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Chapter 2: CellsChapter 2- Cells
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The discovery of cells
Robert Hooke
Anton van Leeuwenhoek
Schleiden & Schwann (Cell Theory)
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The The animal animal cell (3-cell (3-
D)D)Nucleus
Vacuoles
Plasma MembraneMitochondrion
Nucleolus
Cytoplasm
Golgi apparatus
Rough endoplasmic
reticulum
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Label the parts of an animal cell.
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The The plant plant cell cell (3-D)(3-D)Cell wall
Plasma Membrane
Central vacuole
Chloroplasts
Mitochondrion
Nucleus
CytoplasmNucleolus
Golgi apparatus
Rough endoplasmic
reticulum
Smooth endoplasmic
reticulum
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Label the parts of a plant cell.
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C = Chloroplast (next slide)
ER = Endoplasmic Reticulum
G = Granum (next
slide)
M = Mitochondrion
S = Starch Grain
T = Thylakoids (next slide)
V = Vacuole W = Cell Wall
Plant Cell – 22 500 X (electron micrographs)
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3-D structure of a chloroplast
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Organelle Structure Function
Nucleus Consists of:NucleoplasmNuclear envelopeChromatin threadsOne nucleolus or more nucleoli
Controls the activities of the cell such as cell growth & repair of worn-out parts Essential for cell division
Nuclear envelopeSeparates the contents of the nucleus from the rest of the cytoplasm
NucleoplasmDense material within the nucleus
Chromatin threads Network of long thread-like structuresCondenses to become rod-like chromosomesEach thread is made up of proteins and DNA
NucleolusPlays a part in the making of proteins
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Organelle Structure FunctionPlasma Membrane /Cell surface membrane
Partially-permeable membrane that forms a boundary between the cytoplasm of the cell and the outside. Have pores (small holes) on it
Regulate the passage of substances entering and exiting the cell
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Organelle Structure Function
Cytoplasm Jelly-like complex material that contains all the organelles of a cell. Is the part of the protoplasm between the cell surface membrane and nucleus.
Part of the cell where most cell activities occur
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Organelle Structure Function
Mitochondria(plural)Mitochondrion
Contains many folds to increase surface area for synthesis of ATP molecules / energy molecules
‘Power house’ of the cell During aerobic respiration, energy is released
ATP = Adenosine triphosphate
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Organelle Structure FunctionRough Endoplasmic Reticulum (RER)
Ribosomes attached on RER
Ribosomes on it make proteins that are enclosed in vesicles transported to the Golgi apparatus for secretion out of the cell.
Smooth Endoplasmic Reticulum(SER)
No ribosomes attached.
Synthesizes fats and steroids (eg. sex hormones)Detoxifies harmful substances
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Organelle Structure Function
Free ribosomes (a type of proteins made in the nucleolus)
In the In the cytoplasmcytoplasm
Make proteins that are Make proteins that are used within the used within the cytoplasm of the cell.cytoplasm of the cell.
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Organelle Structure FunctionGolgi Apparatus(GA)
[Vesicle movement]http://biologica.concord.org/webtest1/Shout3d_cell_6_1_00/v2_frameset.htm
Consists of flattened spaces surrounded by membranesVesicles seen fusing with one side of GA and pinching off from the opposite side
Stores and modifies substances / proteins made by the RERPackages these substances / proteins in vesicles for secretion out of the cell
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1. Vesicles transport substances within the cell. Small vesicles containing substances made by the ER are pinched off from the ER.
How substances made by the endoplasmic reticulum enter the Golgi apparatus and are finally secreted out of the cell
rough endoplasmic reticulum
vesicle forming
Processes in the Golgi Apparatus
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1. Vesicles transport substances within the cell. Small vesicles containing substances made by the ER are pinched off from the ER.
How substances made by the endoplasmic reticulum enter the Golgi apparatus and are finally secreted out of the cell
rough endoplasmic reticulum
vesicle formingvesicle
pinched off
Processes in the Golgi Apparatus
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1. Vesicles transport substances within the cell. Small vesicles containing substances made by the ER are pinched off from the ER.
2. Vesicles then fuse with the Golgi apparatus and release their contents into the Golgi apparatus. The substances made by the ER may be modified inside the Golgi apparatus.
How substances made by the endoplasmic reticulum enter the Golgi apparatus and are finally secreted out of the cell
rough endoplasmic reticulum
vesicle forming
vesicle fusing with Golgi apparatus
Golgi apparatus
vesicle pinched off
Processes in the Golgi Apparatus
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1. Vesicles transport substances within the cell. Small vesicles containing substances made by the ER are pinched off from the ER.
4. Secretory vesicles fuse with the cell surface membrane and their contents are released outside the cell.
How substances made by the endoplasmic reticulum enter the Golgi apparatus and are finally secreted out of the cell
3. Secretory vesicles containing these modified substances are pinched off from the Golgi apparatus. They then move to fuse with the cell surface membrane.
rough endoplasmic reticulum
vesicle forming
secretory vesicle pinched off
substances released outside the cell
secretory vesicle fuses with cell surface membrane
vesicle pinched off
2. Vesicles then fuse with the Golgi apparatus and release their contents into the Golgi apparatus. The substances made by the ER may be modified inside the Golgi apparatus.
vesicle fusing with Golgi apparatus
Golgi apparatus
Processes in the Golgi Apparatus
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Organelle Structure Function
Centrioles Consists of two short cylinders, facing right angles at each other
organize the assembly of spindle microtubules during cell division.
