Chapter 2

nucleus

separated from the cytoplasm by a nuclear membrane

cytoplasm

separated from the surrounding fluids by a cell membrane, also called the plasma membrane.

protoplasm

The different substances that make up the cell are collectively called

water, electrolytes, proteins, lipids, and carbohydrates

protoplasm is composed of

Structural proteins

present in the cell mainly in the form of long filaments that are polymers of many individual protein molecules

microtubules

provide the cytoskeletons of cellular organelles such as cilia, nerve axons, the mitotic spindles of cells undergoing mitosis, and a tangled mass of thin filamentous tubules that hold the parts of the cytoplasm and nucleoplasm together in their respective compartments.

functional proteins

usually composed of combinations of a few molecules in tubular-globular form; mainly the enzymes of the cell; often mobile in the cell fluid

carbohydrates

play a major role in cell nutrition

intracellular organelles

highly organized physical structures

cell membrane

(also called the plasma membrane) envelops the cell and is a thin, pliable, elastic structure only 7.5 to 10 nanometers thick

Phospholipids

most abundant cell membrane lipids

hydrophilic

soluble in water

hydrophobic

soluble only in fats

cholesterol

They mainly help determine the degree of permeability (or impermeability) of the bilayer to watersoluble constituents of body fluids.

proteoglycans

which are mainly carbohydrates bound to small protein cores—are loosely attached to the outer surface of the cell as well.

glycocalyx

the entire outside surface of the cell often has a loose carbohydrate coat

cytoplasm

filled with minute and large dispersed particles and organelle

cisternae

This organelle helps process molecules made by the cell and transports them to their specific destinations inside or outside the cell.

ribosomes

Attached to the outer surfaces of many parts of the endoplasmic reticulum are large numbers of minute granular particles called

rough (granular) endoplasmic reticulum

where ribosomes are present in the reticulum

smooth endoplasmic reticulum

has no attached ribosomes

Golgi apparatus

composed of four or more stacked layers of thin, flat, enclosed vesicles lying near one side of the nucleus. This apparatus is prominent in secretory cells, where it is located on the side of the cell from which secretory substances are extruded.

lysosomes

vesicular organelles that form by breaking off from the Golgi apparatus; they then disperse throughout the cytoplasm

Hydrolytic enzymes

are highly concentrated in lysosomes

peroxisomes

they are believed to be formed by self-replication (or perhaps by budding off from the smooth endoplasmic reticulum) rather than from the Golgi apparatus; they contain oxidases rather than hydrolases

Secretory Vesicles

secretion of special chemical substances

Mitochondria

powerhouses of the cell; self-replicative

nucleus

control center of the cell and sends messages to the cell to grow and mature, replicate, or die; contains DNA and genes

genes

determine the characteristics of the cell’s proteins, including the structural proteins, as well as the intracellular enzymes that control cytoplasmic and nuclear activities; also control and promote cell reproduction

nuclear membrane

also called the nuclear envelope

nuclear pores

The nuclear membrane is penetrated by several thousand

nucleoli

The nuclei of most cells contain one or more highly staining structures called

nucleic acid

The essential life-giving constituent of the small virus is a ___ embedded in a coat of protein.

diffusion

involves simple movement through the membrane caused by the random motion of the molecules of the substance

Active transport

involves actually carrying a substance through the membrane by a physical protein structure that penetrates all the way through the membrane

Pinocytosis

ingestion of minute particles that form vesicles of extracellular fluid and particulate constituents inside the cell cytoplasm

phagocytosis

ingestion of large particles, such as bacteria, whole cells, or portions of degenerating tissue

lysosomes

Tissues of the body often regress to a smaller size

lysozyme

dissolves the bacterial cell wall

lysoferrin

binds iron and other substances before they can promote bacterial growth

lysozyme, lysoferrin, 5.0 pH acid

bactericidal agents in lysosomes

autophagy

“to eat oneself.”; a housekeeping process whereby obsolete organelles and large protein aggregates are degraded and recycled

autophagosomes

Worn-out cell organelles are transferred to lysosomes by double-membrane structures called

endoplasmic reticulum function

1. It provides the enzymes that control glycogen breakdown when glycogen is to be used for energy.

2. It provides a vast number of enzymes that are capable of detoxifying substances, such as drugs, that might damage the cell. It achieves detoxification by processes such as coagulation, oxidation, hydrolysis, and conjugation with glycuronic acid.

Golgi Apparatus

provide additional processing of substances already formed in the endoplasmic reticulum; synthesize certain carbohydrates that cannot be formed in the endoplasmic reticulum

ATP

composed of nitrogenous base adenine, pentose sugar ribose, three phosphate radicals

pyruvic acid

On entry into the cells, glucose is converted by enzymes in the cytoplasm into