In this chapter you will learn:
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What are Cells?
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Cell structures and their functions
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Plant cell structures and their functions
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Similarities & differences between animal and plant cells
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Cell Specialisation - Animal
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Similarities & differences between animal and plant cells
What are Cells?
Living things are made of cells. Cells are very small.
Cells can be seen through a microscope. Cells were first discovered by Robert hooke in 1665.
Animal and plants are made up of lots of cells. Mostly plant and animal cells are 0.01 – 0.10 mm in size. Each cell in human body have 23 pairs of chromosomes. Bacteria are made of single cells.
Cells have many types of shapes. Group of cells make a tissue. Cells play a different types of role in our body.
Cells need things like glucose and oxygen to exist. Both animal and plant cells have nucleus.
Cell structures and their functions
Cell membrane is the outer layer of cell. Cell membrane controls the passage of substances into and out of the cell.
Nucleus controls the activities of the cell. Nucleus holds genetic information that are necessary for cell growth.
Cytoplasm is like a Jelly-like substance, where chemical reactions occur.
Ribosomes are a cell structure that makes protein.
The most important function of the mitochondria is to produce energy. They contain the enzymes for respiration.
Plant cell structures and their functions
Chloroplast are organelles that have the green pigment, chlorophyll, which absorbs light energy for photosynthesis.
Cell wall made from cellulose fibres that provides strength to the cell and supports the plant.
Permanent vacuole filled with cell sap to help maintain the cell's turgidity.
Similarities & differences between animal and plant cells
They both have a nucleus.
They both have a cytoplasm.
They have a cell membrane.
They contain mitochondria.
They contain ribosomes.
Differences
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Plant cells have a cellulose cell wall that is made from cellulose fibres.
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Plant cells have a vacuole filled with cell sap.
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They have chloroplasta that contains the enzymes needed for photosynthesis.
They have nucleus to the side of the cell.
Plant cells have rectangular shape.
Cell Specialisation - Animal
Cells have to perform different jobs. Cells display specialised features to perform these jobs more effectively.
Sperm Cells
The head contains enzymes that helps penetrate the egg cell membrane to allow fertilisation.
The middle part is packed with mitochondria to release energy that is needed to swim.
The tail of the cell enables the sperm to swim to the ovum.
Sperm cells contain the genetic information.
Nerve Cells
Nerve cells are specialized to carry messages through electric signals.
The nerve cell is covered with a fatty sheath.
Nerve cells have a long axon to carry the impulse to the target organ.
Nerve cells have branched connections at each end.
Red blood cells
Red blood cell contain haemoglobin which transports oxygen to other cells.
Red blood cells carry oxygen around the body. Red blood cells are a flat disc shape.
Red blood cells have a thin outer membrane.
Cell Specialisation - Plant
Xylem Cell
Xylem cells have a small tubes that carry water from the roots to the leaves.
Cells have no end walls between them Their walls become thickened and woody.
Xylem forms a continuous, hollow tube.
Root Hair Cell
The root hair cell has a large surface area to increase the rate of absorption.
Cells have thin walls that allow plants to absorb more water .
Palisade Cell
The function of cell is to enable photosynthesis to be carried out.
Cells contain about 70% of the chloroplasts.