. Gap junctions are common in embryos, where communication between cells is essential for development.

Question 18

A muscle tear injury would probably involve the rupture of which type of cell junction?

Answer 18

—-» Anchoring junction

Question 19

Cell Wall

Answer 19

A protective layer external to the plasma membrane in plants, bacteria, fungi, and some protists.

Question 20

Which animal cell junction is analogous to a plasmodesma?

Answer 20

—-» A gap junction

Question 21

How do mitochondria, smooth ER, and the cytoskeleton all contribute to the contraction of a muscle cell?

Answer 21

Mitochondria supply energy in the form of ATP. The smooth ER helps regulate contraction by the uptake and release of calcium ions. Microfilaments function in the actual contractile apparatus.

Question 22

Read 4.22 from the book (Table in which descriptions have been mentioned)

Answer 22

Go and Read 4.22 from the book (Table in which descriptions have been mentioned)