Chapter 3: The Cellular Level of Organization

Vocabulary flashcards covering key terms and concepts from the lecture notes.

Homeostasis

A biological term that refers to a DYNAMIC state of BALANCE within parameters that are compatible with life.

Cell Theory

A theory formulated by Theodor Schwann, Matthias Schleiden, and Rudolph Virchow stating that the cell is the basic unit of life.

Plasma Membrane

A flexible outer boundary of a cell.

Cytoplasm

Everything between the plasma membrane and the nucleus, including cytosol and organelles.

Cytosol

Intracellular fluid.

Organelles

Subcellular structures with specific functions; compartmentalization of chemical reactions.

Nucleus

The control center of the cell; contains DNA.

Phospholipid Bilayer

A double layer of phospholipid molecules that forms the primary structure of cell membranes.

Amphipathic

Having both polar and nonpolar regions in a molecule.

Hydrophilic

Attracted to water; polar.

Hydrophobic

Repelled by water; nonpolar.

ICF (Intracellular Fluid)

The fluid inside the cell.

ECF (Extracellular Fluid)

The fluid environment outside the cell membrane.

Interstitial Fluid (IF)

Extracellular fluid NOT contained within blood vessels.

Fluid-Mosaic Model

A model describing the cell membrane as fluid, with lipids and proteins that are not rigidly locked in place.

Integral Proteins

Proteins embedded in the cell membrane; usually transmembrane.

Peripheral Proteins

Proteins found on the inner or outer surface of the lipid bilayer.

Glycoprotein

A protein with carbohydrate molecules attached which extend into the extracellular matrix, aiding in cell recognition.

Glycocalyx

A fuzzy-appearing coating around the cell formed from glycoproteins, glycolipids, and other carbohydrates.

Selective Permeability

The characteristic of a membrane that allows only substances meeting certain criteria to pass through it unaided.

Passive Transport

The movement of substances across the cell membrane without the expenditure of cellular energy.

Active Transport

The movement of substances across the cell membrane using ATP.

Concentration Gradient

The difference in concentration of a substance inside versus outside of the membrane.

Electrochemical Gradient

The combination of concentration gradient and electrical gradient affecting ions.

Diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration.

Simple Diffusion

Diffusion directly through the phospholipid bilayer.

Facilitated Diffusion

Diffusion with the help of membrane proteins (carrier-mediated or channel-mediated).

Osmosis

Net diffusion movement of water (the solvent) through a semipermeable membrane.

Osmolarity

Is the measure of the total concentration of solute particles.

Tonicity

The ability of a solution to alter a cell's water volume.

Isotonic Solution

A solution with the same non-penetrating solute concentration as that of the cell’s cytosol.

Hypertonic Solution

A solution with a higher non- penetrating solute concentration than the cell’s cytosol.

Hypotonic Solution

A solution with a lower non- penetrating solute concentration than the cell’s cytosol.

Filtration

The process that uses a hydrostatic pressure gradient (water pressure) that pushes the fluid from a higher pressure area to a lower pressure area.

Sodium-Potassium Pump

An ion pump that binds specifically and reversibly with the substance being transported, moves the solutes against their concentration gradient, and requires energy (ATP).

Primary Active Transport

Active transport that requires energy directly from the hydrolysis of ATP.

Secondary Active Transport

Active transport that requires energy indirectly from the ionic gradients created by the primary active transport process.

Vesicular Transport

The transport of large particles, macromolecules, and fluids across the membrane in membranous sacs called vesicles requiring cellular energy à ATP.

Exocytosis

The transport of a substance out of the cell.

Endocytosis

The transport of substance into the cell.

Phagocytosis

The endocytosis of large particles.

Pinocytosis

The process that brings into the cell fluid containing dissolved substances.

Receptor-Mediated Endocytosis

Endocytosis by a portion of the cell membrane containing receptors specific for a certain substance.

Transcytosis

The transport of a substance into, across, and then out of the cell.

Vesicular Trafficking

The transport of a substance from one area or organelle in the cell to another area or organelle.

