Topic 2-Glossary Flashcards
Mucus
A thick slimy fluid secreted by the cells lining many organs. Mucus is produced for example, by cells in the gas-exchange system, the digestive system and the reproductive system. Apart from water, its main component is a protein called mucin. Mucus acts as a lubricant and a protective layer.
Cilia
Hair-like extensions of the cell membrane in cells lining the airways, that help keep microbes/dust/particles out of the lungs
Epithelial
Cells which form the outer surface of many animals, line cavities and tubes and cover the surface of internal organs
Epithelium
Epithelia, cells working together form this tissue
Columnar epithelium
Column-shaped epithelial cells, often with mircrovilli on free surface
Trachea
Vertebrate windpipe. Kept open by C shaped rings of cartilage, with smooth muscle in its wall and ciliated lining.
Bronchus
One of the large airways that take air into and out of the lungs. The trachea splits into 2 main bronchi, one going to the right lung and one to the left. Each bronchus has cartilaginous plates and smooth muscle in its walls and a ciliated lining with mucus producing cells.
Bronchiole
Small airway ending in alveolus. Contains smooth muscle abundantly in the walls, lacks cartilage and mucus glands of bronchi.
Diaphragm
A thin sheet of muscle situated between the lungs and the abdominal organs of a mammal. Contraction of this muscle causes the diaphragm to flatten and air to be drawn into the lungs.
Pathogen
An organism capable of causing disease
Alveoli/Alveolus
The tiny air sacs in the lungs where gas exchange takes place. The alveoli are lined by a layer of cells known as squamous epithelium. These cells are very thin and this helps to ensure efficient diffusion of oxygen from the alveoli into the blood and of carbon dioxide from the blood into the alveoli. The total surface area of all the alveoli in the lungs is very large. This large surface area also helps to ensure efficient diffusion. Also contains surfactant producing cells.
Macrophages
These cells remove dust and debris and bacteria
Concentration gradient
A concentration gradient occurs when a substance (e..g. oxygen) exists at a higher concentration in one place than another, with intermediate concentrations in between.
Surface area to volume ratio
Calculated by dividing the total surface area of a cell or organism by its volume. As an organism gets larger its surface area to volume ratio decreases.
Gas exchange surface
The layer across which oxygen and carbon dioxide are exchanged
Fick’s Law
A law which relates some of the factors affecting the rage of diffusion across a gas exchange surface. Fick’s law states that rate of diffusion is proportional to : surface area x difference in concentration/thickness of gas exchange surface
Amine Group
NH2 attached to central carbon
Carboxylic acid group
COOH attached to central carbon
Residual (R) group
The variable side chain - varies between different amino acids. Attached to the central carbon.
Peptide bond
The bond joining 2 amino acids in a protein. Amino acids together by condensation. When a protein is digested, the peptide bonds are broken down by hydrolysis.
Primary structure
The sequence of amino acids in a polypeptide chain which determines the final (tertiary) shape of a protein.
Secondary structure
Interactions between the R groups cause the polypeptide chain to form some three dimensional shapes (2 main types: a - helix and B - pleated sheet) prior to folding into the final specific three dimensional shape.
a - helix
Common secondary structure where the chain of amino acids is coiled around its long axis, stabilised by hydrogen bonds between the C=O of the carboxylic acid and the -NH of the amine group of different amino acids.
B - pleated sheet
Common secondary structure where the polypeptide chain folds back on its self in the same plane, also stabilised by hydrogen bonds.
Tertiary structure
The specific three-dimensional structure of a protein. The tertiary structure of a protein is very important in determining its function.
Quartenary structure
A protein made of several polypeptide chains held together e.g. haemoglobin
Globular protein
Proteins which assume a compact spherical shape. Functions of these proteins often rely on their specific shape allowing interaction with other molecules e.g. enzymes, antibodies.
Fibrous protein
Proteins which remain as long chains, often cross-linked together for extra strength . Structural function.s
Phospholipid
A phospholipid molecule is a lipid with two distinct sections. It has a head region consisting of glycerol and a phosphate group. This part of the molecule is attracted to water. The other end consists of 2 fatty acid tails. This end of the molecule repels water. Phospholipids are important components of cell membranes where they are arranged in a bilayer with the heads pointing outwards and the tails pointing towards each other
Polar
A molecule or part of a molecular is polar when the sharing of the electrons within it is not quite even; one end becomes slightly positive and the rest is slightly negative
Hydrophilic
Water-attracting. For instance, in a phospholipid molecule the phosphate group attracts water molecules and the fatty acid part of the molecule repels water molecules.
Hydrophobic
Water-repelling. in a phospholipds molecule the fatty acid part of the molecule repels water molecules and the phosphate group attracts water molecules
Micelle
A phospholipid monolayer that has formed a spherical shape so that the hydrophobic fatty acid tails point inwards and the hydrophilic phosphate head points outwards..
Fluid mosaic model
Name given to current model of the structure of the unit (cell) membrane, composed of a phospholipid bilayer (which gives fluid properties to the membrane) in which proteins may be imbedded (giving the mosaic like effect).
Glycoprotein
A protein molecule with a polysaccharide attached.
Glycolipid
A molecule consisting of a lipid and a carbohydrate. They form part of the cell-surface membrane. They have similar functions to glycoproteins; for example, they help cells to bind to each other to form tissues.
Channel protein
Molecules that span the cell membrane. They have water-filled pores. They have a specific shape so only molecules/icons with matching shapes can pass. Some of the pores can be opened or closed.
Diffusion
The movement of molecules from where they are in a high concentration to where they are in a lower concentration. Small molecules such as oxygen diffuse through cell membranes into cells.
Facilitated diffusion
Transport across a cell membrane that is passive (requires no additional energy), moves substances down their concentration gradient (from high to low) and uses carrier Large molecules and ions can only cross cell membranes with the aid of carrier proteins.
Carrier protein
Proteins within cell membranes that have specifically shaped binding sites for ions or molecules that are required to cross membranes.
Osmosis
Osmosis is a special sort of diffusion. It is the net movement of water from a dilute solution (a high concentration of water molecules) to a concentrated solution (a low concentration off water molecules) through a partially permeable membrane. Alternatives: “down a water concentration gradient” or “from a high water potential too a low water potential.”
Osmotic pressure
Pressure which causes the movement of water from a solution of higher water potential/lower solute concentration to solution of lower water potential/ higher solute concentration
Water potential
A measure of the ability of water molecules to move. Water always moves from a higher water potential to a lower water potential. A solution in which there is a higher concentration of free water molecules has a higher water potential than one which has a lower concentration of free water molecules. In osmosis water moves from the solution with the higher water potential through a partially permeable membrane into the solution with the lower water potential.
Active transport
Movement of substances across a membrane against a concentration gradient. Active transport involves the use of specific carrier proteins in cell membranes. It also requires energy in the form of ATP.
ATP
Adenosine triphosphate (ATP) is an important molecule found in all living cells. IT is involved in the transfer of energy. Most of the ATP in a cell is produced from ADP and phosphate using energy transferred during the process of respiration. When ATP is broken down, ADP and phosphate are produced and a small amount of energy is made available. This energy may be used in active transport; to synthesise large molecules such as proteins from smaller ones such as amino acids; and for movement in cells such as sperm and muscle cells.
Exocytosis
A process which involves the transport of substances out of cells. Proteins made in a cell are often modified in the Golgi apparatus. Vesicles are pinched off from the Golgi apparatus and these contain the modified protein. The vesicles move through the cytoplasm and fuse with the cell surface membrane, releasing the protein from the cell.
