Answer the following questions

Q1. Peroxisomes are spherical organelles that are found in all animal cells (except the red blood corpuscles) and various plant cells. These organelles have a diameter ranging from 0.2 to 1 micrometer and contain a different types of oxidases. Oxidases are enzymes that utilize molecular oxygen to metabolize organic compounds. The end product of oxidase action is hydrogen peroxide, which is a reactive oxygen species. Peroxisomes also contain an enzyme called catalase, which degrades hydrogen peroxide to water and oxygen. Fatty acid oxidation also takes place in the peroxisomes. However, the energy released during such oxidation is converted to heat, and the acetyl groups are transferred to the cytoplasm for the synthesis of cholesterol (Corpas & Barroso, 2014).

Q2. Ribosomes are cellular organelles that consist of ribosomal proteins and four ribosomal RNA (rRNA) molecules, organized into large and small subunits. These subunits associate with messenger RNA (mRNA) and certain proteins like initiation factors (IF) and elongation factors (EF), for the purpose of synthesizing proteins. Ribosomes are found either as free entities within the cytoplasm or may be associated with the Rough Endoplasmic Reticulum. The mRNA-rRNA interaction attracts transfer RNA (tRNA), which contains an amino acid. The repetitive binding of various tRNA carrying different amino acids leads to the production of a peptide chain or protein. The destined protein may be carried to the plasma membrane or may get distributed in the cytosol (Brandman, 2012).

Q3. There are various cytoskeletal structures that provide shape and integrity to a cell. These structures also aid in the movement of a cell. Cytoskeleton structures include microtubules, which are made of tubulin proteins. Cilia are a group of microtubular entities, which are extensions of the plasma membrane. They beat in a rhythmic fashion, to propel materials across the cellular surface and also aid in cellular movement. For example, the presence of cilia in human sperms, helps them to be transported, through the female genital tract. Apart from motile cilia, certain nonmotile (that does not aid in movement) are found in photoreceptor cells (Keady, Le, & Pazour, 2011).

References
Brandman., O. (2012). “A ribosome-bound quality control complex triggers degradation of
nascent peptides and signals translation stress”. Cell, 151 (5), 1042–54.
Corpas., F, & Barroso., J. (2014). “Functional implications of peroxisomal nitric oxide (NO)
in plants”. Front Plant Sci., 5, 97
Keady., B, Le., Y, & Pazour., G. (2011). Lack of IFT20 causes cone cell degeneration. Mol
Biol Cell, 22,921–930