The diagram shows two cells taken from the same organism - HSC - SSCE Biology - Question 34 - 2015 - Paper 1

Disadvantageous mutations can have varying effects depending on whether they occur in somatic cells or germ cells.

• Somatic Cells: When a mutation arises in somatic cells, it affects only the individual organism. This could lead to issues such as malfunctioning organs or diseases like cancer if cell growth and regulation are disrupted. The mutation can result in a lower survival rate, affecting the organism's ability to thrive or reproduce.

• Germ Cells: In the case of germ cells, a mutation can be passed on to future generations. This could potentially lead to inherited disorders in offspring, thereby affecting not just the individual but the entire population. The presence of such mutations may also introduce challenges in adaptation and survival, ultimately impacting the evolutionary trajectory of the species.

Current models have clarified the roles of tRNA and mRNA in protein synthesis:

1. Interaction of tRNA and mRNA: tRNA molecules carry specific amino acids to the ribosome, matching their anticodons to the codons on mRNA, ensuring the correct sequence of amino acids is produced.

2. Structure of mRNA: mRNA serves as a template for translation, providing the necessary code for amino acid sequences through its nucleotide sequences.

3. Codon Recognition: Each codon on mRNA corresponds to a particular amino acid. This specificity is vital for accurate protein synthesis, as any change in the mRNA sequence can lead to changes in the protein structure and function.

4. Efficiency of Translation: Understanding these models has also allowed scientists to elucidate the efficiency of processes that govern how proteins are synthesized, improving our ability to manipulate these processes for biotechnological applications.

The action of genes plays a crucial role in embryonic development through several mechanisms:

1. Gene Regulation: Specific genes are activated or silenced during different stages of development, guiding the differentiation of cells into specialized types, such as muscle or nerve cells. This regulation is key to forming complex tissues and organs.

2. Morphogens: Genes produce morphogens, which are signaling molecules that dictate the pattern of tissue development based on their concentration gradients. This mechanism helps establish the body plan and organ placement.

3. Genetic Pathways: Numerous genes function within interconnected pathways, and the proper expression of these genes ensures that development proceeds in a coordinated manner. Disruptions in these pathways can lead to developmental disorders.

4. Environmental Interactions: Genes also interact with environmental factors, influencing how organisms develop in response to external stimuli, such as nutrients or stressors, ensuring adaptability and survival.