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Page 1: Chapter 2 cells 2011

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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 threads

One nucleolus or more nucleoli

Controls the activities of the cell such as cell

growth & repair of worn-out parts Essential for cell division

Nuclear envelope

Separates 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 Function

Plasma 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 Function

Rough 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 Function

Golgi 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 Function

Vacuole 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 Function

Chloroplast Contains chlorophyll(green pigment which absorbs light energy for photosynthesis).

In plant cells

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Organelle Structure Function

Cell 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.

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A 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