BY1 definitions

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  • Created by: zopetre_
  • Created on: 21-01-17 13:09
Organic
Molecules that have a high proportion of carbon atoms.
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Inorganic
A molecule or ion that has no more than one carbon atom.
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Dipole
A polar molecule with a positive and a negative charge, separated by a very small distance.
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Hydrogen bond
The weak attractive force between a hydrogen atom with a partial positive charge and an atom with a partial negative charge, usually oxygen or nitrogen.
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Monosaccharide
An individual sugar molecule.
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Isomere
Molecules with the same chemical formulae but a different arrangement of atoms.
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Polymer
A large molecule comprising repeated units, monomers, bonded together.
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Ester bond
An oxygen atom joining two atoms, one of which is a carbon atom attached by a double bond to another oxygen atom.
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Peptide bond
The chemical bond formed by a condensation reaction between the amino group of one amino acid and the carboxyl group of another.
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Organelles
A specialised structure with a specific function inside a cell.
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Prokaryote
A single-celled organism lacking membrane-bound organelles, such as a nucleus, with its DNA free in the cytoplasm.
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Eukaryote
An organism containing cells that have membrane-bound organelles, with DNA in chromosomes within the nucleus.
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Tissue
Groups of cells with the same structure and function working together.
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Organ
A group of tissues in a structural unit, working together and performing a specific function.
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Resolution
The smallest distance between two points that can be separately distinguished.
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Diffusion
The passive movement of a molecule or ion down a concentration gradient, from a region of high concentration to a region of low concentration.
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Passive
Not requiring energy provided by a cell.
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Facilitated diffusion
The passive transfer of molecules or ions down a concentration gradient, across a membrane, by protein carrier molecules in the membrane.
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Active transport
The movement of molecules or ions across a membrane against a concentration gradient, using energy from the hydrolysis of ATP made by the cell in respiration.
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Osmosis
The diffusion of water, from a region of higher water potential to a region of lower water potential, through a selectively permeable membrane.
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Water potential
A measure of the free energy of water molecules, measured in kilopasacals.
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Turgid
A plant cell that holds as much water as possible. Further entry of water is prevented as the cell wall can't expand further.
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Pressure potential
The pressure exerted by the cell contents on the cell wall.
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Solute potential
A measure of the osmotic strength of a solution. It is the reduction in water potential due to the presence of solute molecules.
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Catalyst
A molecule which speeds up a chemical reaction, but remains unchanged at the end of a reaction.
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Metabolic pathway
A sequence of enzyme-controlled reactions in which a product of one reaction is a reactant in the next.
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Active site
Site on an enzyme with a particular three-dimensional structure that permits binding with a substrate.
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Enzyme-substrate complex
Intermediate structure formed during an enzyme-catalysed reaction in which the substrate and enzyme bind temporarily, such that the substrates are close enough to react.
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Activation energy
The minimum energy that must be put into a chemical system for a reaction to occur.
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Denatured
An enzyme's active site is permanently distorted by the irreversible breaking of hydrogen bonds, preventing substrate binding and reducing the rate of reaction.
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Inactivation
Reversible reduction of enzyme activity at low temperature as molecules have insufficient kinetic energy to form enzyme-substrate complexes.
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Limiting factor
Factor is limiting when an increase in its value causes an increase in the rate of reaction.
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Inhibitor
A molecule or ion that reduces the rate of an enzyme-controlled reaction.
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Competitive inhibition
Reduction of the rate of an enzyme-controlled reaction by a molecule or ion that has a complementary shape to the active site, similar to the substrate, and binds to the active site, preventing the substrate from binding.
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Non-competitive inhibition
Reduction of the rate of an enzyme-controlled reaction by a molecule or ion that binds to the enzyme somewhere other than the active site, altering the shape of the active site, so that the substrate cannot bind.
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Immobilised enzyme
Enzyme molecules bound to an inert material, over which the substrate molecules move.
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Biosensor
A device that combines a biomolecule, such as an enzyme, with a transducer, to produce an electrical signal which measured the concentration of a chemical.
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Nucleotide
Monomer of nucleic acid comprising a pentose sugar, a nitrogenous base and a phosphate group.
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Semi-conservative replication
Mode of DNA replication in which each strand of a parental double helix acts as a template for the formation of a new molecule, each containing an original, parental strand, and a newly synthesised, complementary daughter strand.
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Codon
Triplet of bases in mRNA that codes for a particular amino acid, or a punctuation signal.
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Genetic code
The DNA and mRNA base sequence that determines the amino acid sequences in an organism's proteins.
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Intron
Non-coding nucleotide sequence in DNA and pre-mRNA that is removed from pre-mRNA to produce mature mRNA.
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Exon
Nucleotide sequence in DNA and pre-mRNA that remains present in the final mature mRNA, after introns have been removed.
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Transcription
A segment of DNA acts as a template to direct synthesis of a complementary sequence of RNA, with the enzyme RNA polymerase.
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Translation
The sequence of codons on the mRNA is used to assemble a specific sequence of amino acids into a polypeptide chain, at the ribosomes.
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Chromatid
One of the two identical copies of a chromosome, joined at the centromere prior to cell division.
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Centromere
Specialised region of a chromosome where two chromatids join and to which the microtubules of the spindle attach at cell division.
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Diploid
Having two complete sets of chromosomes.
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Haploid
Having one complete set of chromosomes.
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Homologous
The chromosomes in a homologous pair are identical in size/shape, carrying the same gene loci, with genes for the same characteristic. One chromosome of each pair from each parent.
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Mitosis
A type of cell division in which the two daughter cells have the same number of chromosomes and are genetically identical with each other and the parent cell.
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Oncogene
A gene with the potential to cause cancer.
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Meiosis
A two-stage cell division in sexually reproducing organisms that produces four genetically distinct daughter cells each with half the number of chromosomes of the parent cell.
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Chiasma
The site as seen in the light microscope, at which chromosomes exchange DNA in genetic crossing over.
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Independent assortment
Either of a pair of homologous chromosomes moves to either pole at anaphase I of meiosis, independently of the chromosomes of other homologous pairs.
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Other cards in this set

Card 2

Front

Inorganic

Back

A molecule or ion that has no more than one carbon atom.

Card 3

Front

Dipole

Back

Preview of the front of card 3

Card 4

Front

Hydrogen bond

Back

Preview of the front of card 4

Card 5

Front

Monosaccharide

Back

Preview of the front of card 5
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