Receptor-mediated endocytosis is a process that resembles pinocytosis but is far more selective and only allows the entry of specific molecules into the cell. Target substances are bound to receptors on the membrane surface and brought into the cell via coated vesicles.

A cell does not have to have a nucleus. Prokaryotic cells are characterized by the fact that they don't have a nucleus nor any other membrane-bound organelles. However the rest of the statements are true of all cells and comprise cell theory.

Bacterial cells have cell membranes, cell walls, chromosomes, cytoplasm, and ribosomes. They may have flagella or cilia as well. They do not contain any membrane-bound organelles, such as the nucleus, endoplasmic reticulum, or mitochondria.

RNA and DNA have many similarities in structure. They are both nucleic acids, meaning they are polymers of nucleotides; the structure of both DNA and RNA is made by bonding many nucleotide units into a long polymer chain. These chains are created by bonding in the sugar phosphate backbone. Each nucleotide contains a sugar, a phosphate, and a nitrogenous base. When the sugars and phosphates bind, nucleotides are strung together to create the nucleic acid chain.

There are two key structural differences between DNA and RNA. The first is the identity of the sugar used in the sugar phosphate backbone. DNA uses deoxyribose, while RNA uses ribose. Both are pentose sugars, meaning they have five carbons, but the 2' carbon in RNA has a hydroxyl group that is absent in DNA. The second major difference is the identity of the nitrogenous bases used to code genetic information. DNA uses cytosine, guanine, adenine, and thymine. RNA uses cytosine, guanine, adenine, and uracil. Thymine will not be found in RNA and uracil will not be found in DNA.

DNA replication is defined as being semiconservative. This statement means that when a DNA molecule undergoes replication, the DNA helix unwinds and each strand serves as a template for the new strand to be created. Once a new DNA molecule has been created, it is composed of both an old strand (template), and the newly created strand, thus making a new double helix.

While the answer choice about leading and lagging strands is a true statement with regard to DNA replication, it is unrelated to the semiconservative nature of the process.

During DNA replication, DNA polymerase III needs a site of attachment in order to begin DNA strand synthesis. This template is provided by primase, which lays down an RNA primer for DNA polymerase III to attach.

RNA polymerase is not involved in DNA replication (it is involved in translation), and DNA polymerase I is used to replace the RNA primers with DNA nucleotides.

Proteins have a variety of functions in the body, one of which is acting as biological catalysts. These specialized proteins are called enzymes and are used to facilitate all types of chemical reactions in organisms.

Storing genetic information is accomplished by nucleic acids, and energy is provided by carbohydrates. Lipids (or phospholipids to be specific) help create the plasma membrane structure.

The process of translation involves a variety of RNA molecules, all with specific roles necessary in order to create the functional protein. mRNA (messenger RNA) is the product of DNA transcription and provides the template that the ribosome will read. rRNA (ribosomal RNA) helps create the functional ribosomal complex. tRNA (transfer RNA) brings individual amino acids to the ribosome in order to lengthen the growing polypeptide chain.

The genetic code is defined as being both unambiguous and degenerative. The term degenerative means that an amino acid can have multiple codons that code for it. For example, both UCC and UCG code for the amino acid serine. The term unambiguous means that a codon will always code for only one amino acid. For example, UCC will only ever code for serine; it cannot generate any other amino acid.

Each codon has three nitrogenous base units. Since there are four possible bases, there are 64 3-base combinations (64 possible codons). The degenerative nature of the code allow each and every combination to code for an amino acid.

The central dogma of molecular biology states that DNA is transcribed into RNA, which is then translated into protein.