Endoplasmic Reticulum (ER)

A system of interconnected channels (tubes) and parallel membranes enclosing cisterns that is continuous with the outer nuclear membrane (or “envelope”) covering the nucleus and composed of the same lipid bilayer material.

Rough ER (RER)

Endoplasmic reticulum with ribosomes attached for protein synthesis and modification.

Smooth ER (SER)

Endoplasmic reticulum without ribosomes; involved in lipid synthesis, calcium storage, and detoxification.

Golgi Apparatus

Responsible for sorting, modifying, and shipping off the products that come from the rough ER.

Lysosomes

An organelle that contains enzymes that break down & digest unneeded cellular components, such as a damaged organelle.

Autophagy

the process of a cell digesting its own structures.

Apoptosis

Process of programmed cell death.

Mitochondria

Is a double membrane, bean-shaped organelle that is the “energy transformer” of the cell.

Peroxisome

A membrane-bound organelle that contains an abundance of enzymes (oxidases & catalases) used for detoxifying harmful substances & lipid metabolism.

Reactive Oxygen Species (ROS)

Peroxides (O22 -) and free radicals are highly reactive products of many normal cellular processes, including the mitochondrial reactions that produce ATP.

Oxidative Stress

Term used to describe damage to cellular components caused by ROS.

Cytoskeleton

Elaborate series of fibrous protein rods that runs throughout the cytosol providing structural support for cell.

Microtubules

The thickest of the 3 cytoskeletal elements that maintain cell shape and structure and help resist compression of the cell.

Microfilaments

Thinnest of the cytoskeletal elements that are composed primarily of strands of a protein called actin.

Intermediate Filaments

A filament intermediate in thickness between the microtubules and microfilaments.

Nuclear Envelope

Surrounds the nucleus and consists of 2 adjacent lipid bilayers with a thin fluid space in between them.

Nucleolus

A region of the nucleus that is responsible for manufacturing the rRNA necessary for the construction of ribosomes.

Chromatin

Composed of DNA (30%), associated proteins (60%) and RNA (10%).

Chromosomes

A chromosome is composed of DNA and proteins, it is the condensed form of chromatin.

Genome

The entire complement of an organism’s DNA.

Gene

A functional segment of DNA that provides the genetic information necessary to build a protein.

Transcription

DNA à mRNA, the synthesis of a strand of mRNA that is complementary to the gene of interest.

Translation

mRNA à Protein, the process of synthesizing a chain of amino acids called a polypeptide (protein).

Somatic Cell

A general term for a body cell, and all human cells, except for the cells (gametes) that produce eggs & sperm (germ cells), are somatic cells.

Cell Cycle

The sequence of events in the life of the cell from the moment it is created at the end of a previous cell division UNTIL it then divides itself, generating 2 NEW CELLS.

Mitosis

The mitotic phase/nuclear division is the division of genetic material, during which the cell nucleus breaks down and 2 new, fully functional, nuclei are formed.

Cytokinesis

Cytoplasmic division divides the cytoplasm into 2 distinctive cells.

Interphase

The period of the cell cycle when the cell is not dividing.

Stem Cell

An unspecialized cell that can divide without limit as needed and can, under specific conditions, differentiate into specialized cells.

Cellular Differentiation

Is the process by which unspecialized cells become specialized to carry out distinct functions.

Totipotent Stem Cells

The 1st embryonic cells that arise from the division of the zygote and They have the potential to differentiate into any of the cells needed to enable an organism to grow and develop.

Pluripotent Stem Cells

Develop from totipotent stem cells and are the precursors to the fundamental tissue layers of the embryo. They are the ones that have the potential to differentiate into any type of human tissue but cannot support the full development of an organism.

Multipotent Stem Cells

Has the potential to differentiate into different types of cells within a given cell lineage or small of lineages, such as red blood cells or white blood cells.

Oligopotent stem cells

Are multipotent stem cells that have become further specialized and they are limited to becoming one of a few different cell types.

Unipotent Stem Cells

The unipotent cells is fully specialized and can only reproduce to generate more of its own specific cell type.