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Biology- cell structure and transport - Coggle Diagram
Biology- cell structure and transport
Cell structure
Plant cell
additional structures:
Chloroplasts
- absorb light energy for photosynthesis
Cell wall
- strengthens the cell and supports the plant
Permanent vacuole
- filled with cell sap to help keep the cell turgid.
Animal cell
:
Cytoplasm
- where most of the chemical reactions happen
Nucleus
- contains genetic material which controls the cell’s activities
Cell membrane
- controls the movement of substances in and out of the cell
Mitochondria
- where most energy is released in respiration
Ribosomes
- where protein synthesis happens
Cells, tissues and organs
Organells -> cells -> tissues -> organs -> organ systems
Organelle
- cell structure that is specialised to carry out a particular function or job
Cell
- basically structural and functional unit of a living organism
Tissue
- group of cells with similar structures, working together to perform a shared function
Organ
- structure made up of a group of tissues, working together to perform specific functions
Organ systems
- group of organs with related functions, working together to perform body functions
Examples of specialised cells and magnification
Specialised cells are adapted to their function. for example, muscle cells bring parts of the body closer together. they contain protein fibres that can contract when energy is available, making cells shorter.
Animal cells:
Cilited cell
- push and move mucus from one place to another. The cilia in the respiratory tract move mucus containing trapped microbes and dust. Has a thin layer of tiny moving 'hairs' called cilia.
Red blood cells
- transport oxygen from the lungs to the body tissues for respiration. Contains haemoglobin, a pigment that carries oxygen, does not contain a nucleus, which increases the volume of haemoglobin in the cell and very flexible so it can move through narrow blood vessels.
Plant cells:
Root hair cell
- absorb water and minerals from the soil water. Has a long thin extension, the root hair, which provides a large surface area for absorption to happen.
- transport water in the plant and supports the plant. Xyclem cells have no cytoplasm and no end walls. They for a continuous tube in which water can pass freely. The cell walls are strengthened by lignin, a tough waterproof substance.
Calculating magnification- measured size / actual size
Calculating actual size- measured size / magnification
Diffusion and active transport
Diffusion is the net movement of particles from an area of high concentration to an area of low concentration down the concentration gradient. For example, oxygen moves from a high concentration in the lungs to a low concentration in the blood.
Factors affecting rate of diffusion:
Surface area
- as the surface area increases, the rate of diffusion increases. This is because there is more space available for the substances to diffuse though.
Temperature
- as temperature increases, the rate of diffusion increases. This is because the molecules gain kinetic energy and thus move faster.
Concentration gradient
- as the concentration gradient increases, rate of diffusion increases.
Diffusion distance
- a greater diffusion distance slows the rate of diffusion as molecules must travel further.
Substances (oxygen, carbon dioxide, water, dissolved nutrients and urea) can move into and out of a cell or organism via diffusion. This happens across the cell membrane which is selectively permeable.
Active transport is a process that is required to move molecules against a concentration gradient. The process requires energy.
Active transport in plants- For plants to take up mineral ions, ions are moved into root hairs, where they are in a higher concentration than in the dilute solutions in the soil. Active transport then occurs across the root so that the plant takes im the ions it needs from the soil around it.
Active transport in animals- In animals, glucose molecules have to be moved across the gut wall into the blood. The glucose molecules in the intestine might be in a higher concentration than in the intestinal cells and blood- for instance, after a sugary meal- but there will be times when glucose concentration in the intestine might be lower.
All the glucose in the gut needs to be absorbed. When the glucose concentration in the intestine is lower than in the intestinal cells. movement of glucose involves active transport. The process requires energy produced by respiration.
Osmosis
Osmosis is the net movement of water molecules through a partially permeable membrane.
Key terms
:
Turgid
- cells are described as turgid when they are swollen due to a high-water content.
Turgor pressure
- the pressure on the cell wall from the cell membrane pushing upon it. This is a result of the cell becoming turgid as water moves into the cell via osmosis.
Flaccid
- occurs when water moves out of the cell via osmosis. The cell shrinks but the cell membrane does not peel away from the cell wall. If more water leaves the cell, it becomes plasmolyzed.
Playsmolysis
- occurs when there is too little water in cells. In plant cells, the cell membrane peels away from the cell wall.
Water moves in and out of cells through the cell membrane via osmosis. Water provides support for the cell through maintaining the turgor pressure. Water has a high specific heat capacity, this acts as a temperature buffer and this helps because it maintains the optimum temperature for enzyme reactions.
Water particles diffuse from regions of high-water potential to regions of low water potential. When the cell is more concentrated than the surrounding cells, water molecules diffuse into the cell via osmosis, making it turgid. When it is less concentrated than the surrounding cells, water molecules will leave the cell, making it flaccid and leading to plasmolysis. This effect can be investigated by placing cells in solutions to different concentrations.
