cells plant & animal cells. cells how many cells do we have in us? how many cells do we have in...
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CellsCells
Plant & Animal CellsPlant & Animal Cells
CellsCells
How many cells do we have in us?How many cells do we have in us?Brain has estimated 1,000,000,000 neurons Brain has estimated 1,000,000,000 neurons
(one type of cell)(one type of cell)http://www.cybernetics.demon.co.uk/brainsim.htmlhttp://www.cybernetics.demon.co.uk/brainsim.html
Within each cell, there are smaller parts Within each cell, there are smaller parts called called organellesorganelles,, which play different which play different roles in a functioning cell.roles in a functioning cell.
Within each cell, there are smaller parts Within each cell, there are smaller parts called called organellesorganelles,, which play different roles which play different roles in a functioning cell.in a functioning cell.
Cheek cells Onion cells
CellsCells
Animal cellAnimal cell
Cell membraneCell membrane NucleusNucleus Nuclear membraneNuclear membrane CytoplasmCytoplasm MitochondrionMitochondrion Small vacuoleSmall vacuole
Animal cellAnimal cell Cell membraneCell membrane NucleusNucleus Nuclear membraneNuclear membrane NucleolusNucleolus Nuclear poreNuclear pore CytoplasmCytoplasm MitochondrionMitochondrion Small vacuoleSmall vacuole Endoplasmic reticulumEndoplasmic reticulum RibosomesRibosomes Golgi apparatusGolgi apparatus Centrosomes (w centrioles)Centrosomes (w centrioles)
http://distance.stcc.edu/AandP/AP/AP1pages/introduction/cells.htm
Plant cellPlant cell Cell membraneCell membrane NucleusNucleus Nuclear membraneNuclear membrane NucleolusNucleolus Nuclear poreNuclear pore CytoplasmCytoplasm MitochondrionMitochondrion Endoplasmic reticulumEndoplasmic reticulum RibosomesRibosomes Golgi apparatusGolgi apparatus Centrosome (w/o centrioles)Centrosome (w/o centrioles) Cell wallCell wall ChloroplastChloroplast Large vacuole (contains cell sap)Large vacuole (contains cell sap) Starch grains (inside chloroplast)Starch grains (inside chloroplast)
Plant cellPlant cell
Cell membrane Cell membrane
Always presentAlways present Thin boundary enclosing Thin boundary enclosing
cytoplasmcytoplasm Stops cell contents from escapingStops cell contents from escaping Controls substances allowed to Controls substances allowed to
enter and leave cellenter and leave cell Oxygen, food & water allowed inOxygen, food & water allowed in Waste products allowed to leaveWaste products allowed to leave Harmful substances kept OUT!Harmful substances kept OUT!
Thus able to maintain Thus able to maintain structurestructure and and chemical reactionschemical reactions in in cytoplasmcytoplasm
CytoplasmCytoplasm
Always presentAlways present Under light microscope, looks Under light microscope, looks
like thick liquid with particles in itlike thick liquid with particles in it These particles are the cell’s These particles are the cell’s
organellesorganelles..
Site of many chemical reactionsSite of many chemical reactions Liquid part is about 90% water, Liquid part is about 90% water,
with dissolved salts and sugarswith dissolved salts and sugars Proteins (e.g. enzymes) & lipids Proteins (e.g. enzymes) & lipids
are suspended withinare suspended within
NucleusNucleus Present in most cellsPresent in most cells
Exception: e.g. red blood cellException: e.g. red blood cell
Usually only ONE is presentUsually only ONE is present Contains DNA wound up into Contains DNA wound up into
chromosomeschromosomes Controls:Controls:
type and quantity of enzymes type and quantity of enzymes produced in cytoplasmproduced in cytoplasm
Hence determines what the cell Hence determines what the cell will be, e.g. liver cell, muscle cell, will be, e.g. liver cell, muscle cell, nerve cellnerve cell
cell divisioncell division
Nuclear membrane & poresNuclear membrane & pores
Substances may pass Substances may pass through the pores into the through the pores into the cytoplasmcytoplasm mRNA is transcribed in the mRNA is transcribed in the
nucleusnucleus Passes out into cytoplasm Passes out into cytoplasm
where is it translatedwhere is it translated
NucleolusNucleolus
Thought to be region where RNA is madeThought to be region where RNA is made
MitochondrionMitochondrion
Present in majority of cellsPresent in majority of cells Able to move about within Able to move about within
cellcell Internal membrane highly Internal membrane highly
foldedfolded Contains enzymes that Contains enzymes that
control respirationcontrol respiration Are main energy converters Are main energy converters
of the cellof the cell
RibosomeRibosome
Can be free or attached Can be free or attached to the endoplasmic to the endoplasmic reticulumreticulum
Site where proteins are Site where proteins are made (i.e. made (i.e. translationtranslation of of mRNA in proteins)mRNA in proteins)
Endoplasmic ReticulumEndoplasmic Reticulum
Series of tubes & Series of tubes & flattened sacs extending flattened sacs extending throughout cytoplasmthroughout cytoplasm
May change shape and May change shape and connectionsconnections
Enzymes reactions take Enzymes reactions take place on the surfaceplace on the surface
2 types:2 types: Smooth (SER)Smooth (SER) Rough (RER)Rough (RER)
Endoplasmic ReticulumEndoplasmic Reticulum
SERSER Involved in detoxification of Involved in detoxification of
poisons & production of poisons & production of lipids (e.g. filtration and lipids (e.g. filtration and secretion of steroid secretion of steroid hormones)hormones)
E.g. in kidney & liverE.g. in kidney & liver
RERRER Involved in protein Involved in protein
productionproduction
http://www-class.unl.edu/bios201a/spring97/group6/er.html
Golgi ApparatusGolgi Apparatus
Consists of flattened Consists of flattened membrane sacsmembrane sacs
Final packaging location Final packaging location for proteins and lipidsfor proteins and lipids
Vesicles containing these Vesicles containing these substances break away substances break away from the endsfrom the ends
CentrosomeCentrosome
Microtubule organizing Microtubule organizing centre (place where centre (place where microtubules are microtubules are produced)produced)
Animal centrosomes Animal centrosomes have centrioles; plant have centrioles; plant cells don’tcells don’t
When the cell divides, When the cell divides, the centrosome divides the centrosome divides and the centrioles and the centrioles replicate replicate
CentriolesCentrioles
Have a role in Have a role in building cilia and building cilia and flagella, during which flagella, during which time they are referred time they are referred to as basal bodiesto as basal bodies
ChloroplastChloroplast
Present in plant cells & certain single-Present in plant cells & certain single-celled organisms and algaecelled organisms and algae
Has system of membranes thatHas system of membranes thatcarries chlorophyllcarries chlorophyllCarries enzymes that conduct first stages of Carries enzymes that conduct first stages of
photosynthesisphotosynthesisLiquid material between membranes Liquid material between membranes
contains enzymes that continue contains enzymes that continue photosynthesisphotosynthesis
ChloroplastChloroplast
Section through chloroplast (x12000)Section through chloroplast (x12000)
VideoVideo
What is protoplasm?
