The origins of life on Earth

It’s probably best I foreword this by saying it’s impossible to tell how life first formed on Earth. We know how humans evolved; humans evolved apes who evolved from simians and we can date this path back till LUCA (Last Universal Common Ancestor). It is before LUCA where things get hazy. Our best guesses stem from the idea that the Earth was a carbon-dioxide-filled ball of rock, with temperatures far exceeding those of a hot summer’s day. This begs the question how something that can walk, talk and breathe evolved from a climate devoid of oxygen or water, which are essential to all life on Earth today. Despite this, scientists have their best guesses on how ‘something’ came from ‘nothing’.

The Primordial Soup

One way life is thought to have come about is via the ‘primordial soup’. Don’t drink this one, because the primordial soup was monomer chains found on the edge of shorelines and in tide pools near the ocean’s edge. Millions of years ago, ammonia, carbon dioxide and methane in the atmosphere would be present in the air and the water, and when these pools would be struck by lightning, or absorb energy from powerful UV rays, or even absorb heat from underwater geothermal vents, these monomers would join to form polymers which would form the building blocks of life.

J.B.S Haldane coined the term ‘primordial soup’ in 1929, and this is because it is believed when these polymers would join and form, the water would reach a soupy consistency, from which life would reproduce and the simplest amino acids would be synthesized.

The Miller-Urey Experiment

This can be proven by the Miller-Urey experiment of 1953, where a simulation of the primordial soup was conducted. Prior to this, it was believed life came from ‘spontaneous generation’ where life would magically appear. A series of (fairly rudimentary) experiments quickly disproved this. In the 1800s, Pasteur coined the scientific law ‘Omne vivum ex vivo’ (Life only comes from life) and animals don’t just appear randomly. Stanley Miller of the University of Chicago aimed to prove the primordial soup theory by setting up a simulation of what the primordial soup was like. Miller put water in an apparatus, which was gently boiled, water vapour, ammonia, and methane in the space above the liquid water, and a condenser to cool the atmosphere and act like rain. Sparks were added to the atmosphere to simulate lightning, and the experiment was run for one week. The water had gone from clear to a brown-black colour, and analysis showed that complex molecules had indeed formed, including amino acids which assemble to form proteins, and life. However, there are limitations to this experiment that have sparked debate amongst prebiotic chemists worldwide. Repetitions of Miller’s method suggest amino acids could have used the glassware of the experiment in order to catalyse reactions, due to the alkaline primordial soup eroding and dissolving silica from the walls of the glass. Furthermore, atmospheric scientists in 1983 discovered the Earth never had much ammonia or methane before life was around, and instead consisted of carbon dioxide and inert nitrogen. When Miller repeated his experiment with this new make-up of gases…

There was no more brown soup. No amino acids formed.

Aliens?

Francis Crick, the father of the structure of a DNA strand, suggested life could have come from outside Earth. He called it ‘directed panspermia’ which is the intentional placement of lifeforms on Earth by extraterrestrials. The paper suggests that all life forms have an abundance of molybdenum, which is an element not so common to Earth. Crick stated that we have unusually high amounts of molybdenum even though Earth does not have much of it, and that life would not have evolved to become dependent on an element such as molybdenum given its scarcity on Earth. Hence, Crick thought life could have come from a planet rich in molybdenum who ‘planted their seed’ on Earth. However, this theory might have just been a bold speculation given its unorthodox nature and outright abandonment of prebiotic chemistry.

Still a fun one to think about.

The mystery persists

Unfortunately, scientists still do not know how life formed on Earth. One common theory for how life evolved is by studying RNA, which has been fabricated in conditions like prehistoric Earth. Genetic analysis suggests RNA far precedes DNA and protein synthesis, and RNA has been around for millions of years. RNA is thought to have been formed from ‘nothing’, usually from abiotic materials forming chemical cycles in prebiotic oceans. These formed metabolic pathways and this led to the formation of RNA molecules which gave way to life. However, scientists still deem this inconclusive because RNA is an unstable molecule and probably could not have supported itself during Earth’s hostile conditions

References:

1. Fox D. Primordial Soup’s On: Scientists Repeat Evolution’s Most Famous Experiment [Internet]. Scientific American. 2007 [cited 2022 Jun 18]. Available from: https://www.scientificamerican.com/article/primordialsoup-urey-miller-evolution-experiment-repeated/

2. Model. Primordial Soup: Theory & Model - Video & Lesson Transcript | Study.com [Internet]. Study.com. 2021 [cited 2022 Jun 18]. Available from: https://study.com/academy/lesson/primordial-soup-theorymodelquiz.html#:~:text=The%20idea%20of%20the%20primordia l,of%20life%20would%20be%20created.

