A phage is a virus that behaves as a parasite on bacteria and is also referred to as bacteriophage. A temperate phage, is a phage that is able to exist as a prophage while it lives within its host at any point of its life cycle.
A:The Hardy-Weinberg principle states that the genetic variation in a population stays constant over generations in the absence of disruptive factors. The concept predicts that when mating occurs randomly in a vast population, the allele and genotype frequencies remain consistent because they are in equilibrium.
A:The Golgi apparatus collects simple chemicals in the cell and assembles them into large, complex structures such as proteins. It also plays a role in the process of simple chemical secretion by forming closed vesicles around the substance to be transported. These vesicles then pinch off from the Golgi apparatus and drift to the cell's plasma membrane where the transported substance is released from the cell.
A:Just as blueprints direct the building of a house, DNA molecules contain the genetic instructions used in the development and functioning of a living organism. The DNA of eukaryotic organisms such as plants and animals is organized into linear chromosomes and stored within the nucleus of every cell.
A:DNA, also known as deoxyribonucleic acid, belongs to a class of polymeric organic macromolecules called nucleic acids. The only other member of this class is ribonucleic acid, or RNA. Nucleic acids were first discovered in 1869 by the Swiss scientist Friedrich Miescher.
A:Protein turnover refers to the degradation of proteins over time. It reflects the balance between a cells synthesis of protein and that proteins breakdown. This factor determines the concentration of a protein existing within a cell.
A:Atoms emit a photon when an electron falls from a high-energy state to a low-energy state. The conditions under which this process occurs happen in two ways. According to the Cornell Center for Materials Research, electrons either absorb the energy from a photon and jump to a higher energy level or a photon collides with an electron that is already in an excited state.
A:Plant cell vacuoles serve the same vital storage functions for nutrients, water and wastes as those in animal cells but are much larger because they also provide structural stiffness in combination with the plant's cell walls. This is why water-starved plants droop; their cells have essentially deflated. If a living but wilted plant once again receives sufficient water, it regains its former stiffness as the vacuoles refill.
A:Gregor Mendel used pea plants in his research on heredity because they had characteristics that were consistent and easy to recognize. Pea plants had other qualities that also made them ideal for cross-pollination.
A:The NIH Genetics Home Reference Handbook explains that mutations are passed to offspring if these mutations are present in germ line (sperm or egg) cells. Germ line mutations can occur early in the parent's development so that they affect all of the cells in the parent's body, including eventual gametes. These mutations can also occur in gametes alone and therefore only affect offspring.
A:Freckles can be related to a dominant receptor gene for melanocortin-1, but they can also be the result of skin that is more sensitive to light. The skin cells that produce the pigment melanin are called melanocytes. They will produce melanin to protect the skin from sun damage, and when that pigment is transferred to the cells that make up the outer layer of skin, it shows as freckles.
A:A codon is a sequence of three nucleotides in DNA or RNA that either codes for a particular amino acid or tells the cellular machinery to start or stop using the code. A group of codons starts with the initiation codon. It then has codons in sequence that gives instructions on the amino acids to use to build a protein, and it then has a stop codon to signal when the protein assembly is complete. Normally, there is one initiation codon and three stop codons, and most amino acids are represented by more than one codon.
A:Genes, which are segments of DNA acids, are found within the nuclei of cells in living organisms. Genes add specific proteins to chromosomes, which contain the basic genetic code for life. They contain the information needed to build the cells of a living organism and pass traits to offspring. Genes correspond to certain traits, such as number of limbs, blood type, eye color and risk for certain diseases.
A:Mitosis is important because it is essential for growth and repair in the body. Mitosis happens when a parent cell divides, creating two identical copies, referred to as daughter cells. During this process, it is essential that the daughter cells are exactly the same with the same copies of DNA.
A:The pattern of base pairs in the DNA double helix encodes the instructions for building the proteins necessary to construct an entire organism. DNA, or deoxyribonucleic acid, is found within most cells of an organism, and most organisms have their own unique DNA code. One exception to this is cloned organisms, which have the same exact DNA code as their parents do.
A:DNA replicates in order for cells to divide, withy a parent cell divides giving each daughter cell the full DNA string in each nucleus. Without cell division, an organism cannot grow into a plant, a human or an animal. DNA replication allows all cells to contain the full genetic code for the body.
A:A DNA microchip or gene chip is a tiny chip that has many single strands of the DNA from a specific gene attached to it. Sometimes a microchip has more than one gene's DNA on it or different variations of a gene. It is used to test for gene mutations, such as the ones that are thought to be responsible for a larger percentage of hereditary breast cancer cases.