Comprehensive Molecular Genetics, Biotechnology, Ecology, and Evolution Review

Practice vocabulary flashcards covering molecular genetics, gene regulation, biotechnology, organismal and population ecology, community dynamics, and evolutionary mechanisms.

Gene Regulation

The control of gene expression occurring at multiple stages along the gene expression pathway, including chromatin structure, transcription, RNA processing, translation, and post-translational modification.

Barr Body

A condensed, transcriptionally inactive X chromosome formed by random X chromosome inactivation in mammalian female cells to prevent higher gene dosage compared to males.

Alternative Splicing

An RNA processing mechanism where different combinations of exons from a single primary RNA transcript are joined together, allowing one gene to encode multiple distinct protein variants.

Missense Mutation

A base substitution in DNA that alters a codon so that it specifies a different amino acid, such as the mutation in hemoglobin that causes sickle cell disease.

Frameshift Mutation

A genetic mutation caused by an insertion or deletion of nucleotides not in multiples of three, which shifts the triplet reading frame and alters all downstream codons.

Proto-Oncogenes

Normal cellular genes that promote cell cycle progression, which can mutate into oncogenes that drive uncontrolled cell growth and cancer progression.

Reproductive Cloning

A technique that creates a genetically identical whole animal by transferring a diploid somatic cell nucleus into an enucleated egg and implanting the resulting embryo into a surrogate mother.

Therapeutic Cloning

A procedure aimed at culturing pluripotent embryonic stem cells to direct their differentiation into specialized cell types for tissue regeneration and repair.

Recombinant DNA

A DNA molecule artificially formed by combining genetic material from two distinct sources, such as bacterial plasmid vectors and eukaryotic genes.

Restriction Enzymes

Bacterial proteins that cut double-stranded DNA at specific, often palindromic recognition sequences, frequently producing sticky ends useful for genetic engineering.

Restriction Fragment Length Polymorphism (RFLP)

Variations in DNA fragment lengths generated by restriction enzyme digestion that arise due to sequence differences between individuals.

Gel Electrophoresis

A laboratory technique that separates digested DNA fragments by size using an electric field, where smaller, negatively charged fragments migrate faster through an agarose gel toward the positive electrode.

Ecology

The scientific study of interactions between organisms and their living and non-living environments across organismal, population, community, and ecosystem levels.

Abiotic Factors

Non-living physical and chemical components of an environment, such as temperature, water availability, sunlight, nutrients, pH, and wind, that determine species distribution and survival.

Biome

A major ecological life zone characterized by distinct climatic conditions—primarily temperature and precipitation—and recognizable plant and animal communities.

Taiga (Boreal Forest)

A high-latitude terrestrial biome characterized by long, cold winters, short summers, and forests dominated by cold-tolerant coniferous evergreens.

Tundra

A terrestrial biome characterized by freezing temperatures, low precipitation, short growing seasons, low-growing vegetation, and an underlying layer of permanently frozen permafrost.

Lincoln–Petersen Index

A mark–recapture formula, expressed as $N = \frac{M \times S}{R}$, used to estimate total population size ($N$) based on marked individuals released ($M$), total recaptured ($S$), and marked recaptures ($R$).

Carrying Capacity ($K$)

The maximum population size of a species that a particular environment can sustain indefinitely without degradation.

Logistic Growth Model

A population growth model that produces an S-shaped curve, where growth slows and plateaus as population size approaches environmental carrying capacity ($K$).

Density-Dependent Factors

Limiting factors whose effects on population birth or death rates intensify as population density increases, including food depletion, waste accumulation, and nesting competition.

$K$-Selected Species

Equilibrium species characterized by low biotic potential, few offspring, large body size, long lifespans, and significant parental care, which maintain populations near carrying capacity.

Type III Survivorship Curve

A survivorship curve characterized by extremely high mortality rates early in life, with relatively few individuals surviving to advanced age, typical of many plants and invertebrates.

Competitive Exclusion Principle

The ecological rule stating that two species competing for the exact same limiting resources cannot coexist indefinitely, resulting in one species outcompeting and eliminating the other.

