Chapter 3: Cells and Tissues

A comprehensive set of vocabulary flashcards covering cells, organelles, membranes, transport, tissue types, cell division, protein synthesis, and tissue repair based on the lecture notes.

Cell

The basic structural and functional unit of life; cells form tissues and carry out life-sustaining activities.

Cell theory

Four concepts: cells are the basic unit of life; organisms’ activities depend on cells; cell structure determines function; cells arise from preexisting cells.

Major elements of living matter

Carbon, hydrogen, oxygen, and nitrogen make up the bulk of living matter.

Water in cells

Living cells are about 60 percent water, essential for life.

Generalized cell

A representative cell showing the three main regions: plasma membrane, cytoplasm, and nucleus.

Plasma membrane

Flexible outer boundary of the cell that encloses cytoplasm and regulates material passage.

Fluid mosaic model

Plasma membrane structure with a phospholipid bilayer and scattered proteins forming a dynamic mosaic.

Phospholipid bilayer

Two layers of phospholipids with polar heads facing water and nonpolar tails inward, forming the membrane’s basic fabric.

Glycocalyx

Sugar-rich area on the cell surface formed by glycoproteins and glycolipids; involved in cell recognition.

Glycoprotein

Proteins with attached sugar groups; part of the glycocalyx and involved in receptors and cell interactions.

Glycolipid

Lipid with attached sugar groups; contributes to the glycocalyx.

Membrane proteins

Proteins in the plasma membrane that act as enzymes, receptors, channels, or carriers.

Tight junctions

Impermeable junctions that encircle cells and seal them together to prevent passage between cells.

Desmosomes

Anchoring junctions that bind cells together to resist mechanical stress.

Gap junctions

Communicating junctions allowing ions and small molecules to pass between adjacent cells.

Nucleus

Control center of the cell containing DNA; responsible for transmitting genetic information and protein synthesis.

Nuclear envelope

Double membrane surrounding the nucleus with nuclear pores for material passage.

Nuclear pores

Openings in the nuclear envelope that regulate passage of substances between nucleus and cytoplasm.

Nucleolus

Site where ribosomal subunits are assembled.

Chromatin

DNA wrapped around histones; forms chromosomes when a cell divides.

DNA

Deoxyribonucleic acid; genetic material containing genes and instructions for protein synthesis.

RNA

Ribonucleic acid; single-stranded; three types (mRNA, tRNA, rRNA) involved in protein synthesis.

Ribosome

Sites of protein synthesis; can be free in cytoplasm or attached to rough ER.

Rough endoplasmic reticulum (RER)

ER studded with ribosomes; protein synthesis and transport.

Smooth endoplasmic reticulum (SER)

ER lacking ribosomes; lipid metabolism, cholesterol/phospholipid synthesis, detoxification.

Golgi apparatus

Packages, modifies, and ships proteins from the rough ER; forms secretory vesicles and lysosomes.

Lysosome

Membranous sacs with digestive enzymes; intracellular digestion; “stomach” of the cell.

Peroxisome

Contain enzymes that detoxify harmful substances and neutralize free radicals; convert hydrogen peroxide to water.

Mitochondrion

Powerhouse of the cell; site of ATP production via aerobic respiration; double-membrane with cristae.

Cytosol

Semitransparent fluid in cytoplasm that suspends organelles and solutes.

Inclusions

Stored nutrients or cell products (lipid droplets, glycogen granules, pigments, etc.).

Cytoplasm

Cellular material outside the nucleus but inside the plasma membrane; site of most cellular activities.

Cytoskeleton

Internal framework of the cell consisting of microfilaments, intermediate filaments, and microtubules.

Microfilaments

Fine actin filaments involved in cell movement and shape changes.

Intermediate filaments

Rope-like filaments providing mechanical strength and desmosome support.

Microtubules

Tubular structures that determine cell shape, organize organelles, and form the mitotic spindle.

Centrioles

Paired structures near the nucleus that organize the spindle during cell division.

Cilia

Whip-like projections that move substances across the cell surface; contain microtubules.

Flagella

Long projections that propel the cell; example: sperm tail.

Microvilli

Fingerlike extensions increasing surface area for absorption; contain actin filaments.

Selective permeability

Plasma membrane allows some substances to pass while excluding others.

Diffusion

Movement of molecules from high to low concentration due to kinetic energy.

Simple diffusion

Unassisted diffusion through lipid bilayer or channels for lipid-soluble or small solutes.

Osmosis

Diffusion of water across a selectively permeable membrane via aquaporins.

Facilitated diffusion

Diffusion of solutes through membrane via channel or carrier proteins without ATP.

Filtration

Passive movement of water and solutes through a membrane due to a pressure gradient.

