Nikolay's Genetics Lessons on LinkedIn: Inbreeding calculations explained (2024)

Recessive EpistasisSome dihybrid crosses produce a phenotypic ratio that differs from 9:3:3:1, such as 9:3:4, 12:3:1, 9:7, or 15:1. Note that each of these modified ratios can be obtained by summing one or more of the 9:3:3:1 classes expected from our original dihybrid cross. In the following sections, we will look at some modified phenotypic ratios obtained from dihybrid crosses and what they might tell us about interactions between genes.Recessive epistasisEpistasis \(which means standing upon \) occurs when the phenotype of one locus masks, or prevents, the phenotype of another locus. Thus, following a dihybrid cross fewer than the typical four phenotypic classes will be observed with epistasis. As we have already discussed, in the absence of epistasis, there are four phenotypic classes among the progeny of a dihybrid cross. The four phenotypic classes correspond to the genotypes: A_B_, A_bb, aaB_, and aabb. If either of the singly hom*ozygous recessive genotypes \(i.e. A_bb or aaB_\) has the same phenotype as the double hom*ozygous recessive \(aabb\), then a 9:3:4 phenotypic ratio will be obtained. For example, in the Labrador Retriever breed of dogs , the B locus encodes a gene for an important step in the production of melanin. The dominant allele, B is more efficient at pigment production than the recessive b allele, thus B_ hair appears black, and bb hair appears brown. A second locus, which we will call E, controls the deposition of melanin in the hairs. At least one functional E allele is required to deposit any pigment, whether it is black or brown. Thus, all retrievers that are ee fail to deposit any melanin \(and so appear pale yellow\), regardless of the genotype at the B locus.Youtube video: https://lnkd.in/dF7eWG6Q\#nikolays_genetics_lessons

How to Memorize White Blood Cells Types and their AbundanceLeucocytes or leukocytes, colloquially known as white blood cells \(WBCs\), are clear, colorless cells that circulate in the blood and lymph and are integral part of the immune system.\[Leucocytes are divided into the types: neutrophils, eosinophils, basophils, lymphocytes and monocytes. Each of these types has further derivatives, for example Natural killer cells are derivative of lymphocytes.Youtube video: https://lnkd.in/dRSD9QAe\#nikolays_genetics_lessons

How to Memorize EverythingHello friends, since you don t know anything about me, today I would like to tell you something about me.. I graduated from high school \(USSR\) without being an excellent student - I was an average student.. When I graduated from school, I was waiting with horror for the entrance exams to the Institute... \(If I would fail I have to go to army for 2 years as everyone else\)....I submitted documents and found out that there were 18 people for each place, after other applicants found out about such competition - many took away applications and it turned out 12 people per place - it s still a very, very higher competition.. I understood that I couldn t pass.. I was in despair, I went to the library and there I found a book on how to develop memory using mnemonics.. I was reading this book.. I literally studied around the clock and did all the exercises conscientiously.. In the end, I did not pass the competition for free education \(I had only 30 days to prepare, which I mostly spent on mnemonics, what an irony!\), - the company paid for my education.. But the knowledge I gained from that book was more useful to me than anything before in my life. I became such an enthusiast of mnemonics that already in my second year in the Institute I began to teach elective courses in memory development at my Institute.. Usually I recruited students very simply - by walking into the classroom in the middle of the class and asking for 5 minutes.. After which I asked students to give me various random numbers that I wrote down on the backboard with a chalk - when there were about a hundred of them. I would put chalk on the table, turned to the audience and began to repeat the numbers written on the board - first in the order in which they were given to me and then in the reverse order - and then I said the numbers from any place chosen by the students.I didn t do anything else - half the audience immediately signed up for my course. So what am I talking about? Today I made a video where I decided to share with you one of these techniques - which can help you a lot both on exams and just in life..Watch my video: https://lnkd.in/dTuBZzQE\(On the photo me - at age 19 when I was teaching the mnemonic course\)Youtube video: https://lnkd.in/dsak9TK5\#nikolays_genetics_lessons

