Task 1 A) The Eukaryotic cell Organelles: Function: Nucleus The nucleus controls the cell. It is the largest organelle and contains genetic information in DNA which are organized into chromosomes. The nucleus is made of chromatin. Cell membrane The cell membrane is very thin (about 7nm) and it controls the exchange between the cell and its surrounding environment. It has bilayers of phospholipid molecules. It is fluid to allow the exit and entry of molecules. It allows some substances (nutrients) so it’s selectively permeable. Nucleolus This organelle synthesizes ribosomal RNA (rRNA); and makes ribosomes. Cytoplasm It is a watery medium and the location of all chemical reactions. It contains many enzymes; hormones and sugars. It is the fluid in which other organelles are suspended and it provides structure and strength to the cell. Mitochondria This is the site of aerobic respiration and its inner membrane is highly folded to form cristae which is a large surface area for attachment of enzymes. Rough ER It synthesizes and transports protein and has ribosomes attached to it. Smooth ER Unlike the Rough ER it does not have ribosomes attached to it and it makes lipids and steroids. It also helps detoxify drugs and poisons. Ribosome The ribosome is made of RNA and protein; It has a large and a small subunit and it is the site of protein synthesis. It can be found floating free in the cytoplasm or attached to the rough ER Golgi apparatus It is a stack of fattened membranes known as cisternae and formed from the ER. It collects and modifies protein molecules from the ER and packages them and sends them off in vesicles. Microtubules The have a diameter of 7nm and has thin rods made of actin which is a protein. It provides shape to the cell and assists with transport of materials around a cell. Centrioles They are hollow cylinders formed from microtubules and served to form spindles of fiber during cell division which moves chromosomes. Lysosomes Lysosomes are organelles which play the key role of waste removal in the digestion inside a cell. They contain digestive enzymes. They digest excess or worn out organelles, food particles and engulf viruses and bacteria. They are surrounded by a membrane made of phospholipids which keeps the lysosomes separated from the membrane’s external area. Lysosomes have a size ranging from 0.1 to 1.2 micrometers. Vesicles They are used for the movement of molecules around the cell. They are cellular organelles that are composed of a lipid bilayer. They are used to transport material from one place to another. Vesicles also function in metabolism and enzyme storage as well. B) the prokaryotic cell: Organelles: Function: Nucleoid It is the region where the DNA lies Cell wall It helps to maintain the overall shape of the cell. Capsule It is a protective shell outside the cell wall which helps to prevent dehydration. Plasmid These are smaller loops of DNA which can produce extra proteins Mesosome This is where respiration takes place Pili It is used for locomotion or to attach onto target cell receptors. Flagella They are used for movement. Ribosome They are used to make protein. Task 3 unit 11 p2 Tissue types? Diagram/micrograph? Structure? Function? Epithelial tissue?? A single layer of long epithelial cells can be observed and here you can also see compacted rows appearing in columns.? Adapted for absorption and secretion of enzymes and proteins.? Muscle Tissue? ? ?It has a varying length of myofibrils which are low in quantity here compared to the striated muscle tissue. The Smooth muscle tissue is used to form organs within the body e.g. the stomach Adipose? ? It is a loose fibrous connective tissue containing many cells called adipocytes. Its main role is to store energy in the form of fat, although it also cushions and insulates the body. It is primarily located under the skin but can also be found in internal organs They are specialised for the handling of fat in the body It secretes a number of peptide hormones, including leptin, several cytokines and acylation-stimulating protein (ASP), angiotensinogen, , adiponectin, resistin etc., and also produces steroids hormones Connective Tissue? ? The have a circular and almost concave shape, they are found without a nucleus and have a very fine membrane. It has thicker, denser fibres and fewer cells. The matrix is made up mostly of collagen fibres, with fibroblasts arranged in rows. They are made of different type of fibres: Collagen fibres are very strong and provide flexibility. Elastic fibres are very stretchy and assume their original shape after being stretched. Finally, reticular fibres are very thin and provide support for many soft organs and blood vessels. Used to transport oxygen around the body. They have a large surface area to help carry large volumes of oxygen. TASK 4: During development, cells undergo certain changes which makes them change from one type of cell to another due to the genes within these cells switching on or off More often, it is a less specialized cell changing into a more specialized one. This process is known as cell differentiation. This allows the cell to have a different shape and a different amount of organelles inside. They exist many different types of differentiated tissues and I will now proceed to naming a few of them. Ciliated epithelium: the function of ciliated epithelium is to protect some structures of the body from wear and tear by moving secretions and foreign bodies away with a certain direction and speed using the hair like structure that covers surface which is known as “cilia”. The cilia on the surface wafts away dust and bacteria. In order to do this, the cell contains a lot of mitochondria to produce the energy for the cilia to move. It has goblet cells; whose function is to produce the mucus which traps dust and bacteria. In order to produce this mucus, the goblet cells contain a lot of mucins, large glycoproteins formed mostly by carbohydrates. Skeletal muscle: the function of the striated skeletal muscle is to cause movement. It can be found in many parts of the body and, where it performs voluntary work. Most skeletal muscles are attached to bones by bundles of collagen fibers known as tendons. A skeletal muscle refers to multiple bundles of cells called muscle fibers (fascicles). The fibers and muscles are surrounded by connective tissue layers called fasciae. Muscle fibers are cylindrical, and have more than one nucleus. It has multiple mitochondria to meet energy needs, the mitochondria also function as an insulin for the muscle. Skeletal muscle cells also vary from other cells because of the myofilaments within the myofibrils. Within these fibers are proteins known as myosin and actin. The special fibers allow the skeletal muscles to contract. The myofibrils within skeletal muscle cells are divided into parts known as sarcomeres, which are the units of skeletal muscle cell contraction. Spongy bone decreases the thickness of the bone, allowing the ends of long bones to compress as the result of stresses applied to the bone. The Spongy bone is prominent in parts of the bones that are not seriously strained or where traumas arrive from many directions. They also serve as a manufacturing site for red bone marrow which is where hematopoiesis, the production of blood cells, occurs. Lymphocytes are a type of white blood cell which function as part of the immune system. Their numerous roles allow them to appropriately respond to foreign invaders in the body. Some lymphocytes work alone, while others are able to coordinate with other cells. TASK 5: Function Diagram Differences Striated muscle tissue It serves to move the skeleton under conscious control, including movement of limbs, fingers, toes, neck etc… It also functions to move the tissues of facial expressions under conscious control, e.g. ability to smile and to frown. Striated muscle is composed of muscle fibers, made up of thick and thin filaments, but smooth muscle has interconnected cells to form layers. Skeletal muscle is involved in voluntary movement, whereas smooth muscle serves for involuntary movement inside the body. Striated muscle tissue contains organelles such as Golgi apparatus, ER with endoplasmic reticulum, smooth endoplasmic and a lot of mitochondria which are all responsible for cellular ATP production. Smooth muscle tissue contains just about the same organelles but it is also surrounded by cell membrane and cytoplasm. Smooth muscle tissue Smooth muscles help to move food along the gastrointestinal tract as well as breaking the food down further. Smooth muscles also help with the movement of fluids through the body and the elimination of indigestible matter from the gastrointestinal system.