Central Dogma, Cellular Respiration, and Genetics
Central Dogma of Molecular Biology
The central dogma of molecular biology illustrates the mechanisms of transmission and expression of genetic inheritance, following the discovery of its coding in the double helix of DNA. It suggests a unidirectional flow of information from genes to proteins. DNA is transcribed into messenger RNA (mRNA), which is then translated into protein, the functional element of the cell. The dogma also states that only DNA can replicate, thus reproducing and transmitting genetic information to offspring. Francis Crick proposed it in 1970.
Apart.
Replication Origin, Bubble, and Fork
Origin of replication: The site on the chromosome where DNA replication begins. It is a specific nucleotide sequence from which a replication fork evolves, giving rise to two identical DNA strands.
Replication bubble: An area containing replication forks.
Replication fork: At the ends of the replication bubble, the DNA strands form a Y-shaped structure called a fork.
Helicases and Topoisomerases
Helicases: Vital enzymes in living organisms, involved in replication, transcription, recombination, DNA repair, and ribosomal biogenesis. Their function is to break the hydrogen bonds linking the nitrogenous bases, enabling other enzymes to copy the template strand.
Topoisomerases: Isomerase enzymes that act on the topology of DNA. The configuration of the DNA double helix makes separation difficult, which is essential for transcribing the sequence encoding proteins or replicating chromosomes.
Primase RNA and DNA Polymerase
RNA primase: A type of RNA polymerase that synthesizes short RNA fragments (about 10 nucleotides long), known as primers, complementary to the DNA strand being copied during replication.
DNA Polymerase: Enzymes involved in DNA replication, providing each daughter cell with a DNA copy of the original during mitosis. They synthesize new DNA strands by matching deoxyribonucleotide triphosphates (dNTPs) with the corresponding complementary deoxyribonucleotides on the template DNA.
Difference Between Aerobic and Anaerobic Cellular Respiration
Aerobic Respiration: Uses O2 as the final electron acceptor for electrons detached from organic substances. It is the most widespread type, typical of some bacteria and eukaryotic organisms whose mitochondria are derived from them. Organisms that require O2 are called aerobic organisms.
Anaerobic respiration: Oxygen is not involved. Instead, other final electron acceptors are used, usually minerals and products of the metabolism of other organisms.
Difference Between Cellular Respiration and Fermentation
Cellular Respiration: Involves the complete oxidation of organic compounds, with an inorganic substance as the final electron acceptor. It produces 36 or 38 ATP.
Fermentation: Involves incomplete oxidation, where the final electron acceptor is an organic compound. Anaerobic fermentation processes are genuine. Only two ATP are produced.
Definitions
Genotype: The genetic makeup for one or more characters; the alleles that determine a specific phenotype.
Phenotype: The observable nature or set of characteristics of an organism.
Heterozygote: An organism that displays two different alleles for a certain character.
Homozygote: An organism that has two identical alleles for a given character.
Gene: A unit of genetic information; a DNA fragment component of a chromosome.
Allele: One of the alternative forms of a gene occupying the same locus on a pair of homologous chromosomes.
Dominant Inheritance: A type of inheritance in which a dominant allele expresses itself, masking the effect of a recessive allele. It causes a character, where the recessive allele is hidden in hybrid individuals. The terms dominant and recessive apply to both the characters and the alleles governing them.
Intermediate Inheritance: A type of inheritance in which both alleles are equally expressed, resulting in a hybrid phenotype that is intermediate between the parents. In this case, the alleles are often called codominant, and capital letters are used to refer to both alleles.