Unit 1 (Chapter 4, Part 3) Cytosol

Question 1

What is the region of a eukaryotic cell that is inside the plasma membrane but outside the organelles?

Answer 1

Cytosol

BONUS: With prokaryotic cells, the term cytoplasm, refers the region enclosed by the plasma membrane, which includes cytosol and the organelles.

Question 2

What is the sum of all bodily activities and chemical reactions that occur within an organism? Also, a specific set of chemical reactions occurring at the cellular level.

Answer 2

Metabolism (occurs in organelles as well but the cytosol is the central coordinating region for many of these activities)

Question 3

What is the series of steps called involving metabolism?

Answer 3

Metabolic pathways

Question 4

What is the metabolic pathway that results in the breakdown of larger molecules into smaller molecules? Such reactions are often exergonic.

Answer 4

Catabolism

Question 5

What is a metabolic pathway that results in the synthesis of cellular molecules and macromolecules; requires an input of energy?

Answer 5

Analbolism

Question 6

What translates the information within mRNA to form amino acids into polypeptides?

Answer 6

The ribosomes located with the cytosol, attached to the membrane of the nuclear envelope, and as well as the endoplasmic reticulum membrane. They can also be found within mitochondria and chloroplasts.

Question 7

While in eukaryotes, what is a network within the cytosol consisting of three different types of protein filaments called microtubules, intermediate filaments, and actin filaments?

Answer 7

The Cytoskeleton (this is a striking example of protein-protein interactions)

Question 8

What are microtubules (hollow tubule)?

Answer 8

A type of hollow protein filament composed of tubulin proteins that is part of the cytoskeleton and is important for cell shape, organization, and movement.

Question 9

What are intermediate filaments (twisted)?

Answer 9

A type of protein filament of the cytoskeleton of animal cells that helps maintain cell shape and rigidity.

Question 10

What are actin filaments (spiral)?

Answer 10

A thin type of protein filament composed of actin proteins that forms part of the cytoskeleton and supports the plasma membrane; plays a key role in cell strength, shape, and movement.

Question 11

Even though the cytoskeleton is found mostly within the cytosol, where is it also located?

Answer 11

Along the inner nuclear membrane

Question 12

What is the oscillation of a single microtubule between growing (plus end) and shortening phases (plus and negative end); important in many cellular activities, including the sorting of chromosomes during cell division?

Answer 12

Dynamic instability

Question 13

What is a single structure often near the nucleus of a eukaryotic cell that forms a nucleating site for the growth of microtubules; also called a microtubule-organizing center.?

Answer 13

Centrosome

Question 14

What cytoskeleton protein filament does not shorten or lengthen where the length is relatively permanent?

Answer 14

Intermediate filaments

Ex. Keratin for IF in skin, intestinal, and kidney cells, where they important for cell shape and mechanical strength. Also, major constituent of hair and nails.

Also, found within the inner nuclear membrane and provide anchor points for nuclear pores.

Question 15

What is another name for actin filaments?

Answer 15

Microfilament

Question 16

Where are actin filaments, or microfilaments, highly concentrated?

Answer 16

Near the plasma membrane.

Plus ends grow towards the membrane and their sides are anchored to proteins near the membrane.

Question 17

What are motor proteins and what three domains do they consist of?

Answer 17

A type of cellular protein that uses ATP as a source of energy to promote movement; consists of three domains called the head, hinge, and tail.

Question 18

What is the lever arm of a motor protein?

Answer 18

The formation of the hinge and tail together.

Question 19

Where does ATP bind and is hydrolyzed to adenosine diphosphate (ADP) and inorganic phosphate (Pi)?

Answer 19

The head of the motor protein. This binding and hydrolysis causes a bend in the hinge which causes MOVEMENT. This is an example of myosin motor protein “walkin” along an actin filament.

Another example is imagining your legs as myosin and the ground as actin filament.

Question 20

What is the tail region attached to?

Answer 20

Other proteins and other kinds of cellular molecules.

Question 21

What are the three different kinds of motor protein movements?

Answer 21

• Tail region of a motor protein called kinesin is attached to a cargo, and the motor protein moves the cargo from one location to another.
• Alternatively, the motor protein myosin can remain in place and cause the filament to move. (This occurs in muscle contraction).
• The third possibility is when motor proteins and filaments are linked via proteins. The motor protein dynein attempts to walk toward the minus end, they exert a force that causes the microtubules to bend.

Question 22

What is the difference between the cell appendages called flagella and cilia (singular, flagellum and cilium)?

Answer 22

Flagella are longer than cilia and are typically found singly or in pairs.

Cilia are typically shorter and found in bigger groups.

Question 23

What is the role of flagella and cilia?

Answer 23

Cellular movement or the movement of intercellular fluids.

Question 24

How does flagella and cilia, using motor proteins and microtubules, move?

Answer 24

Bends are generated along their length where they push backward against the surrounding fluid.

Question 25

What are some examples of flagella and cilia being used for movement?

Answer 25

For flagellum, sperm cells and certain microorganisms that have a pair of flagella (imagine a human doing the breaststroke under water).

For cilia, some cover all or part of a cell. Protists such as paramecia may have hundreds of adjacent cilia which beat in a coordinated fashion to propel the organism through the water.

Question 26

What is the axoneme?

Answer 26

An internal structure of eukaryotic flagella and cilia that contains microtubules, the motor protein dynein, and linking proteins.

Question 27

What is the array of microtubules within cilia and flagella?

Answer 27

9 + 2 array.

This means, 9 outer doublet microtubules with 2 center single tubules.

The array is connected by radial spokes with the basal base of the flagella or cilia a triplet microtubule which allows them to grow.

Question 28

What are basal bodies?

Answer 28

A site at the base of flagella or cilia from which microtubules grow. Basal bodies are anchored on the cytosolic side of the plasma membrane.

Question 29

What is the name of the key protein that is a component of the radial spokes in an axoneme that determines the 9-fold symmetry of the doublet microtubles?

Answer 29

SAS-6