Chapter 10

Question 1

What are the main benefits of multicellularity?

Answer 1

Division of labor between different cell types. Multicellular organisms also usually have larger genomes, which often results in larger proteomes as well.

Question 2

What does multicellular mean?

Answer 2

Describes an organism consisting of more than one cell, particularly when cell-to-cell adherence and signaling processes and cellular specialization can be demonstrated.

Question 3

What is the benefit of additional proteins?

Answer 3

• many proteins are needed for complex cell communication
• variety of proteins are needed for both arrangement of cells and cell to cell attachment
• additional proteins play a role in cell specialization

Question 4

What is an extracellular matrix (ECM)?

Answer 4

A network of material that is secreted from animal cells and forms a complex meshwork outside of cells. The ECM provides strength, support, and organization.

Question 5

What are the two major ECM components?

Answer 5

proteins and polysaccharides

Question 6

Main functions of ECM?

Answer 6

Strength, structural support, organization, and cell signaling

Question 7

What is collagen?

Answer 7

A protein secreted from animal cells that forms large fibers in the extracellular matrix.

Question 8

Two types of ECM proteins?

Answer 8

adhesive and structural

Question 9

What is elastin?

Answer 9

A protein that makes up elastic fibers in the extracellular matrix of animals.

Question 10

What is glycosaminoglycan?

Answer 10

The most abundant type of polysaccharide in the extracellular matrix (ECM) of animals, consisting of repeating disaccharide units that give a gel-like character to the ECM.

Question 11

What is a proteoglycan?

Answer 11

A long, linear core protein with many GAGs attached to it; found in the ECM.

Question 12

What is chitin?

Answer 12

A tough, nitrogen-containing, polysaccharide polymer that forms the external skeleton of many insects and crustaceans and is found in the cell walls of fungi.

Question 13

What is cellulose?

Answer 13

The main macromolecule of the cell wall of plants and many algae; a linear polymer made of thousands of glucose monomers.

Question 14

primary cell wall:

Answer 14

In plants, a relatively thin and flexible cell wall that is synthesized first between two newly made daughter cells.

Question 15

secondary cell wall:

Answer 15

A thick rigid plant cell wall that is synthesized and deposited between the plasma membrane and the primary cell wall after a plant cell matures and has stopped increasing in size.

Question 16

What are cell junctions?

Answer 16

Specialized structures that adhere cells to each other and to the ECM.

Question 17

What are the three types of cell junctions?

Answer 17

1. Anchoring junctions
2. Tight junctions
3. Gap junctions

Question 18

anchoring junction:

Answer 18

A type of junction between animal cells that attaches cells to each other and to the extracellular matrix (ECM).

Question 19

desmosome:

Answer 19

A mechanically strong type of cell junction between animal cells that typically occurs in spotlike rivets.

Question 20

hemidesmosome:

Answer 20

A mechanically strong type of cell junction that connects an animal cell to the extracellular matrix (ECM).

Question 21

focal adhesion:

Answer 21

A mechanically strong type of cell junction that connects an animal cell to the extracellular matrix (ECM).

Question 22

cadherin:

Answer 22

A cell adhesion molecule found in animal cells that promotes cell-to-cell adhesion. Ca 2+ dependent

Question 23

Why is homophilic binding an important aspect of cadherins?

Answer 23

By expressing only certain types of cadherins, each cell binds only to other cells that express the same cadherin types. This phenomenon plays a key role in the proper arrangement of cells throughout the body, particularly during embryonic development.

Question 24

integrin:

Answer 24

A cell adhesion molecule found in animal cells that connects cells to the extracellular matrix.

Question 25

What is the importance of cadherin and integrin proteins outside of their mechanical role?

Answer 25

Cadherins and integrins are also important in cell communication.

Question 26

tight junction:

Answer 26

A type of junction between animal cells that forms a tight seal between adjacent cells and thereby prevents material from leaking between the cells.

Question 27

transepithelial transport:

Answer 27

The process of moving molecules across an epithelium, such as across the intestinal cells of animals.

Question 28

gap junction:

Answer 28

A type of junction between animal cells that provides a passageway for intercellular transport. Abundant in tissues and organs where cells need to communicate with each other.

Question 29

connexon:

Answer 29

A channel that forms gap junctions in vertebrates, consisting of six connexin proteins in one cell aligned with six connexin proteins in an adjacent cell.

Question 30

middle lamella:

Answer 30

An extracellular layer in plants composed primarily of carbohydrate; cements adjacent plant cell walls together.

Question 31

plasmodesma (plural, plasmodesmata):

Answer 31

A membrane-lined, ER-containing channel that connects the cytoplasm of adjacent plant cells

Question 32

tissue:

Answer 32

A part of an animal or plant consisting of a group of cells having a similar structure and function, for example, muscle tissue.

Question 33

organ:

Answer 33

A collection of two or more tissues that performs a specific function or set of functions.

Question 34

How are tissues and organs formed?

Answer 34

To form tissues and organs, cells undergo six different processes that influence their morphology, arrangement, and number: division, growth, differentiation, migration, apoptosis, and formation of connections.

Question 35

What are the four general types of tissues in animals?

Answer 35

connective, nervous, muscle, and epithelial tissue

Question 36

epithelial tissue:

Answer 36

In animals, a sheet of densely packed cells that covers the body, covers individual organs, or lines the walls of various cavities inside the body.

Question 37

connective tissues:

Answer 37

Groups of cells that connect, anchor, and support the structures of an animal’s body; include blood, adipose (fat-storing) tissue, bone, cartilage, loose connective tissue, and dense connective tissue.

Question 38

nervous tissue:

Answer 38

Networks of cells (neurons) that receive, generate, and conduct electrical signals throughout an animal’s body.

Question 39

muscle tissue:

Answer 39

Bundles of muscle fibers (cells) that are specialized to contract when stimulated and thus generate a force that facilitates movement or exerts pressure.

Question 40

What are the three general tissues types plants have?

Answer 40

dermal, ground, and vascular

Question 41

What is the epidermis?

Answer 41

A layer of dermal tissue on the surfaces of leaves, stems, and roots that helps protect a plant from damage.

Question 42

ground tissue:

Answer 42

Type of tissue that makes up most of the body of a plant and has a variety of functions, including photosynthesis, storage of carbohydrates, and support. Ground tissue can be subdivided into three types: parenchyma, collenchyma, and sclerenchyma.

Question 43

vascular tissue:

Answer 43

A complex plant tissue composed of interconnected cells that form conducting vessels for water, minerals, and organic compounds.