Biology Solomon, 8Th Edition Chapter 4

Front 1

cell theory

Back 1

The unifying concept that:
1. Cells are the basic living units of organization and function in all organisms
2. All cells come from other cells.
Work by Schleiden, Schwann, and Virchow.

Front 2

plasma membrane

Back 2

A structurally distinctive surface membrane that surrounds all cell. By making the interior of the cell an enclosed compartment, the plasma membrane allows the chemical composition of the cell to be different from that outside the cell. (maintain homeostasis)

Front 3

organelle

Back 3

Internal structures that are specialized to carry out metabolic activities, such as converting energy to usable forms, synthesizing needed compounds, and manufacturing structures necessary for functioning and reproduction.

Front 4

prokaryotic cell

Back 4

A cell that lacks a nucleus and other membrane-enclosed organelles. Much smaller (about 1/10) the diameter of the average eukaryotic cell. The DNA is located in the nuclear area, or nucleoid.

Front 5

nuclear area

Back 5

Region of a prokaryotic cell that contains DNA; not enclosed by a membrane.

Front 6

nucleoid

Back 6

Same as nuclear area--

Region of a prokaryotic cell that contains DNA; not enclosed by a membrane.

Front 7

cell wall

Back 7

Extracellular structures that enclose the entire cell, including the plasma membrane. Most prokaryotic cells have these cell walls.

Front 8

ribosome

Back 8

Organelles that are small complexes of ribonucleic acid (RNA) and protein that synthesize polypeptides. The ribosomes of prokaryotic cells are smaller than those found in eukaryotic cells.

Front 9

eukaryotic cell

Back 9

An organism whose cells have nuclei and other membrane -enclosed organelles. Includes protists, fungi, plants, and animals.

Front 10

cytoplasm

Back 10

The part of the cell outside the nucleus.
Various organelles are suspended within the fluid component of the cytoplasm (which is called the cytosol).

Front 11

cell theory

Back 11

The unifying concept that:
1. Cells are the basic living units of organization and function in all organisms
2. All cells come from other cells.
Work by Schleiden, Schwann, and Virchow.

Front 12

plasma membrane

Back 12

A structurally distinctive surface membrane that surrounds all cell. By making the interior of the cell an enclosed compartment, the plasma membrane allows the chemical composition of the cell to be different from that outside the cell. (maintain homeostasis)

Front 13

organelle

Back 13

Internal structures that are specialized to carry out metabolic activities, such as converting energy to usable forms, synthesizing needed compounds, and manufacturing structures necessary for functioning and reproduction.

Front 14

prokaryotic cell

Back 14

A cell that lacks a nucleus and other membrane-enclosed organelles. Much smaller (about 1/10) the diameter of the average eukaryotic cell. The DNA is located in the nuclear area, or nucleoid.

Front 15

nuclear area

Back 15

Region of a prokaryotic cell that contains DNA; not enclosed by a membrane.

(same as nucleoid)

Front 16

nucleoplasm

Back 16

The part of the cell within the nucleus.

Front 17

cytosol

Back 17

The fluid component of the cytoplasm in which various organelles are suspended.

Front 18

endomembrane system

Back 18

Also known as internal membrane system--
The group of membranous structures in eukaryotic cells that interact through direct connections by vesicles; includes the endoplasmic reticulum, outer membrane of the nuclear envelope, Golgi complex, lysosomes, and the plasma membrane.

Front 19

vesicle

Back 19

Small, membrane-enclosed sacs formed by "budding" from the membrane of another organelle. Vesicles transport materials and also carry cargo from one organelle to another. A vesicle can form as a "bud" from the membrane of one organelle and then move to another organelle to which it fuses, thus delivering its contents into another compartment.

Front 20

nucleus

Back 20

1. The central region of an atom that contains the protons and neutrons. 2. A cell organelle in eukaryotes that contains the DNA and serves as the control center of the cell. 3. A mass of nerve cell bodies in the central nervous system. (Typically the the most prominent organelle in the cell).

Front 21

nuclear envelope

Back 21

Consists of two concentric membranes that separate the nuclear contents from the surrounding cytoplasm.

