Evolution, Genetics, and Protein Synthesis Lecture Notes

A comprehensive set of vocabulary flashcards covering Earth's history, fossilization, human evolution, mechanisms of natural selection, DNA structure, Mendelian genetics, and the process of protein synthesis.

Evolution

The process by which living things change over time.

Age of Earth

Approximately $4.5$ billion years.

Extinction Rate

Over $99.9\%$ of all species that have ever lived are now extinct.

Modern Human Existence

Modern humans are thought to have existed for around $300,000$ years.

Fossil

The preserved remains or evidence of an organism from the past, typically found in sedimentary rock.

Mould Fossil

A type of fossil formed when an organism leaves an impression in rock.

Cast Fossil

A type of fossil formed when minerals fill the space left by a mould.

Trace Fossil

Evidence of an organism’s activity, such as footprints, burrows, or nests.

True Form Fossil

A fossil that preserves the actual remains of an organism, such as in amber, ice, or tar pits.

Permineralisation

A process where minerals carried by water fill spaces inside buried remains.

Law of Superposition

A geological principle stating that deeper rock layers are generally older than the layers above them.

Index Fossils

Specific fossils used by scientists to compare and date different rock layers.

Transitional Fossils

Fossils that show characteristics shared between ancestral and more modern groups, providing evidence for gradual evolutionary change.

Bipedalism

Walking on two legs, which was one of the earliest important human adaptations.

Homo sapiens

The scientific name for modern humans.

Hominin

A group consisting of modern humans, extinct human species, and all our immediate ancestors.

Natural Selection

The process occurring when individuals with helpful traits survive and reproduce more successfully than others.

Selection Pressure

Environmental factors, such as predation or food supply, that affect which organisms survive in a population.

Adaptation

Favourable inherited traits that improve an organism's chance of survival and reproduction in a specific environment.

DNA

The genetic material found in the nucleus that carries instructions for building and controlling living organisms.

Double Helix

The twisted-ladder shape of the DNA molecule.

Bases (DNA)

The four molecules that form the rungs of the DNA ladder: Adenine ($A$), Thymine ($T$), Cytosine ($C$), and Guanine ($G$).

Complementary Base Pairing

The rule that $A$ always pairs with $T$ and $C$ always pairs with $G$ in DNA.

DNA Replication

The process by which DNA copies itself accurately when cells divide, using each strand as a template.

Mutation

A change in the DNA sequence that can introduce new variation into a population.

Gene

A section of DNA that codes for a specific protein or inherited trait.

Allele

Different versions or variants of a specific gene.

Dominant Allele

An allele that is expressed in the phenotype if at least one copy is present.

Recessive Allele

An allele that is only expressed in the phenotype when two copies are present.

Genotype

The specific combination of alleles an organism possesses for a gene.

Phenotype

The observable physical or functional characteristics of an organism.

Homozygous

Having two identical alleles for a particular gene.

Heterozygous

Having two different alleles for a particular gene.

Diploid

Cells containing two full sets of chromosomes.

Haploid

Cells containing only one set of chromosomes, such as gametes.

Gametes

Sex cells, specifically sperm and egg cells, that are haploid.

Zygote

A diploid cell formed by the fertilisation of two haploid gametes.

Monohybrid Cross

A genetic cross where only one characteristic is studied at a time.

Dihybrid Cross

A genetic cross where two different traits are studied simultaneously, often resulting in a $9:3:3:1$ phenotypic ratio.

Transcription

The process occurring in the nucleus where an mRNA copy is made from a DNA template strand.

mRNA

Messenger RNA; a single-stranded molecule that carries genetic information from the nucleus to the ribosome.

RNA Polymerase

The enzyme that separates DNA strands and builds the mRNA strand during transcription.

Uracil ($U$)

The nitrogenous base that replaces Thymine ($T$) in RNA molecules.

Translation

The process occurring at ribosomes where mRNA codons are read to assemble amino acids into proteins.

Codon

A sequence of three bases on mRNA that codes for a specific amino acid.

tRNA

Transfer RNA; molecules that carry specific amino acids to the ribosome during translation.

Anticodon

A sequence of three bases on a tRNA molecule that is complementary to an mRNA codon.

Polypeptide Chain

A chain of amino acids joined by peptide bonds, which eventually folds into a functional protein.

Central Dogma

The scientific principle describing the flow of genetic information from DNA to RNA to Protein.

Antibiotic Resistance

An example of evolution in microorganisms where bacteria with resistance mutations survive antibiotic treatment and reproduce.