Slovakia Maturita Biology key terms

A thin double layer of lipids with embedded proteins that surrounds every cell and controls which substances enter or leave it.

An organelle bounded by two membranes in which aerobic respiration takes place, producing most of the ATP a eukaryotic cell uses as energy currency.

A green organelle found in plant cells that contains chlorophyll and carries out photosynthesis, converting light energy into chemical energy stored in sugars.

A protein that speeds up a specific biochemical reaction by lowering its activation energy, and whose activity depends on temperature and pH.

Loss of a protein's three-dimensional shape caused by heat, extreme pH or chemicals, which destroys its function and is usually irreversible.

The process in which a double-stranded DNA molecule is copied before cell division, each new molecule keeping one original strand and one newly built strand.

The copying of the information in a gene from DNA into a molecule of messenger RNA, which then carries it to the ribosome.

The building of a polypeptide chain at the ribosome, where the sequence of codons on messenger RNA is read and matched to transfer RNA carrying amino acids.

A sequence of three nucleotides in messenger RNA that specifies one amino acid or signals where protein synthesis should start or stop.

Nuclear division that produces two daughter nuclei with the same chromosome number as the parent cell, used for growth and repair of body tissues.

Two successive nuclear divisions that halve the chromosome number and produce four genetically different cells, the basis of gamete formation.

Exchange of corresponding segments between homologous chromosomes during the first meiotic division, which creates new combinations of alleles on a chromosome.

One of the alternative versions of a gene that can occupy the same position on a chromosome, such as the forms giving blood group A or B.

The particular combination of alleles an organism carries for a gene or set of genes, which together with the environment shapes its observable traits.

The observable characteristics of an organism, resulting from the interaction between its genetic makeup and the conditions in which it develops.

An allele whose effect appears in the phenotype even when only one copy is present, masking the effect of the recessive allele paired with it.

An allele whose effect on the phenotype is shown only when two copies are present, because a dominant allele masks it in heterozygotes.

A permanent change in the nucleotide sequence of DNA, which may alter a protein, have no effect, or be passed on to offspring if it occurs in gametes.

A tiny infectious particle made of nucleic acid enclosed in a protein coat, which can reproduce only inside a living host cell.

A virus that infects bacteria, attaching to the cell wall and injecting its genetic material so that the host machinery makes new virus particles.

Single-celled organisms without a true nucleus or membrane-bound organelles, having circular DNA and typically a rigid cell wall.

A substance produced by one microorganism or made synthetically that kills or stops the growth of bacteria, and has no effect on viruses.

A kingdom of organisms that absorb nutrients from their surroundings, have cell walls of chitin and bodies made of thread-like hyphae, and reproduce by spores.

The network of branching thread-like hyphae that forms the feeding body of a fungus and grows through its food source.

A close and lasting relationship between organisms of two different species in which both partners usually gain some benefit, as in lichens.

The process by which green organisms use light energy to build sugars from carbon dioxide and water, releasing oxygen as a by-product.

A small opening in the leaf surface, bordered by two guard cells, through which gases and water vapour are exchanged with the atmosphere.

The loss of water vapour from plant surfaces, mainly through the stomata of leaves, which pulls water upward through the plant.

Plant tissue made of dead hollow cells that transports water and dissolved minerals upward from the roots to the shoots and leaves.

Living plant tissue that carries sugars made in the leaves to other parts of the plant, including roots, fruits and growing tips.

The net movement of particles from a region of higher concentration to one of lower concentration, driven by their random motion.

The movement of water across a partially permeable membrane from a dilute solution to a more concentrated one, which can swell or shrink cells.

The ability of an organism to keep its internal conditions, such as temperature and blood glucose, within narrow limits despite outside change.

A chemical messenger released by a gland into the blood, which travels to target organs and alters their activity in a specific way.

A control mechanism in which a change away from the normal level triggers a response that reverses the change and restores balance.

The process by which individuals with inherited features better suited to their environment survive and leave more offspring, so those features spread.

An inherited feature of an organism that improves its chance of surviving and reproducing in the particular environment where it lives.

A sequence of organisms in which each is eaten by the next, showing the direction in which energy passes through a community.

An organism, usually a green plant or alga, that makes its own organic food from sunlight and so forms the starting point of a food chain.

An organism such as a bacterium or fungus that breaks down dead bodies and waste, releasing minerals back into the soil for reuse.