CELL STUFFCELL STUFF

Cell TheoryCell TheoryIs basic unit of structure Is basic unit of structure and function of all living and function of all living thingsthingsActivity, of an organism, Activity, of an organism, is dependent upon is dependent upon individual and collective individual and collective activity of cellsactivity of cells

Specific sub-cellular Specific sub-cellular structures determine structures determine biochemical activities of biochemical activities of cellscells

Continuity of life has a Continuity of life has a cellular basiscellular basis

**Loss of homeostasis Loss of homeostasis within the cell is the within the cell is the basis of any disease basis of any disease

we are confronted we are confronted with.with.

Molecular componentsMolecular components

CarbonCarbon

HydrogenHydrogen

OxygenOxygen

NitrogenNitrogen

Trace elementsTrace elements

Cellular CharacteristicsCellular CharacteristicsDiversity of diameter – 2-Diversity of diameter – 2-10 10 average in humans; average in humans; largest is 100 largest is 100 Length – 2 Length – 2 – 30 cm – 1 – 30 cm – 1 metermeter

Shape – spherical, disk, Shape – spherical, disk, branched, cube- like; branched, cube- like; relates to its functionrelates to its function

3 main components: 3 main components: cytoplasm, nucleus, cytoplasm, nucleus, plasma membraneplasma membrane

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

Integral proteinsIntegral proteins embedded in lipid bilayerembedded in lipid bilayerhelp to transport water help to transport water soluble substances past soluble substances past lipid layer bylipid layer by

forming pores forming pores binding to and carrying binding to and carrying acrossacross

Peripheral proteinsPeripheral proteins found on the exposed found on the exposed membrane surfaces (not membrane surfaces (not embedded)embedded)

most are enzymesmost are enzymes some act mechanically to some act mechanically to help membrane “move” help membrane “move” (muscle contraction)(muscle contraction)

CytoplasmCytoplasm

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

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

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

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

surrounded by 2 membranes surrounded by 2 membranes within which glucose is broken within which glucose is broken down to release energy (cellular down to release energy (cellular respiration)respiration)

contains its own DNAcontains its own DNA

self replicating should energy self replicating should energy requirements increaserequirements increase

thought to play a part in aging.thought to play a part in aging.

RibosomeRibosome““protein factories”protein factories”

some float freely (& produce some float freely (& produce proteins for cellular use) while proteins for cellular use) while others are bound to the ER others are bound to the ER (& produce proteins (& produce proteins bound for export) bound for export)

Endoplasmic reticulumEndoplasmic reticulum canal system connecting canal system connecting the nuclear membrane with the nuclear membrane with the plasma membranethe plasma membrane

2 types, the amount of 2 types, the amount of which depends on the type which depends on the type of cell of cell

Rough ERRough ER membranes with ribosomes membranes with ribosomes attachedattached

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

Smooth ERSmooth ER membranes without membranes without ribosomesribosomes

have a variety of jobs have a variety of jobs depending on the type of depending on the type of cellcell

generally responsible for generally responsible for lipid production and lipid production and handling proteins used handling proteins used within the cell.within the cell.

Golgi apparatusGolgi apparatus “ “stacks of sacs”stacks of sacs”

traffic director for cellular traffic director for cellular proteins; job is to modify, proteins; job is to modify, concentrate and package concentrate and package proteins in specific ways proteins in specific ways depending on the depending on the destination of the protein destination of the protein

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

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

PeroxisomesPeroxisomes abundant in kidney and abundant in kidney and liver cellsliver cells

major job is to detoxify the major job is to detoxify the by-products of metabolism by-products of metabolism so these by-products do so these by-products do not accumulate and poison not accumulate and poison the system.the system.

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

CentriolesCentrioles protein fibers used in mitosis protein fibers used in mitosis to anchor chromosomes to anchor chromosomes during cell divisionduring cell division

Cell ExtensionsCell Extensions MicrovilliMicrovilli – – lines lines intestines; aids intestines; aids in absorptionin absorption

Cilia and Cilia and flagellaflagella – aid – aid in movementin movement

Cell ConnectionsCell Connections DesmosomesDesmosomes – “velcro” – “velcro”

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

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

NucleusNucleusControl center of Control center of cellcell contains genetic contains genetic materialmaterialmost body cells most body cells are nucleated – are nucleated – some some multinucleated, multinucleated, others others anucleatedanucleated

Nuclear membraneNuclear membrane

encloses nucleoplasm, encloses nucleoplasm, nucleoli, and chromatinnucleoli, and chromatin

is selectively is selectively permeablepermeable

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

ChromatinChromatin composed of DNA composed of DNA

(which makes up (which makes up chromosomes) and chromosomes) and histones (proteins histones (proteins around which around which DNA is DNA is wound)wound)

involved in involved in the cell the cell cycle.cycle.

A cell is a living unit greater

than the sum of its parts