Higher Biology Unit 1 Review

Comprehensive vocabulary flashcards covering key definitions, terms, processes, and concepts from Higher Biology Unit 1.

Deoxyribonucleic Acid (DNA) Nucleotide

The basic building unit of DNA, consisting of a deoxyribose sugar, a phosphate group, and a base.

Sugar–Phosphate Backbone

The structural framework of a DNA strand formed by chemical links between deoxyribose sugars and phosphate groups of adjacent nucleotides.

Antiparallel

The arrangement of the two strands in a DNA molecule running in opposite directions, with a deoxyribose at the 3′ end and a phosphate at the 5′ end of each strand.

Plasmids

Circular rings of DNA present in prokaryotes and also found naturally in yeast, a special eukaryotic organism.

Histones

Proteins associated with eukaryotic linear DNA in the nucleus that package and organize chromosomes.

DNA Polymerase

The enzyme that synthesises a complementary DNA strand by adding DNA nucleotides to the deoxyribose (3′) end of a growing strand.

Primer (Replication)

A short strand of nucleotides that binds to the 3′ end of the template DNA strand, allowing DNA polymerase to initiate replication.

Leading Strand

The strand of DNA that is replicated continuously during DNA replication.

Lagging Strand

The strand of DNA that is replicated discontinuously in fragments during replication.

Ligase

The enzyme responsible for joining replicated fragments of DNA together on the lagging strand.

Polymerase Chain Reaction (PCR)

An in vitro technique used for the amplification of specific target regions of DNA.

Primers (PCR)

Short strands of nucleotides complementary to specific target sequences at the two ends of the region of DNA to be amplified.

Heat-Tolerant DNA Polymerase

A specialised DNA polymerase that does not denature at high temperatures, functioning at 70–80°C during PCR synthesis.

Gene Expression

The cellular process involving transcription and translation of DNA sequences to produce functional proteins.

Messenger RNA (mRNA)

A single-stranded RNA molecule transcribed from DNA that carries a copy of the genetic code from the nucleus to ribosomes.

Codon

A triplet of bases on an mRNA molecule that codes for a specific amino acid.

Transfer RNA (tRNA)

Folded RNA molecule that carries a specific amino acid to the ribosome, containing an anticodon at one end and an amino acid attachment site at the other.

Anticodon

An exposed triplet of bases on a tRNA molecule that pairs with a complementary codon on mRNA during translation.

RNA Polymerase

An enzyme that unwinds the double helix, breaks hydrogen bonds between bases, and synthesises a primary mRNA transcript by complementary base pairing.

Introns

Non-coding regions of the primary mRNA transcript that are removed during RNA splicing.

Exons

Coding regions of the primary mRNA transcript that are joined together to form the mature mRNA transcript.

RNA Splicing

The process by which introns are removed and exons are joined together without altering their order to form a mature mRNA transcript.

Alternative RNA Splicing

A mechanism where different mature mRNA transcripts are produced from the same primary transcript depending on which exons are retained.

Phenotype

The physical and physiological traits of an organism determined by proteins produced via gene expression and influenced by environmental factors.

Cellular Differentiation

The process by which an unspecialised cell expresses specific genes to produce characteristic proteins, allowing it to perform specialised functions.

Meristems

Regions of unspecialised cells in plants that retain the ability to divide (self-renew) and/or differentiate.

Stem Cells

Unspecialised cells in animals capable of dividing (self-renewing) and/or differentiating into specialised cells.

Pluripotent Stem Cells

Cells from the very early embryo that can differentiate into any cell type found in the organism.

Multipotent Tissue Stem Cells

Stem cells involved in growth, repair, and renewal that can differentiate into all cell types found within that specific tissue.

Genome

The entire hereditary information of an organism encoded in its DNA sequences.

Point Mutation

A mutation occurring at the single nucleotide level where one nucleotide is substituted for another, altering only one amino acid.

Missense Mutation

A substitution mutation that replaces one amino acid with another, resulting in either a non-functional protein or having little effect.

Nonsense Mutation

A substitution mutation that produces a premature stop codon, leading to a shortened protein.

Splice-Site Mutation

A mutation that causes some introns to be retained and/or some exons to be excluded from the mature mRNA transcript.

Frameshift Mutation

A mutation that shifts reading frames, causing all codons and resulting amino acids after the mutation site to be changed.

Duplication (Chromosome Mutation)

A chromosomal alteration where a section of chromosome is added from its homologous partner.

Deletion (Chromosome Mutation)

A chromosomal mutation involving the complete loss or removal of a section of a chromosome.

Inversion (Chromosome Mutation)

A chromosomal mutation where a section of chromosome is reversed through 180°.

Translocation (Chromosome Mutation)

A chromosomal mutation where a section of chromosome is attached to a non-homologous chromosome.

Vertical Gene Transfer

The transmission of genetic material down generations from parents to offspring via sexual or asexual reproduction.

Horizontal Gene Transfer

The exchange of genetic material between members of the same generation, commonly seen in prokaryotes and viruses.

Natural Selection

The non-random increase in frequency of beneficial DNA sequences that enhance survival and non-random reduction of deleterious sequences.

Stabilising Selection

A type of natural selection where the average phenotype is favoured and extremes of the phenotype range are selected against.

Directional Selection

A type of natural selection where one extreme of the phenotype range is selected for.

Disruptive Selection

A type of natural selection where two or more extreme phenotypes are favoured over intermediate forms.

Species

A group of organisms capable of interbreeding to produce fertile, viable offspring.

Speciation

The evolutionary formation of new biological species through isolation, mutation, and selection.

Allopatric Speciation

Speciation caused by the physical or geographical separation of populations by barriers such as oceans or mountain ranges.

Sympatric Speciation

Speciation occurring within the same geographic habitat brought about by behavioural or ecological isolating mechanisms.

Bioinformatics

The application of mathematical, statistical, and computing sciences to analyse biological sequence data.

Phylogenetic Trees

Branching diagrams generated from genomic sequencing data illustrating evolutionary relationships between organisms and common ancestors.

Pharmacogenetics

The study and use of personal genomic sequence information to select the most effective drugs and dosages for treating disease.