biology chapter 1: cell structure and organisation

• Functions: - Transports proteins made by ribosomes to the Golgi apparatus for secretion out of the cell.
• The light microscope magnifies objects up to 1000x.
• The electron microscope magnifies objects to more than 200,000x.
• A camera can be fitted to either type of microscope to take pictures called micrographs.
• Longitudinal section: Cutting along the length of the cell
• Transverse section: Cutting across at right angles to the longitudinal plane of the cell.
• Red blood cell
• Muscle cell
• Root hair cell
• Chloroplasts are only found in plant cells and contain green pigment known as chlorophyll.
• Chloroplasts are required for photosynthesis.
• Ribosomes are small and round structures either attached to the membrane of the endoplasmic reticulum or lie freely in the cytoplasm.
• Ribosomes are needed to synthesise proteins in the cell.
• RER (rough endoplasmic reticulum) ribosomes make proteins that are usually transported OUT of the cell.
• Free ribosomes make proteins that are used within the cytoplasm of that cell.
• Cells are the basic building blocks of an organism.
• A living tissue is made from a group of cells with a similar structure and function, which all work together to perform a specific function.
• An organ is made of a group of different tissues, which all work together to perform a specific function.
• An organ system is made of a group of different organs, which all work together to perform a specific function.
• An organism is made up of several different systems.
• All living things are made of cells and cells are the building blocks of life.
• Most cells are too small to be seen with our eyes alone.
• Many chemical reactions occur continuously inside these cells to allow the organism to function.
• The cell takes in raw materials and processes these materials to make new molecules.
• The new molecules are either used by the cell itself or transported to other parts of the organism.
• Animal cell: Absent Plant cell: Present.
• The nucleus is a spherical body which is surrounded by a nuclear envelope, consists of a dense material called nucleoplasm, and contains chromosomes which are a network of long-thread like structures which condense to form chromatin during cell division.
• A red blood cell has a circular and biconcave shape to increase the surface area-to-volume ratio, increasing the rate of diffusion of oxygen into and out of the RBC.
• A red blood cell contains haemoglobin, a red pigment that binds to oxygen and transports oxygen from lungs to all parts of the body.
• A vacuole is a fluid-filled space enclosed by a membrane, with animal cells having numerous, temporary, and small vacuoles, and plant cells having a large central vacuole (enclosed by a membrane known as TONOPLAST).
• A root hair cell is long and narrow to increase the surface area-to-volume ratio, enabling water and mineral salts to be absorbed at a faster rate.
• Differentiation is the process by which a cell becomes specialised for a specific function.
• A cell wall is present only in plant cells and bacterial cells, but not in animal cells.
• The cytoplasm forms the major component of the cell, contains enzymes and organelles, and enables most chemical reactions to occur here.
• The smooth endoplasmic reticulum does not have ribosomes attached to its membrane, synthesizes substances such as fats and steroids, and converts harmful substances into harmless materials (detoxification process).
• The nucleus is responsible for the synthesis of proteins required for cell growth and cell repair.
• The Golgi apparatus consists of a stack of flattened spaces surrounded by membranes, chemically modifies substances made by the RER and SER, and stores and packages these substances in vesicles for the secretion out of the cell.
• The cell wall provides a fixed shape for the plant cell and its rigidity serves as an internal support for the plant.
• The rough endoplasmic reticulum consists of a network of flattened spaces lined with a membrane, has a rough surface because ribosomes are attached to the outer surface, and its outer surface is continuous with the nuclear envelope.
• Chloroplasts are absent in root (hair) cells but present in leaf cells.