Cells and Tissues Lecture Notes

Flashcards covering the cellular basis of life, including cell theory, anatomy of a generalized cell, organelles, and membrane transport processes.

Robert Hooke

An English scientist who used a first primitive microscope to describe cells after looking at a thin slice of cork from dead plant tissue.

Antonie van Leeuwenhoek

A scientist who observed pond water under his microscope and called the tiny organisms he saw "animalcules."

Matthias Schleiden

A botanist who stated that all plants are composed of individual units called cells.

Theodor Schwann

A zoologist who stated that all animals are also composed of individual units called cells.

Cell Theory

A theory stating that a cell is the basic structural and functional unit of life, organism activity depends on collective cell activities, biochemical activities are dictated by subcellular structures, and continuity of life has a cellular basis.

Protoplasm

An aqueous colloidal solution of carbohydrates, proteins, nucleic acids, and inorganic salts surrounded by a limiting cell membrane.

Nucleoplasm

The protoplasm found inside the nucleus.

Cytoplasm

The cellular material (nucleoplasm) outside the nucleus and inside the plasma membrane.

Eukaryotic cells

Higher cells like those of the human body that contain membrane-bound organelles.

Prokaryotic cells

Cells that do not have membrane organelles, such as bacteria.

Chloroplasts

Special organelles in plant cells that perform photosynthesis to convert light into chemical energy.

Plasma membrane

A fragile transparent barrier that contains cell contents, is selectively permeable, and separates the cell from the surrounding environment.

Glycoproteins

"Sugar proteins" attached to the plasma membrane that determine blood type, act as receptors for toxins or viruses, and play a role in cell-to-cell recognition.

Fluid Mosaic Model

A model describing the plasma membrane structure as phospholipid layers arranged "tail to tail" with cholesterol and scattered proteins.

Hydrophilic

The "water loving" polar heads of phospholipid molecules that are attracted to water.

Hydrophobic

The "water fearing" nonpolar acid tails that avoid water and line up in the center of the membrane.

Cholesterol

A substance in the plasma membrane that helps to stabilize the membrane and keep it flexible.

Tight junction

An impermeable junction that binds cells together into leak-proof sheets to prevent substances from passing through extracellular space.

Desmosomes

Anchoring junctions that prevent cells subject to mechanical stress, such as skin cells, from being pulled apart.

Gap junctions

Junctions commonly seen in the heart and between embryonic cells that function mainly to allow communication.

Nucleolus

Small, dark-staining round bodies within the nucleus where ribosomes are assembled.

Chromatin

A loose network of "beads" on a string formed by DNA wound around histone proteins, present when a cell is not dividing.

Chromosomes

Dense, rodlike bodies formed by coiled chromatin threads when a cell is dividing.

Cytosol

A semitransparent fluid that suspends other elements in the cytoplasm and is largely composed of water and nutrients.

Inclusions

The "cellular pantry" consisting of stored nutrients or cell products like fat droplets, glycogen granules, or pigments.

Organelles

The "metabolic machinery" of the cell, engineered to carry out specific functions; literally means "little organs."

Mitochondria

Threadlike or sausage-shaped organelles known as the "powerhouses" of the cell.

Ribosomes

Tiny, round bodies made of proteins and ribosomal RNA that are the actual sites of protein synthesis.

Endoplasmic Reticulum (ER)

A network of channels that serves as a microcirculatory system for the cell's substances, primarily proteins.

Rough ER

The "cell membrane factory" combination of ribosome-membranes especially abundant in cells that export protein products.

Smooth ER

A continuation of the rough ER that lacks ribosomes and functions in lipid metabolism and detoxification of drugs.

Golgi Apparatus

The "principal traffic director" of cellular proteins that modifies, packages, and ships proteins.

Lysosomes

The "demolition sites" of the cell containing powerful digestive enzymes to break down bodies.

Peroxisomes

Membranous sacs containing oxidase enzymes used to detoxify harmful substances like alcohol and disarm free radicals.

Cytoskeleton

An elaborate network of protein structures acting as the "bone and muscles" of the cell to determine shape and support organelles.

Centrioles

Paired, rod-shaped bodies that generate microtubules and direct the formation of the mitotic spindle during cell division.

Cilia

Whiplike cellular extensions that move substances along the cell surface.

Microvilli

Tiny fingerlike extensions of the plasma membrane that increase surface area for absorption in intestinal or kidney tubule cells.

Fibroblast

An elongated cell with abundant rough ER and a large Golgi apparatus used to secrete protein building blocks.

Erythrocytes (RBC)

Concave disk-shaped cells that carry oxygen in the bloodstream.

Macrophage

A phagocytic cell that extends long pseudopods to crawl through tissue to reach infection sites.

Solvent

The substance present in the largest amount in a solution, also known as the dissolving medium.

Intracellular fluid

A solution found inside the plasma membrane containing water, gases, nutrients, and salts.

Interstitial fluid

The rich, nutritious fluid that continuously bathes the exterior of our cells.

Selective Permeability

A property of a barrier that allows some substances to pass through while excluding others.

Diffusion

A passive process where molecules move from a region of higher concentration to a region of lower concentration.

Osmosis

The diffusion of water through a selectively permeable membrane.

Aquaporins

Water pores created by proteins in the membrane that allow water to pass easily.

Filtration

A process by which water and solutes are forced through a membrane by fluid or hydrostatic pressure.

Active transport

A process requiring metabolic energy (ATP) and protein carriers to move substances against concentration gradients.

Exocytosis

A type of vesicular transport used to move substances out of the cell, such as hormones or mucus.

Endocytosis

An ATP-requiring process that engulfs extracellular substances by enclosing them in a small membranous vesicle.

Phagocytosis

A term meaning "cell eating."

Pinocytosis

A term meaning "cell drinking" where the cell gulps droplets of extracellular fluid.