Biological Sciences
Important Definitions:
Abioticnon-living parts of an ecosystem
AdaptionAny behavior or physical characteristic that helps an individual survive and reproduce in its environment
Alleleversion of a gene that codes for a specific version of a trait
different versions of the same gene
Amino Acidsubunits that make up proteins
AnalogousStructuresstructures that perform similar functions but do not share a recentevolutionaryrelationship
AngiospermsPlants that bear seeds in a closed ovary
Artificial SelectionPeople choose which organisms reproduce in order to influence the traits that future generations of a species will have.
“Ase”molecules that end in –ase often help carry out specific chemical reactions
Autosomesnon-sex chromosomes
Bilateral Symmetrya structure that is identical on either side of a central line.
Biodiversitythe variety of life forms in an area
Biosphereall the living things on Earth and their environments
Bioticliving parts of an ecosystem and the things they produce
Breedsimilar organisms within a species that have been developed by artificial selection in order to have certain traits.
Carrierallele that carries a trait, but does not express the trait
Carrying Capacitythe largest population that an ecosystem can support at a given time
Cell Cyclethe set of stages a cell passes trough during its lifetime
Cellular Respirationbiological process in which glucose is broken down into simpler molecules
Cladisticsa method of classifying organisms based on their evolutionary relationships
Cladograma diagram that shows the evolutionary relationships amongst a group of organisms
Climatographa graphical representation of temperature and precipitation patterns in an area
Codona sequence of three mRNA bases that code for a specific amino acid
Co-dominantoccurs when two different alleles are both dominant for the same trait
(i.e. A and B blood types… both expressed AB if one allele is present)
Commodityproduct made by humans that can be sold and traded
Communitygroup of populations that live in a particular area
Consumeran organism that obtains energy by eating other organisms
Cross-breedingprocess of selecting different breeds or species to mate
Cytokinesisthe process in which the cytoplasm and organelles of a cell divide to form two daughter cells
Decomposerorganism that breaks down the remains of living things into simplersubstances
Differential Reproductionprocess in which certain members of a population produce moreoffspring than others
Diploid Cellcell containing both chromosomes of each pair of homologous chromosomes
Dominant Alleleallele is expressed in an individual if the individual possesses just one copy of the allele
DNADeoxyribonucleic Acid
the molecule that stores genetic information in living things
Ecological Nichethe role of an organism in its ecosystem
Ecologythe study of interactions among organisms and the non-living parts of their environments
Ecosystemall the living and non-living things in an area
Evolutionchange in a population of organisms over time
change in allele frequencies of a population over time
Extinctionoccurs when a species no longer has any living individuals
Fossilsthe remains or traces of organisms that lived long ago
Functiona specific purpose or role
Gameteone of the daughter cells produced during meiosis
Genesa location on a DNA molecule that contains the information needed to make a specific protein
Genetic Driftchanges in allele frequencies in a population that result from random events
Genetic Engineeringchanging an organism’s DNA through methods other than selective breeding
Genetic Equilibriumoccurs when allele frequencies of a population do not change over time
Genetically Modified Organismorganisms containing DNA form different sources (GMO)
Genotypethe specific set of alleles an organism possesses
Gymnospermsplants that bear seeds that are not in an ovary
Haploid Cellcell containing one-half the number of chromosomes of a normal body cell (it contains only one chromosome of each pair of homologouschromosomes)
Heterozygoustwo different alleles for the trait
Homologous Chromosomeschromosomes in a single cell that contain the same genes
HomologousStructuresstructures that share an evolutionary relationship
Homozygoustwo copies of the same allele for a trait
Hybridthe offspring of two different breeds or species
Individualssingle organisms (at the most specific ecological level)
Industrial Agriculturethe mass production of crops and livestock
Integrated Pest Management(IPM)use of a combination of methods for controlling agricultural pests
Invertebrateanimal that does not have a backbone
Limiting Factorbiotic or abiotic condition that regulates the size or distribution of a population
Meiosiscell division in which a single parent cell produces four daughter cells, each of which as ½ of the number of chromosomes of the parent cell
Mitosisthe process in which the nucleus of a cell divides to form two genetically identical nuclei
Mitochondriaorganelles in cells that produce energy for the cell
Motilemoving, or having the ability to move independently
Multiple-Allele Traittrait for which more than two alleles exist in a population
Mutationchange in a base sequence in DNA
Natural Resourcea material that humans use that is found in nature
Natural Selectionprocess in which individuals with certain traits survive and reproduce at a higher rate than individuals without those traits
Non-renewableResourcenatural resource that cannot be replaced during a human lifetime
Nucleotidesthe subunits that make up DNA
sugar molecule + phosphate group + nitrogen-containing molecule
Organellespecialized part of a cell that has a specific function
Overharvestingoccurs when humans take so many individuals from an ecosystem that the population cannot recover
Phenotypethe specific set of traits an organism expresses
Photosynthesisa biological process in which light energy is used to drive the chemical reaction between carbon dioxide and water in order toproduce glucose and oxygen
Polymerschemicals composed of repeating units
Populationall the organisms of a certain species that live in a particular area
Predationthe act of killing and feeding on another organism.
