Evidence for Evolution – Comparative Biochemistry, Fossils, and Dating Methods

Vocabulary flashcards cover key terms from the lecture on biochemical evidence for evolution, mitochondrial DNA, bioinformatics, fossil formation, and dating techniques.

Comparative Biochemistry

The study of similarities and differences in the chemical composition of organisms (DNA, proteins) to infer evolutionary relationships.

DNA Code

Universal sequence of four nucleotide bases (A, T, C, G) shared by all living things, supporting common ancestry.

Mutation

Random change in DNA sequence that creates new genes and contributes to genetic variation.

Natural Selection

Evolutionary process in which advantageous traits increase an organism’s reproductive success and become more common over generations.

Genetic Drift

Random changes in allele frequencies in a population, often affecting small populations, leading to evolutionary change.

Speciation

Formation of new species when populations become reproductively isolated and diverge genetically.

Comparative Genomics

Field that compares whole genomes of different species to identify conserved and unique genes.

Genome

Complete set of genetic material in an organism, including all of its genes and non-coding sequences.

Endogenous Retrovirus (ERV)

Remnant of ancient viral DNA integrated into a host genome; 8 % of the human genome contains ERVs that match chimpanzee ERVs at 16 loci.

Protein Sequence

Specific order of amino acids in a protein, determined by DNA, used to compare evolutionary relationships among species.

Amino Acid (AA)

Building block of proteins; 20 standard amino acids are coded by DNA and represented by single-letter abbreviations in comparisons.

Ubiquitous Protein

Protein present in virtually all organisms and essential for life, e.g., cytochrome C.

Cytochrome C

Ubiquitous respiratory protein of 104 amino acids; highly conserved and identical in humans, chimps, and gorillas.

Evolutionary Divergence

Accumulation of genetic differences between lineages after they split from a common ancestor.

Mitochondrial DNA (mtDNA)

Small circular DNA found in mitochondria, inherited maternally, useful for tracing recent ancestry.

Mitochondrial Eve

Hypothetical most-recent female ancestor whose mtDNA is ancestral to all modern humans.

Maternal Inheritance

Transmission of genetic material exclusively through the mother, characteristic of mtDNA.

Bioinformatics

Use of computational tools to store, analyze, and compare biological data such as DNA and protein sequences.

Annotation (Genomics)

Process of identifying genes, start/stop codons, and functional elements within a DNA sequence using software.

Fossil

Any preserved trace of past life, including bones, shells, footprints, burrows, or impressions.

Fossilisation

Process by which organic remains are preserved, often involving rapid burial and mineral replacement.

Sedimentary Rock

Rock formed from accumulated sediments; primary context for fossil preservation and stratigraphic studies.

Principle of Superposition

Stratigraphic rule stating that in undisturbed layers, older strata lie beneath younger strata.

Stratigraphy

Study of rock layers (strata) to establish relative ages of fossils and geological events.

Index Fossil

Widely distributed fossil species that existed for a short geologic duration, used to correlate rock layers.

Relative Dating

Method of ordering fossils or rocks chronologically without assigning exact numerical ages.

Absolute Dating

Technique that provides quantitative age estimates for rocks or fossils, e.g., radiometric methods.

Radioactive Decay

Spontaneous transformation of an unstable isotope into a stable form, releasing particles or radiation.

Isotope

Atoms of the same element with the same number of protons but different numbers of neutrons.

Half-Life

Time required for half of a radioactive isotope in a sample to decay.

Potassium-Argon Dating

Radiometric method measuring decay of potassium-40 to argon-40 to date rocks older than ~100 000 years.

Carbon-14 Dating (Radiocarbon)

Technique measuring decay of carbon-14 to nitrogen-14 to date organic remains up to ~60 000 years old.

Calibration (Radiocarbon)

Adjustment of radiocarbon dates using known-age records (e.g., tree rings) to correct for atmospheric variations in C-14 levels.

Mass Spectrometer

Laboratory instrument that measures isotopic abundances (e.g., argon-40) for radiometric dating.

Quick Burial

Rapid coverage of remains by sediment, reducing decomposition and promoting fossilisation.

Petrification (Mineral Replacement)

Process in which minerals fill the pores of bone or wood, turning them into stone while preserving structure.

Peat

Water-logged, oxygen-poor soil that can preserve soft tissues and bones due to inhibited decay.

Alkaline Soil

Soil with basic pH; preserves bone minerals well and favors fossil formation.

Chromosome Fusion

Hypothesized event where two ancestral chimpanzee chromosomes fused to form human chromosome 2, explaining 23 vs. 24 chromosome pairs.

Chimpanzee–Human DNA Similarity

Observation that chimpanzees share >98 % of DNA sequence identity with humans, indicating close relatedness.

Common Ancestor

An ancestral species from which two or more descendant species evolved.

Mutation Rate (mtDNA)

Higher frequency of mutations in mitochondrial DNA relative to nuclear DNA, enabling recent lineage studies.

Aerobic Respiration

Energy-producing metabolic pathway occurring in mitochondria, requiring oxygen.

Site of Fossil Discovery (Water Bodies/Caves)

Locations where rapid burial in sediment or cave collapse enhances fossil preservation and discovery success.

Incomplete Fossil Record

Limitation arising because fossilisation conditions are rare, many fossils remain undiscovered, and entire organisms are seldom preserved.