<span>In bacteria, DNA polymerase adds an incorrect base to a growing strand of DNA about once in every 100 000 bases added. The result is a mismatch such as the pairing of A with C.
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The lac repressor protein is bound to the operator region of the lac operon when there is no lactose in the medium. When introduced in lactose, it binds to an allosteric site on the repressor causing its to change conformation and release from the operator. This allows the polymerase that is bound to the promoter region to proceed transcription of the lac operon genes (LacZ, Lac A, and Lac Y). Translation of these genes forms enzymes that enable the organism to break down lactose for energy.
A cell membrane pump helps human cells to maintain a relatively constant sodium and potassium concentration.
<u>Option: A</u>
<u>Explanation:</u>
Sodium potassium pump is a plasma membrane protein that utilizes energy ATP — Triphosphate Adenosine turning into ADP — Adenosine Diphosphate to deliver intracellular and extracellular sodium (NA+) and potassium (K+) ions sequentially. The purpose of this entire mechanism is to preserve cell equilibrium.
The extracellular medium has a greater concentration of Na while the K concentration of the intracellular fluid is lower. Proteins trap sodium ions in the cytoplasm and pump them out from the cells to preserve cell stability while preserving concentrations. Within the cells proteins inject potassium ions into the cell.
Lysosomes have lytic enzymes, the cell wall gives support, chloroplasts act in photosynthesis, and the endoplasmic reticulum act during protein and lipid synthesis.
<h3>What is the lysosome?</h3>
The lysosome is an organelle that contains hydrolytic enzymes used to break proteins, whereas the cell wall is a structure that provides physical support to plant cells.
Chloroplasts are plant organelles used during photosynthesis and the endoplasmic reticulum acts during the production of proteins and lipids.
In conclusion, lysosomes, chloroplasts (plant and algae) and endoplasmic reticulum are eukaryotic organelles with diverse functions, whereas the cell wall provides structural support to plant and fungi cells.
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I) Locus- the chromosomal site where a specific gene is located. A locus is a fixed position on a chromosome, like the position of a gene or a marker. Each chromosome carries ,many genes; human's estimated haploid (n) protein coding genes are about 20,000, on the 23 different chromosomes.
ii) Interference; the observed double crossover frequency differs from the expected double crossover frequency. Cross over interference is used to refer to the non-random placement of crossovers with respect to each other during meiosis. It results in widely spaced crossovers along chromosomes. Interference may exert its effect across whole chromosomes. As chromosomes in many eukaryotes are large, interference must be able to act over megabase lengths of DNA.
iii) Linkage- the tendency for genes located in close proximity on the same chromosome to be inherited together. Normally when two genes are close together on the same chromosome, they do not assort independently and are said to be linked. Whereas genes located on different chromosomes assort independently and have a recombination frequency of 50%, linked genes have a recombination frequency that is less than 50%.
iv) Recombination- the process by which a new pattern of alleles on a chromosome is generated. Genetic recombination is the production of offspring with combinations f traits that differ from those found in either parent. During meiosis in eukaryotes, genetic recombination involves the pairing of homologous chromosomes. This may be followed by information transfer between the chromosomes.