Primary Successionthe development of an ecosystem in an area that didnot previously support life
Produceran organisms that can make its own food
Radial Symmetrya structure that radiates out form a central point
Recessive Alleleallele expressed only if an individual possesses two copies of the allele
Recombinant DNADNA that combines genetic material from different sources
Replication Forka region in a DNA molecule in which the two DNA strands have begun to separate in preparation for DNA replication
Renewable Resourcea natural resource that can be replaced during a human lifetime
RNAribonucleic acid
a molecule that is involved in the transcription and translation of the information in DNA
Secondary Successionoccurs when an ecosystem is re-established in an area that previously supported life
Semiconservative each strand in a DNA molecule serves as a template for a complementary strand
Replication
Sex Chromosomechromosomes that determine the sex of an organism
Sex-Influenced Traittrait that is coded by a gene on an autosome, but that is expressed differently in males and females
Sex-linked Traittrait that is coded for by a gene that exists only on a sex Chromosome
Speciesa group of organisms that resemble each other structurally and that are capable of interbreeding
(this definition does not work for organisms that reproduce asexually)
Species Diversitythe number and distribution of species in a particular area
Structurethe arrangement of an object’s parts or elements
Successionthe natural process that establishes or replaces biotic and abiotic factors in an ecosystem
Symbiosisthe interaction between organisms of different species over a period of time
Traitcharacteristics of an organism that is determined by a specific gene or genes
Transcriptionthe process in which a strand of DNA is copied
Transitional Fossilsfossils that provide evidence for how a certain species has evolved over time
Translationthe process in which the base sequence of the mRNA is converted into a protein
Trophic Levelthe position of an organism in a food chain
Vascular Tissuestube-like structures that move water and nutrients throughout a plant
Vertebrateanimal that does have a backbone
Points to Ponder
The biological sciences involved the study of living things and their interaction with one another and the environment. A key concept in biology is that structure and function are directly related on both macroscopic and microscopic levels (like cellular or chemical levels). We have seen this in chemistry where the structure of the molecule (polarity) controls its properties (dissolvability, melting point, etc.).
We have defined a system as a group of related parts that work together to perform a function or complete a task. All organisms are systems. This means that they have related parts that work together (as they are living, they work together to live, grow and reproduce).
Another example of a biological system is a cell. Cells themselves are also composed of many smaller systems. Each of these tiny systems carries out specific processes. These tiny systems are called organelles. Plant and animal cells are similar, but not exactly alike. For example, only plant cells have cell walls (which are rigid to provide support and protection), chloroplasts (which are involved in glucose production), and vacuoles (which release waste products and maintain appropriate cell pressure). Both plant and animal cells contain mitochondria, the power center for the cell.
One important process of plants is photosynthesis. Photosynthesis uses light energy to convert carbon dioxide and water into glucose and oxygen. In this way, light energy is transformed into chemical energy. The opposite of this process is cell respiration. In cell respiration, food molecules are broken down to release energy. In aerobic respiration, the glucose and oxygen combine to form carbon dioxide and water and energy (called ATP). Cell respiration can also occur without the presence of oxygen. This is called anaerobic respiration. One example of anaerobic respiration is fermentation. Note that respiration (commonly spoken of in relation to breathing) is not the same as cellular respiration (which takes place within a single cell).
Classification is another important facet in biology. Classification is often based upon anatomy, but physical characteristics can be misleading. Organisms can also be classified based on their evolutionary history. The more closely related organisms will chare an ancestor more recently in their evolutionary chain. Genetic Analysis can also be used to classify organisms. In this case, animals are classified based upon the similarities in their genes. Many times anatomical similarities will correspond to evolutionary relationships.
Today, we classify organisms into three domains and six kingdoms. Translated from Wikipedia:
The three-domain system is a biological classification introduced by Carl Woese in 1990[1] that divides cellular life forms into archaea, bacteria, and eukaryotedomains. The Archaea Domain includes the kingdom Archaebacteria. Characteristics of this group include: no nuclear membrane, distinct biochemistry and RNA markers from eubacteria, often living in extreme environments, single-celled, both motile and nonmotile. The Bacteria Domain includes the kingdom Eubacteria. They also lack a nucleus. These are the traditional bacteria.
The Eukarya Domain includes the Animalia, Plantae, Fungi and Protista Kingdoms. They all have a nuclear membrane. The Animalia, Plantae and Fungi Kingdoms are all contain multi-cellular organisms. Fungi also contain single-cellular organisms. Protista only contains single-cellular organisms. Animalia never contains cell walls. Plantae and Fungi always contain cell walls. Protista may or may not contain cell walls. Animalia and Fungi cannot make its own food. Plantae does make its own food. Protista may or may not make its own food. Animalia is motile. Plantae and Fungi are not motile. Protista may or may not be motile.
These two breakdowns are followed by phylum, class, order, family, genus, and species. So, when I learned it, classification was King Phillip Came Over ForGrape Soda. You’ll need to add Dapper in front (Dapper King Phillip…) to remember: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.
