How Do Cells Work?How Do Cells Work?

A Cell is a System that Works in a A Cell is a System that Works in a SystemSystem

A A systemsystem is made up of a group of parts is made up of a group of parts that interact to perform a functionthat interact to perform a function

Group of parts:Group of parts: organization of different elements or sub-organization of different elements or sub-

systems systems that accomplish a functionthat accomplish a function

Interactions:Interactions:relations and communications between the relations and communications between the partsparts

Function:Function: the product, action or consequence of the the product, action or consequence of the interactionsinteractions

Examples of SystemsExamples of Systems

SystemSystem Group of Group of partsparts InteractionInteraction FunctionFunction

iPodiPodBody, Body,

electronics, electronics, battery, battery,

earphonesearphones

Store and Store and organize data, organize data,

energize, energize, produce soundproduce sound

Play music, Play music, videos...videos...

Screw Screw driverdriver

Shaped tip, Shaped tip, shaft, handleshaft, handle

Transfer Transfer rotation rotation Turn a screwTurn a screw

CardiovasculCardiovascularar

Heart, arteries, Heart, arteries, capillaries, capillaries,

veins.veins.

Pump, regulate, Pump, regulate, distributiondistribution

Transport the Transport the bloodblood

EducationEducationSchool Boards,School Boards,

Schools, Schools, EducatorsEducators

Transfer Transfer knowledge and knowledge and

culturecultureSocializeSocialize

PLANTPLANT CELLS CELLS (parts)(parts)

1. Cell Wall1. Cell Wall

5. Endoplasmic Reticulum

3. Cytoplasm

7. Mitochondria

2. Plasma Membrane

6. Chloroplast

4. Nucleus

8. Vacuoles

DNA

ANIMALANIMAL CELLS CELLS (parts)(parts)

4. Endoplasmic Reticulum

2. Cytoplasm

5. Mitochondria

1. Plasma Membrane

3. Nucleus

6. Vacuoles

DNA

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Cells need nutrientsCells need nutrients

Nutrients: The particles from which Nutrients: The particles from which cells are nourished. They are cells are nourished. They are derived from digested foodderived from digested food

Inputs and OutputsInputs and Outputs

Inputs: Inputs are substances that enter Inputs: Inputs are substances that enter the cell and are necessary to its activitiesthe cell and are necessary to its activities

Main Inputs: Water, nutrients and oxygenMain Inputs: Water, nutrients and oxygen

The cell’s mitochondria release the energy The cell’s mitochondria release the energy from the nutrients when the nutrients from the nutrients when the nutrients come in contact with oxygen.come in contact with oxygen.

These nutrients are used as material for These nutrients are used as material for construction (to grow) or repair (to heal) construction (to grow) or repair (to heal) the organism.the organism.

Inputs and OutputsInputs and Outputs

Outputs: Wastes or useless Outputs: Wastes or useless substances that must leave the cellsubstances that must leave the cell

Main outputs: Water, carbon dioxide, Main outputs: Water, carbon dioxide, and waste from cellular functionsand waste from cellular functions

The Cell and its The Cell and its EnvironmentEnvironment

The cell membrane is like the border The cell membrane is like the border between two countries.between two countries.

At a border crossing agents verify At a border crossing agents verify the items people transport. Items the items people transport. Items like firearms, food and plants are like firearms, food and plants are usually forbidden. Customs posts usually forbidden. Customs posts help in this verification.help in this verification.

The cell membrane verifies materials The cell membrane verifies materials entering the cell or exiting it.entering the cell or exiting it.

Like a customs post, a cell membrane Like a customs post, a cell membrane lets certain substances to enter or lets certain substances to enter or exit, but forbids passage to others.exit, but forbids passage to others.

Because the membrane only lets Because the membrane only lets certain substances pass we call this certain substances pass we call this type of membrane type of membrane selectively selectively permeable.permeable.

DiffusionDiffusion To enter a cell membrane a To enter a cell membrane a

substance must move.substance must move.

Diffusion is the movement of Diffusion is the movement of particles when they shift from a particles when they shift from a region where they are region where they are more more concentrated toconcentrated to a region where a region where they are they are less concentratedless concentrated..

Substances enter and exit the cell by Substances enter and exit the cell by diffusion.diffusion.

OsmosisOsmosis Water is the most abundant Water is the most abundant

substance both inside and outside substance both inside and outside the cell. Approximately 70% of a cell the cell. Approximately 70% of a cell is water.is water.

In the cell, the water contains various In the cell, the water contains various dissolved particles: nutrients, carbon dissolved particles: nutrients, carbon dioxide, waste.dioxide, waste.

Water particles are very small: they Water particles are very small: they can enter and exit the cell easily.can enter and exit the cell easily.

Water particles move from areas with Water particles move from areas with low amounts of dissolved substances low amounts of dissolved substances into areas of higher amounts.into areas of higher amounts.

The passage of water across a The passage of water across a membrane that only allows certain membrane that only allows certain substances to pass is called substances to pass is called osmosisosmosis..

http://www.stjohn.ac.th/Department/school/bio_pix/osmosis.gif

Vital Functions of the CellVital Functions of the Cell

Energy contained in the food is Energy contained in the food is released during a chemical reaction released during a chemical reaction called called cellular respirationcellular respiration. .

Plants produce their food themselves Plants produce their food themselves with a function called with a function called photosynthesisphotosynthesis..

PhotosynthesisPhotosynthesis Plants use sunlight as a source of energyPlants use sunlight as a source of energy

Sunlight in plant cells manufactures sugars Sunlight in plant cells manufactures sugars called called carbohydratescarbohydrates from water and from water and carbon dioxide.carbon dioxide.

The water comes from the roots, which The water comes from the roots, which draws it from the soil.draws it from the soil.

The leaves absorb carbon dioxide present The leaves absorb carbon dioxide present in the air.in the air.

PhotosynthesisPhotosynthesisOutputs

Oxygen

Carbohydrates

Chemical reactionoccurring in the

plant cell(chloroplasts)

Inputs

Carbon Dioxide

Water

Solar Energy

Cellular RespirationCellular Respiration In living things, cellular respiration is In living things, cellular respiration is

necessary. It transforms carbohydrates into necessary. It transforms carbohydrates into energy.energy.

This transformation takes place in the This transformation takes place in the mitochondria.mitochondria.

The mitochondria absorbs carbohydrates The mitochondria absorbs carbohydrates and oxygen and then a chemical reaction and oxygen and then a chemical reaction causes the oxygen to release the energy causes the oxygen to release the energy present in the carbohydrates.present in the carbohydrates.

This energy can then be used by the cellsThis energy can then be used by the cells

Cellular RespirationCellular Respiration

Chemical reactionoccurring in the

animal or plant cell(mitochondria)

Inputs Outputs

Oxygen

Carbohydrates

Carbon Dioxide

Water

Energy