Biology Definitions Flashcards
Copies the genetic instructions from DNA in the nucleus, and carries the instructions to the cytoplasm.
Messenger RNA( mRNA )
Helps form ribosomes, the organelle where proteins are assembled.
Ribosomal RNA (rRNA )
Brings amino acids to ribosomes, where they are joined together to form proteins.
Transfer RNA (tRNA )
The addition of nucleotides to the growing mRNA strand.
Elongation
The beginning of transcription; occurs when RNA polymerase binds to the promoter of a gene.
Initiation
Ending of transcription and occurs when RNA polymerase crosses a stop ( termination ) sequence in the gene.
Termination
Group of three nitrogen bases in RNA or DNA that is the genetic code word for a single amino acid or for a start or stop signal.
Codons
The three-base frame that divides the bases into codons.
Reading frame
Structure found in all cells that is the site of protein synthesis.
Ribosome
Nonliving aspect of the environment such as sunlight and water.
Abiotic factors
Are the living aspects of the environment. They consist of other organisms, including members of the same and different species.
Biotic factors
Two species within the same area coexist and adapt by developing different specializations.
Character displacement
Is a relationship between two species, or individuals of the same species, that strive for the same resources in the same place.
Competition
An organism that must eat or consume other organisms to obtain energy and nutrients.
Consumer
Branch of biology that is the study of how living things interact with each other and with their environment.
Ecology
Role that a particular species plays in its ecosystem, including all the ways that the species interacts with the biotic and abiotic factors in the ecosystem.
Niche
All the organisms of the same species that live in the same area.
Population
Type of organism that uses light energy or chemical energy to make food for itself and other organisms.
Producers
Aquatic biome such as a pond, lake, stream, or river in which the water contains little or no salt.
Freshwater biome
Predator species that plays a special role in its community because changes in its population affect the population of many species in the community.
Keystone species
Interaction between two organisms of unlike species; one organism acts as a predator that captures and feeds on the other organism, which serves as the prey.
Predator-prey relationship
A situation in which a species completely dies out and no members remain.
Extinction
The relationship between organisms of different species that strive for the same resources in the same place.
Interspecific competition
The relationship between organisms of the same species that strive for the same resources in the same place.
Intraspecific competition
Close relationship between two species in which at least one species benefits.
Symbiosis
Type of species that first colonizes a disturbed area.
Pioneer species
Change in the numbers and types of species that live in a community that occurs in an area that has never before been colonized by organisms and lacks soils.
Primary succession
Change in the numbers and types of species that live in a community that occurs in an area that has soil and was previously colonized but has been disturbed.
Secondary succession
Bar graph that represents the number of individuals of each sex and age ( or age group ) in a population.
Population pyramid
Movement of individuals out of a population
Emigration
Movement of individuals into a population.
Immigration
Regular movement of individuals or populations each year during certain seasons, usually to find food, mates, or other resources.
Migration
Organism that makes its own food.
Autotrophs
Type of organism that obtains food by breaking down the remains of dead organisms or other organic wastes into its various components, including nutrients that can be used by other organisms.
Decomposers
Organism that gets food by consuming other organisms.
Heterptrophs
Type of decomposer that consumes dead animals.
Scavengers
All the living things in a given area together with the physical and chemical factors of the nonliving environment.
Ecosystem
Total mass of organisms at a given trophic level in a food chain or food web.
Biomass
An organism’s feeding position in a food chain.
Trophic level
The evaporation that occurs from the land surface along with transpiration.
Evapotranspiration
Release of water vapor into the atmosphere from stomata in the leaves of plants.
Transpiration
Process of changing nitrogen gas to nitrates that is carried out by nitrogen-fixing bacteria in the soil or in the roots of legumes.
Nitrogen fixation
The variety of life within a particular habitat, often measured by the number of different species.
Biodiversity
An area with similar climate that includes similar communities of plants and animals.
Biome
Average weather in an area over a long period of time.
Climate
Group of similar, land-based ecosystems, such as tropical rain forests, temperate grasslands, or tundras.
Terrestrial biomes
Area in a body of water that is deeper than 200 meters where sunlight does not penetrate to allow photosynthesis to take place.
Aphotic zone
Water-based biome, or group of similar water-based ecosystems; including freshwater or marine biomes.
Aquatic biomes
Aquatic biome in the salt water of the ocean.
Marine biomes
Area in a body of water that extends to a maximum depth of 200 meters and where enough sunlight penetrates to allow photosynthesis to take place.
Photic zone
Largest population size of a species that can be supported by the environment.
