Functional Anatomy of the Cell

10-15 µm

Cell diameters typically range from

oocyte (140 µm in diameter)

Largest cell

Eukaryotic cell

possesses a membrane-bound nucleus and membrane-bound organelles

Cell membrane

forms selectively permeable barrier

Proteasomes

breakdown and recycle proteins

Cytosol

intracellular fluid

Cytoplasm

intracellular fluid and everything dissolved in it

Plasma membrane

separates two aqueous compartments (ECF and ICF) and forms selectively-permeable barrier

Glycocalyx

coat on extracellular surface of membrane: glycolipids, glycoproteins, and carbohydrates, important for cell recognition

Amphipathic

has both a hydrophobic and hydrophilic end

Hydrophilic end of phospholipid

phosphate group

Hydrophobic end of phospholipid

fatty acids

Cholesterol

embedded in phospholipid bilayer adds to membrane rigidity

Peripheral proteins

located at extracellular or intracellular face of plasma membrane, bound to the surface itself or non-covalently bonded to integral proteins

Integral proteins

embedded in plasma membrane or attached via covalent bonds; transmembrane proteins, proteins that are embedded but do not span the membrane, proteins that are anchored to the membrane by covalent bonds

Transmembrane proteins

span the entire plasma membrane

Carriers

carry things from ECF to ICF or vice versa

Channels

hole through the carrier which things can pass through

Receptors

binds to chemical messengers (e.g. hormones)

Recognition

cell's ability to distinguish one type of neighboring cell from another

Enzymes

catalyze reactions

Cell-cell interactions

direct interactions between cell surfaces that play a crucial role in the development and function of multicellular organisms

Microtubules

long hollow cylinders made up of polymers of tubulin, larger diameter and more rigid compared to microfilaments

Functions of microtubules

Component of simple fibers, cilia, and flagella; Main portion of cytoskeleton; Aids in movement; Provides track for movement of cargo throughout the cytosol

Microfilaments

thin filaments, two stranded helical polymers of actin, more common in periphery of cell

Microfilaments function

Anchor plasma membrane proteins to the cytoskeleton; Important in cytokineses; Aids in cell motility; Forms a track for movement of cargo with molecular motor myosin

Intermediate fibers

polymers of protein subunits, great diversity in proteins (e..g keratin (epithelial cells), desmin (muscle)), rope-like fibers

Intermediate fiber function

Mechanical stability to cells

Flagella

propel cells, composed of microtubules in a 9+2 array, move in a whip-like motion

Cilia

mix substance at cell surface, composed of microtubules in a 9+2 array, move in a wave-like motion

Basal body

point or origin of growth

Centriole

cylinder composed of nine groups of microtubule triplets, 9+0 array

Centrosome

microtubule organizing center, two centrioles at right angles

Nucleus

site of DNA storage, DNA replication and transcription

Nuclear envelope

double membrane around nucleus; Outer membrane studded with ribosomes; Inner membrane smooth, facing nucleoplasm

Nuclear pores

transport pathways into and out of nucleus

Nucleolus

small round dense structures within nucleus, site of transcription of ribosomal RNA

Ribosomes

site of protein synthesis, read RNA to make proteins

Endoplasmic reticulum

one site of protein synthesis, lipid synthesis and Ca2+ storage; membrane-bound (single); continuous with nuclear envelope; extensive network of sacs and tubules

Cisternae

sacs of ER

Rough ER

student with ribosomes, protein synthesis, protein modification within lumen

Lumen

the cavity or channel within a tube or tubular organ/organelle

Smooth ER

no ribosomes, lipid, and carbohydrate synthesis

Sarcoplasmic reticulum

smooth ER within muscle cells which functions as a calcium storage site

Golgi apparatus

site of protein/lipid modification, sorting, and packaging; Flattened series of membranous sacks (not connected); Receives proteins and lipids from ER; Chemically modifies proteins and lipids; Packages proteins and lipids into secretory vesicles preparation for the process of exocytosis

Exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane

Mitochondria

site of oxygen-dependent ATP production; inner membrane contains ETC

Crista (cristae, pl)

shelf like projections of the inner membrane

Mitochondrial DNA

in the form of a closed circle - about 37 genes in the human; inherited from mother

Lysosomes

garbage disposals, degradative enzymes

Degradative enzymes

enzyme which degrades biological molecules.

Autolysis

release digestive enzymes into cytosol to break down cellular components

Lysosomes functions

Break down of macromolecules; Breakdown of worn-out organelles; autolysis;

Peroxisomes

contain enzymes that catalyze reactions that produce H2O2, oxidative enzymes; Especially abundant in kidney and liver

Oxidative enzymes

enzyme that catalyses an oxidation reaction

Functions of peroxisomes

Detoxification; Breakdown of fatty acids into smaller units; Breakdown of lipids

Primary lysosome

fuses with internalized material within endosomes to degrade them within other lysosomes

Secondary lysosomes

amino acids and other building blocks recycled for new synthesis