Key Definitions - Structures and Functions in living organisms Flashcards
define organelle.
a specialised structure found inside of cells, e.g. a nucleus
define cell.
the basic building blocks of all living organisms
define tissue.
a collection of cells with similar structure and function
define organs.
collection of tissues performing specific functions
define organ system.
group of organs that work together to form organisms
define cell differentiation.
the process where cells become specialised by producing different proteins
define cell membrane.
a partially permeable barrier that surrounds the cell (allows some substances to move in and out of the cell)
define cell wall.
a fully permeable outer layer found in some cells. In plants it is made from cellulose and in fungi, chitin
define chloroplast.
an organelle that is the site of photosynthesis
define cytoplasm.
contains dissolved nutrients and all of the organelles of the cell and the site of many metabolic reactions
define mitochondria.
an organelle that is the site of aerobic respiration
define nucleus.
an organelle found only in eukaryotic cells and contains the genetic material (DNA) and controls the activities of the cell
define ribosomes.
organelles that are the site of protein synthesis
define stem cells.
undifferentiated cell that can divide rapidly to produce specialised cells
define vacuole.
found in plant cells, contains dissolved nutrients and supports the shape of the cell
define lipids.
a group of molecules including fats and oils, made from fatty acid chains and glycerol containing the elements carbon, hydrogen and oxygen. Can test for them using the emulsion test.
define proteins.
large polymers made from amino acids, containing the elements carbon, hydrogen, oxygen, nitrogen and occasionally other elements like sulphur, involved in repairing and the growth of cells. Can test for them using the biuret test.
define amino acids.
the monomer from which proteins are assembled from
define starch.
a carbohydrate made from glucose monomers, containing the elements carbon, oxygen and hydrogen and acts as an energy store in plants. Can test for starch using iodine.
define glycogen.
a carbohydrate made from glucose that acts as an energy store in animals
define enzymes.
proteins that are biological catalysts that increase the rate of reactions by providing an alternative pathway with a lower activation energy
define active site.
part of the enzyme that is complementary to the shape of the substrate which can change shape if the enzyme is exposed to extreme pH solutions or high temperatures. This would result in less enzyme-substrate complexes.
define diffusion.
the net movement of substances from an area of high to low concentration, down a concentration gradient and can be across a partially permeable membrane
define concentration gradient.
the difference in concentration between two areas
define surface area to volume ratio.
the size of the object compared with the area that is in contact with the environment
define oesophagus.
a muscular tube that takes food from the mouth to the stomach
define alimentary canal.
the digestive tract running from the mouth to the anus
define peristalsis.
the contraction and relaxation of muscles all along the alimentary canal that pushes the food along
define amylase.
an enzyme produced in the salivary glands and pancreas that speeds up the breakdown of starch into maltose
define duodenum.
the first part of the small intestine where food is broken down by the pancreatic juices; lipids –> fatty acids + glycerol by lipases, proteins –> peptides/amino acids by proteases such as trypsin and carbohydrates like starch, that get broken down into maltose by amylase
define ileum.
Second part of the small intestine where the products of digestion are absorbed, adapted with one cell thick wall (short diffusion distance), high surface area (villi and microvilli) and high concentration gradient (capillaries)
define bile.
made in the liver, stored in the gall bladder and works in the duodenum where it emulsifies lipids and with pancreatic juices, neutralises stomach acid
define colon.
first part of the large intestine where water is reabsorbed
