Summary of Ritmos Biológicos

00:00:00 - 00:20:00

In the "Ritmos Biológicos" YouTube video, the speaker explores the concept of biological rhythms, which are cyclical changes in biological variables in organisms resulting from sequences of processes operating at different velocities. These rhythms can be divided into those aligned with intrinsic properties and geophysical cycles, such as the day-night cycle. The day-night cycle brings about various conditions associated with light, including vision and photosynthesis, as well as potential damage due to solar radiation. The speaker also discusses circadian rhythms, which have 24-hour cycles, and ultradian and infradian rhythms with shorter and longer cycles, respectively. Organisms in coastal intertidal zones adjust their activity cycles based on tidal and lunar rhythms, increasing their chances of survival. The biological clock maintains circadian rhythms, and research suggests the nucleus supraquiasmático, a small group of neurons located in the brain, could be the biological clock. The molecular clock mechanism involves negative feedback loops involving proteins PERIOD (PER) and REVERBALpha (RVER), forming a negative feedback loop that regulates the circadian rhythm.

• 00:00:00 In this section of the "Ritmos Biológicos" YouTube video, the speaker discusses the concept of biological rhythms, which are the cyclical changes in biological variables in organisms. These rhythms result from sequences of processes that occur at different velocities, leading to variations in variables such as body temperature and hormone concentrations. The speaker uses the example of body temperature to illustrate how processes that regulate temperature work at different velocities throughout the day, resulting in a daily temperature cycle. Biological rhythms can be divided into those that align with the intrinsic properties of the process and those that align with regular geophysical cycles, such as the day-night cycle. The day-night cycle, which is the most significant geophysical factor affecting biological processes, brings about various conditions associated with light, such as vision and photosynthesis, as well as increased production of free radicals and potential damage to cellular structures and genetic material due to solar radiation. The speaker also mentions that various human physiological variables, such as temperature, hormone concentrations, physical activity, and sleep stages, exhibit changes in 24-hour cycles, which are called circadian rhythms. Additionally, there are ultradian rhythms, which have cycles shorter than 24 hours, and infradian rhythms, which have cycles longer than 24 hours. Among the ultradian rhythms, those that align with geophysical cycles include tidal rhythms and circadian rhythms. The speaker explains that the lunar cycle, which lasts approximately 24.8 hours, results in two high tides per day due to the gravitational attraction of the moon and the centrifugal force of the Earth's rotation.
• 00:05:00 In this section of the "Ritmos Biológicos" YouTube video, the speaker discusses how organisms in coastal intertidal zones adjust their activity cycles based on tidal and lunar rhythms. These rhythms, including circadian and infradian rhythms, help organisms anticipate environmental changes and increase their chances of survival. The speaker explains that while some organisms synchronize their cycles with geophysical cues, others align with lunar cycles, which have a duration of approximately 29.5 days. The study presented in the video focused on cianobacteria with different activity rhythms and found that the population that aligned most closely with the lighting conditions dominated, regardless of the initial proportions. Another study involving squirrel monkeys showed that those with their biological clocks intact had a higher survival rate than those whose clocks were disrupted. The value of these rhythms lies in their ability to help organisms prepare for predictable environmental changes, allowing them to initiate necessary processes in advance.
• 00:10:00 In this section, it is discussed how biological rhythms adjust to geophysical events through the coordination of an organism's internal biological clock with external cycles, especially those of light. Plants like the mimosa, studied by French geophysicist Dr. Homer, showcase clear daily leaf opening and closing rhythms affected by light exposure. Circadian rhythms persist even in constant darkness due to an endogenous clock mechanism. These biological rhythms serve an ecological purpose, ensuring species survival by synchronizing internal processes with external conditions. Factors like light, feeding times, auditory signals, and hormonal pulses can synchronize these rhythms, highlighting the adaptive function of circadian rhythms in coordinating physiological processes with environmental changes, as seen in studies on fish populations in underground rivers in Mexico.
• 00:15:00 In this section of the "Ritmos Biológicos" YouTube video, the discussion revolves around the discovery of the biological clock that maintains circadian rhythms in animals. The research suggests that the nucleus supraquiasmático, a small group of neurons located in the base of the brain, could be the biological clock. This hypothesis was supported by experiments where lesions in the supraquiasmático region caused animals to lose their endogenous rhythm. Conversely, transplants of supraquiasmático tissue from rats with different endogenous rhythms restored the rhythmicity in the lesioned animals, but with a rhythm different from their original one. The nucleus supraquiasmático contains neurons that spontaneously depolarize and maintain a rhythm close to 24 hours, suggesting that the clock mechanism is within the neurons themselves. Further studies on fruit flies led to the identification of genes involved in the clock mechanism, which were named clock genes. These genes encode proteins that are expressed in periodic cycles in the neurons of the supraquiasmático nucleus. The model of the molecular clock consists of two processes of transcription and translation of the clock genes, forming a negative feedback loop. This loop involves the interaction between clock and cryptochrome proteins, which regulate each other's expression and control the circadian rhythm.
• 00:20:00 In this section of the YouTube video titled "Ritmos Biológicos," the circadian clock mechanism is discussed, specifically focusing on negative feedback loops involving proteins PERIOD (PER) and REVERBALpha (RVER). The mechanism begins with the dinero clock protein of mal one binding to the cis-elements of various genes, including PER and RVER, initiating transcription and stabilizing the resulting proteins. The dinero clock protein then enters the nucleus and displaces the mal one protein, halting transcription. RVER alpha enters the nucleus and inhibits the promoter of mal one, causing its concentration to decrease, and eventually leading to the transcription and nuclear entry of PER and RVER, closing the cycle. The circadian clock molecular mechanism is illustrated in the video, showing how the cycle initiates with the dinero clock protein and the involvement of negative feedback loops in various organisms, including flies, plants, and bacteria.