CELLS CELLS. CELL THEORY Living things are composed of cells (multicellular organisms) Cells are the...

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