Biology Key Words

Question	Answer
Enzymes (Inside Body Cells)	They act as biological catalysts to speed up the useful reactions.
Catalyst	A substance that increases the speed of a reaction, without being changed or used up in the reaction.
Denatured	If an enzymes shape is changed due to temperature or PH it won't work any more: it has been denatured.
Digestive Enzymes	They break down big molecules into smaller ones that are able to pass easily through the walls of the digestive system.
Amylase Enzyme	Converts starch into sugars like maltose and dextrins. It does this in the salivary gland, the small intestine and the pancreas.
Protease Enzyme	Converts proteins into amino acids. It does this in the stomach where it is called pepsin, the small intestine and he pancreas.
Lipase Enzyme	Converts lipids into glycerol and fatty acids. It does this in the pancreas and the small intestine.
Lipids	Lipids are fats and oils.
Enzymes (In the Digestive System)	They are produced by specialised cells in glands and in the gut lining. Different enzymes caltalyse the breakdown of different food molecules.
Respiration	The process of releasing energy from glucose, which goes into every cell.
Aerobic Respiration	Respiration using oxygen. It is the most efficient way of releasing energy from glucose and happens all the time in plants and animals. Most of these reactions take place in the mitochondria.
Glycogen	Some glucose is stored as glycogen. It is mainly stored in the liver but each muscle has it's own supply. During vigorous exercise some of the glycogen is converted back into glucose to provide more energy.
Anaerobic Respiration	It means without oxygen and is the incomplete breakdown of glucose, which produces lactic acid.
Oxygen Debt	Repaying the oxygen you didn't get to your muscles in time. This means you have to keep breathing hard for a while after you stop exercising.
Biological Detergents	Enzymes, mainly proteases and lipases, are the biological ingredient ideal for removing stains like food and blood.
DNA	DNA contains all the instructions to put an organism together and is found in the nucleus. It also determines what protein the cell produces which in turn determines what type of cell it is.
Chromosomes	Really long molecules of DNA.
Gene	A gene is a section of DNA containing the instructions to make a specific protein. The gene simply tells which order to put the amino acids together in.
Mitosis	Making new cells for growth and repair. A body cell divides to make new cells identical to the original with the same amount of chromosomes.
Asexual Reproduction	Reproducing through mitosis such as strawberry plants forming runners. The offspring have exactly the same genes so there is no variation.
Gametes	Sex cells which combine to form a new individual. They only have one copy of each chromosome so that one sex cell from the mother can combine with one from the father and still end up with the right number of chromosomes in the body cell.
Sexual Reproduction	Reproduction through meiosis - two gametes joining together. This form of reproduction forms variation because the new individual has a mixture of two sets of chromosomes.
Stem Cells	Undifferentiated cells which can develop into any type of cell depending on the instructions given.
23rd Pair of Chromosomes	These are labelled either XX, a girl, or XY, a boy. One of the letters is from the mother, X, and the other is from the father, X or Y.
Alleles	Alleles are different versions of the same gene. (Gametes only have one allele.) In genetic diagrams letters are used to represent alleles.
Homozygous	When an organism has two alleles for a particular gene the same.
Hetrozygous	When two alleles for a particular gene are different.
Dominant Allele	When the two alleles are different only one can determine the characteristic present - this it the dominant allele. (Often shown using a capital letter.)
Recessive Allele	The allele of which characteristic is not shown when two alleles are different. A recessive allele is only shown when both alleles are recessive. (Often shown a a lower case letter.)
Cystic Fibrosis	A genetic disorder of the cell membrane resulting in the body producing a lot of thick sticky mucus in the air passages and in the pancreas. It is caused by a recessive allele which means for a child to have it both parents have to either be carriers of sufferers.
Polydactyly	A genetic disorder where a baby is born with extra fingers of toes. It doesn't usually cause any other problems so isn't life-threatening. This disorder is caused by a dominant allele so can be inherited even if only one parent has it.
Genotype	What alleles you have, e.g. BB, Bb, bb.
Phenotype	The actual characteristic, e.g. blue eyes.
Fossils	The remains of organisms from many years ago. They form in rocks in three ways.
Gradual Replacement by Minerals	Things like teeth, shells and bones don't decay easily and so last a long time when burried eventually being replaced by minerals as they decay. The surrounding sediment also turns to rock but the fossils stay distinct.
Casts and Impressions	When an organism is burried in soft material like clay the clay later hardens around it as it decays. This leaves a cast of the organism such as a burrow or footprint in cement.
Preservation	In amber and tar pits there is no oxygen or moisture so decay microbes can't survive meaning there is no decay. In glaciers it is too cold for decay microbes to work and peat bogs are too acidic.
Extinction	This happens if you can't evolve quick enough.
Species	A group of similar organisms that can reproduce to give fertile offspring.
Speciation	The development of new species. It occurs when populations of the same species become so different that they can no longer breed together to produce fertile offspring.
Isolation	When populations of a species are separated. This can happen due to a physical barrier such as a flood or an earthquake.
Natural Selection	This would be caused due to conditions on either side of the barrier being different resulting in different characteristics becoming more common in each population. Eventually the different populations will have changed so much they won't be able to breed together because they have become separate species.
Nucleus	Contains genetic material that controls all the activities of the cell.
Cytoplasm	Gel like substance where most of the chemical reactions happen. It contains enzymes that control these chemical reactions.
Cell Membrane	Holds the cell together and controls what goes in and out.
Mitochondria	These are where most of the reactions for respiration take place. Respiration releases energy that the cell needs to work.
Ribosomes	These are where proteins are made in the cell.
Cell wall	(Only in plant cells.) It is made of cellulose, and supports and strengthens the cell.
Permanent Vacuole	(Only is plant cells.) Contains cell sap, a weak solution of sugar and salts.
Chloroplasts	(Only in plant cells.) These are where photosynthesis occurs, which makes food for the plant. They contain a green substance called chlorophyll.
Yeast	Yeast is a microorganism which has a nucleus, cytoplasm and a cell membrane surrounded by a cell wall.
Bacteria	Bacteria are single celled microorganisms with cytoplasm and a cell membrane surrounded by a cell wall. The genetic material floats in the cytoplasm because bacteria cells don't have a nucleus.
Diffusion	The net movement of particles from an area of high concentration to an area of low concentration.
Guard Cells	Special cells that open and close the stomata in a leaf.

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	Created by Becca Westwell about 9 years ago