Realized Niche

The actual portion of the fundamental niche that a species occupies in an ecosystem in the presence of competitors and biological constraints.

Commensalism

A symbiotic interspecific interaction in which one organism benefits and the other organism is neither helped nor harmed ($+/0$), such as barnacles riding on humpback whales.

10% Rule

The thermodynamic ecological principle stating that only approximately $10\%$ of the energy stored as biomass at one trophic level is transferred into biomass at the subsequent trophic level.

Keystone Species

A species that exerts a disproportionately large effect on maintaining ecological community diversity relative to its abundance, such as predatory sea stars (Pisaster) or sea otters.

Ocean Acidification

The reduction of seawater pH resulting from the absorption of excess atmospheric $CO_2$, which decreases the availability of carbonate ions needed for calcifying organisms to build shells and skeletons.

Natural Selection

A mechanism of evolution in which individuals possessing heritable traits that confer survival or reproductive advantages survive and reproduce at higher rates, altering population allele frequencies over time.

Artificial Selection

The selective breeding of domesticated plants and animals by humans to promote desirable phenotypic traits across successive generations.

Homologous Structures

Anatomical features across diverse species that exhibit structural similarity due to shared evolutionary ancestry, despite having potentially different modern functions.

Vestigial Structures

Remnants of anatomical structures that served important functions in an organism's ancestors but have reduced or no function in modern descendants, such as the human appendix.

MC1R Gene

A pigmentation-controlling gene whose mutations produce dark coat variants in rock pocket mice, conferring camouflage and survival advantages on dark volcanic lava substrates.

Microevolution

Generation-to-generation shifts in allele frequencies within a population's gene pool, representing evolutionary change on the smallest scale.

Hardy–Weinberg Equilibrium

A theoretical model of a non-evolving population in which allele frequencies ($p + q = 1$) and genotype frequencies ($p^2 + 2pq + q^2 = 1$) remain stable over generations.

Bottleneck Effect

A form of genetic drift resulting from a sudden, catastrophic reduction in population size that produces a surviving gene pool with significantly reduced genetic diversity.

Founder Effect

A genetic drift phenomenon occurring when a small subset of individuals separates from a larger population to establish a new colony, carrying only a restricted fraction of the original gene pool.

Gene Flow

The transfer of alleles into or out of a population's gene pool due to the migration and interbreeding of fertile individuals or gametes.

Disruptive Selection

A mode of natural selection that favors individuals at both extremes of a phenotypic distribution while selecting against intermediate phenotypes.

Stabilizing Selection

A mode of natural selection that favors intermediate phenotypes over extreme variations, reducing phenotypic variance around an optimal population mean.

Sexual Dimorphism

Pronounced differences in secondary sexual characteristics and appearances between males and females of the same species, often driven by sexual selection.

What is gene regulation?

Control of when, where, and how much a gene is expressed.

How do different cell types produce different proteins?

They express different sets of genes.

What is commonly meant by "junk" DNA?

DNA without an identified function, much of which does not encode proteins.

Is all noncoding DNA functionless?

No. Some noncoding DNA regulates genes or produces functional RNA.

What modification is added to the 5′ end of eukaryotic pre-mRNA?

A 5′ cap.

What modification is added to the 3′ end of most eukaryotic pre-mRNAs?

A poly-A tail.

What process removes intervening sequences from pre-mRNA?

RNA splicing.

Which sequences are removed during pre-mRNA splicing?

Introns.

Which sequences remain in mature mRNA after splicing?

Exons.

Do all exon sequences encode protein?

No. Exons can also contain untranslated regions.

What is alternative splicing?

The production of different mRNAs from one pre-mRNA by selecting different exons.

How does alternative splicing affect the proteins a gene can produce?

Different mRNA variants can produce different protein variants.

How can humans and Caenorhabditis elegans have similar numbers of genes?

Gene count alone does not determine organismal complexity.

How can alternative splicing contribute to human protein diversity?

It allows one gene to produce multiple protein variants.

How is X-linked gene dosage balanced in female mammals?

One X chromosome is largely inactivated in each somatic cell.

What is a Barr body?

A condensed, largely inactive X chromosome.

