Briefly explain the process of genetic information transfer.
The process of genetic information transfer involves the movement of genetic material from one organism to another. It primarily occurs through two main mechanisms:
1. Vertical transfer: This is the natural transmission of genetic information from parents to offspring. During sexual reproduction, the genetic material (DNA) from the mother and father combines to create a unique set of genetic instructions in the offspring. This transfer ensures the inheritance of traits and characteristics from previous generations.
2. Horizontal transfer: This is the transfer of genetic material between individuals of the same or different species, which is typically involved in genetic diversity and adaptation to environmental changes. There are various mechanisms by which horizontal gene transfer can occur, including:
- Transformation: The uptake of free extracellular DNA from the environment by a recipient organism, which integrates the acquired DNA into its genome.
- Transduction: The transfer of genetic material between bacteria mediated by bacteriophages (viruses that infect bacteria). During the infection cycle, the phage can transfer bacterial DNA from one bacterium to another.
- Conjugation: The direct transfer of genetic material between two bacterial cells through a physical connection called a pilus. In this process, a plasmid (a small, circular DNA molecule) is transferred from a donor cell to a recipient cell, allowing the recipient cell to acquire new genetic traits.
These processes of genetic information transfer contribute to genetic diversity and the evolution of organisms by allowing the exchange of beneficial traits and capabilities between different individuals and species.
34. Which of the following vitamin when in deficiency in pregnant women can lead to birth defects?
a. Vitamin B1
b. Folic acid
c. Vitamin C
d. Vitamin K
b. Folic acid
The process of genetic information transfer refers to the transmission of hereditary information from one generation to the next. It involves DNA replication, transcription, and translation.
1. DNA Replication: The first step in genetic information transfer is the replication of DNA. This process occurs during cell division (mitosis) and is essential for ensuring that each new cell receives an identical copy of the genetic material. DNA replication begins at specific sites called origins of replication, where enzymes called DNA helicases unwind and separate the two strands of the DNA helix. Another enzyme called DNA polymerase adds new nucleotides, complementary to the existing strands, to create two identical DNA molecules.
2. Transcription: The next step is transcription, where a copy of the genetic information stored in the DNA is made in the form of RNA. This copy, called messenger RNA (mRNA), carries the instructions for protein synthesis. Transcription starts with the initiation phase, where an enzyme called RNA polymerase binds to a specific region on the DNA called the promoter. The DNA strands separate, and the RNA polymerase adds nucleotides to the growing mRNA chain, using one DNA strand as a template. This process continues until the RNA polymerase reaches a termination signal, resulting in the formation of a mature mRNA molecule.
3. Translation: Translation is the final step in genetic information transfer, where the mRNA is used to synthesize proteins. This process occurs in the ribosomes, small cellular structures composed of ribosomal RNA (rRNA) and proteins. During translation, the mRNA molecule is read in groups of three nucleotides called codons. Each codon corresponds to a specific amino acid. Transfer RNA (tRNA) molecules, with anticodons complementary to the codons on the mRNA, bring the corresponding amino acids to the ribosome. The ribosome helps fuse the amino acids together, forming a polypeptide chain that eventually folds into a functional protein.
These three steps, DNA replication, transcription, and translation, are essential for the transfer of genetic information in living organisms.