mr exham igcse biology - cells

MAKING SENSE OFCELLS

IGCSE Biology1.1 Life Processes – Cells

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Copyright © 2014 Henry Exham

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Learning Objectives• Can you remember the processes in MRS C

GREN that are common to most living things?• Can you recognise cell structures such as the

nucleus, cytoplasm, cell membrane, cell wall, chloroplast and vacuole, and describe their functions?

• What are the major differences between plant and animal cells?


MRS GREN• MRS C GREN stands for the 8 characteristics of

living things. • All living organisms from a simple bacteria to

plants and animals, can do all of these processes.


MovementReproductionSensitivity

GrowthRespirationExcretionNutrition


Control

Cells – The Building Blocks Of Life

• All living organisms are composed of cells.• The simplest organisms are made of one

single cell.• More complex organisms like animals and

plants are made of many cells and are called multicellular organisms.

• In multicellular organisms there are many different types of cells that are specialised to carry out particular functions.


Watch this video clip about cells


http://www.bbc.co.uk/learningzone/clips/cells-and-their-function/1832.html

A general animal cellCell membrane

Cytoplasm

Nucleus

Mitochondria


A general plant cellCell membrane

Cell wall

Mitochondria

Vacuole

Cytoplasm

Chloroplast


Nucleus

Nucleus• Largest organelle.• Controls the activities of the cell.• Contains chromosomes.• Chromosomes carry genes.• The genes determine which proteins the cell

can make.


Nucleus

Cell Surface Membrane• Forms a boundary between the cytoplasm and

the outside of the cell.• Some chemicals can pass through this barrier

and the cell can control what comes in and out. • It is selectively permeable.


Cell membrane

Cytoplasm• Jelly like substance which contains all of the

organelles (e.g. nucleus and mitochondria). • Many of the cell’s chemical reactions take place

in the cytoplasm. • These are called metabolic reactions.


Cytoplasm

Mitochondria• Carry out some of the reactions of respiration. • Therefore releasing energy for the cell.• Cells that have a high demand for energy

usually have many mitochondria, such as muscle cells.


Mitochondria

Cell Wall• Found only in plant cells.• It is made of a non-living material called

cellulose.• Helps the cell keep its shape.• It is freely permeable.


Cell wall

Chloroplast• Found in some plant cells.• Contains chlorophyll.• Chlorophyll is a green pigment.• It absorbs light energy to make food in the

process of photosynthesis.


Chloroplast

Vacuole• Found only in plant cells.• Filled with cell sap.• Cell sap is a store of dissolved sugars, mineral

ions, and other solutes.• Helps keep the cell’s shape.


Vacuole

SummaryCell structures and their functions

Cell structure Plant or animal cell Function

Nucleus Both Controls the activity of the cell using genes

Cell Membrane Both Controls what enters and leaves the cell

Cytoplasm Both Location of cell metabolic reactions

Mitochondria Both Site of respiration

Cell Wall Plant only Made of cellulose, gives cell strength

Chloroplast Plant only Site of photosynthesis

Vacuole Plant only Contains cell sap which helps keep cell’s shape


Watch this video clipCopyright © 2014 Henry Exham

http://www.bbc.co.uk/learningzone/clips/parts-of-plant-and-animal-cells/10602.html

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