Master Biology Glossary: Consolidated Terms &
Definitions grade 12 IEB syllabus:
Core Molecular Genetics (DNA, RNA, Protein Synthesis)
• Amino Acid: The building block of proteins. There are twenty standard amino
acids, and their sequence defines a specific protein.
• Anticodon: A three-base sequence on a tRNA molecule that is
complementary to a specific codon on an mRNA strand.
• Codon: A three-base sequence on an mRNA molecule that codes for a
specific amino acid or signals the start/stop of translation.
• Complementary Base Pairing: The specific hydrogen bonding between
nitrogenous bases: A with T (in DNA) or U (in RNA), and G with C.
• DNA (Deoxyribonucleic Acid): A double-stranded nucleic acid that carries
the genetic instructions for all known organisms. Its structure is a double helix.
• DNA Polymerase: The enzyme that catalyzes the formation of bonds between
complementary nucleotides during DNA replication.
• DNA Replication: The biological process of producing two identical replicas
of DNA from one original DNA molecule.
• Double Helix: The twisted ladder-like structure of a DNA molecule.
• Exon: A segment of a DNA or RNA molecule containing information that
codes for a protein. (See Coding DNA).
• Gene: A unit of heredity; a section of DNA that carries the genetic code for a
specific protein or functional RNA molecule.
• Genetic Code: The set of rules by which information encoded in DNA or
mRNA is translated into proteins.
• Helicase: The enzyme that unwinds the DNA double helix by breaking
hydrogen bonds during replication.
• Intron: A non-coding sequence of DNA that is transcribed into mRNA but is
removed before translation. (See Non-coding DNA).
• Messenger RNA (mRNA): A type of RNA that carries a copy of the genetic
code from DNA in the nucleus to the ribosome.
,• Mutation: Any alteration in the nucleotide sequence of an organism's DNA.
• Mutagen: An environmental agent (e.g., radiation, chemicals) that can cause a
mutation.
• Nitrogenous Base (Base Pair): The molecules (A, T, C, G in DNA; A, U, C, G in
RNA) that form the "rungs" of the DNA/RNA ladder and pair specifically.
• Nucleotide: The monomer of nucleic acids, consisting of a sugar, a phosphate
group, and a nitrogenous base.
• Nucleic Acid: A macromolecule, such as DNA or RNA, that stores and
transmits genetic information.
• Point Mutation: A gene mutation involving a change in a single nucleotide
(e.g., substitution).
• Protein Synthesis: The cellular process of building proteins, involving
transcription and translation.
• Purine: A type of larger, double-ring nitrogenous base (Adenine and
Guanine).
• Pyrimidine: A type of smaller, single-ring nitrogenous base (Cytosine,
Thymine in DNA; Cytosine, Uracil in RNA).
• Ribosomal RNA (rRNA): A type of RNA that makes up the ribosome and
helps control translation.
• Ribosome: The cellular structure where protein synthesis (translation) occurs.
• RNA (Ribonucleic Acid): A single-stranded nucleic acid crucial for protein
synthesis (mRNA, tRNA, rRNA).
• RNA Polymerase: The enzyme responsible for synthesizing RNA from a DNA
template during transcription.
• Start Codon (AUG): The codon that signals the start of translation.
• Stop Codon (UAA, UAG, UGA): A codon that signals the end of translation.
• Template Strand: The strand of DNA used as a guide for synthesizing a new
complementary strand.
• Transcription: The first stage of protein synthesis, where a DNA sequence is
copied into mRNA.
• Transfer RNA (tRNA): A type of RNA that carries a specific amino acid to the
ribosome.
, • Translation: The second stage of protein synthesis, where the mRNA code is
read by a ribosome to form a protein.
Genetic Variation & Mutations
• Deletion: A type of gene mutation where one or more nucleotides are
removed from the DNA.
• Frameshift Mutation: A mutation caused by an insertion or deletion that
shifts the reading frame of the genetic code.
• Insertion: A type of gene mutation where one or more extra nucleotides are
added to the DNA.
• Substitution: A type of point mutation where one nucleotide is replaced by
another.
Biotechnology & Applications
• DNA Profiling (DNA Fingerprinting): A technique to identify individuals
based on unique patterns in their non-coding DNA.
• Electrophoresis: A lab technique that uses an electric current to separate
DNA fragments by size.
• Polymerase Chain Reaction (PCR): A technique used to make billions of
copies of a specific DNA segment.
• Restriction Enzyme: An enzyme that cuts DNA at specific nucleotide
sequences.
• Short Tandem Repeat (STR): Short, repeating DNA sequences (4-5 base
pairs) whose variable repeat numbers are used for DNA profiling.
Medical Applications (Antibiotics)
• Antibiotic: A substance used to counteract bacterial infections, often by
inhibiting protein synthesis.
• Chloramphenicol: An antibiotic that prevents the formation of peptide bonds
between amino acids.
• Tetracyclines: A class of antibiotics that prevent tRNA attachment to the
ribosome.
