have no nucleus and they are all single-celled organisms. Prokaryotes include all organisms in the Domain Bacteria and Domain Archaea.
· are single-celled or multi-cellular organisms consisting of cells with a nucleus that contains linear strands of genetic material and include all organisms within the Domain Eukarya. This cell type also commonly has organelles (such as a nucleus) throughout their cytoplasm. Plant cells and Animals cells are special types of eukaryotic cells that have two organelles of note involved in the cells energy production: chloroplasts and mitochondria.
· which can be fast and efficient, leads to offspring genetically identical to the parent (a clone); it occurs in all prokaryotes (Domain Archaea & Domain Bacteria) and in some eukaryotes (Domain Eukarya). A good example of an asexually reproducing animal is the Texas desert lizard that has populations consisting only of females and reproduces through parthenogenesis.
sperm penetrates the protective zone around the egg, the egg blocks any additional sperm entry, and the sperm and egg membranes fuse. The egg then completes its second meiotic division, and the haploid nuclei of the egg and sperm fuse, forming a diploid zygote.
· first the circular chromosome duplicates itself and then the cell splits into two identical new cells.
· enables existing cells to generate new, genetically identical cells. This makes it possible for organisms to grow and to replace cells that die. Mitosis is a process by which cells duplicate themselves. It occurs in just four steps, following replication of chromosomes. It leads to the production of two daughter cells from one parent cell.
· is the process by which gametes are produced in sexually reproducing organisms. It results in gametes that have only half as much genetic material as the parent cell and that differ from one another with respect to the combinations of alleles they carry.
· a middleman molecule-taking the instructions for protein production from DNA to another part of the cell where, in accordance with the RNA instructions, amino acids are pieced together into proteins.
· are a storehouse of information, an instruction book. The process by which this information is used to build an organism occurs in two main steps: transcription, in which a copy of a gene’s base sequence is made, and translation, in which that copy is used to direct the production of a protein.
· is the first step in the two-step process by which DNA directs the synthesis of proteins. In transcription (occurring in the nucleus in eukaryotic cells), a single copy of one specific gene in the DNA is made, in the form of a molecule of mRNA, and this moves to the cytoplasm where it can be translated into a protein.
· is a visual display of a complete set of chromosomes. A karyotype is a useful diagnostic tool because it can be prepared very early in a fetus’s development to assess whether there is an abnormality in the number of chromosomes or in their structure, such as in the case of Down syndrome. Down syndrome is caused by having an extra copy of chromosome 21.
· the use of technology to modify organisms, cells, and their molecules to achieve practical benefits. Modern molecular methods make it possible to cut and copy DNA from one organism and deliver it to another, not necessarily the same species. With these methods, biotechnology has achieved some important successes in medicine, agriculture, and forensics, but the field is still in its infancy.