Cells: The Basic Units of the Body

Comprehensive vocabulary flashcards covering cell structure, organelles, membrane transport, the cell cycle, and cell death based on Chapter 03 lecture outline.

Cell

The basic unit of structure and function in the body.

Micrometers ($\mu m$)

The unit of measurement used for cells.

Differentiated

A term describing cells that have developed specialized characteristics.

Nucleus

A major part of the cell that contains genetic material and directs cell activities.

Cytoplasm

The part of the cell consisting of organelles suspended in a liquid called cytosol.

Cytosol

The fluid portion of the cytoplasm.

Cell (Plasma) Membrane

The outer boundary of the cell that maintains integrity and is selectively permeable.

Phospholipid Bilayer

The cell membrane framework consisting of water-soluble (hydrophilic) heads and water-insoluble (hydrophobic) tails.

Cholesterol

A lipid that stabilizes the cell membrane and helps keep it impermeable to water-soluble substances.

Cellular Adhesion Molecules (CAMs)

Proteins like selectins and integrins that guide cells on the move, such as white blood cells moving toward infection sites.

Ribosomes

Structures composed of protein and RNA that provide structural support and enzyme activity to link amino acids in protein synthesis.

Rough Endoplasmic Reticulum (RER)

A membrane-bound system studded with ribosomes that conducts protein synthesis.

Smooth Endoplasmic Reticulum

A tubular transport system without ribosomes that conducts lipid synthesis.

Golgi Apparatus

A stack of flattened, membranous sacs that refines, packages, and delivers proteins made on the RER.

Mitochondria

Fluid-filled sacs called the "powerhouse of the cell" where chemical reactions extract energy from nutrients to produce ATP.

Lysosomes

Membranous sacs referred to as "garbage disposals" of the cell that contain enzymes to digest proteins, bacteria, and debris.

Peroxisomes

Membranous sacs containing enzymes that digest lipids, alcohol, and hydrogen peroxide.

Microfilaments

Tiny rods of actin that provide cellular movement, such as muscle contraction.

Microtubules

Larger tubes of tubulin that maintain cell shape and make up cilia, flagella, and centrioles.

Centrosome

A "central body" near the nucleus that contains two centrioles used to produce spindle fibers during cell division.

Cilia

Short, motile extensions of the cell membrane that beat in a coordinated manner to propel substances like mucus.

Flagella

A long, motile extension (like a sperm tail) that causes an entire cell to move.

Microvilli

Tiny extensions of the cell membrane composed of actin that increase surface area for absorption.

Chromatin

Consists of the cell's chromosomes, containing DNA wound around proteins, used to store information for protein synthesis.

Diffusion

The passive movement of atoms, molecules, or ions from a region of higher concentration to a region of lower concentration.

Facilitated Diffusion

A passive process using ion channels or transporters to move water-soluble substances like glucose across the membrane.

Osmosis

The passive movement of water across a selectively permeable membrane toward a region of higher impermeant solute concentration.

Isotonic Solution

A solution with the same osmotic pressure as the cell, resulting in no net gain or loss of water.

Hypertonic Solution

A solution with higher osmotic pressure than the cell, causing the cell to lose water and shrink (crenation).

Hypotonic Solution

A solution with lower osmotic pressure than the cell, causing the cell to gain water and potentially burst (lyse).

Filtration

A passive process that forces molecules through membranes by exerting pressure, such as blood pressure in capillaries.

Active Transport

Movement of substances against a concentration gradient using carrier molecules (pumps) and ATP energy.

Pinocytosis

A type of endocytosis where the cell membrane engulfs droplets of liquid.

Phagocytosis

A type of endocytosis where the cell membrane engulfs solid particles.

Transcytosis

A process involving receptor-mediated endocytosis followed by exocytosis to transport substances across tightly connected cell barriers.

Interphase

A very active period in the cell cycle where the cell grows, maintains functions, and replicates DNA during the $S$ phase.

Mitosis

The division of the nucleus, occurring in four stages: prophase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm, which begins during anaphase and uses a contractile ring of actin to create a cleavage furrow.

Telomeres

Chromosome tips that shorten with each mitosis, providing a mitotic clock for the cell.

Oncogenes

Abnormal forms of genes that control the cell cycle but are overexpressed, leading to tumor formation.

Tumor Suppressor Genes

Genes that normally limit mitosis; if inactivated or removed, they can no longer regulate cell division.

Totipotent

Stem cells, such as a fertilized egg, that can specialize to become any cell type.

Pluripotent

Stem cells that can become a limited number of cell types.

Apoptosis

Programmed cell death; a normal, stepwise process of development.

Necrosis

Cell death resulting from damage; it is not a normal process.