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Deoxyribonucleic acid is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.
Genetics is the study of genes, genetic variation, and heredity in organisms. It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene.
Mutagenesis is a process by which the genetic information of an organism is changed by the production of a mutation. It may occur spontaneously in nature, or as a result of exposure to mutagens. It can also be achieved experimentally using laboratory procedures. A mutagen is a mutation-causing agent, be it chemical or physical, which results in an increased rate of mutations in an organism's genetic code. In nature mutagenesis can lead to cancer and various heritable diseases, and it is also a driving force of evolution. Mutagenesis as a science was developed based on work done by Hermann Muller, Charlotte Auerbach and J. M. Robson in the first half of the 20th century.
Non-coding DNA (ncDNA) sequences are components of an organism's DNA that do not encode protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules. Other functional regions of the non-coding DNA fraction include regulatory sequences that control gene expression; scaffold attachment regions; origins of DNA replication; centromeres; and telomeres. Some non-coding regions appear to be mostly nonfunctional, such as introns, pseudogenes, intergenic DNA, and fragments of transposons and viruses. Regions that are completely nonfunctional are called junk DNA.
Max Ludwig Henning Delbrück was a German–American biophysicist who participated in launching the molecular biology research program in the late 1930s. He stimulated physical scientists' interest into biology, especially as to basic research to physically explain genes, mysterious at the time. Formed in 1945 and led by Delbrück along with Salvador Luria and Alfred Hershey, the Phage Group made substantial headway unraveling important aspects of genetics. The three shared the 1969 Nobel Prize in Physiology or Medicine "for their discoveries concerning the replication mechanism and the genetic structure of viruses". He was the first physicist to predict what is now called Delbrück scattering.
Molecular genetics is a branch of biology that addresses how differences in the structures or expression of DNA molecules manifests as variation among organisms. Molecular genetics often applies an "investigative approach" to determine the structure and/or function of genes in an organism's genome using genetic screens.
dnaQ is the gene encoding the ε subunit of DNA polymerase III in Escherichia coli. The ε subunit is one of three core proteins in the DNA polymerase complex. It functions as a 3’→5’ DNA directed proofreading exonuclease that removes incorrectly incorporated bases during replication. dnaQ may also be referred to as mutD.
The origin of replication is a particular sequence in a genome at which replication is initiated. Propagation of the genetic material between generations requires timely and accurate duplication of DNA by semiconservative replication prior to cell division to ensure each daughter cell receives the full complement of chromosomes. This can either involve the replication of DNA in living organisms such as prokaryotes and eukaryotes, or that of DNA or RNA in viruses, such as double-stranded RNA viruses. Synthesis of daughter strands starts at discrete sites, termed replication origins, and proceeds in a bidirectional manner until all genomic DNA is replicated. Despite the fundamental nature of these events, organisms have evolved surprisingly divergent strategies that control replication onset. Although the specific replication origin organization structure and recognition varies from species to species, some common characteristics are shared.
Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector. An example is the viral transfer of DNA from one bacterium to another and hence an example of horizontal gene transfer. Transduction does not require physical contact between the cell donating the DNA and the cell receiving the DNA, and it is DNase resistant. Transduction is a common tool used by molecular biologists to stably introduce a foreign gene into a host cell's genome.
The LexA repressor or LexA is a transcriptional repressor that represses SOS response genes coding primarily for error-prone DNA polymerases, DNA repair enzymes and cell division inhibitors. LexA forms de facto a two-component regulatory system with RecA, which senses DNA damage at stalled replication forks, forming monofilaments and acquiring an active conformation capable of binding to LexA and causing LexA to cleave itself, in a process called autoproteolysis.
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protein-coding genes and non-coding genes. During gene expression, DNA is first copied into RNA. RNA can be directly functional or be the intermediate template for the synthesis of a protein.
Alexander J. Varshavsky is a Russian-American biochemist and geneticist. He works at the California Institute of Technology (Caltech) as the Morgan Professor of Biology. Varshavsky left Russia in 1977, emigrating to United States.
Evelyn M. Witkin was an American bacterial geneticist at Cold Spring Harbor Laboratory (1944–1955), SUNY Downstate Medical Center (1955–1971), and Rutgers University (1971–1991). Witkin was considered innovative and inspirational as a scientist, teacher and mentor.
Angelika Amon was an Austrian American molecular and cell biologist, and the Kathleen and Curtis Marble Professor in Cancer Research at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, United States. Amon's research centered on how chromosomes are regulated, duplicated, and partitioned in the cell cycle. Amon was elected to the American Academy of Arts and Sciences in 2017.
Mutation Frequency Decline (mfd) is the gene which encodes the protein Mfd. Mfd functions in transcription-coupled repair to remove a stalled RNA polymerase that has encountered DNA damage and is unable to continue translocating.
