Cell Biology & Biochemistry Essentials

Vocabulary flashcards covering key scientists, cell theory, organelles, membrane components, types of cell death, carbohydrate chemistry, lipids, proteins, enzymes, and vitamins for comprehensive exam review.

Robert Hooke

Scientist who discovered and named cells after observing cork under a microscope.

Felix Dujardin

First to describe the cell’s jelly-like material, calling it sarcode (later renamed protoplasm).

Sarcode

Early term for the cell’s jelly-like interior; later called protoplasm.

Protoplasm

Colloidal living substance inside cells; term popularized by Jan Evangelista.

Matthias Schleiden & Theodor Schwann

Founders of classical cell theory that all organisms are made of cells and all cells arise from pre-existing cells.

Robert Brown

Botanist who discovered the cell nucleus.

Anton van Leeuwenhoek

Microscopist who observed free cells and the nucleus of red blood cells.

Classical Cell Theory (3 tenets)

1) All living things are composed of cells. 2) Cells come from pre-existing cells. 3) The cell is the basic structural and functional unit of life.

Modern Cell Theory (4 points)

Adds: the cell is the physiologic & morphologic unit, organism properties depend on cells, cells carry genetic material, and the cell is the smallest unit of life.

Prokaryote

Simple, single-celled organism without a true nucleus or membrane-bound organelles (e.g., bacteria).

Eukaryote

Cell type with true nucleus and membrane-bound organelles; forms most protists, fungi, plants, and animals.

Fluid Mosaic Model

Describes the flexible lipid bilayer with embedded integral proteins and peripheral proteins on the surface.

Peripheral Protein

Protein attached to the membrane surface; often functions as a receptor.

Integral Protein

Protein embedded within the lipid bilayer; may form ion channels.

Membrane Fluidity

Property controlled by fatty-acid saturation and cholesterol content; cholesterol decreases fluidity at high temperature and increases it at low temperature.

Phospholipid

Major membrane lipid composed of glycerol (or sphingosine), fatty acids, phosphate, and an alcohol head group.

Glycolipid

Membrane lipid containing carbohydrate (cerebroside, globoside, ganglioside) attached to ceramide.

Phosphoglyceride

A glycerol-based phospholipid with two fatty acids and a phosphate-linked head group.

Sphingolipid

Lipid built on sphingosine; includes sphingomyelin and glycosphingolipids.

Cerebroside

Simple glycolipid composed of ceramide plus one sugar (glucose or galactose).

Globoside

Neutral glycolipid containing ceramide plus two or more sugars (e.g., glucose and galactose).

Ganglioside

Complex glycolipid with oligosaccharide and sialic acid; abundant in nervous tissue.

Pump (membrane protein)

Active-transport protein that moves solutes against a gradient using ATP (e.g., Na⁺/K⁺ ATPase).

Carrier (membrane protein)

Protein that transports molecules either actively or by facilitated diffusion.

Channel (membrane protein)

Protein pore allowing rapid passive ion flow down a concentration gradient.

Na⁺/K⁺ ATPase Pump

Membrane pump exporting 3 Na⁺ out and importing 2 K⁺ into the cell per ATP.

Chloroplast

Plant organelle containing chlorophyll; site of photosynthesis in thylakoid membranes.

Rough Endoplasmic Reticulum

ER studded with ribosomes; synthesizes membrane and secretory proteins.

Smooth Endoplasmic Reticulum

ER lacking ribosomes; synthesizes lipids and steroid hormones.

Ribosome

Cytoplasmic RNA-protein particle that is the site of protein synthesis.

Mitochondrion

Organelle where aerobic respiration and ATP production occur; the cell’s powerhouse.

Golgi Apparatus

Stack of flattened cisternae that modifies, sorts, and packages proteins and lipids.

Lysosome

Membrane vesicle containing hydrolytic enzymes for intracellular digestion (‘cell garbage disposal’).

Vacuole

Membrane-bound space filled with fluid; prominent in plants for storage and turgor.

Nucleolus

Dense nuclear region where rRNA transcription and ribosome assembly occur.

Microtubule

Hollow tubulin cylinder involved in intracellular transport, cilia, flagella, and mitotic spindle.

Microfilament

Double-stranded actin filament that supports cell shape and drives muscle contraction and movement.

Mitosis

Type of cell division producing two genetically identical diploid daughter cells for growth and repair.

Meiosis

Two successive divisions producing four haploid gametes genetically different from the parent.

Aneuploidy

Abnormal number of chromosomes (e.g., trisomy 21 in Down syndrome).

Necrosis

Uncontrolled cell death due to injury, ATP depletion, or membrane damage.

Autophagy

Self-eating process where cells digest their own components via lysosomes.

Atrophy

Decrease in tissue size from cell shrinkage or loss.

Apoptosis

Programmed cell death involving cell shrinkage, fragmentation, and phagocytosis of apoptotic bodies.

Carbohydrate

Polyhydroxy aldehyde or ketone or compound yielding them; general formula Cₙ(H₂O)ₙ.

Monosaccharide

Single sugar unit (3–7 carbons) that cannot be hydrolyzed to simpler carbohydrates.

Disaccharide

Carbohydrate composed of two monosaccharides linked by a glycosidic bond.

Oligosaccharide

Carbohydrate containing 3–10 monosaccharide units; often part of glycoproteins and glycolipids.

Polysaccharide

Polymer of many monosaccharides; may be storage (starch, glycogen) or structural (cellulose, chitin).

Glucose

Primary blood sugar (dextrose); most abundant hexose; central to energy metabolism.

