Glossary
5' cap
A modified guanine nucleotide added to the 5' end of a pre-mRNA molecule during RNA processing, protecting it from degradation and aiding ribosome binding.
Example:
The 5' cap acts like a protective helmet on the mRNA, shielding it from enzymes that might otherwise break it down in the cytoplasm.
Biotechnology
The application of biological processes, organisms, or systems to produce products or technologies intended to improve human lives.
Example:
The use of bacteria to produce human insulin for diabetics is a prime example of biotechnology in medicine.
Cell Specialization
The process by which cells develop distinct forms and functions, primarily due to differential gene expression.
Example:
During embryonic development, stem cells undergo cell specialization to become diverse cell types like muscle cells, nerve cells, or skin cells.
DNA (Deoxyribonucleic Acid)
The double-stranded nucleic acid that carries the genetic instructions for the development, functioning, growth, and reproduction of all known organisms and many viruses.
Example:
The DNA in every human cell contains the complete genetic blueprint for building and operating a person.
DNA Polymerase
An enzyme that synthesizes new DNA strands by adding complementary nucleotides to a template strand during DNA replication.
Example:
As new DNA strands are built, DNA polymerase meticulously checks for errors, ensuring high fidelity in the genetic copy.
DNA Replication
The semi-conservative process by which a cell makes an exact copy of its entire DNA genome before cell division.
Example:
Before a skin cell divides to repair a wound, it undergoes DNA replication to ensure each new cell receives a complete set of genetic instructions.
Enhancers
DNA sequences that can be located far from a gene but increase the rate of its transcription when bound by specific transcription factors.
Example:
Even though an enhancer might be thousands of base pairs away, it can loop around and interact with the promoter to boost gene expression.
Evolution
The change in the heritable characteristics of biological populations over successive generations, driven by mechanisms like natural selection, genetic drift, and gene flow.
Example:
The development of antibiotic resistance in bacteria over decades is a clear example of evolution occurring at a rapid pace.
Exons
Coding regions within a gene that are transcribed into RNA and remain in the mature mRNA molecule after splicing, eventually being translated into protein.
Example:
The exons of a gene contain the actual instructions for building a protein, similar to the main plot points of a story.
Gel Electrophoresis
A laboratory technique used to separate DNA fragments, RNA molecules, or proteins based on their size and electrical charge by moving them through a gel matrix.
Example:
After cutting DNA with restriction enzymes, gel electrophoresis is used to visualize and separate the fragments, creating a unique banding pattern.
Gene Cloning
The process of making multiple identical copies of a specific gene or DNA sequence, typically by inserting it into a bacterial plasmid.
Example:
Researchers perform gene cloning to produce large quantities of a specific protein for study or therapeutic use, such as human growth hormone.
Gene regulation
The process by which cells control which genes are expressed (turned on or off) and to what extent, allowing them to adapt to changes and perform specialized functions.
Example:
A liver cell expresses genes for detoxification enzymes, while a neuron expresses genes for neurotransmitter synthesis, demonstrating specific gene regulation for cell function.
Genetic Engineering
The direct manipulation of an organism's genes using biotechnology to alter its characteristics or produce new products.
Example:
Scientists use genetic engineering to insert genes for pest resistance into crop plants, reducing the need for chemical pesticides.
Genetic diversity
The total number of genetic characteristics in the genetic makeup of a species, crucial for a population's ability to adapt to changing environments.
Example:
A population of wild flowers with varied petal colors and disease resistances exhibits high genetic diversity, increasing its chances of survival against new pathogens.
Helicase
An enzyme that unwinds and separates the two strands of the DNA double helix during DNA replication and transcription.
Example:
During DNA replication, helicase acts like a zipper, unzipping the DNA molecule to allow other enzymes access to the strands.
Introns
Non-coding regions within a gene that are transcribed into RNA but are subsequently removed during RNA processing.
Example:
In eukaryotic genes, introns are like commercial breaks in a TV show; they are present in the initial recording but are cut out before the final broadcast.
Ligase
An enzyme that joins DNA fragments together by forming phosphodiester bonds, particularly important in sealing gaps during DNA replication and repair.
Example:
After DNA polymerase fills in gaps on the lagging strand, ligase acts as a molecular glue, connecting the newly synthesized fragments.
Mutation
A random change in the DNA sequence, which can introduce new variations into a population's genetic makeup.
Example:
A single nucleotide mutation in a gene might change a protein's shape, potentially leading to a new trait like antibiotic resistance in bacteria.
Natural Selection
The process by which individuals with traits better suited to their environment are more likely to survive, reproduce, and pass on those advantageous traits to their offspring.
