hybrid sterility

Examples of hybrid sterility in the following topics:

• Reproductive Isolation

  • A postzygotic barrier occurs after zygote formation; this includes organisms that don't survive the embryonic stage and those that are born sterile.
  • Hybrid individuals in many cases cannot form normally in the womb and simply do not survive past the embryonic stages; this is called hybrid inviability.
  • In another postzygotic situation, reproduction leads to the birth and growth of a hybrid that is sterile and unable to reproduce offspring of their own; this is called hybrid sterility.

• sp2 Hybridization

  • In order to explain the bonding, the 2s orbital and two of the 2p orbitals (called sp2 hybrids) hybridize; one empty p-orbital remains.
  • sp2 Hybridization in Ethene and the Formation of a Double Bond
  • In this case, carbon will sp2 hybridize; in sp2 hybridization, the 2s orbital mixes with only two of the three available 2p orbitals, forming a total of three sp hybrid orbitals with one p-orbital remaining.
  • The carbon atoms are sp2 hybridized.
  • Recognize the role of sp2 hybridized atoms in sigma and pi bonding.

• Hybrid Zones

  • An area where two closely-related species continue to interact and reproduce, forming hybrids, is called a hybrid zone.
  • Over time, the hybrid zone may change depending on the fitness strength and the reproductive barriers of the hybrids .
  • Over time, via a process called hybrid speciation, the hybrids themselves can become a separate species.
  • For a hybrid zone to be stable, the offspring produced by the hybrids have to be less fit than members of the parent species.
  • Discuss how the fitness of a hybrid will lead to changes in the hybrid zone over time

• Surgical Sterilization

  • Sterilization refers to any of a number of medical techniques that intentionally leave a person unable to reproduce.
  • Sterilization methods include both surgical and non-surgical, and exist for both males and females.
  • Sterilization procedures are intended to be permanent; reversal is generally difficult or impossible.
  • The removal of the ovaries is not necessary for sterilization, but can treat and prevent ovarian cancer.
  • This is frequently used for the sterilization of animals, but rarely for humans.

• Heat

  • To achieve sterilization, different techniques and tools are used.
  • Autoclaving (pressure cooking) is a very common method for moist sterilization.
  • When sterilizing in this way, samples are placed into a steam chamber.
  • Pressure sterilization is the prevailing method used for medical sterilization of heat-resistant tools.
  • Other heat sterilization methods include flaming and incineration.

• Radiation

  • Sterilization by irradiation with gamma rays may, in some cases affect material properties.
  • Electron beam processing is also commonly used for sterilization.
  • Irradiation is used by the United States Postal Service to sterilize mail in the Washington, DC area.
  • Some foods (e.g. spices, ground meats) are irradiated for sterilization.
  • UV light is commonly used to irradiate and sterilize laminar flow cabinets between uses.

• Unclassified and Uncultured Bacteria

  • To overcome these uncertainties, modern bacterial classification emphasizes molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridization, as well as sequencing genes that have not undergone extensive lateral gene transfer, such as the rRNA gene.
  • Specimens that are normally sterile, such as blood, urine, or spinal fluid, are cultured under conditions designed to grow all possible organisms.

• Filtration

  • Fluids that would be damaged by heat, irradiation, or chemical sterilization can be sterilized by microfiltration using membrane filters.
  • Fluids that would be damaged by heat (such as fluids containing proteins like large molecule drug products, but also wine and beer), irradiation, or chemical sterilization can only be sterilized by microfiltration using membrane filters.
  • The filtration equipment and the filters may be purchased as pre-sterilized disposable units in sealed packaging, or must be sterilized by the user, generally by autoclaving at a temperature that does not damage the fragile filter membranes.

• sp3 Hybridization

  • sp3 hybrid orbitals form when a single s and three p orbitals hybridize.
  • In hybridization, carbon's 2s and three 2p orbitals combine into four identical orbitals, now called sp3 hybrids.
  • For example, in the ammonia molecule, the fourth of the sp3 hybrid orbitals on the nitrogen contains the two remaining outer-shell electrons, which form a non-bonding lone pair.
  • Ethane can form by replacing one of the hydrogen atoms in CH4 with another sp3 hybridized carbon fragment.
  • Explain the process of hybridization as it applies to the formation of sp3 hybridized atoms.

• Hybridization in Molecules Containing Double and Triple Bonds

  • In chemistry, hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for describing bonding properties.
  • The hybrids are named for the atomic orbitals involved in the hybridization.
  • For this molecule, carbon will sp2 hybridize.
  • In this case, sp hybridization leads to two double bonds.
  • Describe the role of hybridization in the formation of double and triple bonds.