Mammalian fertilization comprises sperm migration through the female reproductive tract, biochemical and morphological changes to sperm, and sperm-egg interaction in the oviduct. Recent gene knockout approaches in mice have revealed that many factors previously considered important for fertilization are largely dispensable, or if they are essential, they have an unexpected function. These results indicate that what has been observed in in vitro fertilization (IVF) differs significantly from what occurs during “physiological” fertilization. This Review focuses on the advantages of studying fertilization using gene-manipulated animals and highlights an emerging molecular mechanism of mammalian fertilization.
People contribute to <span>antibiotic resistance by not completing their full course of antibiotics as prescribed by doctors when they are sick. This allows the bacteria to adapt to the antibiotic because the incomplete treatment did not kill the bacteria. Another way in which bacteria are becoming resistant to antibiotics is the widespread use of antibiotics in everyday consumer products, such as cleaners and beauty products. These antibiotics end up in the environment, and diluted exposure to these antibiotics by bacteria allows the bacteria to develop a resistance. </span>
Meiosis - the cells divide to produce 4 haploid cells
C. - because each bead can represent an amino acid.
