Basic Cell Structure

CellsBasic building blocks of lifeUnderstanding of cell structure is critical to the study of biotechnology

CellSmallest living unit of an organismGrow, reproduce, use energy, adapt, respond to their environment

CellMany cannot be seen with the naked eyeA cell may be an entire organism or it may be one of billions of cells that make up the organism

CellsDivided and classified in many waysOne common classification method is the presence or absence of a cell necleus

NucleusRelatively large structure with a cellDirects cell activitiesSome simple single celled organisms lack a nucleus

Common structuresOrganelles – smaller parts of the cell with specific funtionsCell membrane – acts as a gatekeeper

Cell membraneControls what enters and leaves the cellPlants, algae and bacteria typically have a tough outer structure known as a cell wall

Cell wallProvides additional structure and protects the cell from pressure caused by movement of waterAnimal cells do not have walls

CytoplasmOrganelles are surrounded by a jelly like substancePrimary component is water

NucleusLargest and most identifiable part of the cell

Other organellesRibosomesMitochondriaGolgi bodiesEndoplasmic reticulum

Other organellesLysosomesVacuolesChloroplasts in plants

NucleusBrain of the cellSite of much of the manipulation done in biotechnology

NucleusControls activity of the cellRound or oval structureTypically found in the middle of the cellAppears darker than surrounding material

NucleusSurrounded by a membrane that controls passage of materials in and out of the area

NucleusContains DNADNA is located on chromosomesMost organisms are diploid – have tow chromosomes for each trait

DiploidHumans – 23 pairGoldfish – 90 chrms, 45 pair

Cytoplasmic Organelles

Organelles are required for proper cell functionRibosome – make proteins for cellular use and communicationMay be attached to endoplasmic reticulum

Endoplasmic reticulum

Layered membraneous Make and transport proteins

VacuoleLarge organelle, without specific shapeStore waste or raw materials used in synthesis of proteins

Golgi BodiesGolgi apparatusSimilar to endo. Ret.Look like a thick elastic band that has been folded several times

Golgi BodiesAdds modifications to unfinished proteinsMakes lysosomes

LysosomeSmall roundStore enzymes that break down food into chemical compoundsDestroy cell organelles and the cell itself

MitochondriaEnergy factoriesRod shapedChange food into molecules that can be used for energy

MitochondriaContain DNACan replicate themselves

ChlorplastFound in plants and some other organismsContain chlorophyll

Cellular processesRespirationOsmosisDiffusionPhotosynthesis

RespirationCells break down carbohydrates and other molecules to produce energyOxidation of glucose is one of most common forms

RespirationBreaking down of sugar into water, carbon dioxide, and energyEnergy is used to do the work of the cell

Osmosis & DiffusionTransport of raw materials, wastes, and synthesized materials out of the cell

DiffusionMovement of molecules, especially gases and liquids from areas of high concentration to areas of low concentration

OsmosisSpecific type of diffusionMovement of water through a membrane from areas of high concentration to areas of low concentration

EquilibriumDiffusion and osmosis happen to enable a cell to reach equilibrium

Cellular reproductionThree waysFissionMitosisMeiosis

FissionProkaryotesCell grows larger and makes a second copy of its DNAAt some point the cell membrane divides the cell by the growth of a transverse septum

FissionTwo new cells are formed as the division grows inward from either side of the cellTwo cells now called “daughter cells”Sometimes known as “binary fission”

MitosisEukaryotesRequires 6 stagesInterphase, prophase, metaphase, anaphase, telophase, cytokinesis

MitosisCreates cells that are identical to the original cell.Have the entire compliment of chromosomes existing in pairs - diploid

MeiosisDivision of sex cellsStages of Meiosis I: Interphase I, prophase I, metaphase I, anaphase I, telophase I, cytokinesis I

MeiosisMeiosis IIInterphase II, prophase II, metaphase II, anaphase II, telophase II, cytokinesis II

MeiosisEach cell receives one chromosome from each pair randomlyResulting cells have half the normal number of Chromosomes - haploid