ClickBiology Cambridge IGCSE Biology Extended Level Cells
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Cambridge IGCSE BiologyExtended Level
Cells
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You should be able to:
• Identify and describe the structure of plant cells and animal cells, and describe the functions of their parts.
• Describe the difference between animal cells and plant cells.
• Explain the structure and function of specialised cells: red blood cell, muscle cells, ciliated cells, xylem vessels and root hair cells.
• Define the terms tissue, organ and organ systems, with examples.
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A section through a liver cell (animal cell):
cell membrane
cytoplasm
nucleus
DNA
controls what enters and leaves the cell
metabolic (chemical) reactions occur here
contains the DNA and so controls the cell
contains the coded instructions to make proteins
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Under a microscope
nucleus
cytoplasm
cell membrane
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In the cytoplasm…
• There are ribosomes– They are found on rough endoplasmic
reticulum (R.E.R) and vesicles.– Very important function in the cell.– The place where proteins are made by joining
amino acids together in a long chain.– The instructions carried by DNA in the
nucleus decides the sequence needed to make a particular protein.
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Making Proteins
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Rough Endoplasmic Reticulum
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Ribosomes are found in…
• ALL TYPES OF CELLS!!!– BACTERIA– PROTOCTISTS– FUNGI– ANIMALS– PLANTS
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Mitochondria
• The place that aerobic respiration occurs.
• Oxygen is used to release energy from glucose.
• Cells that use a lot of energy have many mitochondria
e.g: Sperm – swimmers Neurones – transmit impulses
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MITOCHONDRIA ARE FOUND IN ALL CELLS EXCEPT PROKARYOTES (BACTERIA)
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Section through a palisade cell of a leaf (plant cell)
cell membrane
nucleus
cytoplasm
chloroplast
large sap vacuole
cellulose cell wall
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Under a microscope
large sap vacuole
cellulose cell wall
chloroplast
cytoplasm
nucleus
cell membrane
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Cell wall under the microscope• The Cell wall is made of Cellulose.
• Cellulose belongs to a group of substances called polysaccharides, which we will look at in Unit 4.
• The cellulose fibres help to support and protect the cell.
• If the cell absorbs a lot of water and swells, the cell wall stops it bursting.
• The cell wall is fully permeable, the spaces between the fibres allow even very large molecules to go through.
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Chloroplasts
• Never found in animal cells.• Contain a green colouring pigment called
chlorophyll.• Chlorophyll absorbs energy from sunlight which
is then used for making food (starch grains).• Animal cells never have starch granules.
Instead, they have glycogen.• Starch is found in the cytoplasm NOT inside
chloroplasts.
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You should be able to:
• Identify and describe the structure of plant cells and animal cells, and describe the functions of their parts.
• Describe the difference between animal cells and plant cells.
• Explain the structure and function of specialised cells: red blood cell, muscle cells, ciliated cells, xylem vessels and root hair cells.
• Define the terms tissue, organ and organ systems, with examples.
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Comparing animal and plant cells
Found in both animal and plant cells
Found only in plant cells
cell membrane cellulose cell wall
nucleus large sap vacuole
cytoplasm chloroplast
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Coursebook Page 24Do all questions on page 24
Finish for homework
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You should be able to:
• Identify and describe the structure of plant cells and animal cells, and describe the functions of their parts.
• Describe the difference between animal cells and plant cells.
• Explain the structure and function of specialised cells: red blood cell, muscle cells, ciliated cells, xylem vessels and root hair cells.
• Define the terms tissue, organ and organ systems, with examples.
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Specialised Cells
• Not all cells are the same.
• They have different features that depend on their function within an organism.
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Red blood cells transport oxygen
cell surface membrane cytoplasm contains no nucleus
cytoplasm contains haemoglobin
bi-concave disc shape
allows more room for haemoglobin
increases surface area over which absorption of oxygen can occur
haemoglobin is a protein which carries the oxygen molecules
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Muscle cells contract and enable movement of the body
nucleuscell surface membrane
protein strands
The strands of protein slide over each other making the muscle cell (fibre) shorter and causing the muscle to contract
Muscle cells have many nuclei
muscle
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Ciliated cells move bacteria and dust away from the lungs
cilia
magnification X3000
nucleus
Cilia are small extensions of the cell. They beat rhythmically to sweep mucus, which has trapped bacteria and dust, away from the lungs
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Xylem vessels transport water and minerals up the plant
xylem vessel
lignin
no cytoplasm
longitudinal sectioncross-section
water-proof and strong;helps support the plant
hollow: allows for continuous flow of water and dissolved mineral ions
xylem vessels are continuous tubes
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Root hair cells absorb minerals and water from the soil
cytoplasmcontains no chloroplasts as no photosynthesis is needed
root hairincreases surface area for absorption of water and mineral ions
Cross-section of a root hair cell
cell membrane semi-permeable, so will allow water and mineral ions into the cell
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Nerve cells transmit information in the form of electrical impulses
Direction of information
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You should be able to:
• Identify and describe the structure of plant cells and animal cells, and describe the functions of their parts.
• Describe the difference between animal cells and plant cells.
• Explain the structure and function of specialised cells: red blood cell, muscle cells, ciliated cells, xylem vessels and root hair cells.
• Define the terms tissue, organ and organ systems, with examples.
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A tissue is a group of cells of similar structure that perform a shared function
Animal tissues:muscle tissue
nervous tissue
upper epidermal tissue
palisade mesophyll tissue
spongy mesophyll tissue
lower epidermal tissue
Tissues found in the leaf
Cross-section of a leaf
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An organ is a structure made of a group of tissues working together to
perform specific functions
Plant organs include the stem and the leaves
heart
stomach
lungs liver
brain kidneys
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An organ system is a group of organs that coordinate to perform related functions
In plants the shoot is an organ system consisting of leaves and the stem
lymphaticsystem
respiratorysystem
digestivesystem
excretorysystem
reproductivesystem
muscularsystem
skeletalsystem
nervoussystem
endocrinesystem
circulatorysystem
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Levels of organisation
nerve cell nervous tissue
brain nervoussystem
Homo sapiens
smallest largest
cell tissue organ organsystems
organism
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Now you should be able to:
• Identify and describe the structure of plant cells and animal cells, and describe the functions of their parts.
• Describe the difference between animal cells and plant cells.
• Explain the structure and function of specialised cells: red blood cell, muscle cells, ciliated cells, xylem vessels and root hair cells.
• Define the terms tissue, organ and organ systems, with examples.
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Now write down everything you remember from the presentation
• Don’t refer to your text book straight away, see what information you have retained.
• Check the notes you have made by checking your book.