Tissue, Organs & Systems
Cells are the structural unit of life many cells join together to form tissues. Cells are the smallest living parts of any living thing. Cells have the same needs as any living organism and carry out many of the same activities. Cells contain smaller parts, each with a specialized job.
Tissues area group of cells working together to perform a function. Many tissues join together to make an organ. An organ is a group of tissues working together to perform a job. Organs join together to make systems which are groups of organs working together to make a certain job. Systems join together to make an organism which is a living individual. |
A cell is the smallest unit that can carry on all the processes of life. All organisms are made of cells, organisms are made of several organ systems, each organ system contains several organs, each organ contains several tissues; each tissue is made of cells. Cells are very tiny they could be seen only through a microscope. We have two types of cells:
- Animal Cell
- Planet Cell
Main cell parts description
1. Cell wall: Non living structure which is made of cellulose. It supports the plant from pressure and regulars its shape.
2. Cell membrane: A complex semi permeable structure which allows substances in and out the cell
3. Cytoplasm: jelly like substance where most chemical reactions happen
4. Nucleus: Contains DNA. It controls the activities of the cell and carries genetic materials.
5. Vacuole: A fluid made of cell sap. It contains some usefull materials and waste
6. Chloroplast: Large bodies containing chlorophyll e=where Photosynthesis takes place
7. Mitochondria: It consists of a double membrane and is the site of aerobic respiration.As you can see from the diagram, there are some features found in plant cells but not in animal cells.
Features found in both plant and animal cells:
Animal cells store sugars in glycogen form but plant cells store it as starch.
Animal cells have an irregular shape but plant cells have a regular shape.
Both types of cells contain Mitochondria these are structures that convert chemical energy in foods to energy that could be used in moving, dividing, etc., it is evidence that the cell is an Active Cell.
1. Cell wall: Non living structure which is made of cellulose. It supports the plant from pressure and regulars its shape.
2. Cell membrane: A complex semi permeable structure which allows substances in and out the cell
3. Cytoplasm: jelly like substance where most chemical reactions happen
4. Nucleus: Contains DNA. It controls the activities of the cell and carries genetic materials.
5. Vacuole: A fluid made of cell sap. It contains some usefull materials and waste
6. Chloroplast: Large bodies containing chlorophyll e=where Photosynthesis takes place
7. Mitochondria: It consists of a double membrane and is the site of aerobic respiration.As you can see from the diagram, there are some features found in plant cells but not in animal cells.
Features found in both plant and animal cells:
- Cell surface membrane: This is a partially permeable membrane separating the cell from the environment its made of lipid and protein, it controls movement of substances in and out, its strong but flexible.
- Cytoplasm: This is a jelly like substance, its made of mostly water and protein. Metabolic reactions occur in it.
- Nucleus: This determines how the cell behaves and it contains chromosomes made of strings of DNA which also determines which proteins the cell should make etc.
- Cell Wall: This is a rigid layer surrounding the cell made of cellulose, it gives the plant its shape and prevents it from bursting.
- Chloroplasts: They are sacs which contain chlorophyll which is a green pigment that traps sunlight for photosynthesis.
- Vacuole: This is a large room in the center of the cell, it stores sugars and salts and controls movement of water in and out of the cell.
Animal cells store sugars in glycogen form but plant cells store it as starch.
Animal cells have an irregular shape but plant cells have a regular shape.
Both types of cells contain Mitochondria these are structures that convert chemical energy in foods to energy that could be used in moving, dividing, etc., it is evidence that the cell is an Active Cell.
Feature
Cell wall Chloroplast Vacuole Food stored within Carbohydrates Protein Fats Shape Size |
Plant cell
Present and made from cellulose Present Present Starch, glucose Can store protein Oil Regular shape because of cell wall Large |
Animal cell
Absent Absent Absent Glycogen Can not store protein Fats Irregular shape Small |
Specialised Animal Cells
Red Blood Cells: Red blood cells are found in the blood of animals, its function is to transport oxygen from the lungs to all the body cells, and carbon dioxide from the body cells to the lungs.
They are adapted by four ways: They have a biconcave disc shape that gives it a large surface area to carry more oxygen.
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Muscle Cells: They are cells found in muscles in animals, they contract and relax together to move the organisms.
Their function is to contract to support and move the body. They are adapted by two ways, First, Is that they are made of contractile filament to help in contraction. Second is it contains lots of mitochondria to supply the cell with energy. |
Ciliated Cells: Ciliated cells are present in the trachea and bronchi of out respiratory system.
Their function is to use their cilia to move the mucus up the trachea to the throat. The mucus traps bacteria and dust particles. When it reaches the throat, mucus is swallowed to the stomach where the acid kills the bacteria. They are adapted by the tiny hair like projections called cilia which sweeps the contaminated mucus upwards. The mucus is secreted by goblet cells which are next to cilliated cells. |
Specialised Plant Cells
Root Hair Cells: These are cells situated in the roots of plants. They contain no chloroplasts.
Their function is to absorb water and minerals from the soil. And to anchor the plant in the soil. They are adapted by 3 ways. One, they have an extension that increases the surface area for more water intake. Two, they have a large number of mitochondria for respiration to become more active. Three a concentrated vacuole to help absorbing water by osmosis. |
Xylem Vessels: It transports water and minerals to the plant. The xylem cells are dead and are made of long hollow tubes running throughout the root, stem, and leaves. It has thick cell walls.
Their function is to transport water and minerals from the roots to the leaves and the rest of the plant through the stem. And to support the plant. Phloem cells: They transport sugar and amino acids to the body from the place they were made (the leaf). The phloem cells are long cells joined together. The cell wall where 2 phloem cells join together has holes which allows the cytoplasm of both cells to communicate passing down the dissolved food. |
Animal Tissue
Skeletal tissue: Supports and protects softer tissues and allows for movement Blood: Transports substances around the body Nervous tissue: Sets up nerve impulses and transmits them to the rest of the body. Epithelium: Lines tubes such as the gut and covers surfaces such as the skin Connective tissue: Binds and strengthens other tissues such as tendons Muscle tissue: Contracts to support and move the body Plant Tissue Mesophyll: Photosynthesis Strengthening tissue: Supports/holds up the plant Epidermis: Protects against water loss, and may be involved in absorbtion of water and ions Parenchyma: Fills spaces between other plant tissues and may be involved for storage Vascular tissue: Transports materials through plant body |