3.4 The Cellular Level Of Organization: Cytoplasm

Front 1

What are the two components of cytoplasm?

Back 1

1. Cytosol

2. Organelles

Front 2

What is the cytosol?

Back 2

Semifluid portion of cytoplasm in which organelles and inclusions are suspended and solutes are dissolved. Also called intracellular fluid.

Front 3

What are the different types of dissolved and suspended components in cytosol? (8 things).

Back 3

Ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, organic molecule storage aggregations, and waste products.

Front 4

What are two types of organic molecule aggregations? What do they consist of?

Back 4

Lipid droplets: triglycerides

Glycogen granules: glycogen molecules

Front 5

What is the cytoskeleton?

Back 5

Complex internal structure of cytoplasm consisting of microfilaments, microtubules, and intermediate filaments.

Front 6

What are the two main functions of the cytoskeleton?

Back 6

1. Serves as a scaffold that helps determine a cell's shape and organize the cellular contents.

2. Aids movement of organelles within the cell, of chromosomes during cell division, and of whole cells such as phagocytes.

Front 7

What are microfilaments? What are they composed of?

Back 7

The thinnest elements of the cytoskeleton, composed of the proteins actin and myosin.

Front 8

What are the two general functions of microfilaments?

Back 8

They help generate movement and provide mechanical support.

Front 9

What are microvilli?

Back 9

Microscopic, fingerlike projections of the plasma membranes of cells that increase surface area for absorption, especially in the small intestine and proximal convoluted tubules of the kidneys.

Front 10

What are intermediate filaments?

Back 10

Protein filament, ranging from 8 to 12 nm in diameter, that may provide structural reinforcement, hold organelles in place, and give shape to a cell.

Front 11

What are microtubules?

Back 11

Cylindrical protein filament, largest of the cytoskeletal components, consisting of the protein tubulin; provides support, structure, and transportation.

Front 12

Which cytoskeletal component helps form the structure of centrioles, cilia, and flagella?

Back 12

Microtubules help to form centrioles, cilia, and flagella.

Front 13

What are organelles?

Back 13

Tiny structures that perform different functions in the cell.

Front 14

Each type of organelle has its own set of _____.

Back 14

Set of enzymes.

Front 15

How many organelles are in a cell, and how many different types of organelles?

Back 15

Varies, depending on type of cell.

Front 16

What is the centrosome?

Back 16

A dense network of small protein fibers near the nucleus of a cell, containing a pair of centrioles and pericentriolar material.

Front 17

What surrounds the centrioles?

Back 17

Pericentriolar material.

Front 18

What is pericentriolar material?

Back 18

Material containing hundreds of ring-shaped complexes composed of the protein tubulin.

Front 19

What are the functions of tubulin complexes?

Back 19

Growth of the mitotic spindle, which plays a critical role in cell division, and for microtubule formation in nondividing cells.

Front 20

What happens to centrosomes during cell division, and why?

Back 20

Centrosomes replicate so that succeeding generations of cells have the capacity for cell division.

Front 21

If you observed that a cell did not have a centrosome, what could you predict about its capacity for cell division?

Back 21

A cell without a centrosome probably would not be able to undergo cell division.

Front 22

What are cilia?

Back 22

A hair or hairlike process projecting from a cell that may be used to move the entire cell or to move substances along the surface of the cell. Singular is cilium.

Front 23

What are flagella?

Back 23

Hairlike, motile process on the extremity of a bacterium, protozoan, or sperm cell. Singular is flagellum.

Front 24

What are the functions of cilia and flagella?

Back 24

1. Cilia move fluids along a cell's surface.

2. A flagellum moves an entire cell.

Front 25

What are ribosomes?

Back 25

A cellular structure in the cytoplasm of cells, composed of a small subunit and a large subunit that contain ribosomal RNA and ribosomal proteins; the site of protein synthesis.

Front 26

What are the functions of ribosomes?

Back 26

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.

Front 27

Where are subunits of ribosomes synthesized and assembled?

Back 27

Large and small ribosomal subunits are synthesized separately in the nucleolus within the nucleus, and are then assembled in the cytoplasm.

Front 28

What is the endoplasmic reticulum (ER)?

Back 28

A network of channels running through the cytoplasm of a cell that serves in intracellular transportation, support, storage, synthesis, and packaging of molecules. Portions of ER where ribosomes are attached to the outer surface are called rough ER; portions that have no ribosomes are called smooth ER.

Front 29

What are the functions of rough endoplasmic reticulum?

Back 29

Rough ER synthesizes glycoproteins and phospholipids that are transferred into cellular organelles, inserted into the plasma membrane, or secreted during exocytosis.