3. Wikipedia Contributors. Primordial soup [Internet]. Wikipedia. Wikimedia Foundation; 2022 [cited 2022 Jun 18]. Available from: https://en.wikipedia.org/wiki/Primordial_soup

4. Hartsfield T. What the famous Miller-Urey experiment got wrong [Internet]. Big Think. Big Think; 2021 [cited 2022 Jun 18]. Available from: https://bigthink.com/hardscience/millerurey/#:~:text=The%20simple%20amino%20acids%20did,t o%20have%20affected%20the%20results.

5. Wells J. The Miller-Urey Experiment - Chemical Evolution | BioTechSquad [Internet]. BioTechSquad |. 2017 [cited 2022 Jun 18]. Available from: https://nature.berkeley.edu/garbelottoat/?p=582#:~:text=Th e%20Miller%2DUrey%20experiment%20was,the%20theor etical%20ideas%20of%20A.I.

6. Orlic C. The Origins of Directed Panspermia [Internet]. Scientific American Blog Network. 2013 [cited 2022 Jun 18]. Available from: https://blogs.scientificamerican.com/guest-blog/the-originsof-directed-panspermia/ Anay Bindroo

Coexistence of humans and dinosaurs

Growing up, it was fed to us that dinosaurs walked the Earth hundreds of millions of years before us, but has anyone ever stopped and pondered upon whether this was completely true or not? Recent cutting-edge research in archeology has allowed us to reach a thorough understanding of our history, as well as that of species who we share, or once did share, the Earth with. Fossils, namely, have made monumental impacts in the field, acting as a direct lineage to our planet’s past. However, scientists have discovered that not all organisms leave fossils. Soft tissues of dead organisms decay rapidly, meaning the animal cannot be preserved. This is why some animals like bats and rodents, amongst others, are not preserved as fossils (American Geosciences Institute, 2022). This unleashes a myriad of questions in a domino effect. Could there be species who lived before us that we don’t know about? Is our knowledge of the timeline of different species on Earth entirely accurate? Is it, in any way, possible that humans, 233 million years ago, had soft tissues and thus did not leave any proof of their existence? Thus, is it possible that

Theory of Natural Selection, whereby he stated that organisms evolve by adapting to their physical environment, and that only the fittest survive and reproduce, passing on their advantageous characteristics to their offspring. What if humans evolved from harder by natural selection? Though there is currently no evidence in support of this, equally no this begs the question: if dinosaurs died from an asteroid, how could natural selection protect humans? As of now, there is no concrete evidence that directly explains the extinction of dinosaurs. Besides the theory that they were killed by an asteroid or a comet, some believe it was simply due to an insufficient number of plankton, making it difficult to sustain the food cycle. If this were the case, can it be that the human population itself was very small, thus reducing the competition for food, hence their survival, and not the dinosaurs’, assuming both species had different food sources? While all this may sound quite far-fetched and hypothetical, it’s important to note that it is based solely on theories we currently use and rely on in scientific research and development. Therefore, hile there is no evidence that proves it to be completely factual, there is also no evidence that suggests its impossibility. So, ask yourself again; what if humans and dinosaurs coexist once upon a time?

Leann Qadan 12KNO

Darwin, an English naturalist, established his

Nutritional Biochemistry & Astrobiology

Biochemistry is the area of science that explores the chemical processes within living organisms – essentially bringing together biology and chemistry, as the name implies, to apply chemistry to the research of living organisms. Biochemistry is particularly useful in space exploration to explore the nutritional biochemistry of astronauts as well as the universal query of ‘is there life beyond Earth?’.

