Definitions Flashcards
Central Dogma
The 2 step process (transcription and translation) by which the information in genes flows into proteins.
DNA - RNA - Proteins
Archaeon
One of the two divisions of prokaryotes, often found in hostile environments such as hot springs or concentrated in brine.
Bacterium
One of the two divisions of prokaryotes; some species cause disease.
Cell
The basic unit from which a living organism is made. Consists of an aqueous solution of organic molecules enclosed by a membrane.
Chloroplast
Specialized organelle in algae and plants which contains chlorophyll and serves as the site in which photosynthesis takes place.
Chromosome
Long, threadlike structure composed of DNA and proteins that carries the genetic information of an organism. It becomes visible as a distinct entity when a plant or animal cell prepares to divide.
Cytoplasm
Contents of a cell that are contained within its plasma membrane but, in the case of eukaryotic cells, contained outside the nucleus.
Cytoskeleton
A microscopic network of protein filaments and tubules in the cytoplasm of many living cells, giving them shape and coherence.
Cytosol
The aqueous component of the cytoplasm of a cell, within which various organelles and particles are suspended.
DNA
Deoxyribonucleic acid. The carrier of genetic information.
Electron Microscope
Instrument that illuminates a specimen using beams of electrons to reveal and magnify the structures of very small object, such as organelles and large molecules.
Eukaryote
An organism whose cells have distinct nucleus and cytoplasm
Evolution
The process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth.
Fluorescence Microscope
Instrument used to visualize a specimen that has been labeled with a fluorescent dye; samples are illuminated with a wavelength of light that excites the dye, causing it to fluoresce.
Genome
The complete set of genes or genetic material present in a cell or organism
Homologous
Describes genes, chromosomes or any structures that are similar because of their common evolutionary origin. It can also refer to similarities between protein sequences or nucleic acid sequences.
Micrometer
Unit of length equal to one millionth (10^-6) of a meter
Microscope
Instrument for viewing extremely small objects.
Mitochondrion
(plural = mitochondria) Membrane enclosed organelle, about the size of a bacterium, that carries out oxidative phosphorylation and produces most of the ATP in eukaryotic cells.
Model Organism
A living thing selected for intensive study as a representative of a large group of species.(Eg. the mouse representing mammals, a certain yeast representing unicellular eukaryotes and E. coli representing bacteria)
Nucleus
Prominent, rounded structure that contains the DNA of a eukaryotic cell.
Organelle
A discrete structure or sub-compartment of a eukaryotic cell that is specialized to carry out a particular function. (Eg. Mitochondria)
Photosynthesis
The process by which plants, algae, and some bacteria use the energy of sunlight to drive the synthesis of organic molecules from carbon dioxide and water.
Plasma Membrane
The protein-containing lipid bilayer that surrounds a living cell.
Prokaryote
Major category of living cells distinguished by the absence of a nucleus. Prokaryotes include the archaea and the eubacteria (commonly called bacteria)
Protein
Polymer built from amino acids that provides cells with their shape and structure and performs most of their activities.
Protozoan
(plural = protozoa) A free-living, non-photosynthetic, single-celled, motile eukaryote
Ribosome
Large macromolecular complex, composed of ribosomal RNAs and ribosomal proteins, that translates messenger RNA into protein.
RNA
Ribonucleic acid. Molecule produced by the transcription of DNA; usually single stranded. It’s a polynucleotide composed of covalently linked ribonucleotide subunits. It serves a variety of structural, catalytic and regulatory functions in cells.
Peroxisomes
Organelles which generate and degrade hydrogen peroxide and are the site of beta oxidation of fatty acids.
Lysosomes
Organelles which break down proteins and release them as amino acids. (Recycling organelle)
Reticulocyte
Immature RBC
Operon
A set of linked genes organised by one promoter
Transcription Factor/Regulatory Proteins
A protein that controls the rate of transcription of genetic information (gene expression) from DNA to messenger RNA, by binding to a specific DNA sequence and acting like a switch to control transcription. They can either activate or repress.
Gene expression
The process by which information from a gene is used in the synthesis of a functional gene product.
The promoter region
Binds the enzyme RNA polymerase and correctly orients the enzyme to begin its task of making an RNA copy of the gene.
Regulatory DNA sequences
Sequences in the gene which are used to switch the gene on or off. Nearly all bacterial and eukaryotic genes have this.
