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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