In animal cells
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Organelle Structure Function
Vacuole Fluid filled space bound by a partially permeable membraneUsually exists temporarily
Stores dissolved sugars, mineral ions and other solutes.
In animal cells
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Organelle Structure FunctionVacuole Fluid filled space Fluid filled space
surrounded by a surrounded by a partially partially membrane membrane known as known as tonoplasttonoplast
contains cell sap contains cell sap such as nutrients such as nutrients and mineral saltsand mineral salts
In plant cells
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Organelle Structure FunctionChloroplast Contains chlorophyll
(green pigment which absorbs light energy for photosynthesis).
In plant cells
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Organelle Structure FunctionCell wall Fully permeable
layer of non-living material found outside the plasma membrane. Contains cellulose
Gives plant cell a fixed shapeGives protection from injury
In plant cells
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Differences between animal
and plant cellAnimal Plant
Cell wall absent present
Chloroplasts absent present
Vacuoles small and many usually large and central
Stores food as glycogen granules starch granules
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Specialized cells Specialized cells are slightly different from typical cells in
that they have been modified and adapted to better carry out certain functions.
Some examples areRed blood cell in mammalsXylem cell in plantsRoot hair cell in plants
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Specialised / Differentiated cells
Differentiation: A process in which the zygote undergoes a change from a simple to complex structure.
(contains DNA from both parents)
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cell membrane
Cytoplasm with a red pigment protein called haemoglobin. It carries oxygen.
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Red blood cellsStructure of RBC in relation to its function?
Adaptation: Circular, biconcave shape
Function: Increases surface area to volume ratio. Thus, oxygen diffuse in and out at a faster rate.
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Red blood cellsStructure of RBC in relation to its function?
Adaptation: Nucleus is absent
Functions:Carry more haemoglobin and hence more oxygen . It also enables them to fold easily to squeeze through narrow capillaries.
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Root hairFunctions Adapted for the absorption of water and
mineral salts from the soil. Anchor the plant firmly to the ground.
nucleus
Central vacuole
Plasma membrane
Cytoplasm
Cellulose cell wall
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Structure of the root hair cell in relation to its function
Structure:Long and narrow protrusion
Function:Increases surface area to volume ratio forabsorption of water and mineral salts.
Structure:Large vacuole
Function:Increases the concentration of salts and sugars.Thus, higher rate of absorption of water.
Root hair cell
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The Xylem VesselThe Xylem Vessel
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Xylem cells Dead cells which have lost their
nucleus and cytoplasm Hollow and placed end-to-end to
conduct water and dissolved mineral salts from the roots to the rest of the plant.
Contain lignin, a woody substance that increases the strength of the vessel. This helps in the support of the plant.
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Hollow long vessel
Narrow lumen
Xylem Vessel
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Young Xylem vessels Matured
xylem vessels
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The Xylem VesselFunctions To provide mechanical strength to plant body. To conduct water & mineral salts from root to all
parts of plant.
What is its adaptation to its function? Lignified cell wall for strength to support the
plant. Narrow lumen & hollow, long vessel for water
and mineral salts transport.
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Division of labourMulti-cellular organism
each cell types specialises in performing one particular function
the more highly developed the organism is, the greater is the degree of division of labour
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Division of labourAdvantage :
Ensures smooth and efficient functioning of the organism.
Different function can be performed at the same time.
4141A group of cells work together to form a tissue.
intestinal epithelium (tissue) made up of intestinal epithelial cells
epithelium in the trachea (tissue) made up of epithelial
cells and gland cells
cartilage in the trachea (tissue) made up of
connective tissue cells
epithelium in the lungs (tissue) made up of
epithelial cells
connective tissue in the lungs made up of
connective tissue cells
muscle cell
neurones
intestinal epithelial cell
epithelial cell
gland cell
muscle tissue made up of muscle cells
nervous tissue made up of neurones (nerve cells)
connective tissue cell
connective tissue cell
epithelial cell
Specialised Cells, Tissues, Organs & Specialised Cells, Tissues, Organs & SystemsSystems
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Different tissues combine to form an organ.
trachea (organ)
lungs (organs)
stomach (organ)
intestine (organ)
muscle tissue
cartilage (tissue)
muscle tissue connective tissue
nervous tissue
intestinal epithelium (tissue)
epithelium (tissue)
epithelium (tissue)
Specialised Cells, Tissues, Organs & Specialised Cells, Tissues, Organs & SystemsSystems
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Several organs work together to make up an organ system.
lungs (organs)
trachea (organ)
intestine (organ)
stomach (organ)
digestive system (organ system)
respiratory system (organ system)
Specialised Cells, Tissues, Organs & Specialised Cells, Tissues, Organs & SystemsSystems
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human (organism)
digestive system (organ system)
respiratory system (organ system)
Various organ systems work together to make up an organism.
Specialised Cells, Tissues, Organs & Specialised Cells, Tissues, Organs & SystemsSystems