Question

The correct sequence between genes and their phenotypic expression is (A) RNA-DNA-protein-trait (B) DNA-RNA-protein-trait (C) protein-DNA-RNA-trait (D) trait-DNA-RNA-protein (E) trait-protein-DNA-RNA

Short answer

The correct sequence between genes and their phenotypic expression is option (B) DNA-RNA-protein-trait.

Step-by-step solution

Understand the Central Dogma of Molecular Biology

The Central Dogma of Molecular Biology states that information flows in one direction: from DNA to RNA to proteins.

Match the Options with the Central Dogma

Evaluate the given options and find the one that corresponds to the process described in the Central Dogma.

Choose the correct answer

Option B, DNA-RNA-protein-trait, is the correct sequence in which information is converted into functional products leading to a specific trait. So, B is the correct answer.

Key concepts

DNA

DNA stands for deoxyribonucleic acid, and it is essentially the blueprint for all living organisms. It carries the genetic information necessary for the growth, development, functioning, and reproduction of all life forms. DNA is composed of two strands that coil around each other to form a double helix. These strands consist of molecules called nucleotides, which are made up of a sugar, a phosphate group, and a nitrogenous base.

• The sequence of the nucleotides encodes genetic instructions, much like letters form words and sentences.
• There are four types of nitrogenous bases in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). In the double helix, A pairs with T, and C pairs with G.
• DNA replication is a crucial process for cell division, ensuring that each new cell has an exact copy of the DNA.

DNA serves as the starting point in the Central Dogma of Molecular Biology, providing the template for RNA synthesis.

RNA

RNA, or ribonucleic acid, acts as the messenger carrying instructions from DNA for controlling the synthesis of proteins. It is similar to DNA but has some key differences:

• RNA is usually single-stranded, unlike the double-stranded DNA.
• It contains the sugar ribose instead of deoxyribose found in DNA.
• RNA uses the base uracil (U) instead of thymine.

The process of transcribing DNA into RNA includes steps known as transcription, where a particular segment of DNA is copied into RNA by the enzyme RNA polymerase. There are different types of RNA, with messenger RNA (mRNA) being pivotal in protein synthesis.

Understanding RNA's role is essential for grasping how genetic information is translated into the proteins that perform life's functions.

protein synthesis

Protein synthesis is the biological process that allows cells to build proteins, which are complex molecules essential for numerous cell functions and processes. It occurs in two main stages: translation and transcription.

• During transcription, DNA is transcribed into mRNA in the nucleus.
• Translation follows, occurring in the cytoplasm where the mRNA is decoded to build proteins.
• The ribosome, a cell's protein factory, reads the sequence of the mRNA in sets of three bases known as codons.
• Each codon specifies a particular amino acid, the building blocks of proteins.
• Transfer RNA (tRNA) brings the right amino acids to the ribosome, matching them with the mRNA template.

The result is a polypeptide chain that folds into a functional protein. This process highlights the crucial work RNA performs as the bridge between the genetic code in DNA and the formation of essential proteins.

phenotypic expression

Phenotypic expression refers to the observable characteristics of an organism, which arise from the interaction of its genotype with the environment. The Central Dogma provides the framework for how genetic information results in these traits.

• The genetic code for traits is stored in the DNA.
• This code is first transcribed into mRNA and then translated into proteins through the process of protein synthesis.
• Proteins carry out various cellular functions that manifest as phenotypic traits.

For example, a flower's color, height of a plant, or even the metabolism of an organism can all be traced back to specific proteins produced as a result of transcription and translation. Hence, phenotypic expression is the end product of this seamless and incredibly complex pathway from DNA to trait.