Cell structure, specialization, movement in and out of cells

• Cell membrane - made of a double layer of fat and some proteins. holds together the cell contents
• Cytoplasm - jelly-like substance; its main component (around 70%) is water. Contains many dissolved substances, such as salts, sugars and amino acids.
• nucleus - rounded organelle. It contains chromosomes, which are made of DNA. Controls all the activities of the cell
• DNA - carries genetic information in the form of genes
• cell wall - mostly made of cellulose fibres, which form a mesh around the outside of the cell membrane. These fibres are slightly elastic but they are tough. They provide shape and support to the cell and prevent it from bursting when it absorbs water. Fully permeable
• central vacuole - contains a watery fluid called cell sap; it also contains some chemicals, such as mineral salts, lipids, proteins and pigments. Helps the cell to stay rigid.
• chloroplasts - They are green because they contain many chlorophyll molecules; a pigment that traps light energy and converts it to chemical energy. This energy is used to carry out photosynthesis
• mitochondrion - A significant part of aerobic respiration (breakdown of glucose in the presence of oxygen). The energy released drives many chemical reactions inside the cell.
• vesicles - Stores and transports cell products.
• ribosomes and endoplasmic rectulum - Ribosomes are the site of protein synthesis
• root hair cell - absorption of water and minerals from soil. The finger-like extension increases the surface area for absorption
• palisade mesophyll - photosynthesis. contains most of the chloroplasts in the leaf which maximize energy production during photosynthesis.
• Ciliated epithelial cell - Sweeps mucus upwards in trachea and bronchi. Cilia are hair-like extensions which are constantly moving. They sweep mucus upwards, away from the respiratory system.
• red blood cell - transports oxygen from lungs to body cells. Its biconcave shape increases the surface area for oxygen to move into or out of the cell. The cell has no nucleus, so there is more room in the cytoplasm for many haemoglobin molecules. (red pigment which transports oxygen)
• egg cell - The cytoplasm of the cell contains yolk. This is a food store for the new individual to use in the first stages of its development.
• sperm cell - The cell has a long tail. It uses this tail to swim to meet the egg and fertilise it.
• Turgid


  Swollen due to a high-water content
• Turgor pressure


  Pressure on the cell wall from the cell membrane. This is a result of cell becoming turgid as water moves into the cell via osmosis
• Flaccid


  Water moves out the cell via osmosis. cell shrinks but cell membrane doesn't peel away from cell wall
• Plasmolysis


  Too little water in cells. in plant cells, cell membrane peels away from cell wall
• Water


  • Provides support for the cell through maintaining turgor pressure
  • Provides medium for metabolic reactions
  • Maintains optimum temperature for enzyme reactions
• Isotonic solution


  A solution with the same water potential as the contents of the cells