nucleus
cytoplasm
cell membrane
-living materials of the cell
Cell Organization
PlantPlant AnimalAnimal
Organelles Organelles Nucleus, vacuole, Nucleus, vacuole, chloroplasts.chloroplasts.
Nucleus, cytoplasm,Nucleus, cytoplasm,vacuolevacuole
CellsCells epidermal cellepidermal cell epithelial cellepithelial cell
TissuesTissues epidermal layerepidermal layer epithelial layerepithelial layer
OrgansOrgans LeafLeaf SkinSkin
SystemsSystems NutritionNutrition ProtectiveProtective
OrganismOrganism Balsam plantBalsam plant MouseMouse
Differences between Plant and Animal Cells
PlantPlant AnimalAnimal
1.1. Cellulose cell wall is presentCellulose cell wall is present AbsentAbsent
2.2. Chloroplast is presentChloroplast is present AbsentAbsent
3.3. One or a few large, central One or a few large, central permanent vacuole/spermanent vacuole/s
Many, small, variable size, Many, small, variable size, temporary vacuolestemporary vacuoles
4.4. Larger cell and distinctive Larger cell and distinctive outlineoutline
Smaller cell and not so Smaller cell and not so distinctive outlinedistinctive outline
5.5. Starch granulesStarch granules Glycogen granulesGlycogen granules
Evidence?Evidence?
Break cell membranesBreak cell membranes Centrifuge cell fragments in salt solutionCentrifuge cell fragments in salt solution Spin are varying speeds (slow to fast)Spin are varying speeds (slow to fast) Heaviest organelles settle firstHeaviest organelles settle first
Nuclei, chloroplasts, mitochondria, membrane Nuclei, chloroplasts, mitochondria, membrane fragments, ribosomesfragments, ribosomes
Each fraction studied in isolationEach fraction studied in isolation
NB.NB. Activities of isolated organelles may not be the Activities of isolated organelles may not be the same as their activities in a whole living cell.same as their activities in a whole living cell.
ArtefactsArtefacts
Tissues often undergo drastic treatment Tissues often undergo drastic treatment before examination.before examination.FixationFixationDehydrationDehydrationStainingStaining
Cell structures may be distorted; may not Cell structures may be distorted; may not represent structures found in living cells.represent structures found in living cells.
ArtefactsArtefacts
These artificial features are called These artificial features are called artefactsartefacts..
Take what you’ve learnt with a pinch of Take what you’ve learnt with a pinch of salt; salt; seeingseeing is not always is not always believingbelieving in in these circumstances.these circumstances.
Differentiated Animal CellsDifferentiated Animal Cells
white blood cell
red blood cell
cheek cells
sperm
nerve cell
muscle cell
Amoeba
Paramecium
Differentiated Plant CellsDifferentiated Plant Cells
Onion Epidermal Cells
Root Hair Cell
root hair
Guard Cells
Identify the organelles!Identify the organelles!
A:A: cell wallcell wallB:B: cell membranecell membraneC:C: mitochondrionmitochondrionD:D: nuclear nuclear
membrane/nuclmembrane/nucleuseus
F:F: Nuclear poreNuclear poreG:G:NucleolusNucleolusH:H: VacuoleVacuoleI:I: Golgi Golgi
apparatusapparatus
Modification of Cell Structure for Specific Functions
Differentiation- the process of change into new type of cells/tissues
Root Hair Cell
Red Blood Cell
Xylem vessels
water and minerals enter a plant through the
tiny root hairs
water and minerals enter a plant through the
tiny root hairs
xylemxylem soil particlessoil particles
Root Hair CellRoot Hair Cell
Type of cellsType of cells
FunctionFunction
Cells with elongated protrusion and a large vacuole
absorbs water and dissolved minerals from the roots to all parts of the plantprovide large surface area to volume ratio for efficient absorption
Red Blood CellRed Blood Cell
Type of cellsType of cells
FunctionFunction
Biconcave disc cells without nucleus packed with red pigment, haemoglobin
absorbs oxygen from the lungs to all parts of the bodyprovide large surface area to volume ratio for efficient absorption
XylemXylem
Type of cellsType of cells
FunctionFunction
phloemxylem
cross-section of stem
dead cells thickened with lignin forming a long hollow tube
carries water and dissolved minerals from the roots to all parts of the plantprovide mechanical support to the plant