Front 22

nuclear pores

Back 22

Consists of protein complexes found at intervals where the membranes come together. Nuclear pores regulate the passage of materials between nucleoplasm and cytoplasm.

Front 23

gene

Back 23

A segment of DNA that serves as a unit of hereditary information; includes a transcribable DNA sequence (plus associated sequences regulating its transcription) that yields a protein or RNA product with a specific function.

Front 24

chromosome

Back 24

Structures in the cell nucleus that consist of chromatin and contain the genes. The chromosomes become visible under the microscope as distinct threadlike structures during cell division.

Front 25

chromatin

Back 25

The complex of DNA and protein that makes up eukaryotic chromosomes, which appears as a network of granules and strands in cells that are not dividing.

Front 26

nucleolus

Back 26

Specialized structure in the cell nucleus formed from regions of several chromosomes; site of assembly of the ribosomal subunits.

Front 27

endoplasmic reticulum (ER)

Back 27

An interconnected network of internal membranes in eukaryotic cells enclosing a compartment, the ER lumen. Rough ER has ribosomes attached to the cytosolic surface; smooth ER, a site of lipid biosynthesis, lacks ribosomes.

Front 28

ER lumen

Back 28

The internal space the membranes enclose.
In most cells the ER lumen forms a single internal compartment that is continuous with the compartment formed between the outer and inner membranes of the nuclear envelope.

Front 29

smooth ER

Back 29

The primary site for the synthesis of phospholipids and cholesterol needed to make cell membranes. Smooth ER synthesizes steroid hormones, including reproductive hormones, from cholesterol. In liver cells, smooth ER is important in enzymatically breaking down stored glycogen. The smooth ER also stores calcium ions. (lacks ribosomes)

Front 30

rough ER

Back 30

Outer surface is studded with ribosomes that appear as dark granules. The rough ER plays a central role in the synthesis and assembly of proteins. Many proteins that are exported from the cell (such as digestive enzymes), and those destined for other organelles, are synthesized on ribosomes bound to the ER membrane.

Front 31

transport vesicle

Back 31

Small cytoplasmic vesicles that move substances from one membrane system to another.

Front 32

Golgi complex

Back 32

(Named after Camillo Golgi)
Organelle composed of stacks of flattened, membranous sacs. Mainly responsible for modifying, packaging, and sorting proteins that will be secreted or targeted to other organelles of the internal membrane system or to the plasma membrane.

Front 33

cisterna

Back 33

Stacks of flattened membranous sacs that make up the Golgi complex.

Front 34

cis face

Back 34

(the entry surface) An area of the Golgi stack typically located nearest the nucleus and receives materials from transport vesicles bringing molecules from the ER.

Front 35

trans face

Back 35

(the exit surface) Is closest to the plasma membrane. It packages molecules in vesicles and transports them out of the Golgi.

Front 36

medial region

Back 36

The area between the cis face and the trans face, located in the Golgi stack.

Front 37

lysosome

Back 37

Small sacs of digestive enzymes dispersed in the cytoplasm of most animal cells.
Because lysosomal are active under rather acidic condition, the lysosome maintains a pH of about 5 in its interior. (However, beware of "leaky" lysosomes).

Front 38

primary lysosome

Back 38

Formed by budding from the Golgi complex. Their hydrolytic enzymes are synthesized in the rough ER. As these enzymes pass through the lumen of the ER, sugars attach to each molecule, identifying it as bound for a lysosome. This signal permits the Golgi complex to sort the enzyme to the lysosomes rather than to export it from the cell.

Front 39

secondary lysosome

Back 39

A larger vesicle (than the primary lysosome) which is formed when one or more primary lysosomes fuse with the vesicle containing the ingested material. Powerful enzymes in the secondary lysosome come in contact with the ingested molecules and degrade them into their components. Sometimes, lysosomes break down organelles and allow their components to be recycled or used as an energy source.

Front 40

peroxisome

Back 40

Membrane-enclosed organelles containing enzymes that catalyze an assortment of metabolic reactions in which hydrogen is transferred from various compounds to oxygen. During these oxidation reactions, they produce hydrogen peroxide. They break down fatty acid molecules and synthesize certain phospholipids. In humans, they detoxify certain toxic compounds.

