School in a Book: Biology and Genetics

I remember learning basic biology in school. It was a long time ago, and yet, most of this stuff stuck. It’s everywhere, after all–in the news, in other books. And yet, after creating this list, I was struck by the fine delineations, especially regarding the differences between genes, genetic traits, chromosomes, alleles, and DNA. Interesting review here.

Basic Biology

7 characteristics of living things: Respiration (usually air respiration); reproduction; movement; digestion of both water and nutrients); metabolism; death; and cell-based structure.

Common name: Name commonly used for a species of animal or plant

Scientific name: Official name of an animal or plant. This is usually in Latin and made up of the genus and species names, but sometimes also contains the name of the sub-species.

Classification/taxonomy: The organizing of things into groups according to their shared features

The eight levels of the taxonomy of living things: Domain, kingdom, phylum, class, order, family, genus, species. (Many species are also divided into subspecies called races, breeds or varieties.)

Species: The taxonomic level at which all the members can mate and reproduce offspring of their kind

The two domains of living things: Prokaryota and eukaryota

Prokaryote: A living thing whose cells have nucleuses. (The plural form is prokaryota.)

Eukaryote: A living thing whose cells do not have nucleuses. (The plural form is eukaryota.) 

The five kingdoms of living things: Bacteria, archaea, fungi, protistas, plantae and animalia

Bacteria: A type of single-celled organism that exists everywhere on earth. Most types have not been studied.


Fungi: Living things that lack chlorophyll and feed on living and dead things, including mold, yeast and mushrooms. Fungi are not plants, but they are plant-like. They grow in damp, dark places. Some fungi are helpful, as yeast and cheese mold. Others are poisonous to animals and plants.


Protozoa: Single-celled eukaryotes that feed on organic matter

Amoeba: A type of protozoa, fungi, algae or animal that can change shape, usually by extending out pseudopods (fluid-filled sacs in the shape of arms or tentacles)

X characteristics of plants: A living thing that gets energy from the sun,

3 characteristics of animals: A distinct orientation (i.e., a top and a bottom); symmetry; mobility; and a reliance on living, biological organisms for energy. Note that mobility is different from movement in that it is wider in range. For example, a plant may move closer to the light and grow roots, but it doesn’t wholly move and the movement takes a long time and is distance limited.

The human taxonomy: Domain: eukaryota; kingdom: animalia; phylum: chordata (since they have a stiff rod that supports the body); class: mammalia; order: primates; family: Hominidae; genus: Homo; species: Homo sapiens.

Habitat: The natural environment in which a species lives and thrives

Life cycle: The stages of growth and development of living things. This is different for different species; for example, frogs have a tadpole stage and caterpillars have a cocoon stage.

Generation: All members of a species bearing offspring around the same time

Male: Boy offspring; fertilizes the egg

Female: Girl offspring; produces the egg(s) and sometimes births the offspring

Sexual reproduction: Reproduction involving two parents, one male and one female

Asexual reproduction: Reproduction involving only one parent. Algae, mosses and some ferns use asexual reproduction because they don’t have flowers. Other ferns alternate using sexual and asexual reproduction.

Vegetative reproduction/vegetative propagation: When a plant can reproduce itself by itself asexually. Examples: plants that grow from bulbs (like tulips), from runners (like strawberries), from tubers (like potatoes), from cuttings and even from just a few cells (as in a lab). Note that for growing from cuttings, the cutting might need to stand in water and grow roots first before being planted in dirt.

Fertilization: Adding DNA to the egg that starts its growth

Mating: The pairing of opposite-sex animals that results in fertilization

Fertilization/conception: The union of a human egg (ovum) and sperm, usually occurring in the fallopian tube of the mother after sex

Embryo: The newly conceived form of life between the fertilized egg (zygote) stage and the fetus stage

Fetus: The unborn baby who is past the embryonic stage (about nine weeks into the pregnancy)

Ovulation: The release of eggs from the ovaries

Food web: A series of interlinked food chains. Creates interdependence.

Food chain: A series of plants and animals that use each other for food. It starts with a plant that gets food from the sun, then continues with the animal that eats that plant and so on.

Excretion: The elimination of metabolic waste

Homeostasis: Biological equilibrium, when a living thing’s internal conditions (such as temperature and mineral levels) are steady

Decomposition: The natural erosion of dead organic materials

Dormant: Still alive but not actively growing; for example, a seed. 