Nutritional Biochemistry

The physiological effects of ‘weightlessness’ that occurs while in zero gravity is profound. However, research in how space travel affects nutritional issues including absorption, metabolism, and excretion, is still in its early stages [1]. Mildly simple issues such as muscle and bone loss due to a deficit in calorie intake while on the ISS (International Space Station) have been found refined solutions due to research in nutritional biochemistry. Furthermore, gravity level alternation causes a significant impact on your muscles and bones as they weaken, primarily in the legs and lower back. Gravity always acts on you while on Earth, contrasting to microgravity in space where your muscles that are no longer used as much to hold your body up For example, if your leg muscles don’t hold your body weight up by standing for months at a time, they become used to this and weaken. While space station research in nutrition helps us understand how to prevent and treat muscle atrophy and bone loss, optimizing countermeasures for astronauts is particularly important as space exploration takes on new gravity levels such

Signs of life on other planets

A research project during early 2022 by Dylan C. Gagler, Bradley Karas, professors at Arizona State University, researched enzyme function to discover a new ‘biochemical universality’. With the use of genomic datasets, they presented how enzyme functions form classes with their similar properties – proving previous organism classification methods valid. By comparing their predictions with a consensus model for the last universal common ancestor (LUCA), their results establish the existence of a new kind of biochemical universality, independent of the properties of Earth’s molecular chemistry [3]. If by tracing all organisms’ one common ancestor from over 4 billion years ago, we can find abnormalities in samples taken from space – ones that do not match up with any substances on Earth. This is essentially one of the first steps towards finding new properties of life outside our known planet.

Astrobiology in extra-terrestrial life

The Drake equation, formulated in 1961 by astrophysicist Frank Drake, is used to estimate the number of communicating civilizations in our galaxy, or the chances of finding intelligent life in the Milky Way. Recent discoveries of numerous planets in the Milky Way have raised the chances significantly.

The Drake equation goes in order from easiest to hardest, as said by astrophysicist Kaitlin Rasmussen [4]. While variables like L remain purely speculative, scientists can now answer with some certainty things such as average star formation rates in the Milky Way. A key issue with this formula is that any attempt to solve it requires guesswork for many of the variables, leading to wildly onal_biochemistry_of_space_flight_-fpdis.pdf [Accessed 19 Jun. 2022].

Credit: University of Rochester.

It would take a long time before scientists could even begin to put rough estimates into the equation, but progress has been made so far. In 1995, Michel Mayor and Didier Queloz from the University of Geneva detected the first exoplanet orbiting a sunsimilar star outside our solar system. Now known as 51 Pegasi b, it is found 50 lightyears from Earth in the constellation of Pegasus. Its orbit is so close to its sun that its "year" is only four days long, or 102 hours long and its surface temperature close to 1093°C or 2000° F Since then, we have discovered 4,940 new exoplanets as of March 2022. Out of those, a project done at the University of Puerto Rico expects 53 planets that "optimistically" could be suitable for life, and among those, 13 that are more likely to be habitable [5].

[2] Johnson, M. (2020). Bone and Muscle Loss in Microgravity. [online] NASA. Available at: https://www.nasa.gov/mission_pages/station/research/statio n-science-101/bone-muscle-loss-in-microgravity/.

[3]The Planetary Society. (n.d.). The Fermi paradox and Drake equation: Where are all the aliens? [online] Available at: https://www.planetary.org/articles/fermiparadox-drake-equation.

[4]ScienceDaily. (n.d.). Scaling laws in enzymes may help predict life ‘as we don’t know it’. [online] Available at: https://www.sciencedaily.com/releases/2022/02/220228161 618.htm [Accessed 19 Jun. 2022].

[5]https://www.facebook.com/spacecom (2018). Drake Equation: Estimating the Odds of Finding E.T. [online] Space.com. Available at: https://www.space.com/25219drake-equation.html.

WHY DO WE AGE?

Aging is universal: it’s a part of everyone’s life Human cells and therefore humans are not built to last forever. Molecular changes at cellular level, causes progressive decline in physiological organ functions leading to disease, disability and finally death.

On a cellular level there are nine hallmarks or main biological processes which are considered to be the core reasons behind ageing:

These hallmarks are divided into three groups:

· Primary hallmarks damage cellular functions and are the foundational causes of age associated damage. Antagonistic hallmarks are responses to the damage hallmarks. They beneficial at low levels but at high levels become deleterious.

