Biology Chapter on Enzymes and Protein Synthesis

RNA polymerase is an enzyme responsible for synthesizing RNA using a DNA template strand. This process is called transcription.

Aminoacyl-tRNA synthetases are enzymes that attach specific amino acids to their corresponding tRNA molecules. This attachment forms a high-energy bond between the carboxyl group of the amino acid and the 3' or 2' hydroxyl group of the tRNA, preparing it for protein synthesis.

During translation, the ribosome reads the mRNA sequence from the 5' end to the 3' end. As it moves along the mRNA, it adds amino acids to the growing polypeptide chain, starting from the N-terminus and extending towards the C-terminus.

When a ribosome has tRNAs bound to both the A and P sites, it is ready for peptidyl transfer. This involves the transfer of the polypeptide chain from the P-site tRNA to the amino acid attached to the A-site tRNA. Essentially, the carboxyl end of the polypeptide chain in the P-site joins with the amino group of the amino acid in the A-site.

Transcription is the process of synthesizing RNA from a DNA template. RNA polymerase is the key enzyme involved in this process.

tRNA, or transfer RNA, is a type of RNA molecule that carries amino acids to the ribosome during protein synthesis. Each tRNA is specific for a particular amino acid.

Translation is the process of converting genetic information from mRNA into a protein sequence. This process occurs at the ribosome, where tRNAs bring amino acids to the mRNA template.

The A site, or aminoacyl site, is a binding site on the ribosome where the incoming aminoacyl-tRNA carrying the next amino acid to be added to the polypeptide chain binds. The P site, or peptidyl site, is where the tRNA bound to the growing polypeptide chain is located.

The process where the amino end of a newly synthesized amino acid on the A-site tRNA is joined to the carboxyl group of the polypeptide chain linked to the P-site tRNA, forming a peptide bond.

A type of cellular transport that involves the movement of molecules through protein channels or pores embedded in the membrane.

A type of cellular transport that involves the movement of molecules across a membrane via protein translocators.

A type of cellular transport that involves the movement of molecules in membrane-bound vesicles.

The compartment within the cell where ribosomes assemble and are exported back to the cytoplasm.

The main site of cellular digestion, maintaining a pH of 2.0 to 2.5, containing F-type ATPases that pump protons into the organelle, and having heavily glycosylated membrane proteins.

The process where proteins synthesized in the ER are transported to the Golgi apparatus.

The process where proteins are returned from the Golgi apparatus to the ER.

The telomerase enzyme is a specialized enzyme responsible for maintaining the length of telomeres at the ends of chromosomes. Telomeres act as protective caps, preventing DNA degradation and chromosome fusion during DNA replication. Telomerase uses its RNA component to act as a template for synthesizing DNA sequences at the telomeres, extending the chromosome ends and preventing their shortening with each replication cycle.

The lagging strand is synthesized discontinuously during DNA replication because DNA polymerase can only add nucleotides in the 5' to 3' direction. As the replication fork moves along, the lagging strand template is exposed in fragments. DNA polymerase synthesizes short Okazaki fragments, which are later joined together by DNA ligase to form a continuous strand.

The restriction point (R) is a critical checkpoint reached in the G1 phase of the cell cycle in mammalian cells. At this point, a cell commits to entering the S phase (DNA replication) and completing the cell cycle. The restriction point ensures that the cell has grown sufficiently, has sufficient nutrients, and has received the necessary growth signals to proceed with DNA replication.

Meiosis II is a division process in which sister chromatids separate, resulting in the formation of four haploid daughter cells, each containing one copy of each chromosome. This process is similar to mitosis, where sister chromatids are also separated, but it occurs in meiotic cells, which have undergone a previous round of chromosome pairing and recombination during Meiosis I.

A form of a gene that has a slightly different DNA sequence compared to other forms of the same gene, but codes for the same type of RNA or protein.

The point on a chromosome where spindle microtubules attach during cell division.

Cells having two sets of chromosomes (one set from each parent).

The stage in mitosis when microtubules attach to kinetochores on chromosomes.

If a purebred yellow-seeded pea plant is crossed with a purebred green-seeded plant, and all offspring are yellow, what is the probability of getting a green-seeded offspring if one of these yellow offspring is crossed with a green-seeded plant?

A chromosome constitution that would not lead to a viable human baby.

If two parents with normal phenotypes have a child with an autosomal recessive trait, what is the likely genotype of the parents?

A statement that is incorrect about X-linked recessive traits.

A genetic condition where an affected woman almost always has an affected mother, and an affected man usually has a mother who carries the recessive allele. A phenotypically normal woman whose father was affected is likely to be heterozygous for the condition.

The process of exchange of genetic material between homologous chromosomes, resulting in new combinations of alleles. This process occurs during meiosis I.

The physical separation of homologous chromosomes during meiosis I, leading to independent assortment of alleles from each parent.

The use of radioactive isotopes to label DNA or protein to track their movement during viral infection. Hershey and Chase used sulfur-35 to label protein, and phosphorus-32 to label DNA.

Regions of DNA that are highly repetitive and are found at the ends of chromosomes. They protect the ends of chromosomes from degradation and promote stability.

Regions of DNA that are highly repetitive and are found at the constricted region of chromosomes. They serve as the attachment point for spindle fibers during cell division.

The unwinding of the DNA helix, separating the two strands to allow for replication. It is aided by helicase, single-stranded binding proteins, and topoisomerase.

A type of mutation that changes a codon for an amino acid into a stop codon, resulting in a truncated and often non-functional protein.