Bacterial genomes are generally smaller and less variant in size among species when compared with genomes of eukaryotes. Bacterial genomes can range in size anywhere from about 130 kbp to over 14 Mbp. A study that included, but was not limited to, 478 bacterial genomes, concluded that as genome size increases, the number of genes increases at a disproportionately slower rate in eukaryotes than in non-eukaryotes. Thus, the proportion of non-coding DNA goes up with genome size more quickly in non-bacteria than in bacteria. This is consistent with the fact that most eukaryotic nuclear DNA is non-gene coding, while the majority of prokaryotic, viral, and organellar genes are coding. Right now, we have genome sequences from 50 different bacterial phyla and 11 different archaeal phyla. Second-generation sequencing has yielded many draft genomes ; third-generation sequencing might eventually yield a complete genome in a few hours. The genome sequences reveal much diversity in bacteria. Analysis of over 2000 Escherichia coli genomes reveals an E. coli core genome of about 3100 gene families and a total of about 89,000 different gene families. Genome sequences show that parasitic bacteria have 500–1200 genes, free-living bacteria have 1500–7500 genes, and archaea have 1500–2700 genes. A striking discovery by Cole et al. described massive amounts of gene decay when comparing Leprosy bacillus to ancestral bacteria. Studies have since shown that several bacteria have smaller genome sizes than their ancestors did. Over the years, researchers have proposed several theories to explain the general trend of bacterial genome decay and the relatively small size of bacterial genomes. Compelling evidence indicates that the apparent degradation of bacterial genomes is owed to a deletional bias.
Michael Morris Rosbash is an American geneticist and chronobiologist. Rosbash is a professor and researcher at Brandeis University and investigator at the Howard Hughes Medical Institute. Rosbash's research group cloned the Drosophila period gene in 1984 and proposed the Transcription Translation Negative Feedback Loop for circadian clocks in 1990. In 1998, they discovered the cycle gene, clock gene, and cryptochrome photoreceptor in Drosophila through the use of forward genetics, by first identifying the phenotype of a mutant and then determining the genetics behind the mutation. Rosbash was elected to the National Academy of Sciences in 2003. Along with Michael W. Young and Jeffrey C. Hall, he was awarded the 2017 Nobel Prize in Physiology or Medicine "for their discoveries of molecular mechanisms controlling the circadian rhythm".
Titia de Lange is the Director of the Anderson Center for Cancer Research, the Leon Hess professor and the head of Laboratory Cell Biology and Genetics at Rockefeller University.
Nina Papavasiliou is an immunologist and Helmholtz Professor in the Division of Immune Diversity at the German Cancer Research Center in Heidelberg, Germany. She is also an adjunct professor at the Rockefeller University, where she was previously associate professor and head of the Laboratory of Lymphocyte Biology. She is best known for her work in the fields of DNA and RNA editing.
Susan Thomas Lovett is an American molecular biologist who is the Abraham S. and Gertrude Burg Professor of Microbiology at Brandeis University. She is interested in the mechanisms that allow the genetic material in cells to remain stable over time.
References
- 1 2 3 Memarian, Jahandad (June 26, 2016). "Houra Merrikh on Overcoming Adversity and Becoming a Leading Scientist". Huffington Post. Retrieved March 26, 2018.
- 1 2 3 4 Yong, Ed (November 15, 2018). "A Bold New Strategy for Stopping the Rise of Superbugs". The Atlantic. Retrieved October 22, 2019.
- ↑ "How head-on collisions of DNA protein machines stop replication: The collisions promote mutations that may help bacteria adapt to stress". ScienceDaily. August 15, 2017. Retrieved October 22, 2019.
- ↑ "It's In the Genes w/ Houra Merrikh". Everything You Know Is Wrong. Archived from the original on October 22, 2019. Retrieved October 22, 2019.
Her research into the mutagenic nature of co-directional gene collisions were revolutionary in the field and won her the 2016 Vilcek Prize for Creative Promise in Biomedical Science.
- ↑ Yong, Ed (January 29, 2017). "Trump's Immigration Ban Is Already Harming American Science". The Atlantic. Retrieved October 22, 2019.
- 1 2 3 "GSA member Houra Merrikh honored with Vilcek Prize for Creative Promise". Genes to Genomes. March 3, 2016. Retrieved October 22, 2019.
Working with former GSA Board member Susan Lovett
- ↑ "Graduate Students: 2000s". Brandeis Magazine. Brandeis University. Winter 2016. Retrieved October 22, 2019.
- ↑ Cepelewicz, Jordana (November 22, 2017). "Bacteria Sacrifice DNA Repair for Better RNA". Quanta Magazine. Retrieved October 22, 2019.
- ↑ Palisoc, Mhean (January 3, 2019). "Merrikh Lab Working to Defeat Drug-Resistant Superbugs". Science and Technology Research News. Retrieved October 22, 2019.
- ↑ "Il y a peut-être une solution pour stopper la résistance aux antibiotiques". Slate.fr (in French). December 31, 2018. Retrieved October 22, 2019.
- ↑ ""Anti-Evolution Drugs" Could Offer New Strategy against Antimicrobial Resistance Crisis". GEN - Genetic Engineering and Biotechnology News. November 19, 2018. Retrieved October 22, 2019.
- ↑ Rasmussen, Ray (August 15, 2017). "How DNA Protein Machines Collide Head on and Stop Replication". Science and Technology Research News. Retrieved October 22, 2019.
- ↑ "Project Information - NIH RePORTER - NIH Research Portfolio Online Reporting Tools Expenditures and Results". projectreporter.nih.gov. Retrieved March 26, 2018.
- ↑ "The Vilcek Foundation - The Vilcek Foundation - 2016 Vilcek Prize in Biomedical Science and Theatre". www.vilcek.org. Retrieved March 26, 2018.
- ↑ "14 UW researchers win 2015 Innovation Awards". UW News. Retrieved March 26, 2018.
- ↑ "User profiles for Houra Merrikh". Google Scholar. Retrieved December 21, 2019.
