Molecular Genetics Quiz

Molecular Genetics

• Molecular genetics is the study of DNA structure, cellular activities (including replication), and its role in determining an organism's overall makeup.

History of DNA

• 1868: Friedrich Miescher, a Swiss physician, was interested in the cell nucleus's composition.
• 1920s: Phoebus Levene studied the chemical composition of DNA.
• 1928: Frederick Griffith discovered the transforming principle.
• 1944: Avery, MacLeod, and McCarty confirmed DNA as the transforming principle.
• 1949: Four nitrogenous bases (purines and pyrimidines) were identified.
• 1950s: Franklin, Watson, and Crick used X-ray crystallography to develop the double helix model, with phosphates on the outside.
• 1952: Hershey and Chase determined DNA as the hereditary material.
• 1950: Chargaff's ratios of nitrogenous bases (A-T, C-G) played a critical role in understanding DNA structure.
• 2003: Human genome released.
• 2012: CRISPR developed as a gene editing tool.
• 2020: Complete human genome mapped.

LUCA (Last Universal Cellular Ancestor)

• LUCA represents the last universal cellular ancestor.
• The Tree of Life shows the evolutionary relationships among all organisms.

Gene Ontology (GO) and Protein Domains

• Gene ontology (GO) expansions and innovations are associated with conserved protein domains.
• Conserved domains between species are used to determine associated GO terms.
• GO terms in black are associated with protein domains conserved across eukaryotes, archaea, and bacteria.
• GO terms in blue are associated with Pfam domains not shared by humans and archaea or bacteria.

DNA Structure and Organization

• DNA is a nucleic acid; a polymer of nucleotides.
• DNA in eukaryotic cells is in the nucleus; in prokaryotes, it's in the cytoplasm.
• DNA's structure is coiled; supported by histones (proteins).
• A nucleosome is 8 histones wrapped by DNA, allowing for compact packing.
• Genes are segments of DNA that code for proteins.
• Genes vary in size, from a few hundred to over 2 million DNA bases.

The Nucleus, Chromosomes, and Genes

• The nucleus contains chromosomes, which, in turn, contain DNA.
• DNA comprises genes.
• Deoxyribonucleic acid (DNA) is made up of ACTG nitrogenous bases.

Genome

• A genome is an organism's complete set of DNA.
• The human genome was completely mapped in 2020.
• Humans have a large number of genes.

Molecular Level Details

• DNA is a double helix.
• Nucleotides are the building blocks of DNA (phosphate, sugar, bases).
• Purines (A, G) have a double ring; pyrimidines (C, T) have a single ring.
• Hydrogen bonds connect base pairs (A-T, G-C).
• Phosphodiester bonds create the DNA backbone.
• DNA is antiparallel.
• The major and minor grooves are crucial for protein recognition and binding.

Epigenetics

• Epigenetics refers to functional changes to the genome affecting gene expression without altering DNA sequence.
• Epigenetic changes can be rapid and dynamic or persistent and heritable.
• Differences in identical twins can be linked to epigenetic changes.

Blockchain and Genomes

• Blockchain technology can be used to secure and store genomes.