bio

Biology Vocabulary List (Simple Definitions)

DNA & Genetics

• DNA: Instructions that tell cells how to work.

• Nucleic Acid: A molecule like DNA or RNA that carries genetic info.

• Chromosome: A bundle of DNA found in the nucleus.

• Gene: A part of DNA that gives instructions for one trait.

• Nucleotide: The building block of DNA (made of sugar, phosphate, and a base).

• DNA Bases (A, T, G, C): Letters that pair up (A-T, G-C) and make the code in DNA.

• Replication: Copying DNA before a cell divides.

RNA & Protein Synthesis

• RNA: A copy of DNA used to make proteins.

• RNA Bases (A, U, G, C): A pairs with U, G pairs with C in RNA.

• mRNA: Carries the message from DNA to the ribosome.

• tRNA: Brings amino acids to the ribosome.

• Transcription: Making mRNA from DNA.

• Translation: Making proteins from mRNA.

• Amino Acid: Building blocks of proteins.

• Codon: A group of 3 mRNA bases that code for 1 amino acid.

• Anticodon: A group of 3 tRNA bases that match with the mRNA codon.

Mutations & Chromosomes

• Mutation: A change in the DNA sequence.

• Point Mutation: One base is changed.

• Frameshift Mutation: A base is added or deleted, shifting the whole sequence.

• Karyotype: A picture of all the chromosomes in a cell.

• Nondisjunction: When chromosomes don’t separate properly.

• Trisomy 21: Having 3 copies of chromosome 21 (causes Down syndrome).

Cells & Division

• Diploid: A cell with two sets of chromosomes (46 in humans).

• Haploid: A cell with one set of chromosomes (23 in humans).

• Mitosis: Cell division that makes 2 identical body cells.

• Meiosis: Cell division that makes 4 different sex cells.

• Somatic Cell: A body cell.

• Gamete: A sex cell (sperm or egg).

Genetics Terms

• Allele: A version of a gene (example: blue or brown eyes).

• Dominant: A trait that shows even if only one copy is present.

• Recessive: A trait that shows only if two copies are present.

• Homozygous: Two of the same alleles (AA or aa).

• Heterozygous: Two different alleles (Aa).

• Genotype: The genes an organism has.

• Phenotype: The physical traits that show.

Pedigrees & Inheritance

• Pedigree: A family tree that shows how traits are passed on.

• Autosomal Dominant: Trait appears if at least one dominant allele is present.

• Autosomal Recessive: Trait only appears if two recessive alleles are present.

Evolution & Natural Selection

• Evolution: Change in species over time.

• Natural Selection: When traits that help survival become more common.

• Overproduction: Having more offspring than the environment can support.

• Variation: Differences between individuals.

• Adaptation: A trait that helps an organism survive.

• Selective Pressure: Something that affects survival (like predators or food).

• Competition: Fighting for resources like food or mates.

• Fitness: How well an organism survives and reproduces.

• Speciation: The formation of new species.

Evidence for Evolution

• Fossils: Remains of ancient life.

• Comparative Embryology: Comparing embryos of different species.

• Comparative Analogy: Comparing similar functions in different species.

• Comparative Biochemistry: Comparing DNA or proteins of different species.

• Homologous Structures: Body parts that look similar but have different uses.

• Analogous Structures: Body parts that have similar functions but different structures.

• Vestigial Structures: Body parts that no longer have a use (like human tailbone).

Cladograms & Evolutionary Trees

• Cladogram: A diagram that shows how species are related.

• Extinct: A species that no longer exists.

• Common Ancestor: An early organism that two or more species came from.

• Outgroup: A species that is less related to the others (used for comparison).