Carrying capacity
Individuals that do not have the genetic disorder themselves, but they carry the mutant allele and can pass it to their offspring.
Carriers
Monomer of a protein.
Amino acids
Doctrine that genetic instructions in DNA are copied by RNA, which carries them to a ribosome where they are used to synthesize a protein ( DNA to RNA to protein )
Central dogma of molecular biology
Observations by Erwin Chargaff that concentrations of the four nucleotide bases differ among species; and that, within a species, the concentrations of adenine and thymine are always about the same and the concentrations of cytosine and guanine are always about the same.
Chargaff’s rules
Relationship between two alleles for the same gene in which both alleles are expressed equally in the phenotype of the heterozygote.
Codominance
Double-stranded nucleic acid that stores genetic information; also known as deoxyribonucleic acid.
DNA
Double spiral shape of the DNA molecule.
Double Helix
Universal code of three-base codons that encodes the genetic instructions for the amino acid sequence of proteins.
Genetic code
All of the hereditary information encoded in the DNA of a species.
Genome
Organism that inherits two different alleles for a given gene. AKA heterozygous.
Heterozygote
International science project that sequenced all 3 billion base pairs of the human genome.
Human Genome Project
Relationship between the alleles for a gene in which one allele is only partly dominant to the other allele do an intermediate phenotype results.
Incomplete dominance
A change in the sequence of bases in DNA.
Mutations
Organic compounds, such as DNA or RNA, that is made of monomers called nucleotides.
Nucleic acid
Monomer of nucleic acids; contains a five-carbon sugar, phosphate group, and nitrogenous base.
Nucleotide
Characteristics, or trait, controlled by more than one gene, each of which may have two or more alleles.
Polygenic traits
Process in which cells make proteins; includes transcription ( DNA to mRNA ) and translation ( mRNA to protein ).
Protein synthesis
A single-stranded nucleic acid that helps make proteins.
RNA
Process in which genetic instructions in DNA are copied to form a complementary strand of mRNA.
Transcription
Containing a gene transferred from another organism.
Transgenic
Process in which the genetic code in mRNA is read, one codon at a time, to make a protein.
Translation
Traits controlled by a gene located on the X chromosomes.
X-linked traits
Energy-requiring movement of molecules across a membrane from a region of lower concentration to a region of higher concentration.
Active transport
Any of the alternative forms of a gene that occurs at a specific place on a chromosome.
Allele
High energy molecule that contains, within its bonds, energy that cells can use.
ATP
Basic unit of life.
Cell
Double-layer of phospholipids that forms a boundary between a cell and the surrounding environment and controls the passage of materials into and out of a cell.
Cell membrane
Process of producing ATP by breaking down carbon-based molecules when oxygen is present.
Cellular respiration
Organelle composed of numerous membranes that are used to convert solar energy into chemical energy; contain chlorophyll.
Chloroplast
Long, continuous thread of DNA that consists of numerous genes and regulatory information.
Chromosome
Cell that has two copies of each chromosome, one from an egg and one from a sperm.
Diploid
Allele that is expressed when two different alleles are present in an organism’s genotype.
Dominant
Interconnected network of thin, folded membranes that produce, process, and distribute proteins.
Endoplasmic reticulum
Protein that catalyzes chemical reactions for organisms.
Enzyme
Sex cell; an egg or sperm cell.
Gamete
Specific region of DNA that codes for a particular protein.
Gene
Cell that has only one copy of each chromosome.
Haploid
Regulation and maintenance of constant internal conditions in an organism.
Homeostasis
Proposed explanation or answer to a scientific question.
Hypothesis
Form of nuclear division that divides a diploid cell into haploid cells; important in forming gametes for sexual reproduction.
Meiosis
Bean shaped organelle that supplies energy to the cell and has its own ribosomes and DNA.
Mitochondria
Process by which a cell divides its nucleus and contents.
Mitosis
Molecular subunit of a polymer.
Monomer
Organelle composed of a double membrane that acts as the storehouse for most of a cell’s DNA.
Nucleus
An individual living thing.
Organism
Measurement of acidity; related to free hydrogen ion ( H+ ) concentration in a solution.
pH
Process by which light energy is converted to chemical energy; produces sugar and oxygen from carbon dioxide and water.
Photosynthesis
Large, carbon based molecule formed by monomers.
Polymer
Model for predicting all possible genotypes resulting from a cross, or mating.
Punnett square
Allele that is not expressed unless two copies are present in an organism’s genotype.
Recessive
Condition or quality of allowing some, but not all, materials to cross a barrier or membrane.
Selective permeability
Group of organisms so similar to one another that they can breed and produce fertile offspring.
Species