Example:
In a forest, green beetles are camouflaged on leaves, while brown beetles are easily seen; over time, natural selection favors the green beetles, increasing their population.
PCR (Polymerase Chain Reaction)
A laboratory technique used to amplify (make many copies of) a specific segment of DNA, even from a very small initial sample.
Example:
Forensic scientists use PCR to amplify tiny amounts of DNA found at a crime scene, allowing for DNA fingerprinting.
Phenotype
The observable physical or biochemical characteristics of an organism, resulting from the interaction of its genotype with the environment.
Example:
A person's eye color, height, and blood type are all aspects of their phenotype, influenced by their genes and sometimes environmental factors.
Poly(A) tail
A long chain of adenine nucleotides added to the 3' end of a pre-mRNA molecule during RNA processing, enhancing stability and aiding export from the nucleus.
Example:
The poly(A) tail on an mRNA molecule helps determine how long the mRNA will survive in the cytoplasm before being degraded.
Primase
An enzyme that synthesizes short RNA primers, which provide a starting point for DNA polymerase to begin synthesizing new DNA strands.
Example:
Without primase laying down an RNA primer, DNA polymerase would have no initial segment to extend, halting DNA replication.
Promoters
Specific DNA sequences located upstream of a gene where RNA polymerase binds to initiate transcription.
Example:
The strength of a gene's promoter dictates how frequently RNA polymerase will bind and begin transcribing that gene.
Protein Folding
The process by which a polypeptide chain acquires its specific three-dimensional structure, essential for its biological function.
Example:
After synthesis, a newly formed protein must undergo precise protein folding to achieve its active shape, like a complex origami structure.
RNA (Ribonucleic Acid)
A single-stranded nucleic acid that plays a crucial role in gene expression, acting as a messenger, a transporter of amino acids, or a component of ribosomes.
Example:
When a gene needs to be expressed, a molecule of RNA is transcribed from the DNA to carry the genetic message out of the nucleus.
RNA Polymerase
An enzyme that synthesizes an RNA strand by reading a DNA template strand and adding complementary RNA nucleotides.
Example:
The RNA polymerase enzyme binds to the promoter region of a gene, initiating the synthesis of a messenger RNA molecule.
RNA Processing
Modifications made to the primary RNA transcript in eukaryotic cells, including splicing, 5' capping, and polyadenylation, to produce a mature mRNA molecule.
Example:
Before leaving the nucleus, a newly transcribed RNA molecule undergoes extensive RNA processing to remove non-coding regions and add protective caps.
Recombinant DNA Technology
A set of techniques used to combine DNA from different sources into a single molecule, often for genetic engineering purposes.
Example:
Creating a plasmid that contains a human gene and a bacterial gene for antibiotic resistance involves recombinant DNA technology.
Recombination
The shuffling of genetic material, typically during sexual reproduction (meiosis), which creates new combinations of existing alleles.
Example:
During meiosis, homologous chromosomes exchange segments through crossing over, leading to recombination and unique combinations of traits in offspring.
Regulatory Sequences
Specific DNA sequences that control the transcription of genes by binding to regulatory proteins.
Example:
The presence of certain regulatory sequences near a gene determines whether it will be highly expressed or remain mostly silent in a particular cell type.
Ribosomes
Cellular organelles responsible for protein synthesis, composed of ribosomal RNA (rRNA) and proteins, found in the cytoplasm or attached to the endoplasmic reticulum.
Example:
The ribosomes are the cell's protein factories, where the genetic code from mRNA is converted into functional proteins.
Silencers
DNA sequences that, when bound by specific transcription factors, decrease or repress the rate of transcription of a gene.
Example:
In certain developmental stages, silencers might prevent the expression of genes that are no longer needed, ensuring proper cell differentiation.
Transcription
The process of synthesizing an RNA molecule from a DNA template, occurring in the nucleus of eukaryotic cells.
Example:
When a cell needs to produce insulin, the gene for insulin is first copied into an mRNA molecule through transcription.
Transcription Factors
Proteins that bind to specific DNA sequences (like promoters, enhancers, or silencers) to regulate the rate of gene transcription.
Example:
A specific transcription factor might be activated by a hormone, then travel to the nucleus to turn on a set of genes involved in a cellular response.
Translation
The process by which ribosomes synthesize proteins using the genetic information encoded in an mRNA molecule.
Example:
In the cytoplasm, translation occurs as ribosomes read the mRNA codons and assemble amino acids into a polypeptide chain.
tRNA
Transfer RNA; a type of RNA molecule that carries specific amino acids to the ribosome during translation, matching them to corresponding mRNA codons.
Example:
Each tRNA molecule has an anticodon that base-pairs with an mRNA codon, ensuring the correct amino acid is added to the growing protein.