Front 30

What are the functions of smooth endoplasmic reticulum?

Back 30

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 cells.

Front 31

What are the structural and functional differences between rough and smooth ER?

Back 31

Rough ER has attached ribosomes; smooth ER does not. Rough ER synthesizes proteins that will be exported from the cell; smooth ER is associated with lipid synthesis and other metabolic reactions.

Front 32

What is the Golgi complex?

Back 32

An organelle in the cytoplasm of cells consisting of four to six flattened sacs (cisternae), stacked on one another, with expanded areas at their ends.

Front 33

What are the functions of the Golgi complex?

Back 33

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.

Front 34

What are you looking at?

Back 34

Golgi complex.

Front 35

How do the entry and exit faces of the Golgi complex differ in function?

Back 35

The entry face receives and modifies proteins from rough ER; the exit face modifies, sorts, and packages molecules for transport to other destinations.

Front 36

What are the three general destinations for proteins that leave the Golgi complex?

Back 36

Some proteins are secreted from the cell by exocytosis, some are incorporated into the plasma membrane, and some occupy storage vesicles that become lysosomes.

Front 37

What are you looking at?

Back 37

Lysosomes.

Front 38

What are lysosomes?

Back 38

An organelle in the cytoplasm of a cell, enclosed by a single membrane and containing powerful digestive enzymes.

Front 39

Lysosomal enzymes work best at what pH? This results in the import of what ion?

Back 39

Acidic pH.

Hydrogen ions (H+).

Front 40

The lysosomal interior has a pH of what, as compared to the pH of _____ of cytosol.

Back 40

Lysosomal pH: 5

Cytosol pH: 7

Front 41

What are the functions of lysosomes?

Back 41

1. Digest substances that enter a cell via endocytosis and transport final products of digestion into cytosol.

2. Carry out the digestion of worn-out organelles.

3. Implement autolysis, the digestion of an entire cell.

4. Accomplish extracellular digestion.

Front 42

What is the name of the process by which worn-out organelles are digested by lysosomes?

Back 42

Digestion of worn-out organelles by lysosomes is called autophagy.

Front 43

What is a disorder caused by faulty or absent lysosomal enzymes?

Back 43

Tay-Sachs Disease.

Front 44

What is autolysis?

Back 44

Self-destruction of cells by their own lysosomal digestive enzymes after death or in a pathological process.

Front 45

What is a peroxisome?

Back 45

Organelle similar in structure to a lysosome that contains enzymes that use molecular oxygen to oxidize various organic compounds; such reactions produce hydrogen peroxide; abundant in liver cells. Also known as microbodies.

Front 46

What is a proteasome?

Back 46

Tiny cellular organelle in cytosol and nucleus containing proteases that destroy unneeded, damaged, or faulty proteins.

Front 47

Clumps of misfolded proteins (from failure of proteasomes to degrade abnormal proteins) accumulate in brain cells of people with which two diseases?

Back 47

Parkinson's disease and Alzheimer's disease.

Front 48

What are you looking at?

Back 48

A mitochondrion.

Front 49

What is a mitochondrion?

Back 49

A doublemembraned organelle that plays a central role in the production of ATP; known as the “powerhouse” of the cell. Plural is mitochondria.

Front 50

An increase in the number of mitochondria in muscle cells is due to what?

Back 50

Regular exercise.

Front 51

A mitochondrion consists of what?

Back 51

An outer mitochondrial membrane and an inner mitochondrial membrane with a small fluid-filled space between them.

Front 52

The inner mitochondrial membrane contains a series of folds called what?

Back 52

Mitochondrial cristae.

Front 53

What is the mitochondrial matrix?

Back 53

The central fluid-filled cavity of a mitochondrion, enclosed by the inner mitochondrial membrane.

Front 54

What are the functions of mitochondria?

Back 54

1. Generate ATP through reactions of aerobic cellular respiration.

2. Play an important early role in apoptosis.

Front 55

How do the mitochondrial cristae contribute to its ATP-producing function?

Back 55

Mitochondrial cristae increase the surface area available for chemical reactions and contain some of the enzymes needed for ATP production.

Front 56

What is apoptosis?

Back 56

Programmed cell death; a normal type of cell death that removes unneeded cells during embryological development, regulates the number of cells in tissues, and eliminates many potentially dangerous cells such as cancer cells.

Front 57

What happens during apoptosis?

Back 57

During apoptosis, the DNA fragments, the nucleus condenses, mitochondria cease to function, and the cytoplasm shrinks, but the plasma membrane remains intact. Phagocytes engulf and digest the apoptotic cells, and an inflammatory response does not occur.