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CELLULAR STRUCTURES AND THEIR FUNCTIONSCELL

Definition:

Circumscribed mass of protoplasm containing nucleus

Smallest and basic unit of life

Capable of growth and reproduction

Granular Epithelial cellcapable of secretionPlasma Cellsproduce proteins2 Major Parts:

Nucleus

Cytoplasm

Function: Communication

Cell metabolism and energy release

Reproduction and inheritance

Structure:

Organellesspecialized structures in cell that perform a

specific function (ex. nucleus)o Membrane boundhas a membrane surrounding

(ex. nucleus, golgi, mitchondria, lysosomes, ER)

o Non membrane boundno enveloping membranesurrounding the structure (ex. centrioles andribosome)

Cytoplasmjelly like substance that hold organelles

o Organelles (suspended in the cytosol)o Inclusion (suspended in the cytosol)o

Cytoskeleton

o ComponentsOrganelles that contains DNA:

Nucleus [46]

Mitochondria [1] (from the mother only)Generalized/ Perfect cellcontains all the structures of the other cells(does not exist)

Microfilamentsfor contraction (muscle cells)Mitochondriapower house of the cell

Cell Membraneouter most component of the cell

Function:

Selective barrier that determines what can pass in and out ofthe cell

Encloses the cytoplasmo Extracellularsubstances outside of the cell

o Intracellularsubstances inside the cellMajor molecules that make up a cell membrane:

Phospholipids

Proteins

Microtubulesassist in cell division

Flagellapropel sperm cellMicrovilliincrease surface area of a cellRibosome

2 Kinds of Ribosome

o Free ribosomemanufacture proteins for cell

consumptiono Attached ribosome -proteins are secreted

Polarhydrophilic (water loving) head [phosphate]Non-polarhydrophobic (water fearing) tail [fatty acid]Bilaminar structureproteins floating on a sea of lipidsWhy do molecules pass through the cell membrane?

1. Directly through (Diffusion)

O2 and CO22. Membrane Channels

Proteins that extend from one side of the cell membrane toanother

Passive Transport Mechanismmoves bec. of the differenceof concentration

Active Transport Mechanismenergy is required3. Carrier Molecule

The shape must be compatible with the shape of the carriermolecule

4. Vesicle

Can transport a number of materials through the utilization cell membrane

2 Kinds of Ion Channelso Gated Channeloften closed (Na+)o Non-gated Channelaka leaky always open (K

Diffusionmovement of concentration from higher concentration to

lower concentration (solute)Concentration gradient

Measures conc. difference of 2 points Greater the distance the faster the solute will travel

Difference of concentration of substances

Filtrationmovement of fluid through a partition with holesFenestrationformation of Urine

Mediated Transport Mechanismmade possible because of a carriermolecule

Facilitated Diffusion(passive) w/o energy required

Active Transport Mechanismfrom low to high

concentration

o ATP is requiredOsmosiswater molecules move down the concentration gradient(solvent)

Osmotic Pressureforce required to prevent the movement

of water Hydrostatic pressureprevents net molecules of water in th

tube

Hypertonichigh concentration of solute and lower waterconcentration in the cytoplasm (shrink)

Hypotoniclower concentration of solutes to a higher

concentration of water in the cytoplasm (swell)

Isotonicsolutes and water are same

Lysiswhen a cell swell

Crenationwhen a cell shrinks

Endocytosisbulk transport mechanism

2 Types of Endocytosiso Pinocytosiscell drinking (liquid)

o Phagocytosiscell eating (macromoleculessolid)

Ligandssubstance to be interralized

Endosomepre lysosomal compartments (dethatched theligand to the receptor)

Cell Structures:Cytoplasminside cell; jelly like fluid; gives the cell a shape and holorganelles in place

Nucleuscontrol center of the cell

Nuclear envelopeedge of nucleusNuclear porespassageway of materialsChromosomeinside nucleus; part of genetic make up; made up ofDNA and proteins

Nucleolusproduces ribosomeRibosometypes of ribosome

Small

LargeRERsite of protein synthesis

SERno ribosome; lipid synthesisGolgi Apparatus[RER] cytoplasm; closely packed stacks; serves as

passageway; distributes protein and lipids

Cis faceentry passageway

Intermediateactual process of modification

Trans faceexit face; maturing siteSignal Peptideinitial segment that signals whether the ribosome is fsecretion or not

Secretory Vesicledistribute materials of the cell2 Types of Respiration

Aerobic Respirationrequires oxygen

Anaerobic Respirationno oxygenMicrovilli - absoption

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Cytoskeletoncells framework

Microtubuleslargest in diameter

Intermediate filamentsmedium in diameter

Microfilamentssmallest in diameterWhy do substance move? bec of constant random motion