Apologia Biology - Module 4

The Cell Theory

The idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

Cytology

The study of cells

Ingestion

The ability to take in nutrients; this includes absorption, which is the ability to bring dissolved materials into the cell

Digestion

The ability to break food or nutrients down into simpler forma (by hydrolysis or with the help of enzymes) so it can be utilized

Respiration

The ability to release energy from the breakdown of food molecules

Transport

The ability to distribute or circulate molecules from one part of a cell to another

Homeostasis

The ability to maintain internal stability (also known as regulation)

Synthesis

The ability to combine simple chemicals into complex molecules (same as biosynthesis discussed in Module 2)

Secretion

The ability to release biosynthesized substances

Excretion

The ability to remove soluble metabolic waste from the cell

Egestion

The ability to remove nonsoluble, undigested waste from the cell

Irritability

The ability to respond to stimuli

Movement

The ability to move

Reproduction

The ability to produce more cells

Organelle

A tiny cellular structure that carries out a specific function necessary for the cell to survive

Prokaryotic cell

A cell that has no nucleus or other distinct, membrane-bound organelles

Eukaryotic cell

A cell with a membrane-bound nucleus and other distinct membrane-bound organelles

Plazma membrane

The semipermeable membrane between the cell contents and the cell's surroundings

Cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Cytoplasmic streaming

The motion of cytoplasm in a cell that results in a coordinated movement of the cell's contents.

Ribosomes

Non-membrane-bound organelles responsible for protein synthesis

Cell wall

A rigid layer of nonliving material on the outside of certain cells, usually plant and bacteria cells

Middle Iamella

The thin film between the cell walls of adjacent plant cells.

Nuclear Membrane

A highly-porous membrane that separates the nucleus from the cytoplasm

Endoplasmic Reticulum

An organelle composed of an extensive network of folded membranes that performs several tasks within a cell.

Rough ER

ER that is dotted with ribosomes

Smooth ER

ER that has no ribosomes

Golgi Apparatus

The organelles where proteins and lipids are stored and then modified to suit the needs of the cell

Vacuole

Larger membrane-bound organelle used for storage of food, water, or waste

Vesicle

Smaller membrane-bound organelle used mainly for transport of food, waste, or products synthesized for secretion

Secretory Vesicles

Vesicle that holds products of biosynthesis (like proteins) and transports them to the plasma membrane for secretion

Central Vacuole

A large vacuole that rests at the center of most plant cells and is filled with water

Lysosome

The organelle in animal cells responsible for hydrolysis reactions that break down proteins, carbohydrates (polysaccharides, disaccharides), and some lipids.

Peroxisome

A cell organelle containing enzymes that catalyze the decomposition of fatty acids and hydrogen peroxide

Mitochondria

Double-membrane bound organelles in which nutrients are converted to energy.

Plastids

Double-membrane-bound organelles found in the cells of plants, algae, and some protozoa, generally involved in either the manufacture or storage of food

Chloroplasts

Plastids containing the green pigment, chlorophyll, used in photosynthesis

Chromoplasts

Plastids containing yellow, orange, or red pigments used in photosynthesis

Leucoplasts

Nonpigmented plastids that store starches or oils

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

Microfilaments

Fine, threadlike proteins found in the cell's cytoskeleton

Intermediate Filaments

Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments

Microtubules

Spiral strands of protein molecules that form a tubelike structure

Centrioles

Paired organelles (positioned at right angles to each other) that organize fibers required for cell division; found in animal cells

Centrosome

A small region near the nucleus that is the main organizing site for microtubules; in animal cells it contains the two centrioles

Fluid mosaic model

A model proposing that the plasma membrane is composed of a mosaic of components (mainly phospholipids, proteins, and cholesterol) that are free to move fluidly within the plane of the membrane

Phospholipid

A lipid in which one of the fatty acid molecules has been replaced by a molecule that contains a phosphate group.

Semipermeable Membrane

A membrane that allows some molecules to pass through but does not allow other molecules to pass through.

Passive Transport

movement of molecules across the cell membrane without energy input from the cell

Active Transport

Movement of molecules through the plasma membrane aided by a process that requires energy input

Concentration

A measurement of how much solute exists within a certain volume of solvent

Concentration Gradient

The difference in the concentration of like molecules in two areas, like on each side of a plasma membrane

Diffusion

The random motion of molecules from an area of high concentration to an area of low concentration. (with a concentration gradient until its concentration becomes equal throughout the area (reaches equilibrium)

Osmosis

The diffusion of water through a semipermeable membrane from an area of high water concentration (low solute concentration) to low water concentration (high solute concentration)

Hypotonic solution

A solution that has a low solute concentration (and so a high water concentration) relative to another solution

Hypertonic solution

A solution that has a high solute concentration (and so a low water concentration) relative to another solution

Isotonic solution

A solution that has the same solute concentration (and water concentration) relative to another solution

Plasmolysis

Collapse of a walled cell's cytoplasm due to a lack of water

Cytolysis

The rupturing of a cell due to excess internal pressure.

Facilitated diffusion

The movement of certain molecules across a cell membrane through protein channels from high concentration to low concentration

Endocytosis

The process of moving particles into the cell by means of vesicles forming from the cell membrane

Exocytosis

The process of moving particles out of the cell by means of vesicles membranes fusing with the cell membrane

Pinocytosis

The process by which a cell absorbs extracellular fluid containing dissolved particals