CELLSCELLS

CELL THEORY

Living things are composed of cells

(multicellular organisms)

Cells are the smallest unit of life (single celled organisms – all life

functions)

Cells come from pre-existing cells (binary fission & mitosis)

RELATIVE SIZES• Molecules: 1nm• Membranes: 10nm• Viruses: 100nm• Prokaryotic cells range in

size from 1µm - 10µm• Organelles: up to 10µm• Eukaryotic cells: 10µm -

100µm

Separation Techniques

Lack organized nucleus & membrane enclosed organelles

Nucleoid region – concentration of DNASingle, circular chromosomePlasma membrane, cytoplasm, 70s ribosomesCell wall & capsulePili and flagella

Plasma membrane: present in all cells, phospholipid bilayer, semipermeable, barrier, regulator

Typical Animal Cell

Typical Plant Cell

NUCLEUS• Eukaryotic cells only• Envelope – two

membranes, pores, lamina

• Chromatin - threadlike• Chromosomes – visible

during division• Nucleolus – makes

ribosomes

Ribosomes: protein synthesis2 subunits made of RNA and protein (80S)free (intracellular); attached (extracellular)

Endoplasmic Reticulum

Rough:• Ribosomes• Secretory proteins, vesicles• Membrane factory

Smooth• No ribosomes• Synthesis – lipids (steroids,

phospholipids)• Metabolism – carbohydrates• Detoxification – liver cells• Muscle cells – pumping Ca

ions into cisternal space

Golgi apparatus: stacks of flattened sacs• Manufacturing, warehousing, modifying, sorting, shipping• Extensive in secretory cells, near E.R.• Processes lysosomes

LYSOSOMES - digestiveLYSOSOMES - digestive Suicide sacs Double membrane, hydrolytic enzymes, autophagy,

development Made by Golgi apparatus WBC – phagocytosis Pompe’s disease – accumulation of glycogen Tay Sachs disease – accumulation of lipids

VACUOLES

• Larger than vesicles• Storage, transport,

waste disposal• Central – plants,

growth, tonoplast, cell sap, pigments, poison

• Contractile – fresh water protists

Endomembrane System

Partitions the cytoplasm, metabolism Physical continuity or vesicles Components :

Nuclear envelope Endoplasmic reticulum (rough, smooth) Golgi apparatus Lysosomes Plasma membrane Various vacuoles

Mitochondrion

Power house – ATP production Cellular respiration – Krebs cycle, ETC DNA & ribosomes Double membrane: outer smooth, inner

folds Inner membrane: cristae (↑ surface area) 2 compartments – inner membrane space &

matrix (enclosed by inner membrane)

Chloroplasts

Green plant cells, contain chlorophyll, photosynthesis

Other plastids – amyloplasts, chromoplasts Double membrane – thylakoids, grana, stroma DNA and ribosomes

Peroxisome

• Single membrane

• Breaks down H2O2

• Detoxify alcohol

• Cooperate w/ mito. & chloroplast

CYTOSKELETON

Structural support, motility, regulation Maintain shape (framework), anchor

organelles, mechanical support Cell location, movement of organelles Types:

microtubules: centrioles, cilia, flagella microfilaments: actin & myosin intermediate fibers: more permanent,

lamina, tension bearing

Centrioles

Animal cells only Contain DNA; replicate Right angles Triplet microtubules Cell division

Cilia & Flagella

Cell locomotion, 9 + 2 microtubules Cilia: numerous, short hairs, oars, line

trachea Flagella: 1-2, long, undulating, sperm Basal body: anchors, triplet microtubules Movement comes from within structure One microtubule pair moving along a

neighboring pair.

Cell Wall Primary: thin, flexible, outer layer Secondary: thick, several layers, durable, inner layer Middle lamella: sticky, pectin, glues cells together Plasmodesmata: channels through cell walls, continuous cytoplasm

Extracellular Matrix

Intercellular Junctions

Plasmodesmata: plants Tight junctions: fused, prevent leakage,

epithelium Desmosomes: anchor, fasten cells into

strong sheets Gap junctions: communication,

cytoplasmic channels, muscles, embryonic development