Insulin

Pancreatic β-cell hormone that lowers blood glucose by promoting uptake and storage.

Glucagon

Pancreatic α-cell hormone that raises blood glucose by stimulating hepatic glucose production.

Diabetes Mellitus

Group of disorders characterized by chronic hyperglycemia due to insulin deficiency or resistance.

Type 1 Diabetes Mellitus

Autoimmune destruction of β-cells causing absolute insulin deficiency; usually onset <30 y.

Type 2 Diabetes Mellitus

Insulin resistance with relative deficiency; associated with obesity; treated with oral hypoglycemics.

Fructose

Sweetest ketohexose found in honey and fruit; hereditary intolerance causes hypoglycemia.

Galactose

Aldohexose component of lactose and brain glycolipids; ‘brain sugar.’

Galactosemia

Genetic absence of enzymes converting galactose to glucose-1-P, leading to cataracts and mental disability.

Ribose

Aldopentose component of RNA and many coenzymes.

Aldonic Acid

Product of mild oxidation of an aldose’s C-1 (e.g., gluconic acid).

Benedict’s Test

Cu²⁺-based assay for reducing sugars; positive result is brick-red Cu₂O precipitate.

Tollen’s Test

Ammoniacal Ag⁺ test for aldehydes; positive gives a silver mirror.

Aldaric Acid

Product of strong oxidation of both C-1 and C-6 of an aldose (e.g., glucaric acid).

Sugar Alcohol

Polyol formed by reduction of monosaccharide carbonyl (e.g., sorbitol).

Glycoside

Acetal formed when the hemiacetal OH of a sugar is replaced by OR; stable in water.

Phosphate Ester (of sugar)

Sugar derivative with phosphate esterified to OH (e.g., glucose-6-phosphate), key intermediates in metabolism.

Amino Sugar

Monosaccharide with an OH replaced by NH₂; e.g., glucosamine in chitin.

Maltose

Reducing disaccharide of two glucose units linked α(1→4); called malt sugar.

Lactose

Milk sugar: β-D-galactose + D-glucose linked β(1→4); reducing disaccharide.

Lactose Intolerance

Deficiency of lactase causing inability to digest lactose, leading to bloating and diarrhea.

Sucrose

Table sugar: α-D-glucose + β-D-fructose via α,β(1→2) bond; non-reducing.

Cellulose

Unbranched β(1→4)-linked glucose polymer; main component of plant cell walls.

Starch

Plant glucose storage polysaccharide composed of amylose and amylopectin.

Glycogen

Animal storage polysaccharide of α(1→4) and α(1→6)-linked glucose with branches every 8–12 residues.

Chitin

Structural polysaccharide of N-acetyl-D-glucosamine in arthropod exoskeletons and fungi cell walls.

Hyaluronic Acid

Acidic heteropolysaccharide of N-acetyl-glucosamine and glucuronate; lubricant in joints and vitreous humor.

Heparin

Highly sulfated, negatively charged polysaccharide anticoagulant stored in mast cells.

Glycoprotein

Protein covalently bonded to carbohydrate chains; functions in cell recognition and immunity.

Glycolipid

Lipid with covalently attached carbohydrate; includes cerebrosides and gangliosides in nerve tissue.

Lipid

Water-insoluble organic molecule soluble in non-polar solvents; includes fats, oils, steroids.

Fatty Acid

Long-chain monocarboxylic acid; may be saturated or unsaturated.

Saturated Fatty Acid

Fatty acid with only single C–C bonds; higher melting point.

Unsaturated Fatty Acid

Fatty acid containing one or more C=C double bonds; lower melting point.

Omega-3 Fatty Acid

Unsaturated fatty acid whose last double bond is three carbons from the methyl end (e.g., DHA).

Omega-6 Fatty Acid

Unsaturated fatty acid with endmost double bond six carbons from methyl end (e.g., linoleic acid).

Essential Fatty Acid

Fatty acid (linoleic, α-linolenic) required in diet because humans can’t synthesize it.

Triacylglycerol

Energy-storage lipid: glycerol esterified with three fatty acids; stored in adipocytes.

Glycerophospholipid

Phospholipid with glycerol backbone, two fatty acids, phosphate, and an alcohol head group.

Sphingomyelin

Phospholipid with sphingosine backbone, fatty acid, phosphate, and choline; major myelin component.

Cholesterol

C₂₇ steroid with fused ring system; modulates membrane fluidity and precursor of steroid hormones.

Steroid Hormone

Cholesterol-derived messenger lipid such as estrogens, androgens, glucocorticoids, mineralocorticoids.

Bile Acid

Cholesterol derivative that emulsifies dietary lipids in the intestine.

Prostaglandin

Eicosanoid with cyclopentane ring; mediates inflammation, fever, and smooth-muscle activity.

Thromboxane

Eicosanoid with cyclic ether; produced by platelets to promote aggregation and vasoconstriction.

Leukotriene

Linear eicosanoid with conjugated double bonds; mediates allergy and asthma responses.

NSAID

Non-steroidal anti-inflammatory drug that inhibits cyclooxygenase (COX) and prostaglandin synthesis.

Biological Wax

Ester of long-chain fatty acid and long-chain alcohol; waterproof protective coating (e.g., beeswax).

Saponifiable Lipid

Lipid containing ester, amide, or glycosidic bonds that hydrolyze in base (e.g., triacylglycerols).

Non-saponifiable Lipid

Lipid lacking hydrolyzable linkages (e.g., cholesterol, steroid hormones, eicosanoids).

Protein

Unbranched polymer of amino acids folded into functional 3-D structures; performs most cellular work.