Cells

Human Cells - Eukaryotic Cytology – the study of cells Cells are the basic structural & functional unit of the body. Vary greatly in size & structure About 60% water Surrounded by interstitial fluid Different cells have different functions A cell’s structure often reflects its function Three main regions Nucleus, cytoplasm, & plasma membrane

Anatomy of a Cell Plasma Membrane Surrounds the cell Acts as a barrier Composed of mostly proteins & phospholipids Facilitates contact with other cells & controls the passage of materials into & out of the cell Selectively Permeable

Anatomy of a Cell Continued… Cytoplasm Substance inside that cell that contains organelles Where most metabolic reactions & activities take place Filled with clear fluid called cytosol Organelles Specialized portions of the cell that carryon specific activities.

Cell Organelles Nucleus Nucleolus Ribosomes Controls cellular activities & contains the genetic information (DNA) Contains nucleolus Nucleolus Produces ribosomes Ribosomes Sites of protein synthesis Located free in the cytosol or attached to the Endoplasmic Reticulum (ER).

Cell Organelles Endoplasmic Reticulum Golgi Apparatus (Golgi Body) Network of interconnected membranes Provides mechanical support Transports material around the cell Two types: Rough ER – protein synthesis Smooth ER – lipid synthesis Golgi Apparatus (Golgi Body) Stack of membranous sacs Refine & packages proteins

Cell Organelles Mitochondria Lysosome Smooth outer membrane & highly folded inner membrane (cristae) Carries out cellular respiration “Powerhouse” of the cell – produces ATP Lysosome Contains digestive enzymes Breakdowns & destroys foreign particles, microorganisms, damaged or worn-out cells, & cell parts

Cell Organelles Cytoskeleton Centrioles Composed of microfilaments & microtubules Involved in contraction, support, & movement Centrioles Found near the nucleus in an area called the centrosome Paired cylinders used in cell reproduction

Cell Organelles Cilia Flagella Numerous hair-like projections Move foreign matter along cell surfaces Flagella Few & long projections Move the entire cell

Cell Physiology A cell is the smallest unit of matter that carries out ALL life processes. Reproduction, development, growth, energy production & use, digestion, waste excretion, response to stimuli, movement, etc…

Membrane Transport Cells must constantly move material between their internal & external environments. Passive Transport – diffusion Movement of material from an area of higher concentration to an area of lower concentration. Active Transport Movement of material from an area of lower concentration to higher concentration. Requires energy – going against the gradient

Types of Passive Transport Facilitated Diffusion Using carrier proteins to move material through the plasma membrane. Osmosis Diffusion of water Three types of solutions Hypotonic - more water moves into the cell Hypertonic – more water exits the cell Isotonic – water enters & exits the cell equally

Blood Cell Reactions to Different Osmotic Solutions Water is drawn out of the cells & into the bloodstream. May reduce swelling Cause no visible changes to cells. Most IV solutions are isotonic. Water rushes into cells, causing cells to swell. Used to treat severe dehydration

Types of Active Transport Solute Pumping Using carrier proteins to move material against the gradient (Uses ATP) Exocytosis Transport of large particles out of the cell Endocytosis Transport of large particles into the cell Pinocytosis Liquids taken in – cell engulfs a drop of water Phagocytosis Solids taken in by engulfing them in vesicles

The Life Cycle of a Cell Interphase Mitosis – Cell Division Cell crows & carries on metabolic activities, DNA synthesis occurs, & manufacturing of parts for cell division. Mitosis – Cell Division Prophase Metaphase Anaphase Telophase/cytokinesis Ends with two daughter cells identical to each other & the parent cell Uncontrolled cell division may lead to cancer.

Protein Synthesis Proteins (Enzymes) run all the chemical reaction in your body Proteins are responsible for all your traits. DNA serves as the master blueprint for making proteins. Proteins are made in two steps: Transcription (DNA RNA) Translation (RNA Protein)