Front 41

glyoxysomes

Back 41

Specialized peroxisomes found in plant seeds containing enzymes that convert stored fats to sugars. The sugars are used by the young plant as an energy source and as a component for synthesizing other compounds.
Animal cells lack glyoxysomes and cannot convert fatty acids into sugars.

Front 42

vacuole

Back 42

A fluid-filled, membrane-enclosed sac found within the cytoplasm; may function in storage, digestion, or water elimination.

Front 43

tonoplast

Back 43

The membrane surrounding a vacuole.

Front 44

food vacuole

Back 44

Fuse with lysosomes that digest the food. Most protozoa have food vacuoles.

Front 45

contractile vacuole

Back 45

Removes excess water from the cells.

Some protozoa have these contractile vacuoles.

Front 46

mitochondrion

Back 46

Intracellular organelles that are the sites of aerobic respiration, an oxygen-requiring process that includes most of the reactions that convert the chemical energy present in certain foods to ATP. Virtually all eukaryotic cells (plant, animal, fungal, and protist) contain these organelles; includes an outer membrane and an inner membrane.

Front 47

endosymbiont theory

Back 47

Endosymbiont means: An organism that lives inside the body of another kind of organism. Endosymbionts may benefit their host (mutualism) or harm their host (parasitism).

Front 48

aerobic respiration

Back 48

An oxygen-requiring process that includes most of the reactions that convert the chemical energy present in certain foods to ATP. During aerobic respiration, carbon and oxygen atoms are removed from food molecules, such as glucose, and converted to carbon dioxide and water.

Front 49

cristae

Back 49

The folds, found in the inner mitochondrial membrane, extend into the matrix. Cristae greatly increase the surface area of the inner mitochondrial membrane, providing a surface for the chemical reactions that transform the chemical energy in food molecules into the energy of ATP.

Front 50

mitochondrial matrix

Back 50

The interior of the compartment enclosed by the inner mitochondrial membrane.

Front 51

chloroplast

Back 51

Membranous organelles that are the sites of photosynthesis in eukaryotes; occur in some plant and algal cells.

Front 52

photosynthesis

Back 52

The biological process that captures light energy and transforms it into the chemical energy of organic molecules (e.g., carbohydrates), which are manufactured from carbon dioxide and water.

Front 53

stroma

Back 53

A fluid space of the chloroplast, enclosed by the chloroplast inner membrane and surrounding the thylakoids; site of the reaction of the Calvin cycle.

Front 54

thylakoid

Back 54

An interconnected system of flattened, saclike, membranous structures inside the chloroplast.

Front 55

grana

Back 55

The stacks of thylakoids.

Front 56

plastids

Back 56

A family of membrane-enclosed organelles occurring in photosynthetic eukaryotic cells; include chloroplasts, chromoplasts, and amyloplasts and other leukoplasts.

Front 57

proplastid

Back 57

Organelles that are plastid precursors; may mature into various specialized plastids, including chloroplasts, chromoplasts, or leukoplasts.

Front 58

chromoplast

Back 58

Pigment-containing plastids that give certain flowers and fruits their characteristic colors.

Front 59

leukoplast

Back 59

Unpigmented plastids; include amyloplasts, which are used for starch storage in cells of roots and tubers.

Front 60

amyloplast

Back 60

Unpigmented plastids; which are used for starch storage in cells of roots and tubers. (like a leukoplast)

Front 61

cytoskeleton

Back 61

A dense network of protein fibers that includes microfilaments, intermediate filaments, and microtubules. It gives cells mechanical strength, shape, and their ability to move. The cytoskeleton also functions in cell division and in the transport of materials within the cell.

Front 62

microtubule

Back 62

The thickest filaments of the cytoskeleton, are rigid, hollow, cylindrical fibers consisting of tubulin protein subunits; major structural components of the cytoskeleton and are also involved in the movement of chromosomes during cell division. Found in mitotic spindles, cilia, flagella, centrioles, and basal bodies.

