Chapter 6- A Tour of the Cell

Question 1

microtubule

Answer 1

A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in the cilia and flagella.

Question 2

endomembrane system

Answer 2

1. The collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
2. Includes:
   - plasma membrane
   - nuclear envelope
   - smooth and rough ER (endoplasmic reticulum)
   - Golgi apparatus
   - lysosomes
   - vesicles
   - vacuoles

Question 3

middle lamella

Answer 3

In plans, a think layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young cells.

Question 4

phagocytosis

Answer 4

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. it is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells).

Question 5

electron microscope (EM)

Answer 5

A microscope that uses magnets to focus an electron beam on or through a specimen, resulting in a practical resolution that is 100-fold greater than that of a light microscope using standard techniques. A transmission electron microscope (TEM) is used to study the internal structure of thin section of cells. A scanning electron microscope (SEM) is used to study the fine details of cell surfaces.

Question 6

nucleoid

Answer 6

A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located.

Question 7

stroma

Answer 7

• The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA.
• Involved in the synthesis of organic molecules from carbon dioxide and water.

Question 8

tight junction

Answer 8

A type of intercellular junction between animal cells that prevents the leakage of material through the space between cells.

Question 9

peroxisome

Answer 9

An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide.

Question 10

fibronectin

Answer 10

An extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular matrix.

Question 11

smooth ER

Answer 11

The portion of the endoplasmic reticulum that is free of ribosomes.

Question 12

vesicle

Answer 12

A membranous sac in the cytoplasm of a eukaryotic cell.

Question 13

nuclear envelope

Answer 13

• In a eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm.
• The outer membrane is continuous with the endoplasmic reticulum.

Question 14

nucleus

Answer 14

The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin

Question 15

ribosome

Answer 15

A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the small nucleolus.

Question 16

thylakoid

Answer 16

A flattened, membranous sac inside a chloroplast. Thylakoids often exist in stacks called grana that are interconnected; their membranes contain molecular “machinery” used to convert light energy to chemical energy.

Question 17

primary cell wall

Answer 17

In plants, a relatively thin and flexible layer that surrounds the plasma membrane of a young cell.

Question 18

vacuole

Answer 18

A membrane-bounded vesicle whose specialized function varies in different kinds of cells.

Question 19

endoplasmic reticulum (ER)

Answer 19

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.

Question 20

cilium

Answer 20

A short appendage containing microtubules in eukaryotic cells. A motile cilium is specialized for locomotion or moving fluid past the cell

• It is formed from a core of nine outer doublet microtubules and two inner single microtubules (the 9+2 arrangement) ensheathed in an extension of the plasma membrane.
• A primary cilium is usually nonmotile and plays a sensory and signaling role; it lacks the two inner microtubules (the 9+0 arrangement)

Question 21

cytoplasm

Answer 21

• The contents of cell bounded by the plasma membrane

- In eukaryotes, the portion exclusive of the nucleus.

Question 22

motor protein

Answer 22

a protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell.

Question 23

collagen

Answer 23

• A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found extensively in connective tissue and bone
• The most abundant protein in the animal kingdom

Question 24

extracellular matrix (ECM)

Answer 24

The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by cells.

Question 25

prokaryotic cell

Answer 25

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with prokaryotic cells (bacteria and archaea) are called prokaryotes.

Question 26

central vacuole

Answer 26

In a mature plant cell, a large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances.

Question 27

cell wall

Answer 27

A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi and some protists. Polysaccharides such as cellulose (in plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are important structural components of cell walls.

Question 28

rough ER

Answer 28

The portion of the endoplasmic reticulum with ribosomes attached

Question 29

intermediate filament

Answer 29

A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments.

Question 30

glycoprotein

Answer 30

a protein with one or more covalently attached carbohydrates