The phospholipids make the basic bag. The proteins are found around the holes and help move molecules in and out of the cell. Cytoplasm This is a fluid that contains a simple mixture of chemicals and nutrients that are the basic living materials for the cell. All organelles are suspended within this. It moves materials around within the cell.
The cell membrane surrounds the cytoplasm. Nucleus: The nucleus is the central part of a cell, it is usually darker than the rest of the cell as it absorbs stain quickly. It is usually the largest structure inside the cell. Most cells have a central, single spherical nucleus but there are many variations. The nuclear membrane has a similar structure to the cell membrane but it contains gaps which allow protein to pass through.
| Goigi Apparatus | The main function of the Golgi apparatus is to be responsible for handling the macromolecules that are required for proper cell functioning | It packages and ships molecules made in the ER. | Lysosome | Lysosomes are spherical bag like structures that are bound by a single layer membrane, however, the lysosome shape and size may vary to some extent in different organisms. The lysosome size ranges between 0.1 to 1.2μm. | Lysosomes function as the digestive system of the cell, serving both to degrade material taken up from outside the cell and to digest obsolete components of the cell itself. | P1 tasks 2 Organs | Anatomy | Physiology
The nucleus regulates all cell activity and is bounded by a double membrane called the nuclear envelope, this membrane separates the contents of the nucleus from the cytoplasm. The Nucleus have two major functions. It stores the cell’s hereditary material, or DNA and it co-ordinates the cell’s activites, which include metabolism, growth, protein synthesis, and reproduction (cell division). ‘Mitochondria are the cell’s power producers’ Bailey, About.com. They convert energy into forms that are usable by the cell.
P2 Outline the Main Tissues Of The Body Epithelial Epithelial tissue is basically the linings of both the internal and external surfaces of the body and can be divided into two groups. The groups depend upon the number of layers of which it is composed. These two groups are simple epithelial and compound. Simple squamous are thin, flat plates and their main function is osmosis (which is the passage of water molecules from a region of low concentration to one of high concentration through a semi-permeable membrane) and diffusion (which is the passage of molecules from a high concentration to a low concentration). They form the lining of cavities such as the mouth, blood capillaries, heart and lung alveoli and make up the outer layers of the skin.
Parasites are part of a large group of organisms called eukaryotes. They are different from bacteria & viruses because their cells share many features with human cells including a defined nucleus. They are usually larger than bacteria, although some environmentally resistant forms are nearly as small. Some parasites only replicate within a host organism, but some can multiply freely in the environment. Parasites can be made up of one cell, as in the case of Giardia, or many cells, as with parasitic
| | | A) | endoplastic reticulum | | | B) | microtubules | | | C) | cytoplasm | | | D) | mitochondria | | | | | | Feedback: The cell's chemical processes take place in a semifluid material called the cytoplasm. This material provides an ideal environment for organelles because of its fluidity. | | 7 CORRECT | | This shows an example of endoplasmic reticulum. What is the significance of its structure? | | | A) | provides a location for DNA production | | | B) | helps decrease surface area | | | C) | allows selective permeability of cell membrane | | | D) | facilitates breakdown of chemical bonds | | | | | | Feedback: The pleats and folds of the endoplasmic reticulum provides a large surface area where cellular functions, such as breaking chemical bonds, can take place.
The third type of squamous tissue is transitional, this is grouped with the stratified. This is found in the bladder or uterus & is designed to withstand the action of urine. Columnar or glandular – These are single layered cylindrical shaped cells. These cells secrete mucous which assist with lubricating the oesophagus to help with passing of food. These cells are found lining food passages.
The cell (or plasma) membrane is the cell’s most important organelle – it controls how substances can move in and out of the cell and is responsible for many of the cell’s properties. The plasma membrane is composed of phospholipids, carbohydrates and proteins arranged in a fluid-mosaic structure. The individual phospholipid molecules can move relative to each other this gives the membrane a “fluid” structure that constantly changes shape, the proteins that are embedded in the phospholipid bilayer vary in shape, size and pattern in the same way as tiles in a mosaic. The phospholipids are arranged in a bilayer, with their polar, hydrophilic phosphate heads facing inwards (which interact with the water in the cytoplasm) on one layer and facing outwards (these interact with the water that surrounds the cell) on the other layer, and their non-polar, hydrophobic fatty acid tails of both phospholipid layers point into the centre of the membrane towards each other in the middle of the bilayer (so they are protected from the water on both sides). Lipid-soluble material moves through the membrane via the phospholipids; so they allow lipid-soluble substances to enter and leave the cell, prevent water-soluble substances entering and leaving the cell.
There are some very general rules to follow when trying to decide if something is living, or non-living. 1. Living things are composed of cells: * Single-cell organisms have everything they need to be self-sufficient. * In multicellular organisms, specialization increases until some cells do only certain things. 2.