Cellular Form and Function

Squamous cell structure

Thin, flat, scaly

Cuboidal cell structure

Squarish

Columnar cell structure

Taller than wide

Polygonal cell structure

Irregular angular shapes, multiple sides

Stellate cell structure

Starlike shape

Spheroid or ovoid cell structure

Round to oval

Discoidal cell structure

Disc-shaped

Fusiform cell structure

Thick in the middle, tapered towards the end

Fibrous cell structure

Threadlike

Micrometer

One millionth of a meter of one thousandth of a millimeter

Cytoplasm

Fluid between nucleus and surface

Transmission electron microscope

Uses beam of electrons rather than light

Scanning electron microscope

Produces dramatic 3D images at high magnification and resolution

Only for surface features

Plasma cell membrane

Surrounds cells, defines cells boundaries, composed of proteins and lipids

Extracellular fluid

Any fluid outside of cell

Phospholipids

75% of membrane lipids

Arranged in bilateral

Hydrophilic phosphate heads face water on each side of membrane

hydrophobic tails directed towards center

Cholesterol

20% of membrane lipids

Glycolipids

5% of membrane lipids

Short carbohydrate chains on extracellular face

Transmembrane proteins

Pass completely through membrane

Peripheral proteins

Adhere to one face of the membrane

Receptors

Bind chemical signals to trigger internal changes

Enzymes

Catalyze reactions including digestion of molecules, production of second messengers

Channel proteins

Allow hydrophilic solutes and water to pass through membrane

Leak channels

Always open

Gated channels

Open only when triggered

Ligand gated channels

Respond to chemical messengers

Voltage gated channels

Respond to charge changes

Mechanically gated channels

Respond to physical stress on cell

Carrier protiens

Bind solutes and transfer them across membrane

Pumps

Carriers that consume ATP

Cell identity markers

Glycoproteins acting as identification tags

Cell adhesion molecules

Mechanically link cell to another cell and to extracellular material

Second messenger

Stimulation of cell by epinephrine

G protein

Intracellular peripheral protein, activated by receptor

Adenylate cyclase

Signal relayed by G protein, converts ATP to cAMP

Kinases

adds phosphate groups to other enzymes, turning them on or off

activated by cAMP

Glycocalyx

Carbohydrate moieties of glycoproteins and glycolipids

protection, immunity, cell adhesion, defense against cancer

Microvilli

Extensions of the membrane that serves to increase surface area

Brush border

Type of microvilli, dense and appear as fringe

Cilla

Serve as antenna for monitoring nearby contusions

Axoneme

Core of motile cilium consisting of microtubules

Dunedin arms

Use energy from ATP to crawl up microtubule, bends cilium

Cystic fibrosis

Hereditary disease in which cells make chloride pumps, but fail to install them in the plasma membrane

Flagellum

Aids in movement, tail of sperm only functional flagellum in humans

Pseudopods

Continually changing extensions of the cell, capture foreign particles

Selectively permeable

Allowing some things through, inhibiting others

Filtration

Particles are driven through membrane by physical pressure

Simple diffusion

Net movement of particles from place of high concentration to place of lower concentration

Factor affecting simple diffusion

Increase

Tempature, steepness of concentration gradient, membrane surface area and permeability

Molecular weight- large molecules move slower

Osmosis

Net flow of water through a selectively permeable membrane

High water concentration to low

Aquaporins

Channel proteins in membrane specialized for water passage

Osmotic pressure

Hydrostatic pressure required to stop osmosis

Hydrostatic pressure

Fluid pressure on membrane

Reverse osmosis

Process of applying mechanical pressure to override osmotic pressure

Osmolarity

Osmotic concentration

Tonicity

Ability of surrounding solution to affect fluid volume and pressure in a cell

Hypotonic solution

Causes cell to absorb water and swell

Hypertonic solution

Causes cell to lose water and shrivel

Isotonic solution

Causes no change in cell volume

Carrier mediated transport

Proteins in cell membrane carry diluted into or out of cell

Saturation

As solute concentration rises, rate of transport rises until transport maximum

uniport

Carrier that moves one type of solute

Symport

Carrier that moves two or more solutes simultaneously in same direction

Antiport

Carrier that moves two or more solutes in opposite directions

Facilitated diffusion

Carrier moves solute down its concentration gradient

Primary active transport

Carrier moves solute through membrane up its concentration gradient

Secondary active transport

Carrier moves solute through membrane

Sodium potassium pump

Important primary active transport

Vesicular transport

moves large particles, fluid droplets, or numerous molecules at once through membrane in vesicles

Vesicles

Bubblelike enclosures of membrane

Endocytosis

Brings material into cell

Exocytosis

Releases material from cell

Phagocytosis

Engulfing and destroying large particles

Phagosome

Merges with lysosome to digest an object

Pinocytosis

Taking in droplets of ECF containing molecules, useful in the cell

Pinosytosis vesicles in cytoplasm “cell drinking”

Receptor mediated endocytosis

Particles find a specific receptors on plasma membrane

Transcytosis

Transport of materials across the cell by capturing it on one side and releasing it on the other

Exocytosis

Discharge material from cell

Cytosol

Clear watery colloid within the cell

Cytoskeleton

Network of protein filaments and cylinders

Structure support, cell shape, organization of cell content

Microfilaments

6 nm thick, made of actin protein, form terminal web (membrane skeleton)

Intermediate filaments

8 to 10 nm thick, within skin cells, made of protein keratin

Cell shape, resist stress

Microtubules

25 nm thick call

Cell shape, hold organelles, railroad tracks for motarproteins

Organelles

internal structures of a cell that carry out specialize metabolic tasks

Nucleus

Largest organelle, contains cells genetic material

Anuclear- without nucleus

Multinuclear- have multiple nuclei

Nuclear envelope

Double membrane around nucleus

perforated by nuclear probes

Regulate molecular traffic

Nuclear lamia

Support nuclear envelope, web of protein filaments

Nucleoplasm

Material within nucleus

Contain chromatin and nucleoli

Endoplasmic reticulum

Network of interconnected membranous channels called cisterns

Rough endoplasmic reticulum

Parallel flattened sacs covered with ribosomes

Produce phospholipids and proteins of all cell membranes

Smooth endoplasmic reticulum

Tubular ER lacking ribosomes

Synthesizes steroids, detoxify alcohol

Ribosomes

Small granules of protein and RNA responsible for protein synthesis

Read generic messages and assemble amino acids into proteins of code

Golgi complex

A system of membranous cisterns that synthesizes carbohydrates and modified newly synthesized portions

Secretory vesicles store proteins for later release

Golgi vesicles sort proteins, splice, and add carbohydrate moieties

Lysosomes

Package of enzymes bound by a membrane

Digestion if most macromolecules

Autophagy

Digestion of cells surplus organelles

Autolysis

Digestion of a surplus of cell by its gel “cell suicide”

Peroxisomes

Resemble lysosomes but contain different enzymes and are produced by endoplasmic reticulum

Proteasomes

Hollow, cylindrical organelles that dispose of surplus proteins

Mitochondria

Organize specialized for synthesizing, ATP, continuously, change, shape, surrounded by double membrane

Cristae

Inner membrane folds of mitochondria