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Ch 4 – A Tour of the Cell. The cell is the basic unit of structure and function in the body. Prokaryote v. Eukaryote Are smaller than eukaryotic cells Lack internal structures surrounded by membranes Lack a nucleus There are three principal parts: plasma membrane (plasmalemma) - PowerPoint PPT Presentation
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Ch 4 – A Tour of the Cell The cell is the basic unit of structure and
function in the body. Prokaryote v. Eukaryote
• Are smaller than eukaryotic cells
• Lack internal structures surrounded by membranes
• Lack a nucleus
There are three principal parts:– plasma membrane (plasmalemma)– cytoplasm and organelles– nucleus..
Prokaryoticflagella
Nucleoid region (DNA)
RibosomesPlasmamembrane
Cell wall
Capsule
Pili
Cytoskeleton
RibosomesCentriole
LysosomeFlagellum
Not in mostplant cells
Nucleus
Smoothendoplasmicreticulum (ER)Golgi
apparatus
Roughendoplasmicreticulum (ER)
Mitochondrion
Plasmamembrane
Cytoskeleton
Mitochondrion
Nucleus
Rough endoplamsicreticulum (ER)
Ribosomes
Smoothendoplasmicreticulum (ER)
Golgi apparatus
Plasmodesmata
Plasmamembrane
Chloroplast
Cell wall
Centralvacuole
Not in animal cells
• The plasma membrane is composed of a phospholipid bilayer with embedded proteins.
Hydrophilicregion ofprotein
Phospholipidbilayer
Hydrophobicregion of protein
(b) Fluid mosaic model of membrane
• The functions of plasma membrane include:– selectively permeable and surrounds the
cellular contents.– regulates the passage of materials into and out
of the cell.– participates in intercellular communications..
Transport of materials across the plasma membrane
• In general:– large macromolecules cannot cross the
membrane– charged molecules cannot cross the membrane– small, non-charged molecules can cross– water can cross..
• The cytoplasm (cytosol) is the gelatinous material inside the cell membrane but outside the nucleus.
• The cytoplasm contains organelles which are sub-cellular structures that perform discrete functions. True organelles are bounded by a phospholipid membrane..
• The nucleus is a double-membrane organelle containing the nucleic acids (DNA) and at least one nucleolus (contains ribosomal RNA).
• This organelle stores the genetic infor-mation and contains the blueprints for almost all protein syntheses.– DNA RNA protein..
Ribosomes ChromaticNuclearenvelope
Nucleolus Pore
Organelles of a Typical Cell
Storage..Vacuole & vesicle
Packages material for export & processes macromolecules
Golgi Apparatus
Passageway for materials
Produces proteins & processes molecules for secretion
Produces lipids & detoxifies drugs & stores Ca++
Endoplasmic
Reticulum (ER) *Rough
*Smooth
Production of proteins – located attached to ER or free-floating
Ribosome
Aerobic cellular respiration:C6H12O6 + 6O2 6CO2 + 6H2O +ATP
Mitochondria
Carries out photosynthesis:6CO2 + 6H2O C6H12O6 + 6O2
Chloroplasts
Contains digestive enzymes. Each contains one specific enzyme.
Lysosome
Surface projections – increase surface area & produce movement..
Cilia, flagella, microvilli
• Plant cells are encased by cell walls
– These provide support for the plant cells
Walls of two adjacentplant cells
Vacuole
Plasmodesmata(channels between cells)
CELL-CELL INTERACTIONS
• Animal cells lack cell walls– They secrete a sticky covering called the extracellular
matrix– This layer helps hold cells together
• Animal cells connect by various types of junctions– Tight junctions– Adhering junctions– Communicating junctions
Extracellular matrix
(a) Tight junctions
(b) Anchoring junctions
(c) Communicating junctions
Plasma membranesof adjacent cells
Extracellular matrix