CELL STUFF

Cell Theory Is basic unit of structure and function of all living things Activity, of an organism, is dependent upon individual and collective activity of cells

Specific sub-cellular structures determine biochemical activities of cells Continuity of life has a cellular basis

* Loss of homeostasis within the cell is the basis of any disease we are confronted with.

Molecular components CarbonHydrogenOxygenNitrogen Trace elements

Cellular Characteristics Diversity of diameter –  average in humans; largest is 100  Length – 2  – 30 cm – 1 meter

Shape – spherical, disk, branched, cube- like; relates to its function 3 main components: cytoplasm, nucleus, plasma membrane

Proteins – scattered throughout the phospholipid bilayer; some act as cell surface markers (recognition sites), receptor sites, etc. Proteins – scattered throughout the phospholipid bilayer; some act as cell surface markers (recognition sites), receptor sites, etc.

Integral proteins embedded in lipid bilayer embedded in lipid bilayer help to transport water soluble substances past lipid layer by help to transport water soluble substances past lipid layer by forming pores binding to and carrying across

Peripheral proteins found on the exposed membrane surfaces (not embedded) found on the exposed membrane surfaces (not embedded) most are enzymes most are enzymes some act mechanically to help membrane “move” (muscle contraction) some act mechanically to help membrane “move” (muscle contraction)

CytoplasmComposition Cytosol – colloid, mostly water, proteins, salts, sugars, suspends cell contents Cytosol – colloid, mostly water, proteins, salts, sugars, suspends cell contents

Inclusions Inclusions other elements present in specific cells based on the cell’s function (glycogen in liver and muscles cells, melanin in skin cells, zymogen in pancreatic cells, mucus, water vacuoles, etc.)

Organelles “little organs” “little organs” each with own membrane to keep separate from the surrounding cytosol each with own membrane to keep separate from the surrounding cytosol

Mitochondria Mitochondria “powerhouse” of the cell “powerhouse” of the cell provides ATP energy numbers of mitochondria within a cell is dependent on the cell’s function (i.e. muscle cells vs. WBC’s); numbers of mitochondria within a cell is dependent on the cell’s function (i.e. muscle cells vs. WBC’s);

surrounded by 2 membranes within which glucose is broken down to release energy (cellular respiration) contains its own DNA self replicating should energy requirements increase thought to play a part in aging.

Ribosome Ribosome “protein factories” some float freely (& produce proteins for cellular use) while others are bound to the ER (& produce proteins bound for export)

Endoplasmic reticulum Endoplasmic reticulum canal system connecting the nuclear membrane with the plasma membrane canal system connecting the nuclear membrane with the plasma membrane 2 types, the amount of which depends on the type of cell

Rough ER membranes with ribosomes attached membranes with ribosomes attached proteins made in ribosomes are sent to the rough ER where sugar groups are added, pinch off into sacs and sent to the Golgi to be shipped out. proteins made in ribosomes are sent to the rough ER where sugar groups are added, pinch off into sacs and sent to the Golgi to be shipped out.

Smooth ER membranes without ribosomes membranes without ribosomes have a variety of jobs depending on the type of cell have a variety of jobs depending on the type of cell generally responsible for lipid production and handling proteins used within the cell. generally responsible for lipid production and handling proteins used within the cell.

Golgi apparatus Golgi apparatus “stacks of sacs” “stacks of sacs” traffic director for cellular proteins; job is to modify, concentrate and package proteins in specific ways depending on the destination of the protein

number of apparatus is dependent on how much secretory activities the cell is involved in.number of apparatus is dependent on how much secretory activities the cell is involved in.

Lysosome Lysosome “suicide sacs” “suicide sacs” contain digestive enzymes contain digestive enzymes abundant in WBC’s abundant in WBC’s major job is to break down cellular materials. major job is to break down cellular materials.

Peroxisomes Peroxisomes abundant in kidney and liver cells major job is to detoxify the by-products of metabolism so these by-products do not accumulate and poison the system.

Cytoskeleton Cytoskeleton proteins that form the framework that supports the cell contents and provide the method by which cellular movement occurs (sperm cells, etc.)

Centrioles Centrioles protein fibers used in mitosis to anchor chromosomes during cell division

Cell Extensions Microvilli – lines intestines; aids in absorption Microvilli – lines intestines; aids in absorption Cilia and flagella – aid in movement Cilia and flagella – aid in movement

Cell Connections Desmosomes – “velcro” Desmosomes – “velcro”

Gap junctions – connection of adjacent membrane channels; heart muscle cells

Tight junctions – connections that prevent movement of material; (blood-brain barrier) Tight junctions – connections that prevent movement of material; (blood-brain barrier)

Nucleus Control center of cell contains genetic material contains genetic material most body cells are nucleated – some multinucleated, others anucleated

Nuclear membrane encloses nucleoplasm, nucleoli, and chromatin is selectively permeable

Nucleolus produce ribosomes produce ribosomes found in large numbers among young cells found in large numbers among young cells

Chromatin composed of DNA (which makes up chromosomes) and histones (proteins around which DNA is wound) composed of DNA (which makes up chromosomes) and histones (proteins around which DNA is wound) involved in the cell cycle. involved in the cell cycle.

A cell is a living unit greater than the sum of its parts