Download Molecular Genetics

From “Continuing Biology” Meg Bayley, David Layzell
Definitions for:
Molecular Genetics
(Biology 3.3)
To revise, cover the right-hand side of the table with a sheet of paper and move down the left column seeing
which words you already know the definitions of (slide the paper down a word at a time to check). Tick these
ones off, and concentrate on the others until you have learnt them all. Then cover the left-hand side of the table
and have a go at writing the words to match the definitions!
If a word on the right-hand side is in bold, there is a definition for it elsewhere in the table.
The shaded words are less important.
Amino acid
Aneuploidy
Anticodon
Barr body
Bivalent
Block mutation
Centromere
Chiasma
Chromatid
Chromatin
Chromosome
Chromosome
mutations
Cistron
Coding Strand
Codon
Complementary
(bases)
Diploid
DNA
Enzyme
Eukaryote
Exon
Frameshift
mutation
Gametic mutation
Gene
Gene mutation
Haploid
Histone
Homologous pair
Inducer
Intron
Karyotype
Lagging strand
Leading strand
Locus
The basic building-block of proteins. Each amino acid consists of an acid (carboxyl)
and basic (amino) end. It is the joining between acidic and basic ends of adjacent
amino acids (condensation) that forms the protein polymer.
Where there is not a complete set of chromosomes e.g. 2n – 1, 2n + 1.
A group of 3 bases on the tRNA.
A condensed X chromosome in females. (Both males and females only need one active
X chromosome.)
The structure formed by the pair of homologous chromosomes during crossing over.
Also called a tetrad because it consists of four chromatids.
See Chromosome mutations.
The attachment point on the chromosome for the spindle fibres.
The visible crossing-over of non-sister chromatids.
A duplicated chromosome joined to its pair. It becomes visible at prophase. When
chromatids separate at anaphase they are referred to as chromosomes.
The genetic material during the resting life (interphase) of the cell. Chromosomes are
only visible during cell division.
Structure found in the nucleus of eukaryotes and the nuclear region of prokaryotes. It
carries the genetic message.
Pieces of chromosomes splitting and moving to give duplication, deletion, inversion
and translocation.
A length of DNA that codes for a polypeptide. Used as a more specific term for gene
DNA complementary to the template strand.
A group of 3 bases on the mRNA.
Two bases that pair together. A is complementary to T and C is complementary to G.
Cells with one 2 sets ( homologous pairs) of chromosomes
Deoxyribonucleic acid The molecule that carries the message within the chromosome.
A catalyst made of protein. Usually ends in the suffix ‘ase’
Type of cell found in Animal, Plant, Fungi and Protist (Protoctist) kingdoms
A gene that is transcribed, a structural gene.
A deletion or addition mutation. It results in scrambling of the message.
A mutation in the sex cells. Can be inherited.
A short region of a chromosome that is responsible for one trait (characteristic).
Addition, deletion, substitution of one or a few bases.
Cells with only a single set of chromosomes eg gametes.
A round protein that DNA coils around during prophase.
A pair of chromosomes with identical loci. One is from the mother and one from the
father.
A molecule that binds to the repressor protein. Transcription occurs because the
repressor molecule cannot bind to the operator site and prevent transcription.
A gene that is not transcribed.
The chart formed when photographs of chromosomes are laid out in order. Karyotypes
are used to identify chromosomal abnormalities.
The strand in replication that is copied 3’ to 5’ as Okazaki fragments and then joined
up.
The strand in replication that is copied in the 5’ to 3’ direction.
Where a gene is located on a particular chromosome.
From “Continuing Biology” Meg Bayley, David Layzell
Metabolic pathway
Monosomic
Mutation
Non-disjunction
Nonsense triplet
Nucleic acid
Nucleotide
Okazaki fragment
Operator site
Operon
Peptide
Point mutation
Polypeptide
Polyploid
Prokaryote
Promotor gene
Protein
Recombination
Regulatory gene
Replication
Repressor
Ribosome
RNA
Rough ER
Somatic mutation
Start codon
Stop codon
Structural gene
Substrate
Template strand
Tetrad
Transcription
Transcription
factor
Translation
Triplet
Trisomic
A series of enzyme-controlled reactions that convert compounds from one to another.
Only one chromosome of that type is present eg males are monosomic for the X
chromosome.
Any change in the genetic code.
The failure of chromatids to separate during anaphase. This results in aneuploidy.
See Stop codon.
DNA or RNA.
The basic unit of nuclei acids. Each nucleotide is made up of 1 sugar (ribose or
deoxyribose), a phosphate group and 1 of 4 bases.
A small section of DNA. These occur because DNA is replicated in the 5’ to 3’ direction
and on the other strand must be made up in short sections (the Okazaki fragments).
The site that a repressor protein can bind to prevent transcription
One or more structural genes plus the associated regulators (including operator site,
promotor site and regulator gene).
A polymer of 2–10 amino acids.
The addition, deletion or substitution of a single base. Often used interchangeably with
gene mutation.
A polymer of 11–100 amino acids.
Cells with three or more sets of chromosomes.
Type of cell found in bacteria and blue-green algae. They lack mitochondria,
chloroplasts, a true nucleus and have a single loop of DNA without protein.
A gene necessary for the initiation of transcription. Transcription occurs when the RNA
polymerase binds to the promotor gene site.
A polymer of more than 100 amino acids. The primary structure is the order or
sequence of amino acids, the secondary structure is the coiling and the tertiary
structure is the folding of the protein. Where two or more proteins interact eg in the
haemoglobin molecule there is a fourth level (quartenary) structure.
Exchange of genetic material from maternal and paternal chromosomes during
crossing-over.
A gene that regulates the action of other genes and is not transcribed.
Copying of the DNA strands. In semi-conservative replication each new DNA molecule
is made of one old and one new strand.
A molecule that can bind to the operator site, preventing transcription.
A molecule made from RNA that makes the rough ER ‘rough’. It attaches to the
mRNA during translation.
A single-stranded molecule. Unlike DNA it uses the sugar ribose instead of deoxyribose
and uses the base uracil (U) rather than thymine (T). The 3 types of RNA are mRNA
(messenger), tRNA (transfer) and rRNA (ribosomal).
Rough Endoplasmic Reticulum A series of tubes and sacs in the cytoplasm, where
protein synthesis is carried out.
A mutation that occurs in the body cells. Cannot be inherited.
The codon that initiates the protein: AUG.
The codon that ends the protein: UAA, UAG, UGA.
A gene that is transcribed.
The substance that an enzyme acts on.
The DNA strand that carries the genetic message. Sometimes it is called the ‘read’ or
‘sense’ strand.
See Bivalent.
The copying of a DNA message onto mRNA. This occurs in the nucleus.
Any protein or enzyme, other than RNA polymerase that is required for transcription.
The making of a protein at the Rough ER.
A group of 3 bases on the sense strand of the DNA.
Where there are three chromosomes of that type, eg Down syndrome is trisomy 21.