What is a consequence of random X inactivation in female mammals?

Different cell populations can express alleles from different X chromosomes.

How can X inactivation contribute to a calico cat's coat?

Different cell patches express different X-linked coat-color alleles.

What is a mutation?

A change in a cell's DNA sequence.

What is a single-nucleotide substitution?

A mutation that replaces one nucleotide with another.

What is a synonymous substitution?

A nucleotide substitution that does not change the encoded amino acid.

What is a missense substitution?

A nucleotide substitution that changes the encoded amino acid.

What is a nonsense substitution?

A nucleotide substitution that creates a premature stop codon.

Are all nucleotide substitutions reflected in the amino acid sequence?

No. Some are synonymous, and others occur outside protein-coding sequences.

What is a frameshift mutation?

An insertion or deletion that shifts the coding sequence's reading frame.

Why can a frameshift be more disruptive than a substitution?

It can change many downstream amino acids and introduce a premature stop.

Do all nucleotide insertions and deletions cause frameshifts?

No. Insertions or deletions in multiples of three preserve the reading frame.

How can a mutation in a regulatory DNA sequence affect gene expression?

It can alter transcription-factor binding and change gene transcription.

How can mutations transform normal cells into cancer cells?

They can activate growth-promoting genes or disable genes that restrain cell growth.

What is an oncogene?

A gene whose abnormal activation can promote uncontrolled cell growth.

What is a tumor suppressor gene?

A gene that normally helps restrain cell growth or maintain genomic integrity.

What is reproductive cloning?

Producing a new organism genetically similar to a nuclear donor.

How is an embryo produced for reproductive cloning?

A somatic cell nucleus is transferred into an egg whose nucleus was removed.

What happens to the embryo in reproductive cloning?

It is implanted into a uterus to develop.

What is therapeutic cloning?

Creating an embryo to derive genetically matched embryonic stem cells for research or potential therapies.

How does therapeutic cloning differ from reproductive cloning?

Therapeutic cloning aims to produce cells, not a new organism.

What are stem cells?

Cells that can self-renew and develop into specialized cell types.

Why might therapeutic cloning be useful in medicine?

It may provide patient-matched cells for studying disease or replacing damaged tissue.

How is cloning used in agriculture?

It reproduces animals or plants with desirable traits.

What is a genetically modified organism?

An organism whose genetic material has been altered using genetic engineering.

What is recombinant DNA?

DNA formed by joining genetic material from different sources.

What is a plasmid?

A small, usually circular DNA molecule that replicates independently of the bacterial chromosome.

How are recombinant DNA plasmids made?

A DNA fragment is joined to a cut plasmid, typically using DNA ligase.

What role do restriction enzymes play in making recombinant plasmids?

They cut plasmid and donor DNA at specific sequences.

Why are bacteria used to copy recombinant plasmids?

They reproduce rapidly and replicate plasmids, producing many DNA copies.

What human protein is produced using recombinant bacteria?

Human insulin.

What other human protein can be produced using recombinant DNA technology?

Human growth hormone.

What is DNA profiling?

Analysis of variable DNA regions to distinguish individuals or assess biological relationships.

What is restriction fragment length polymorphism analysis?

A method comparing lengths of DNA fragments produced by restriction enzymes.

What makes an individual's DNA profile distinctive?

Variation in DNA sequences, especially at multiple variable regions.

How are small DNA fragments generated for RFLP analysis?

Restriction enzymes cut DNA at specific recognition sequences.

How are DNA fragments separated for comparison?

Gel electrophoresis separates them primarily by size.

How are DNA fragment patterns compared?

Bands from different samples are compared by their positions in the gel.

How does DNA fragment size affect movement through a gel?

Smaller fragments generally travel farther than larger fragments.

What does a band in a DNA gel represent?

DNA fragments of similar size.

How does a DNA ladder help interpret a gel?

Its fragments of known sizes provide a reference for estimating sample fragment sizes.

How can fragment numbers be estimated from a gel?

Count distinct bands, noting that fragments of similar size may overlap.

What gel pattern supports a match between a suspect and crime-scene DNA?

Corresponding bands appear at the same positions across the tested regions.