Germination: The waking up of a dormant seed

Metabolism: The set of life-sustaining chemical reactions in organisms

Internal respiration: The movement of oxygen from the outside environment to the cells within tissues, and the transport of carbon dioxide in the opposite direction.

Aerobic respiration: Internal respiration that uses oxygen

Anaerobic respiration: Doesn’t use oxygen

Cell respiration:

Cell: Smallest unit of living matter, but still visible under a microscope. (Try looking at a thin slice of onion membrane.)

Mitosis: Cell division resulting in two genetically identical cells, each with a set of the same chromosomes. Happens when the nucleus of the cell divides.


Cytokinesis: The second stage of cell division in which the cell plate forms to divide the two cells

Enzymes: Macromolecular biological catalysts. Enzymes accelerate chemical reactions.

Thermogenesis: The process of heat production in organisms

ATP: Adenosine triphosphate, an organic chemical that provides energy to drive many processes in living cells, e.g. muscle contraction, nerve impulse propagation, and chemical synthesis.

Basal metabolic rate (BMR): The rate of energy expenditure per unit time by an animal at rest

Calorie/kilocalorie: A unit of energy. A calorie is the amount of heat energy needed to raise the temperature of one gram of water by one degree Celsius at a pressure of one atmosphere, and the kilocalorie is the heat energy required to raise the temperature of one kilogram (rather than a gram) of water by one degree Celsius.

Parasite: Living thing that feeds on other living things and also uses them as their home

Host: The living thing that homes and feeds a parasite

Evolution: The long series of changes that happen to all living things

Extinction: The dying out of a species

Mass extinction: The large-scale dying out of many species (and biodiversity) on earth. Happens due to major weather changes brought on by major events, like an asteroid hitting the earth.

Natural selection: The natural process by which some species adapt and survive and others die out

Artificial selection: The human-controlled process by which some species change and survive and others die out

Adaptation: The process by which a species changes over time to adapt and survive

Basic Genetics

Genetics: The study of genes and heredity

Gene: The instructions inherited from parents that tell the body how to develop a particular characteristic or characteristics in the body (what qualities that characteristic will have). They are in every cell of the body (except red blood cells).

Genetic trait: A single trait that is expressed due to the instructions of the related gene. There can be multiple traits expressed by a single gene.

Heredity: All the traits passed from parents to their offspring

Genome: All of the genetic material of an organism (DNA or RNA)

Gene map: Shows the arrangement of the genes on a chromosome

Chromosome: The bundles that hold all of the individual genes. They are stored in the cell’s nucleus. Humans have 46 chromosomes: 2 sets of 23. Each chromosomes holds many, many genes.

DNA: Dioxyribonucleic acid. The chemical makeup of the genes. Always in a paired double strand and in the shape of a double helix.

RNA: Ribonucleic acid. This molecule reads and regulates genes. Sometimes called a messenger.

Nature versus nurture: Heredity versus environment. Both produce characteristics of an individual living thing, but how they interact is usually often unknown.

X and Y chromosomes: The chromosomes that determine gender. Everyone has one X chromosome, but males have a Y and females have a second X.

Dominant gene: The gene in the gene pair (the allele) that dominates the recessive one, and therefore gets expressed in the organism. Most genes are either dominant or recessive.

Recessive gene: The gene in the gene pair (the allele) that does not dominate the other. The recessive gene is expressed only when there are two associated recessives present, one from each parent. 

Co-dominance: Occurs when the contributions of both genes are visible in the organism

Allele: One of the two associated genes in a gene pair

Homozygote: Both of the alleles of a gene (both copies of a gene) are the same

Heterozygote: The alleles of a gene (both copies of a gene) are the same

Carrier: An organism that has a recessive allele for a genetic trait but does not display it. Can pass the allele onto offspring, who will express it if they inherit the same one from both parents.

DNA profiling/genetic fingerprinting: Determining an individual’s unique DNA code, usually by sampling a particular section of it

Genetic engineering/modification: The direct manipulation of an organism’s genes using biotechnology

GMO: Genetically modified organism

Gene splicing/ recombinant DNA (rDNA): DNA molecules formed in a lab bringing together genes from separate organisms

Cloning: Producing genetically identical individuals of an organism either naturally or artificially. In nature, many organisms produce clones through asexual reproduction.

Hybrid: Subspecies made by crossing two species


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