· Integrative hallmarks the consequence of the damage wrecked by primary and hallmarks, and lead organ decline and function decline of the body.

Primary Hallmark

1.Genomic I [1]

DNA is the cell’s instruction manual, containing all of the information needed to synthesize the proteins essential for life.

The stability of DNA is constantly endangered by threats – exogenous (eg. exposure to radiation) and endogenous (DNA duplication errors). These mutations to the genetic code, causes instructions to be unclear, impeding the cell’s ability to function properly and leading to disease, including cancer.

2.Epigenetic Alterations

In addition to the DNA code, cells get information from the epigenome that controls gene expression (turns them "on" or "off") thereby determining how genes function [2].

Though all cells have the same DNA, genes are expressed differently, creating different cell types: epigenetics ensures that a skin cell is different from say a brain or a muscle cell. But as we age, genes start to get expressed when they shouldn't be, or get silenced by leading to disease [2]. For if the gene suppressing is silenced, cells could uncontrollably grow becoming cancerous.

.Telomere Attrition

Telomeres are structures at the tips of chromosomes which do not contain critical genetic data. When a cell divides and its DNA is copied, it cannot replicate the entire length of the DNA strand resulting in a portion of the DNA being lost . The loss is from the telomeric instead of the regions containing genes essential for life. also act like markers of f DNA strands keeping chromosome ends from fraying and sticking to each other [3].

Every time a cell divides, the telomeres become shorter. When they get too short the cell stops dividing and either becomes senescent (inactive) or undergoes apoptosis (programmed cell death) [2] The shortening of telomeres can lead to diseases particularly cancer and to ageing.

4.Loss of Proteostasis [2]

Proteins are critical for proper functioning of cells, tissues and organs Proteostasis is essentially the overall ‘management’ and balancing of proteins, including their synthesis, maintenance and degradation when they become damaged.

With ageing, proteostatis starts failing, resulting in unusable proteins not being eliminated This protein accumulation leads to a range of illnesses including Alzheimer’s and Parkinson’s

Antagonistic hallmarks

1.Cellular Senescence [2]

As cells age and become damaged, they stop dividing and die. However, sometimes cells become “senescent” - resistant to death.

Senescent cells generate chemicals which can affect nearby cells prompting them to also turn senescent. Senescent cells contribute to inflammaging, a state of chronic ongoing inflammation. Inflammation is the key factor in ageing and age-related chronic diseases including cancer, atherosclerosis, neurodegenerative diseases and diabetes.

2.Mitochondrial Dysfunction [2]

The mitochondria are the cell’s “powerhouse” generating the energy needed for cells to function. They get dysfunctional with age, impairing their ability to power the cell. This energy deficit affects cellular function, triggers chronic inflammation and other age related metabolic and neurodegenerative diseases.

3.De-regulated Nutrient Sensing [2]

Cells require a constant supply of nutrients to provide the energy they need to function. Cells must therefore be able to store nutrients when they are abundant and access these stores when nutrients are scarce. Furthermore, nutrient levels in our bloodstream need to stay within certain safe ranges.

Any imbalance with the cell's ability to sense or process nutrients, causes problems primarily, insulin resistance. Cells become less accurate at detecting glucose or fat resulting in them not being properly metabolized. This is why agerelated diabetes is fairly common.

Integrative hallmarks

1.Stem Cell Exhaustion [2]

Stem cells have the ability to evolve into any type of cell. They act as an internal repair and renewal system for tissues and are important for immune function, blood production, and other functions. With age, there is a decline in stem cells numbers, their ability to regenerate and their quality. Consequently, tissues and organs lose their ability to recover from damage and begin to fail.

2. Altered Intercellular Communication [2]

Our cells are in constant communication with each other, transmitting billions of signals This intercellular communication is necessary in order to coordinate immune responses to a threat, control metabolic activities and all the other myriad processes that keep our bodies functioning properly.

As cells age, and inflammatory responses increase, communication pathways break down leading to weakened immune systems and changes in endocrine, neuroendocrine, or neuronal pathways

In Conclusion

Aging is a series of interconnected processes: there is a cause-and-effect relationship between many of the hallmarks. To reverse ageing, it is critical to understand what ties together all of the processes that cause our bodies to unravel

[4]. Biological ageing is also clearly impacted by our lifestyles. Living a healthy lifestyle with adequate exercise, a balanced diet, reduced stress levels, emotional stability and good social support will delay ageing.

