BIOPART3

• Water is one of the more abundant molecules in living cells and the one most critical to life as we know it. Approximately 60–70 percent of your body is made up of water
• Water also attracts other polar molecules (such as sugars), forming hydrogen bonds. When a substance readily forms hydrogen bonds with water, it can dissolve in water and is referred to as hydrophilic (“water-loving”).
• Hydrogen bonds are not readily formed with nonpolar substances like oils and fats. These nonpolar compounds are hydrophobic (“water-fearing”) and will not dissolve in water.
• Acids are molecules that raise the hydrogen ion concentration when added to a solution like HCl
• bases are molecules that lower the hydrogen ion concentration when added to a solution like NaOH.
• Salts are formed from the neutralization of an acid and a base. It is important in vital processes such as irritability of muscles and nerves, growth, and repair of tissues.
• Gases are important in oxidation of food molecules to release energy and the two important gases for living organisms are oxygen and carbon dioxide.
• cell is the basic structural and functional unit of living organisms. In other words, in the hierarchy of biological organization, the cell is the simplest collection of matter that can be considered a living entity
• cell theory, one of the unifying principles of biology, states that all biological organisms are composed of cells; cells are the unit of life and all life come from preexisting life
• Unicellular organisms are those organisms made up of a single cell that carries out all of the functions needed by the organism. Some examples include bacterium (plural is bacteria), amoeba, and yeast.
• Multicellular organisms, on the other hand, are those that are made up of multiple cells.
• biconcave shape for easy passage of blood through capillaries.
• Nerve cells, on the other hand, are branched to conduct electrical impulses from one point to another, while muscle cells are long for contraction
• can actually change shape in order to engulf the microorganisms that entered and may harm the body
• microscope is a laboratory instrument used to examine objects that are too small to be seen by the naked eye.
• Microscopes were invented in 1590 and further refined during the 1600s. Cell walls were first seen on dead cells of oak bark by Robert Hooke in 1665 and living cells by Antoni van Leeuwenhoek
• The microscope must accomplish three tasks: produce a magnified image of the specimen (magnification), separate the details in the image to make it clearer (resolution), and render the details visible to the human eyes by showing the difference in brightness Biology for Health Sciences CPH Zabariza between the light and dark areas of the image (contrast). Methods for enhancing contrast include staining or labeling cell components to stand out visually
• Compound/Light microscopes are light-illuminated. The lenses refract (bend) the light in such a way that the image of the specimen is magnified as it is projected into the eye or into a camera.
• electron microscopes (EM) use a beam of electrons to illuminate the specimen. The result is an image of the specimen’s surface that appears three-dimensional. They have higher magnification and resolution
• transmission electron microscope (TEM) is used to study the internal structure of cells Th TEM aims an electron beam through a very thin section of the specimen, much as a light microscope aims light through a sample on a slide
• If we study a cell under a microscope, we would come across three features in almost every cell: plasma membrane, cytoplasm, and nucleus (in this order). Plasma membrane can interact with the external environment, cytoplasm contains the organelles, while the nucleus is in the center containing the precious genetic information about the cell
• plasma membrane is considered as the outermost layer of the cell. You may always hear that the plasma membrane is a semi-permeable membrane
• cell wall is also a covering but is only found in plants and bacteria. It functions to provide definite shape, strength and rigidity, prevent drying up of cells, and protect bacteria and plants from harmful pathogens/disease causing agents
• nucleus is a specialized structure occurring in most cells (except bacteria and blue-green algae) that is always regarded as the control center of the cell.
• The nucleus is separated from the rest of the cell by a double layer, the nuclear membrane.
• The colorless dense sap present Biology for Health Sciences CPH Zabariza inside the nucleus is known as nucleoplasm; it contains the round shaped nucleolus and network of chromatin fibers. The nucleolus functions in the production of the cell’s ribosomes. On the other hand, these fibers are composed of deoxyribonucleic acid (DNA) and protein histone. These fibers condense to form chromosomes during cell division. Chromosomes are where you can find your genes, which are portions of DNA that contain codes or instructions for making proteins.
• The cytoplasm is what you will see between the nucleus and the plasma membrane
• The cytosol is a gel-like material formed by 80% water and contains dissolved substances.
• endoplasmic reticulum is a network of tubular and vesicular structures which are interconnected with one another
• Some parts are connected to the nuclear membrane, while others are connected to the cell membrane. Two types include rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). Their difference is the presence of ribosomes. The ribosome functions as a micro-machine for making proteins for the cell. The ER in general provides internal support to the cytoplasm. However, the functions of RER and SER are different. RER, because it contains ribosomes
• Golgi bodies are organelles that function in the modification, sorting, and packing of materials synthesized in the cell
• This organelle has two ends: cis face situated near the endoplasmic reticulum and trans face situated near the cell membrane.
• Lysosomes are small, spherical, membranous sac found throughout the cytoplasm. They are filled with hydrolytic enzymes. Hydrolytic enzymes break down protein, lipids, nucleic acids, carbohydrate and fat molecules into their simplest units
• Autolysis, more commonly known as self-digestion, refers to the destruction of a cell through the action of its own enzymes
• Peroxisomes are small, membrane-bounded organelles that look very much like empty lysosomes
• Vacuoles, in general, functions in the storage of various substances but may have different roles depending on the type of organism. In animal cells, vacuoles are generally small and help sequester waste products.
• mitochondria is the powerhouse of the cell. It is bound by two membranes which is quite unusual for an organelle
• The reason for the term powerhouse is that this organelle functions in the synthesis of adenosine triphosphate (ATP) which occurs in the matrix and cristae.
• Plastids are also double membrane-bound organelles in the plant cells that primarily involved in the manufacture and storage of food
• Chromoplasts are brightly colored plastids that act as the site of pigment accumulation