Operator
A short DNA sequence within an operon’s promoter region, which is recognized by a transcription regulator (repressor). When regulator binds it blocks access of RNA polymerase to the promoter (preventing transcription of operon)
Combinatorial control
The way groups of transcription regulators work together to determine the expression of a single gene. (Eukaryotic cells)
Induced Pluripotent Stem (iPS) Cells
Cells that look and behave like the pluripotent embryonic stem cells that derived from embryos
Epigenetic inheritance
Cell-memory mechanisms that transmit patterns of gene expression from parent to daughter cell without altering the actual nucleotide sequence of the DNA.
RISC
RNA-induced silencing complex. miRNA is packaged with specialised proteins to form this complex which patrols the cytoplasm in search of mRNAs that are complementary to the bound miRNA molecule.
Transposons
A transposable element is a DNA sequence that has all the information necessary for it to change its position within a genome, sometimes creating or reversing mutations and altering the cell’s genetic identity and genome size. It does this through a mechanism that differs from that of homologous recombination.
Conjugation
Bacterial “sex”
Transformation
When bacteria engulf other species and incorporate new genes into their chromosomes.
Synteny
The conservation of blocks of order within two sets of chromosomes that are being compared with each other. Basically the similarities between two blocks of genes within two different species.
Conserved sequences
Conserved sequences are sequences in a genome that has been kept very similar (not the same, but similar). A major change that makes a gene function less has a detrimental effect on the individual and it will be taken out of the population.
Luca
Last Universal Common Ancestor
LINEs
A type of retrotransposon.
Long Interspersed Nuclear Elements. They are the transposable elements which take up the largest proportion of the human genome.
Pseudogene
DNA sequence that closely resembles that of a functional gene but contains numerous mutations that prevent its proper expression.
Most arise from the duplication of a functional gene, followed by the accumulation of damaging mutations in one copy.
Alu Sequence
A type of retrotransposon.
Family of mobile genetic elements that comprises about 10% of the human genome; this short, repetitive sequence is no longer mobile on its own, but requires enzymes encoded by other elements to transpose.
Copy Number Variation
Large segment of DNA, 1000 nucleotide pairs or greater, that has been duplicated or lost in an individual genome (compared to the “reference” genome sequence).
Divergence
Differences in sequence that accumulate over time in DNA segments derived from a common ancestral sequence.
Exon shuffling
A molecular mechanism for the formation of new genes. It is a process through which two or more exons from different genes can be brought together ectopically, or the same exon can be duplicated, to create a new exon-intron structure.
Gene duplication and divergence
A process by which new genes can form; involves the accidental generation of an additional copy of a stretch of DNA containing one or more genes, followed by an accumulation of mutations that over time can alter the function of either the original or its copy.
Gene family
A set of related genes that has arisen through a process of gene duplication and divergence. Agene familyis a group ofgenesthat share important characteristics. In many cases, genesin afamilyshare a similar sequence of DNA building blocks (nucleotides).
Germ cell
Cell type in a diploid organism that carries only one set of chromosomes and is specialized for sexual reproduction. A sperm or an egg; also called gamete.
Germ line
The lineage of reproductive cells that contributes to the formation of a new generation of organisms, as distinct from somatic cells, which form the body and leave no descendants in the next generation.
Homologous gene
Genes that are similar because of their common evolutionary origin. Can also refer to similarities between protein sequences or nucleic acid sequences.
Horizontal gene transfer
Process by which DNA is passed from the genome of one organism to that of another, even to an individual from another species. This contrasts with “vertical” gene transfer, which refers to the transfer of genetic information from parent to progeny.
Mobile genetic element
Short segment of DNA that can move, sometimes through an RNA intermediate, from one location in a genome to another; an important source of genetic variation in most genomes. Also called a transposon.
Open reading frame
Long sequence of nucleotides that contains no stop codon; used to identify potential protein-coding sequences in DNA.
Phylogenetic tree
Diagram or “family tree” showing the evolutionary relationships among a group of organisms or proteins.
Point mutation
Change in a single nucleotide pair in a DNA sequence.
Purifying selection
Preservation of a specific nucleotide sequence driven by the elimination of individuals carrying mutations that interfere with its functions.
Retrotransposon
Type of mobile genetic element that moves by being first transcribed into an RNA copy that is reconverted to DNA by reverse transcriptase (which is actually encoded by the retrotransposon itself) and inserted elsewhere in the chromosomes.
Retrovirus
RNA-containing virus that replicates in a cell by first making a double-stranded DNA intermediate that becomes integrated into the cell’s chromosome.
