Cell and Tissues

Vocabulary flashcards covering cell structure, transport, and cell division topics from the notes.

Cell

The structural and functional unit of the human body; carries out the chemical activities of life and divides to form or repair tissues.

Nucleus

The cell’s control center; houses DNA and directs protein synthesis; essential for cell reproduction.

Nucleolus

Region within the nucleus where ribosomal RNA (rRNA) synthesis occurs.

Nuclear envelope

A double membrane with pores that encloses the nucleoplasm and regulates passage of substances into and out of the nucleus.

Chromatin

DNA and protein combination inside the nucleus that condenses to form chromosomes during cell division.

Plasma membrane

The cell membrane; a phospholipid bilayer with proteins, cholesterol, and a glycocalyx that encloses the cell.

Phospholipid bilayer

The fundamental structure of the plasma membrane, with hydrophilic heads and hydrophobic tails.

Hydrophilic heads

Water-loving parts of phospholipids facing the watery environment.

Hydrophobic tails

Water-fearing parts of phospholipids facing inward away from water.

Proteins in the plasma membrane

Embedded proteins that perform transport, signaling, and other functions.

Cholesterol (membrane)

Sterol that stabilizes and modulates membrane fluidity.

Glycocalyx

Carbohydrate-rich layer on the cell exterior aiding protection and cell recognition.

Tight junctions

Impermeable junctions that prevent leakage between cells (e.g., intestinal lining).

Desmosomes

Anchoring junctions that resist mechanical stress (e.g., in skin and heart).

Gap junctions

Communicating junctions that allow direct passage of small molecules between adjacent cells.

Cytoplasm

The material between the nucleus and the plasma membrane; site of most cellular activities.

Cytosol

Fluid portion of the cytoplasm containing dissolved substances.

Inclusions

Stored nutrients and cell products (e.g., lipids, glycogen, pigments).

Organelles

Membrane-bound or non-membrane-bound structures performing specific cell functions.

Ribosomes

Sites of protein synthesis; composed of proteins and rRNA; free ribosomes synthesize intracellular proteins; rough ER ribosomes synthesize extracellular proteins.

Endoplasmic reticulum (ER)

A network of interconnected membranes in the cytoplasm that functions as the cell’s transport system.

Rough ER

ER with ribosomes; synthesizes and modifies proteins for export and membranes; manufactures membrane lipids.

Smooth ER

ER lacking ribosomes; involved in lipid metabolism and detoxification.

Golgi apparatus

Modifies, packages, and ships proteins; receives from rough ER and ships via secretory vesicles.

Lysosomes

Membrane-bound sacs with digestive enzymes that digest worn-out organelles and foreign substances.

Peroxisomes

Membrane-bound sacs with enzymes that detoxify harmful substances and neutralize free radicals.

Cytoskeleton

Network of protein filaments providing shape, support, and movement; includes microfilaments, intermediate filaments, and microtubules.

Microfilaments

Actin filaments (~7 nm) involved in cell movement and shape.

Intermediate filaments

Fibrous proteins (~10 nm) providing mechanical strength.

Microtubules

Tubulin polymers (~25 nm) forming tracks for organelle movement and cell shape.

Actin

Protein subunit of microfilaments involved in movement and structure.

Tubulin

Protein subunit of microtubules forming hollow tubes for transport and structure.

Mitochondria

Powerhouse of the cell; produce ATP (adenosine triphosphate) for energy.

ATP (adenosine triphosphate)

Energy currency of the cell; used to drive cellular processes.

Microvilli

Tiny fingerlike extensions increasing surface area for absorption; supported by actin.

Specialized cell

One of over 200 cell types with varied size, shape, and function; structure relates to function.

Fibroblasts

Elongated cells with extensive rough ER and Golgi for fiber protein secretion; important in wound healing and collagen production.

Erythrocytes (red blood cells)

Biconcave discs maximizing oxygen uptake and flow; lack organelles to maximize hemoglobin space.

Epithelial cells

Cells that cover and line organs; form sheets; tightly packed; supported by intermediate filaments and desmosomes.

Muscle cells

Skeletal, cardiac, and smooth muscle cells; elongated with abundant contractile filaments enabling movement.

Adipocytes

Fat cells; spherical with a large lipid droplet for nutrient storage.