Let’s take a closer look at plants. One way plants may differ is how they move water and nutrients through their bodies. Vascular Plants, (trees and grass, for example), use tube-like structures (vascular tissue) to move water and nutrients. Non-vascular Plants, (mosses, for example), have water and nutrients passing directly from cell to cell. Another way plants differ is in their method of reproduction. Some plants (seed plants) use seeds for reproduction, others (seedless plants), do not. Seedless plants use spores to reproduce. In seedless plants, the spores leave the parent plant as single-celled, unfertilized structures. Cell division and reproduction begins after the spore lands in a suitable spot. Seed plants are not all entirely alike, either. Some enclose their seeds (angiosperms), and others do not (gymnosperms). In some gymnosperms, the seeds are partially enclosed. In both cases, the seeds are fertilized during pollination before they leave the parent plant.
Let’s take a closer look at animals. Animals can also be classified in a myriad of ways. For example, some animals are classified based upon symmetry. Those that are symmetrical around a central point (like a sea anemone), have radial symmetry. Those that are symmetrical on a central line (like a human), have bilateral symmetry. Some animals that are mostly symmetric will have some asymmetric body parts. These parts usually perform some important function (like attracting mates, for example). Animals can also be classified based upon their method of reproduction. Sexual reproduction occurs when sex cells from two different parent organisms combine to form an offspring. Usually this occurs between a male and female parent. Asexual reproduction, on the other hand, occurs within a single organism. Some organisms can reproduce both sexually and asexually.
Another classification is the presence of a backbone – vertebrate vs. invertebrates. Jellyfish, insects and worms do not have backbones. Mammals, birds, fish and reptiles do. NOTE: while we are most familiar with vertebrate animals (those with a backbone), 95% of the animals on Earth are invertebrates. The method of circulation (open vs. closed) can also be used to classify animals. In open circulation, the blood flows through large vessels only, and empties into the body cavity. In closed circulation, the blood flows through both large and small vessels, and does not empty into the body cavity. Insects, crustaceans, and mollusks have open circulation, mammals, birds, fish and reptiles do not. Also, type of digestion (simple vs. complex) can be used to classify animals. Simple digestion occurs when a single opening is used for both input and output of food. Complex digestion, which is far more common, has food flowing through a system from food to anus. Flatworms have simple digestion, vertebrates have complex digestion.
One of the main tenets in biology is DNA. DNA is a polymer, or a large molecule made up of many similar subunits. Its structure is a double helix. It is composed of a sugar molecule, a phosphate group and a nucleotide which contains a base. The four bases of the nucleotides in DNA are Adenine (A), guanine (G), Cytosine (C) and Thymine (T). These bases form attachments in the helix in complimentary groups… C with G and A with T. Different sections in a DNA strand code for making a particular protein. These sections are called genes. Amazingly enough, while genes in different species vary, the genetic code is universal. This is considered to be evidence of a common ancestor for all living things. While every cell contains the same DNA, only some parts of the DNA are “turned on” in each cell. This allows cells to be different. The specific genes (and therefore proteins) that are turned on result in the type of cell created.
While DNA is located inside the nuclei of cells, the proteins created by the cells are not in the nucleus. This means that the “code” must be carried from inside the nucleus to outside of the nucleus. This occurs through RNA. While DNA is composed of a double strand, RNA is a single strand. In addition, thymine occurs in DNA, while uracil is contained in RNA. Both thymine and uracil connect only with adenine. There are three types of RNA. The first is messenger RNA (mRNA) which copies the information in the DNA molecule, (called transcription). To begin this process, the DNA strand must be separated. Then, half of it is copied. The DNA strand that is copied is called the transcribed strand. After the mRNA strand is built, it leaves the nucleus. Once outside of the nucleus, the process of creating the protein continues in the cytoplasm. Now, the transfer RNA (tRNA) and ribosomal RNA (rRNA) translate the information into a protein. This is called translation.
Like DNA, proteins are also polymers. The subunit of a protein is an amino acid. While proteins are often composed of hundreds of amino acids, there are only about 20 different naturally occurring amino acids. Each of the singular amino acids in a protein is crucial. If even one is changed or removed, the protein will cease to function correctly. How is the protein coded? Three mRNA bases in a row create a code for an amino acid. This group of three is called a codon. Some amino acids are only represented by one possible grouping (codon). Others are represented by more than one possible group of three bases. The protein is thus assembled as each group of three bases is coded into an amino acid. The tRNA is responsible for this process of translating the mRNA into the protein. At the end of the tRNA molecule is an anticodon which is complementary to the mRNA codon. This interaction between the mRNA (original code) and tRNA (translating code) only works if rRNA is present. The rRNA creates a ribosome which acts as a catalyst to assemble the protein. It begins by binding the tRNA molecule. Then it moves along the mRNA molecule matching the codons and anticodons. Once the proteins form, the tRNA molecule is released from the ribosome. The process stops when a stop codon is reached (at the end of the mRNA code).