Definitions grade 12 IEB syllabus:
Core Molecular Genetics (DNA, RNA, Protein Synthesis)
• Amino Acid: The building block of proteins. There are twenty standard amino
acids, and their sequence defines a specific protein.
• Anticodon: A three-base sequence on a tRNA molecule that is
complementary to a specific codon on an mRNA strand.
• Codon: A three-base sequence on an mRNA molecule that codes for a
specific amino acid or signals the start/stop of translation.
• Complementary Base Pairing: The specific hydrogen bonding between
nitrogenous bases: A with T (in DNA) or U (in RNA), and G with C.
• DNA (Deoxyribonucleic Acid): A double-stranded nucleic acid that carries
the genetic instructions for all known organisms. Its structure is a double helix.
• DNA Polymerase: The enzyme that catalyzes the formation of bonds between
complementary nucleotides during DNA replication.
• DNA Replication: The biological process of producing two identical replicas
of DNA from one original DNA molecule.
• Double Helix: The twisted ladder-like structure of a DNA molecule.
• Exon: A segment of a DNA or RNA molecule containing information that
codes for a protein. (See Coding DNA).
• Gene: A unit of heredity; a section of DNA that carries the genetic code for a
specific protein or functional RNA molecule.
• Genetic Code: The set of rules by which information encoded in DNA or
mRNA is translated into proteins.
• Helicase: The enzyme that unwinds the DNA double helix by breaking
hydrogen bonds during replication.
• Intron: A non-coding sequence of DNA that is transcribed into mRNA but is
removed before translation. (See Non-coding DNA).
• Messenger RNA (mRNA): A type of RNA that carries a copy of the genetic
code from DNA in the nucleus to the ribosome.
,• Mutation: Any alteration in the nucleotide sequence of an organism's DNA.
• Mutagen: An environmental agent (e.g., radiation, chemicals) that can cause a
mutation.
• Nitrogenous Base (Base Pair): The molecules (A, T, C, G in DNA; A, U, C, G in
RNA) that form the "rungs" of the DNA/RNA ladder and pair specifically.
• Nucleotide: The monomer of nucleic acids, consisting of a sugar, a phosphate
group, and a nitrogenous base.
• Nucleic Acid: A macromolecule, such as DNA or RNA, that stores and
transmits genetic information.
• Point Mutation: A gene mutation involving a change in a single nucleotide
(e.g., substitution).
• Protein Synthesis: The cellular process of building proteins, involving
transcription and translation.
• Purine: A type of larger, double-ring nitrogenous base (Adenine and
Guanine).
• Pyrimidine: A type of smaller, single-ring nitrogenous base (Cytosine,
Thymine in DNA; Cytosine, Uracil in RNA).
• Ribosomal RNA (rRNA): A type of RNA that makes up the ribosome and
helps control translation.
• Ribosome: The cellular structure where protein synthesis (translation) occurs.
• RNA (Ribonucleic Acid): A single-stranded nucleic acid crucial for protein
synthesis (mRNA, tRNA, rRNA).
• RNA Polymerase: The enzyme responsible for synthesizing RNA from a DNA
template during transcription.
• Start Codon (AUG): The codon that signals the start of translation.
• Stop Codon (UAA, UAG, UGA): A codon that signals the end of translation.
• Template Strand: The strand of DNA used as a guide for synthesizing a new
complementary strand.
• Transcription: The first stage of protein synthesis, where a DNA sequence is
copied into mRNA.
• Transfer RNA (tRNA): A type of RNA that carries a specific amino acid to the
ribosome.
, • Translation: The second stage of protein synthesis, where the mRNA code is
read by a ribosome to form a protein.
Genetic Variation & Mutations
• Deletion: A type of gene mutation where one or more nucleotides are
removed from the DNA.
• Frameshift Mutation: A mutation caused by an insertion or deletion that
shifts the reading frame of the genetic code.
• Insertion: A type of gene mutation where one or more extra nucleotides are
added to the DNA.
• Substitution: A type of point mutation where one nucleotide is replaced by
another.
Biotechnology & Applications
• DNA Profiling (DNA Fingerprinting): A technique to identify individuals
based on unique patterns in their non-coding DNA.
• Electrophoresis: A lab technique that uses an electric current to separate
DNA fragments by size.
• Polymerase Chain Reaction (PCR): A technique used to make billions of
copies of a specific DNA segment.
• Restriction Enzyme: An enzyme that cuts DNA at specific nucleotide
sequences.
• Short Tandem Repeat (STR): Short, repeating DNA sequences (4-5 base
pairs) whose variable repeat numbers are used for DNA profiling.
Medical Applications (Antibiotics)
• Antibiotic: A substance used to counteract bacterial infections, often by
inhibiting protein synthesis.
• Chloramphenicol: An antibiotic that prevents the formation of peptide bonds
between amino acids.
• Tetracyclines: A class of antibiotics that prevent tRNA attachment to the
ribosome.