White blood cells

Immune cells (e.g., macrophages) that move via pseudopods and phagocytose pathogens; contain many lysosomes.

Cell physiology

How cells metabolize nutrients, grow, reproduce, move, respond to stimuli, and transport substances across membranes.

Solutions

Homogeneous mixtures; solvent is water; solutes include electrolytes, glucose, nutrients, gases, hormones, enzymes.

Intracellular fluid

Fluid inside cells (nucleoplasm and cytosol) containing gases, nutrients, and salts.

Extracellular fluid

Fluid outside cells; includes interstitial fluid and plasma.

Maintenance of homeostasis (electrolyte concentration)

Regulation of Na+, K+, and Ca2+ levels; intracellular transport and extracellular hormonal controls (e.g., aldosterone, parathyroid hormone, vitamin D).

Diffusion

Passive movement of solutes from high to low concentration; includes simple diffusion and osmosis.

Simple diffusion

Lipid-soluble solutes move directly through the phospholipid bilayer (e.g., O2, CO2).

Osmosis

Diffusion of water through aquaporin channels to balance osmotic pressure.

Hypertonic

Higher solute concentration outside the cell; water moves out and the cell shrivels.

Isotonic

Equal solute concentration inside and outside; no net water movement.

Hypotonic

Lower solute concentration outside the cell; water moves in and the cell swells.

Facilitated diffusion

Diffusion through a channel or carrier protein; for ions or glucose; selective by size/charge.

Channel protein

Proteins that form pores/channels allowing specific molecules or ions to pass.

Carrier protein

Proteins that bind a specific molecule and change shape to transport it across the membrane.

GLUTs (glucose transporters)

Carrier proteins that transport glucose into cells.

Active transport

Movement requiring energy (ATP); includes vesicular transport and ion pumps.

Vesicular transport

Movement of substances in or out of the cell via vesicles; requires ATP.

Exocytosis

Secretion or ejection of substances; vesicles fuse with the plasma membrane to release contents.

Endocytosis

Uptake of substances by enclosing them in a vesicle.

Phagocytosis

A type of endocytosis (cell eating) of large particles; performed by macrophages.

Pinocytosis

A form of endocytosis (cell drinking) taking in droplets of extracellular fluid.

Sodium–potassium pump

Active transporter using ATP to move Na+ out and K+ in; maintains electrochemical gradients.

Passive transport

Movement across membranes without energy input (diffusion, osmosis).

Mitosis

Cell division producing two genetically identical diploid daughter cells; stages include prophase, metaphase, anaphase, telophase.

Meiosis

Cell division producing four haploid daughter cells; includes meiosis I and II, with crossing-over and genetic variation.

Prophase

Chromosomes condense; spindle forms; nucleus disappears.

Metaphase

Chromosomes align at the cell equator.

Anaphase

Sister chromatids separate and move toward opposite poles.

Telophase

Nuclei form around separated chromatids; cytokinesis divides cytoplasm.

Prophase I

Homologous chromosomes pair (tetrads) and crossing-over occurs; genetic variation begins.

Metaphase I

Tetrads align at the equator; homologous chromosomes separate during meiosis I.

Anaphase I

Homologous chromosomes separate and migrate to opposite poles.

Telophase I

Two haploid cells form; chromosomes may relax; cytoplasm divides.

Meiosis II

Second division separating sister chromatids, producing four haploid cells.

Diploid

Cell with two sets of chromosomes (2n).

Haploid

Cell with one set of chromosomes (n).

Crossing-over

Exchange of genetic material between homologous chromosomes during meiosis I.

Tetrad

Pair of homologous chromosomes, each with two sister chromatids, aligned during meiosis I.

Chromatid

One of two identical halves of a duplicated chromosome; held at the centromere.

Sister chromatids

Two identical copies of a replicated chromosome that separate during anaphase II.

DNA base pairing

Rules for base pairs: A pairs with T (DNA), C pairs with G (DNA); in RNA, A pairs with U.

Adenine–Thymine (A–T)

DNA base pairing: A binds to T.

Cytosine–Guanine (C–G)

DNA base pairing: C binds to G.

Adenine–Uracil (A–U)

RNA base pairing: A binds to U.

RNA

Ribonucleic acid; carries genetic information for protein synthesis; uses uracil instead of thymine.

DNA

Deoxyribonucleic acid; stores genetic information with A–T and C–G base pairing.