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..

Prokaryotic flagella Nucleoid region (DNA) Ribosomes Plasma membrane Cell wall Capsule Pili

Cytoskeleton Ribosomes Centriole Lysosome Flagellum Not in most plant cells Nucleus Smooth endoplasmic reticulum (ER) Golgi apparatus Rough Mitochondrion Plasma membrane

Cytoskeleton Mitochondrion Nucleus Rough endoplamsic reticulum (ER) Ribosomes Smooth endoplasmic reticulum (ER) Golgi apparatus Plasmodesmata Plasma membrane Chloroplast Cell wall Central vacuole Not in animal cells

The plasma membrane is composed of a phospholipid bilayer with embedded proteins. Hydrophilic region of protein Phospholipid bilayer Hydrophobic region 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 Chromatic Nuclear envelope Nucleolus Pore

Organelles of a Typical Cell Ribosome Production of proteins – located attached to ER or free-floating Endoplasmic Reticulum (ER) *Rough *Smooth Passageway for materials Produces proteins & processes molecules for secretion Produces lipids & detoxifies drugs & stores Ca++ Golgi Apparatus Packages material for export & processes macromolecules Vacuole & vesicle Storage..

Contains digestive enzymes. Each contains one specific enzyme. Lysosome Contains digestive enzymes. Each contains one specific enzyme. Chloroplasts Carries out photosynthesis: 6CO2 + 6H2O C6H12O6 + 6O2 Mitochondria Aerobic cellular respiration: C6H12O6 + 6O2 6CO2 + 6H2O +ATP Cilia, flagella, microvilli Surface projections – increase surface area & produce movement..

CELL-CELL INTERACTIONS Plant cells are encased by cell walls These provide support for the plant cells Walls of two adjacent plant cells Vacuole Plasmodesmata (channels between cells)

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 Plasma membranes of adjacent cells