3.4

Question 1

What are cytoplasm?

Answer 1

consists of all the cellular contents between the plasma membrane and the nucleus tiny structures that perform various functions in the cell.

Question 2

What is cytoskeleton?

Answer 2

a network of protein filaments that extends throughout the cytosol.

Question 3

What are microfilaments?

Answer 3

the thinnest elements of the cytoskeleton

Question 4

What are microtubules?

Answer 4

the largest of the cytoskeletal components, are long, unbranched hollow tubes composed mainly of the protein tubulin.

Question 5

What are organelles?

Answer 5

specialized structures within the cell that have characteristic shapes, and they perform specific functions in cellular growth, maintenance, and reproduction.

Question 6

What are centrosome?

Answer 6

microtubule organizing center, located near the nucleus, consists of two components: a pair of centrioles and the pericentriolar matrix.

Question 7

What are the functions of the centrosomes?

Answer 7

1. The pericentriolar matrix of the centrosome contains tubules that build microtubules in non dividing cells
2. The pericentriolar matrix of the centrosome forms the mitotic spindle during cell division.

Question 8

What are the functions of the cilia and flagella?

Answer 8

1. Cilia move fluids along a cell’s surface

2. A flagellum moves an entire cell

Question 9

What is flagella?

Answer 9

flagella are similar in structure to cilia but are typically much longer.

Question 10

What are mitochondrial proteins?

Answer 10

Ribosomes that are located within mitochondria

Question 11

What are the functions of ribosomes?

Answer 11

1. ribosomes associated with endoplasmic reticulum synthesize proteins destined for insertion in the plasma membrane or secretion from the cell
2. Free ribosomes synthesize proteins used in the cytosol.

Question 12

What are the functions of Endoplasmic Reticulum?

Answer 12

1. Rough ER synthesizes glycoproteins and phospholipids that are transferred into cellular organelles, inserted into the plasma membrane, or secreted during exocytosis.
2. Smooth ER synthesizes fatty acids and steroids, such as estrogens and testosterone; inactivates or detoxifies drugs and other potentially harmful substances; removes the phosphate group from glucose-6-phosphate; and stores and releases calcium ions that trigger contraction in muscle fibres.

Question 13

What is Golgi complex?

Answer 13

The first step in the transport pathway is through an organelle called the Golgi complex. It consists of 3 to 20 saccules, small, flattened, membranous sacs with bulging edges that resemble a stack of pita bread.

Question 14

What is entry (cis) face and what is exit (trans) face?

Answer 14

entry face is a saccule that faces the rough ER. The concave exit face is a saccule that faces the plasma membrane. Sac between the entry and exit faces are called intermediate saccules.

Question 15

What are the functions of the Golgi complex?

Answer 15

1. Modifies, sorts, packages, and transports proteins received from the rough ER
2. Forms secretory vesicles that discharge processed proteins via exocytosis into extracellular fluid; forms membrane vesicles that ferry new molecules to the plasma membrane; forms transport vesicles that carry molecules to other organelles, such as lysosomes.

Question 16

What are lysosomes?

Answer 16

They are membrane-enclosed vesicles that form from the Golgi complex.

Question 17

What is autophagy?

Answer 17

The process by which entire worn-out organelles are digested is called autophagy.

Question 18

What are autophagosome?

Answer 18

In autophagy, the organelle to be digested is enclosed by a membrane derived from the ER to create a vesicle called an autophagosome; the vesicle then fuses with a lysosome.

Question 19

What is autolysis?

Answer 19

Lysosomal enzymes may also destroy the entire cell that contains them, a process known as autolysis.

Question 20

What example describes extracellular digestion?

Answer 20

One example occurs during fertilization. The head of a sperm releases lysosomal enzymes that aid its penetration of the oocyte by dissolving its protective coating in a process called the acrosomal reaction.

Question 21

What are the functions of lysosomes?

Answer 21

1. Digest substances that enter a cell via endocytosis and transport final products of digestion into cytosol
2. Carry out autophagy, the digestion of worn-out organelles
3. Implement autolysis, the digestion of an entire cell
4. Accomplish extracellular digestion

Question 22

What are peroxisomes (microbodies)?

Answer 22

Another group of organelles similar in structure to lysosomes, but smaller, are the peroxisomes. Peroxisomes contain several oxidases, enzymes that can oxidize various organic substances. For instance, amino acids and fatty acids are oxidized in peroxisomes as part of normal metabolism.

Question 23

What is proteasome?

Answer 23

Continuous destruction of needed, damaged, or faulty proteins os the function of tiny barrel-shaped structures consisting of four stacked rings of proteins around a central core.
For example, proteins that are part of metabolic pathways need to be degraded after the have accomplished their function.

Question 24

What are mitochondria?

Answer 24

Because they generate most of the ATP through aerobic (oxygen-requiring) respiration, mitochondria are referred to as the “powerhouses” of the cell.

Question 25

What does mitochondria consists of?

Answer 25

external mitochondrial membrane and an internal mitochondrial membrane with small-filled space between them. The internal mitochondrial membrane contains a series of folds called mitochondrial cristae. The central fluid-filled cavity of a mitochondrion, enclosed by the internal mitochondrial membrane, is the mitochondrial matrix

Question 26

What is apoptosis?

Answer 26

Mitochondria also play an important and early role in apoptosis, the orderly, genetically programmed death of a cell.

Question 27

What are the functions of mitochondria?

Answer 27

1. Generate ATP through reactions of aerobic cellular respiration.
2. Play an important early role in apoptosis