Topic 1 - Cells

Topic 1 - CellsCell TheoryFunctions necessary for lifeSurface area to volumeMulticellular vs Unicellular1.1 Cell TheoryAll living things are made of cells.or at least one cellCells carry out the functions of life, and have certain common features:Surrounded by a membraneContain genetic material, which gives instructions to perform actionsMost actions are reactions enzymesCells have their own energy systemThe smallest living thingIs a cell!Unicellular organisms are made up of a single cell, and they carry out all of the functions of life by themselves.These functions are:NutritionExcretionMetabolismHomeostasisGrowthReproductionResponse

Multicellular organismsMulticellular organisms are composed of many cells, which perform the functions of life together.ExceptionsStriated muscle tissueMuscular tissue is multinucleate

FungiAseptate HyphaFungi can have long uninterrupted tube-like structures called hyphae, many nuclei

Giant AlgaeCan grow up to 100mm with only one nucleus

Lets see some!Microscope BasicsName the partsHow to focusHow to trouble shootHow to drawHow to determine size

The Parts!

Focusing a microscopePut the slide on the stageALWAYS focus at low power firstAt low power, use the COARSE adjustment knob, then once you have found the image use the fine adjustment knob

Increasing MagnificationAlign the image in the middle of the Field of ViewSwitch to the next highest magnificationUse the FINE adjustment knob to bring the image in to focusHow to draw things in BiologyThree key steps1. Draw straight lines!

2. Join lines carefully to form continuous structures, such as cells

Drawing ContinuedDraw lines freehand, but use a ruler for labeling lines.

Determining MagnificationMagnification = size of image/actual size of specimenHow big is the stuff Im looking at though?Depends on magnification you are on

Size is relativehttp://www.biology.arizona.edu/cell_bio/tutorials/cells/cells2.html

Useful Units and How to get there

Adapted from http://i-biology.net/ibdpbio/02-cells/cell-theory/Eyepiece 10x

Objective 4x, 10x, 40x, 100x

Limitations on Cell SizeIn the cytoplasm of the cell, many chemical reactions take place: METABOLISMThe rate of these reactions is proportional to the volume of the cellThe cell acquires materials for these reactions through the cell membrane. (and excretes as well)

Which of these two sizes of cells would be more efficient?Socrative

Unicellular LifeDo we see all the functions of life being accounted for in this single Paramecium?

Unicellular organismsSometimes form colonies of cells, such as in Volvox aureus.Figure 1 shows seven colonies, with 500 or more cells on the outsideThese are still uni-cellular the cells need to be fused in a single mass to be considered multicellularSocrative

Multicellular OrganismsCaenorhabditis elegans (C. elegans) is one of the best known examples of a multicellular organismBasic cell differentiation has a mouth, pharynx, intestine, anus, both sets of reproductive organs, nervous systemEmergent properties come as a result of the interactions of these parts

Cell DifferentiationCells adapt to perform different functionsCellsTissues organized groups of cells that perform a functionOrgans groups of tissue that work together Organ Systems i.e. esophagus, stomach, small intestine, large intestineOrganismsGene Expression220 DIFFERENT types of cells are present in the human body all have the same 25,000 genes!Difference comes in Gene Expression which genes do the cells express?Example Rod cells in the eyeContain all 25,000 genes, but only expressthe genes that allow them to perform their function.Socrative: If a lens cell produced pigments like a rodcell, how would this impact our vision?

Stem CellsTwo Properties:Can divide again and again to produce copious quantities of new cells.Can differentiate in different ways to produce different cell typesTwo types: Totipotent ALL POWERFUL, EmbryonicPluripotent Still pretty powerful, Bone Marrow

EvaluationStem cells must be harvested from embryonic tissueEthical Dilemmas Is it ethical to harvest embryos to provide a potential cure for diseases that are currently plaguing humanity?Other sources?Three types of stem cells

Pros and Cons to each

Stem Cell Therapy1. Cells are removed from the patient.2. Cells are frozen or stored.3. Cells are induced to differentiate in to a variety of ways (varies based on type). Cells are then replicated in culture.4. Cells are introduced in to the patient, and allowed to attach on to existing tissue.

Stargardts Macular DystrophyCauses total vision loss as a result of a mutation of a gene in retinal cellsDevelops in children between 6-12Started with mice -> progressed to human trialsEmbryonic Stem Cells lead to the recovery of a womans sight at the age of 50.

Step 1 Harvest ESCStep 2 Induce ESC to diff. in to retinal cellsStep 3 Introduce in to patient, allow to grow to full maturityLeukemiaCancer of the bloodSymptoms: Overproduction of white blood cellsTreatment: Using Adult Stem Cells

Step 1 Large needle inserted in to bone, allowing for bone marrow to be extractedStep 2 ASCs are extracted from marrow and frozenStep 3 Chemotherapy is administered to the patient, killing cancer cellsStep 4 ASCs are reintroduced back in to the body,