Biology Key Concepts: DNA, Evolution, and Classification

DNA

Blueprint for protein found in the nucleus, contains nucleotides: sugar, phosphate, and nitrogenous bases (purines: adenine, guanine, pyrimidines: cytosine, thymine), two stranded (double-helix ladder), and is heritable (traits passed to daughter cells).

Protein synthesis

The process involving DNA unzipping, mRNA transcription, mRNA leaving the nucleus to join a ribosome, and tRNA bringing amino acids to the ribosome to grow a protein chain.

Evolutionary change

Change in genetic make-up in a population over time.

Mutation

A change in an expression of one protein.

Chromosomal mutations

Involves the expression of many genes and have large consequences.

Genetic drift

A change in gene expression (allele frequency) due to reproductive success (or mortality) in small populations.

Gene flow

Change in population allele frequency that results from migration.

Natural selection

Survival of the fittest, where those most fit are able to produce more offspring, thus increasing their genes in the population.

Non-random mating

Mate selection of traits, often physical (visible) or may be behavioral (a fine song).

Speciation

The emergence of a new species.

Species

A group of organisms that cannot interbreed with another group under natural conditions and produce viable offspring.

Microevolution

Changes in DNA, mutations, natural selection, and adaptation.

Macroevolution

Speciation, process of speciation, divergent and disruptive selection, gene flow, and genetic drift.

Directional selection

A favored extreme trait, e.g., horses getting larger over time.

Stabilizing selection

An average trait that is strongly conserved.

Disruptive selection

A trait that favors two extremes but no average, leading to divergent evolution and adaptive radiation.

Convergent evolution

When similar selection pressures act on two different, genetically isolated populations, potentially leading to ecological equivalents (e.g., kangaroos and deer).

Evolution by gradual change

The idea that evolutionary change is slow and gradual, moving at a fairly steady rate.

Punctuated equilibrium

The concept that change is very slow or in equilibrium and is then punctuated by periods of rapid change.

Fossil record

Provides direct evidence of change through time, showing adaptive radiation and extinction.

Embryology

The study of the development of an organism in the early stages of life, where more closely related organisms have more similar embryotic development.

Homologous structures

Kindship can be seen when looking at baby parts that share the same basic underlying structure, e.g., vertebrate limbs.

Biochemical relationships

More closely related organisms will show greater similarities in DNA and protein composition, e.g., cytochrome c, a protein used in energy metabolism.

Taxonomy

The science of classification of organisms.

Carolus Linnaeus

The creator of taxonomy.

Domains

Eukarya, Archaea, Bacteria.

Kingdoms

Archaebacteria, Protista, Fungi, Animalia, Plantae.

Prokaryotes

Unicellular organisms that lack membrane-bound organelles, are very small, and have DNA not associated with proteins.

Eukaryotes

Organisms with membrane-bound organelles, including a nucleus, mitochondria, lysosomes, and vacuoles.

K Fungi

Multicellular absorptive heterotrophs with cell walls containing chitin.

K Plantae

Multicellular photosynthetic autotrophs with cell walls of cellulose and containing chloroplasts.

K Animalia

Multicellular ingestive heterotrophs that lack cell walls, are mostly motile, and do not have chloroplasts.