10 Questions
Which property of the DNA double helix led Watson and Crick to hypothesize the semi-conservative mode of DNA replication?
The complementary base pairing between the two strands
Which type of nucleic acid polymerase is responsible for the synthesis of mRNA from a DNA template?
DNA-dependent RNA polymerase
In the Hershey-Chase experiment, how did the researchers differentiate between DNA and protein in order to prove that DNA is the genetic material?
They used radioactively labeled DNA and protein
What is the main difference between repetitive DNA and satellite DNA?
Repetitive DNA is composed of short, tandemly repeated sequences, while satellite DNA is composed of longer, highly repetitive sequences
What are the two essential roles of the ribosome during translation?
Providing the structural framework and catalyzing the peptide bond formation
Why does the lac operon shut down some time after the addition of lactose in the medium where E. coli is growing?
The lac operon is negatively regulated, and the presence of lactose eventually leads to its shutdown
What is the primary function of a promoter in the context of gene expression?
To recruit RNA polymerase and initiate transcription
Why is the Human Genome Project considered a 'mega project'?
It aimed to sequence the entire human genome, which is an extremely large and complex task
What is the primary application of DNA fingerprinting?
Determining paternity and kinship relationships
What is the main function of exons in the context of gene expression?
To provide the coding sequence for the final protein product
Study Notes
Predicting Amino Acid Sequence
- Given an mRNA sequence, Met-Phe-Phe-Phe-Phe-Phe-Phe, the sequence of amino acids can be predicted using a genetic code checkerboard.
- The sequence of nucleotides in mRNA is AUG UUU UUC UUC UUU UUU UUC, which codes for the amino acid sequence Met-Phe-Phe-Phe-Phe-Phe-Phe.
Mutations and Genetic Code
- Point mutations can result in a change of a single base pair in a gene, leading to a change in the amino acid residue, as seen in sickle cell anemia.
- Insertion or deletion of one or two bases can change the reading frame from the point of insertion or deletion, resulting in a frameshift mutation.
- Insertion or deletion of three or multiple bases can insert or delete one or multiple codons, and the reading frame remains unaltered from that point onwards.
tRNA - The Adapter Molecule
- Francis Crick proposed the existence of an adapter molecule that could read the genetic code and link it to specific amino acids.
- tRNA, or soluble RNA, is the adapter molecule that reads the code and binds to specific amino acids.
Human Genome Project (HGP)
- The Human Genome Project was a 13-year project that aimed to identify all 20,000-25,000 genes in human DNA, determine the sequences of the 3 billion chemical base pairs, and store this information in databases.
- The project was a mega project that required high-speed computational devices for data storage and retrieval, and analysis.
- The project was completed in 2003 and has led to a better understanding of human biology and the potential for new ways to diagnose, treat, and prevent disorders.
DNA Replication
- Watson and Crick's semi-conservative mode of DNA replication was hypothesized based on the property of DNA double helix.
Nucleic Acid Polymerases
- Nucleic acid polymerases can be classified based on the chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesized from it (DNA or RNA).
Test your knowledge on predicting amino acid sequences from mRNA sequences and predicting RNA sequences from amino acid sequences. Practice using a checkerboard to decode genetic information. This quiz is based on topics covered in 'Molecular Basis of Inheritance' class 2023-24.
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