Reverse transcriptase
Enzyme that makes a double-stranded DNA copy from a single-stranded RNA template molecule. Present in retroviruses and as part of the transposition machinery of retrotransposons.
Single-nucleotide polymorphism (SNP)
Single base pair differences in DNA sequence between individual members of a species. (Variants)
Somatic cell
Any cell that forms part of the body of a plant or animal that is not a germ cell or germ-line precursor.
Transposon
General name for short segments of DNA that can move from one location to another in the genome. Also known as mobile genetic elements.
Virus
Particle consisting of nucleic acid (RNA or DNA) enclosed in a protein coat and capable of replicating within a host cell and spreading from cell to cell. Often the cause of disease.
Homologous recombination
Allows an intact chromosome to be used as a template to repair a damaged sequence on its homolog.
Anneal
Recombine (DNA) in the double-stranded form.
PCR Polymerase Chain Reaction
A technique used to make multiple copies of a segment of DNA of interest, generating a large amount of copies from a small initial sample
Microarray
Microarrays can also be used to study which genes and the extent to which certain genes are turned on or off in cells and tissues.
Expression Vector
A plasmid which has a promoter region. The vector is used to introduce a specific gene into a target cell, and can commandeer the cell’s mechanism for protein synthesis to produce the protein encoded by the gene.
cDNA
Complementary DNA. Complementary DNA is DNA synthesized from a single stranded RNA template in a reaction catalyzed by the enzyme reverse transcriptase.
cDNA Library
Collection of DNA fragments synthesized using all of the mRNAs present in a particular type of cell as a template.
Dideoxy (Sanger) DNA Sequencing
The standard method of determining the nucleotide sequence of DNA; utilizes DNA polymerase and a set of chain-terminating nucleotides.
DNA Cloning
Production of many identical copies of a DNA sequence.
DNA Library
Collection of cloned DNA molecules, representing either an entire genome (genomic library) or copies of the mRNA produced by a cell (cDNA library).
DNA Ligase
Enzyme that reseals nicks that arise in the backbone of a DNA molecule; in the laboratory, can be used to join together two DNA fragments.
DNA Microarray
A surface on which a large number of short DNA molecules (typically in the tens of thousands) have been immobilized in an orderly pattern. Each of these DNA fragments acts as a probe for a specific gene, allowing the activities of thousands of genes to be monitored at the same time.
Gene Knockout
A genetically engineered animal in which a specific gene has been inactivated.
Gene Replacement
Technique that substitutes a mutant form of a gene for its normal counterpart to investigate the gene’s function.
Genomic DNA Library
Collection of cloned DNA molecules that represents the entire genome of a cell.
Green Fluorescent Protein (GFP)
Fluorescent protein, isolated from a jellyfish, that is used experimentally as a marker for monitoring the location and movement of proteins in living cells.
Hybridisation
Experimental technique in which two complementary nucleic acid strands come together and form hydrogen bonds to produce a double helix; used to detect specific nucleotide sequences in either DNA or RNA.
In Situ Hybridisation
Technique in which a single-stranded RNA or DNA probe is used to locate a complementary nucleotide sequence in a chromosome, cell, or tissue; used to diagnose genetic disorders or to track gene expression.
Plasmid
Small circular DNA molecule that replicates independently of the genome. Used extensively as a vector for DNA cloning.
Recombinant DNA
A DNA molecule that is composed of DNA sequences from different sources.
Recombinant DNA Technology
The collection of techniques by which DNA segments from different sources are combined to make new DNA. Recombinant DNAs are widely used in the cloning of genes, in the genetic modification of organisms, and in molecular biology generally.
Reporter Gene
Gene encoding a protein whose activity is easy to monitor experimentally; used to study the expression pattern of a target gene or the localization of its protein product.
Restriction Nuclease
Enzyme that can cleave a DNA molecule at a specific, short sequence of nucleotides. Extensively used in recombinant DNA technology.
RNA Interference (RNAi)
Cellular mechanism activated by double-stranded RNA molecules that results in the destruction of RNAs containing a similar nucleotide sequence. It is widely exploited as an experimental tool for preventing the expression of selected genes (gene silencing).
RNA-Seq
Sequencing technique used to determine directly the nucleotide sequence of a collection of RNAs.
Transformation
Process by which cells take up DNA molecules from their surroundings and then express genes on that DNA.
Transgenic Organism
A plant or animal that has stably incorporated into its genome one or more genes derived from another cell or organism.
STR
Short Tandem Repeats.