Front 63

tubulin dimer

Back 63

A microtubule elongates by the addition of tubulin dimers. Microtubules are disassembled by the removal of dimers, which are recycled to form new microtubules.

Front 64

MAP
microtubule-associated proteins

Back 64

Proteins important in microtubule function. Classified into two groups; structural MAPs may help regulate microtubule assembly, and they cross-link microtubules, and motor MAPs which use ATP energy to produce movement.

Front 65

MTOC
microtubule-organizing centers

Back 65

The region of the cell from which microtubules are anchored, and possibly assembled. The MTOCs of many organisms (including animals, but not flowering plants or most gymnosperms) contain a pair of centrioles.

Front 66

centrosomes

Back 66

An organelle in animal cells that is the main microtubule-organizing center; typically contains a pair of centrioles and is important in cell division.

Front 67

centriole

Back 67

One of a pair of small, cylindrical organelles lying at right angles to each other near the nucleus in the cytoplasm of animal cells and certain protist and plant cells; each centriole is in the form of a cylinder composed of nine triplets of microtubules.

(Also known as 9x3 structure)

Front 68

kinesin

Back 68

A motor protein that moves organelles toward the plus end of a microtubule.

Front 69

dynein

Back 69

A motor protein that transports organelles in the opposite direction, toward the minus end of a microtubule.

Front 70

9+2

Back 70

Refers to the arrangement of a group of microtubules arranged so there are nine attached pairs of microtubules around the circumference and two unpaired microtubules in the center. This 9+2 arrangement of microtubules is characteristic of virtually all eukaryotic cilia and flagella.

Front 71

basal body

Back 71

Structure involved in the organization and anchorage of a cilium or flagellum. Structurally similar to a centriole; each is in the form of a cylinder composed of nine triplets of microtubules (9x3 structure).

Front 72

microfilament

Back 72

Flexible, solid fibers consisting of two intertwined polymer chains of beadlike actin molecules. They provide mechanical support for various cell structures.

Front 73

actin

Back 73

The protein of which microfilaments consist. Actin, together with the protein myosin, is responsible for muscle contraction.

Front 74

intermediate filament

Back 74

Tough, flexible fibers that provide mechanical strength and help stabilize cell shape. Intermediate filaments prevent the cell from stretching excessively in response to outside forces. All eukaryotic cells, but only some animal groups, including vertebrates, are known to have intermediate filaments.

Front 75

glycocalyx

Back 75

A coating on the outside of an animal cell, formed by the polysaccaride portions of glycoproteins and glycolipids, associated with the plasma membrane.

Front 76

ECM
extracellular matrix

Back 76

A network of proteins and carbohydrates that surrounds many animal cells.

Front 77

collagen

Back 77

Proteins found in the collagen fibers of connective tissues.

Front 78

fibronectins

Back 78

Certain glycoproteins of the ECM that help organize the matrix and help cells attach to it. Fibronectins bind to protein receptors that extend from the plasma membrane.

Front 79

integrins

Back 79

Proteins that serve as membrane receptors for the ECM. These proteins activate many cell signaling pathways that communicate info from the ECM. Integrins may be important in cell movement and in organizing the cytoskeleton so that cells assume a definite shape.

Front 80

cell signaling

Back 80

Mechanisms of communication between cells. Cells signal one another with secreted signaling molecules, or a signaling molecule on one cell combines with a receptor on another cell.

Front 81

cellulose

Back 81

A structural polysaccharide consisting of beta glucose subunits; the main constituent of plant primary cell walls.

Front 82

middle lamella

Back 82

A layer of gluelike polysaccharides that serve to cement together the primary cell walls of adjacent plant cells.

Front 83

primary cell wall

Back 83

Thin, flexible cell wall which a growing plant cell will secrete. This primary cell wall increases in size as it the cell grows.
After the cell stops growing, either new wall material is secreted that thickens and solidifies the primary wall or multiple layers of a secondary cell wall are then formed.

Front 84

secondary cell wall

Back 84

Formed between the primary wall and the plasma membrane.

A plant cell that has stopped growing can secrete this secondary cell wall (with a different chemical composition than that of the primary wall).