B5 Keywords - 21st C Science

Keywords that need to be known for B5

OCR Biology, 21st Century Science

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  • Created on: 30-05-11 17:44
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Keywords for B5
21st Century Science OCR
Amino Acids
Amino Acids are the small molecules which are joined up in long chains to make proteins. All the
proteins in living things are made from 20 different amino acids joined in different orders.
A group of proteins made by white blood cells to fight dangerous microorganisms. A different
antibody is needed to fight each different type of organism. Antibodies bind to the surface of the
microorganism, which triggers other white blood cells to digest them.
A plant hormone that affects plant growth and development. For example, auxin stimulates growth
of roots in cuttings.
Base Paring
The bases in a DNA molecule (A, T, C, and G) always bond in the same way. A and T always bond
together so does C and G.
Long, thin, thread-like structures in the nucleus of a cell made from a molecule of DNA. Chromosomes
carry the genes.
A shoot or leaf taken from a plant, to be grown into a new plant.
How an organism changes as it grows and matures. As a zygote develops, it forms more and more
cells. These are then organised into different tissues and organs.
Double Helix
The shape of a DNA molecule, with two stands twisted in a spiral
Embryonic Stem Cells
Embryonic stem cells are stem cells that have not yet been specialized. All of the genes in the cell are
switched on.
A protein that catalyses (speeds up) chemical reactions in living things
An unborn baby, still in the uterus at the stage of about two months. At this stage the fetus has the
main organs.
The sex sells that fuse to form a zygote. In humans the gametes are the sperm cell and the egg cell.
A section of DNA giving the instructions for a cell about how to make one kind of protein.
Gene Switching
Genes in the nucleus of a cell switch off and are inactive when a cell becomes specialized. Only genes
which the cell needs to carry out its particular job stay active.
Genetic Variation
Differences between individuals caused by differences in their genes. Gametes show genetic
variation, they all have different genes.
Cell division that halves the number of chromosomes to produce gametes. The four new cells are
genetically different from each other and from the parent cell.
Meristem Cells
Unspecialized cells in plants that can develop into any kind of specialized cell.
An organelle in plant cells where respiration takes place

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Cell division that makes two new cells identical to each other and the parent cell
messenger RNA, a chemical involved in making proteins in cells. The mRNA molecule is similar to DNA
but single stranded.…read more


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