Antibiotics are, initially, molecules naturally synthesized by microorganisms to fight against bacteria competing with their environment. This created a pressure of selection on the bacterial populations, leading to the appearance of resistant strains. In fact, when an antibiotic is used, only bacteria with defense systems against this molecule survive (and reproduce).
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These specialized cells and parts of the immune system offer the body protection against disease. This protection is called immunity. Humans have three types of immunity — innate, adaptive, and passive: Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection.
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It's important for a scientist to try to hold all variables constant except for the independent variable. If a control variable changes during an experiment, it may invalidate the correlation between the dependent and independent variable. When possible, control variables should be identified, measured, and recorded.
Answer:Tay-Sachs is an autosomal recessive disease caused by mutations in both alleles of a gene (HEXA) on chromosome 15. HEXA codes for the alpha subunit of the enzyme β-hexosaminidase A. This enzyme is found in lysosomes, organelles that break down large molecules for recycling by the cell.
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