References

[1] López-Otín C, Blasco MA, Partridge L, Serrano M, Kroemer G. The Hallmarks of Aging. Cell. 2013 Jun;153(6):1194–217.

[2] What are the Hallmarks of Aging? - American Federation for Aging Research [Internet]. American Federation for Aging Research. 2021 [cited 2022 Jun 23]. Available from: https://www.afar.org/hallmarksofaging

[3] Hu C. Biology of aging: 9 things that happen in the body as we get older [Internet]. Business Insider. Insider;

2018 [cited 2022 Jun 23]. Available from: https://www.businessinsider.com/biology-of-aging-whybodies-get-old-2018-8#telomeres-may-shorten-3

[4] Young S. Council Post: Will You Live To 200? Five Levels Of Breakthroughs In Longevity Research You Must Know About. Forbes [Internet]. 2021 Dec 10 [cited 2022 Jun 23]; Available from: https://www.forbes.com/sites/forbestechcouncil/2021/05/03 /will-you-live-to-200-five-levels-of-breakthroughs-inlongevity-research-you-must-knowabout/?sh=2147c648263d

How do white blood cells fight diseases?

In order to fight diseases, white blood cells have to fight a variety of things. For instance, when you nick your skin, bacteria can get in, or you could be rubbing your eyes and not realizing that the doorknob you touched could be infected with a cold virus or that you ate something that wasn't cooked or cleaned properly [1] However, your immune system releases white blood cells and other chemicals that can eliminate this threat. The white blood cells in your body fight it off by sneezing. You make more white blood cells constantly, despite their short lives, which can vary from a few days to a few weeks [1]. There are several types, and all are geared towards fighting infection. What are the ways white blood cells kill germs? In our body, white blood cells will latch onto the germs, absorbing them or destroying them. They produce antibodies that keep the germs at bay.

A strong immune system comes from experience. When your body first comes into contact with a certain type of germ, your immune response may be slow. To get rid of your infection, you may need several days of making and using all the germ-fighting parts necessary. Hacking germ codes and destroying them takes time.

A type of white blood cell is referred to as a monocyte, it resides in your blood and tissues and is responsible for finding and killing germs (viruses, bacteria, fungi and protozoa) and eliminating those cells that are infected with them [2] Furthermore, monocytes can treat injuries and prevent infections. They are your cells' firefighters. Their lifecycle begins in the bone marrow (soft tissue inside of the bones), where they grow and train to protect your body [1]. Upon maturation, they enter your bloodstream and tissues to protect you from germs.

Basophils are one of the numerous kinds of white blood cells you have. Those blood cells make up much less than 1% of all of your circulating white blood cells [3]. Basophils are a part of your immune system and are created inside of your bone marrow. Basophils have been first diagnosed in 1879 with the aid of researcher Paul Ehrlich [3]. Due to the fact basophils aren’t as plentiful as other blood cells in people, scientists at the time idea that they didn’t have an awful lot of importance. but, around 100 years later, it became referred to that there are a few different functions of basophils. Basophils have a quick existence span, normally simply one or two days. because of this, research on basophils is frequently limited.

To conclude, white blood cells are a totally essential component as they are able to battle off diseases around your body, whilst you contact something with the aid of no longer understanding, it'd have many germs but white blood cells kill them off.

References

[1]Rachel Reiff Ellis. How Your Immune System Fights Infection [Internet]. WebMD. WebMD; 2015 [cited 2022 Jun 18]. Available from: https://www.webmd.com/coldand-flu/immune-system-fightinfection#091e9c5e812c5621-1-3

[2]White blood cells [Internet]. Healthdirect.gov.au. Healthdirect Australia; 2020 [cited 2022 Jun 18]. Available from: https://www.healthdirect.gov.au/white-blood-cells

[3] WebMD Editorial Contributors. What Are Basophils? [Internet]. WebMD. WebMD; 2021 [cited 2022 Jun 18]. Available from: https://www.webmd.com/a-to-zguides/what-are-basophils