Genetics
Frank J. Dye in Human Life Before Birth, 2019
To make an embryo, it is necessary to use, or express, the genetic information encoded in the DNA molecule (see Figure 4.4B). To reiterate, this information is in a sequence of DNA deoxyribonucleotides (a gene). When the information is expressed, a sequence in DNA is used to dictate a sequence of ribonucleotides in a molecule of RNA. At this point, a team of enzymes separates the two strands of a part of a DNA molecule. Next, one of the two separated strands is used as a template for the formation of an RNA molecule, according to base-pairing rules. With RNA molecules, we have a slight change in these rules because these molecules do not contain ribonucleotides with thymine; uracil is found in place of thymine. The RNA rules are that U hydrogen-bonds with A, and G with C.
General Principles
Sarah Armstrong, Barry Clifton, Lionel Davis in Primary FRCA in a Box, 2019
A gene is the molecular unit of heredity. It is a region of DNA made up of nucleotides DNA has three structures: backbone spiral structure (deoxyribose linked with phosphate bonds)nucleotides – purine (adenine/guanine) or pyrimidine (cytosine/thymine) base combined with a deoxyribose and a phosphate groupdouble helix structure is via complementary base pairing via hydrogen bonds – adenine forms two bonds with thymine, guanine forms three bonds with cytosineEach triplet of bases codes for a specific amino acidDNA ‘clumps’ with proteins in the nucleus to form chromatin. During cell division, chromatin forms pairs of chromosomesThe human genome has 46 chromosomes (23 pairs) containing 3 billion base pairs
The Molecular Model and DNA Double Strand Breaks
K. H. Chadwick in Understanding Radiation Biology, 2019
In addition to providing the basis of the genetic code, the complementary base pairing makes it possible for the DNA molecule to replicate itself correctly during the DNA synthesis (S) phase of the cell cycle. In DNA synthesis, the two ‘old’ strands of DNA loosen and replication starts at many replication origins, proceeding in both directions along the DNA (Benbow et al. 1985; Linskens and Huberman 1990; Douglas et al. 2018). The ‘old’ strands are copied to make two ‘new’ strands with complementary base pairing so that the two new double helices are exact copies of the original double helix and each of the two helices has one ‘old’ strand and one ‘new’ strand (see Figure 1.2). At mitosis, the two new DNA double helices separate into two daughter cells, each of which carries the same genetic information from the original cell.
LncRNA HOXC-AS3 increases non-small cell lung cancer cell migration and invasion by sponging premature miR-96
Published in Expert Review of Respiratory Medicine, 2022
Li Wan, Zaixing Cheng, Quanchao Sun, Ke Jiang
Subcellular fractionation assay was performed to determine the subcellular location of HOXC-AS3 in both H1650 and A549 cells. GAPDH, which can be detected in both cytoplasm and nuclear samples, was used as an internal control in this assay. Similar to GAPDH, HOXC-AS3 can be detected in both nuclear and cytoplasm (Figure 2(a)). The online program IntaRNA 2.0 was used to predict the potential interaction between HOXC-AS3 and premature miR-96. It was observed that these two non-coding RNAs may form base pairing (Figure 2(b)). RNA pull-down assay was performed to confirm the direct interaction between HOXC-AS3 and premature miR-96. Compared to Bio-NC group, Bio-premiR-96 group exhibited significantly higher expression levels of HOXC-AS3, suggesting the direct interaction between them (Figure 2(c), p < 0.001).
Dosimetry study on Auger electron-emitting nuclear medicine radioisotopes in micrometer and nanometer scales using Geant4-DNA simulation
Published in International Journal of Radiation Biology, 2020
Seifi Moradi Mahdi, Shirani Bidabadi Babak
The geometric model of the DNA molecule considered by Raisali et al. (2013) consists of 41 base pair (82 nucleotides), with atom 123I was located at the base position of thymine in the 21st base pair. This position is related to the location of the IdUrd. As shown in Figure 1, each sugar-phosphate group is simulated in volumes, a height of 0.33 nm, an inner radius of 0.5 nm and an outer radius of 1.185 nm. Each nucleotide contains a sugar-phosphate group and its related base, in such way that the volume of each sugar-phosphate group is 0.24 nm3. This volume is the total volume of the atoms of a sugar-phosphate group. All volumes are filled with liquid water. Considering that the spiral of the DNA molecule spins 360° after 10 nucleotide pairs, an angle of 36° is intended to simulate the rotational angle for each nucleotide.
Microsatellite instability and oncological outcomes in Thai patients with endometrial cancer
Published in Journal of Obstetrics and Gynaecology, 2022
Thiti Atjimakul, Panote Wattanapaisal, Supaporn Suwiwat, Worrawit Wanichsuwan, Jitti Hanprasertpong
Endometrial cancer (EC) was included as a common gynaecological cancer in the Global Cancer Statistics report in 2020; over 417,367 new cases were reported in 2020 (Sung et al. 2021). The National Cancer Institute of Thailand has also reported EC as the third most common gynaecological cancer in the Thai female population, with three per 100,000 cases per year (Virani et al. 2017). Most ECs occur sporadically, with only 3–5% being related to germline mutation (Thibodeau et al. 1993; Herman et al. 1998; Boland et al. 2008). Genetic alterations in EC are frequently associated with the loss of mismatch repair (MMR) system. The latter involves a repetitive DNA sequence-repair mechanism that maintains genomic integrity by correcting base substitutions and minor insertion–deletion mismatches generated due to base-pairing errors by DNA polymerase during replication. Mutations in MMR genes, such as mutL homolog 1 (MLH1); mutS homologs 6 (MSH6), 2 (MSH2) and 3 (MSH3); and PMS1 homolog 2 (PMS2), assemble as microsatellite sequences throughout the genome, a phenomenon realised as microsatellite instability (MSI) (Lower et al. 2018).
Related Knowledge Centers
- Adenine
- Cytosine
- DNA
- Nucleic Acid
- Nucleobase
- Rna
- Thymine
- Guanine
- Nucleic Acid Sequence
- Complementarity