Active transport

Transport that requires ATP and a carrier; moves substances against their gradient.

Na+/K+ pump

Sodium-potassium pump; ATP-powered transporter exchanging Na+ out and K+ in; essential for nerve impulses.

Vesicular transport

Bulk transport of substances via vesicles; includes exocytosis and endocytosis.

Exocytosis

Secretion of substances from the cell by vesicle fusion with the plasma membrane.

Endocytosis

Uptake of extracellular substances via vesicle formation; may fuse with lysosomes.

Phagocytosis

Endocytosis of large particles; cell eating; performed by phagocytes.

Pinocytosis

Endocytosis of droplets of extracellular fluid; cell drinking.

Receptor-mediated endocytosis

Highly selective endocytosis triggered by binding to membrane receptors.

Isotonic solution

Solution with the same solute concentration as the cell; no net water movement.

Hypertonic solution

Higher solute concentration than the cell; water moves out, cell shrinks.

Hypotonic solution

Lower solute concentration than the cell; water moves in, cell swells.

Interphase

Longest cell cycle phase; cell metabolically active and duplicates DNA (DNA replication at end).

DNA replication

Process duplicating DNA; produces two identical DNA helices for cell division.

Mitosis

Nuclear division producing two genetically identical nuclei; stages: prophase, metaphase, anaphase, telophase.

Prophase

Chromatin condenses into visible chromosomes; nucleoli disappear; spindle forms.

Metaphase

Chromosomes align at the metaphase plate.

Anaphase

Sister chromatids separate and move to opposite poles.

Telophase

Nuclei form around chromosomes; chromosomes de-condense; nucleoli reappear.

Cytokinesis

Division of the cytoplasm; contractile ring forms a cleavage furrow to produce two cells.

Protein synthesis

Process of building proteins from DNA instructions via transcription and translation.

Gene

DNA segment that carries the information to make a specific protein.

Triplet

Three-base DNA sequence that codes for an amino acid.

Codon

Three-base mRNA sequence that specifies an amino acid during translation.

mRNA

Messenger RNA; carries genetic information from DNA to ribosomes for protein synthesis.

tRNA

Transfer RNA; carries amino acids to the ribosome and has an anticodon.

rRNA

Ribosomal RNA; structural component of ribosomes.

Translation

Process of decoding mRNA into an amino acid sequence at the ribosome.

Transcription

Process of transcribing DNA code into complementary mRNA.

Ribosome

Molecular machine where protein synthesis occurs.

Amino acid

Building blocks of proteins; joined by peptide bonds.

Nucleotides

Building blocks of DNA and RNA; consist of sugar, phosphate, and base.

Epithelial tissue

Tissue that covers and lines surfaces; forms glands; hallmarks include an apical surface and avascularity.

Simple epithelium

Epithelium with a single cell layer: squamous, cuboidal, or columnar.

Simple squamous epithelium

One cell layer of flat cells; diffusion is rapid; lines alveoli and capillaries.

Simple cuboidal epithelium

One layer of cube-shaped cells; forms glands and kidney tubules.

Simple columnar epithelium

One layer of tall cells; often has goblet cells; lines digestive tract.

Pseudostratified columnar epithelium

Single layer that appears stratified; often ciliated; lines respiratory tract.

Stratified squamous epithelium

Many cell layers; protects underlying tissues; skin, mouth, esophagus.

Transitional epithelium

Highly modified stratified epithelium that can stretch; lines urinary system.

Glandular epithelium

Epithelium forming glands that secrete products; endocrine vs exocrine.

Endocrine gland

Ductless gland; secretions (hormones) diffuse into blood vessels.

Exocrine gland

Gland with ducts; secretions exit through ducts to surfaces.

Connective tissue

Tissue that connects, supports, protects, cushions; characterized by extracellular matrix.

Extracellular matrix

Nonliving substance outside cells consisting of ground substance and fibers.

Ground substance

Water-rich matrix with adhesion proteins and polysaccharides; traps water.

Collagen fiber

Strong, rope-like protein fibers providing tensile strength.

Elastic fiber

Fibers that stretch and recoil; provide elasticity.

Reticular fiber

Fine collagen fibers forming an internal skeleton of soft organs.

Bone (osseous tissue)

Hard connective tissue with osteocytes in lacunae; mineralized matrix and collagen.

Osteocyte

Bone cell residing in lacunae.

Lacuna

Small pits housing osteocytes in bone.

Hyaline cartilage

Most common cartilage; glassy appearance; supports airways and joints; fetal skeleton.

Fibrocartilage

Tough cartilage found in intervertebral discs; provides cushion.

Elastic cartilage

Cartilage with elastic fibers; provides elasticity (ears, epiglottis).