How to memorize cell cycles \(mnemonics\)When studying biology and delving into the intricacies of cell biology, one topic that often challenges students is understanding and memorizing the cell cycle. The cell cycle consists of a series of complex phases, and remembering their sequence can be a daunting task. However, mnemonics offer an effective and creative solution to make this process much easier.Understanding the Cell CycleBefore diving into mnemonics, it's essential to understand the basics of the cell cycle. The cell cycle consists of interphase, which is further divided into three stages \(G1, S, G2\), and mitosis \(M phase\). Interphase is where the cell prepares for division, while mitosis involves cell division itself, resulting in two identical daughter cells.Creating Mnemonics for the Cell CycleRemembering the Phases of Interphase \(G1, S, G2\):Mnemonic: "Good Students Graduate"Explanation: Use the first letter of each phase to form the mnemonic. G1 stands for "Gap 1," S stands for "Synthesis," and G2 stands for "Gap 2." So, "Good Students Graduate" helps you remember the sequence.Recalling the Stages of Mitosis \(Prophase, Metaphase, Anaphase, Telophase\):Mnemonic: "Pasta Makes A Tasty Meal"Explanation: Each word in the mnemonic corresponds to the first letter of the mitotic phase, making it easy to recall their order.Remembering Cytokinesis \(Cell Division\):Mnemonic: "Cuts, Divides, Equals Two"Explanation: Think of the actions in cytokinesis cutting or dividing the cell resulting in two daughter cells. This mnemonic reinforces the concept.Overall Cell Cycle Sequence:Mnemonic: "G1, S, G2, Pasta, Cuts"Explanation: Combining the mnemonics for interphase, mitosis, and cytokinesis into one phrase makes it easy to remember the entire cell cycle sequence.Tips for Effective Mnemonic Use:Visualize: Create mental images related to the mnemonic to enhance recall.Practice: Repeat the mnemonic several times until it becomes second nature.Teach Others: Explaining the cell cycle using your mnemonic to someone else reinforces your understanding.Use Visual Aids: Diagrams or drawings can complement your mnemonic for better comprehension.Youtube video: https://lnkd.in/d3--ExZ5\#nikolays_genetics_lessons

How Radiocarbon Dating Works?The fossilized bodies presented in glass cases by journalist and UFO scientist Jaime Maussan at Mexico's parliament are said to be 1,000 years old.The bodies of two alleged "alien" beings were exhibited before politicians in a special session of the Mexican Congress on Wednesday.The fossilized bodies, presented by journalist and self-proclaimed UFO scientist - or ufologist - Jaime Maussan and displayed in glass cases, were retrieved from Cusco in Peru and are said to be 1,000 years old."These specimens are not part of the evolution of our world. They were not recovered from a UFO scrap. They were found fossilized in a diatom moss mine," Maussan said, testifying under oath.Radiocarbon dating, also known as carbon-14 dating or carbon dating, is a widely used method for determining the age of an object containing organic material by measuring the amount of carbon-14 \(^14C\) it contains. By comparing the ratio of carbon-14 to carbon-12 \(or carbon-13\) in the sample to the known ratio in the atmosphere, scientists can calculate the age of the sample.radiocarbon dating, carbon-14 dating, carbon dating, dating methods, archaeological dating, scientific dating, carbon isotopes, radioactive decay, half-life, organic material dating, accelerator mass spectrometry, carbon-14 decay, carbon-14 to carbon-12 ratio, calibration, dating accuracy, archaeology, anthropology, geology, dating ancient artifacts, fossils dating, dating geological samples, radiocarbon analysis, carbon-14 isotopes, radiometric dating, age determination, dating techniques, ancient dating methods, scientific measurements, carbon cycle, historical dating, archaeological dating techniques, organic material age, radioactive isotopes, carbon-14 half-life, carbon-14 decay rate, carbon-14 calibration, carbon-14 dating process, dating accuracy and precision, chronology determination, carbon dating applications, dating ancient civilizations.Youtube video: https://lnkd.in/dBqwzaDn\#nikolays_genetics_lessons

Whom People Perceive As More Attractive?Mixed-ethnicity face shape and attractiveness in humansAnthony C Little 1 , Kimberley J Hockings, Coren L Apicella, Claudia SousaPMID: 23586288 DOI: 10.1068/p7278AbstractMany studies show agreement within and between populations and cultures for general judgments of facial attractiveness. Studies that have examined the attractiveness of specific traits have also highlighted cross-cultural differences for factors such as symmetry, averageness, and masculinity. One trait that should be preferred across cultures is heterozygosity. Indeed, several studies suggest that mixed ethnicity, in terms of appearing to possess a mixture of traits from different human population groups, may be found attractive, which could reflect preferences for heterozygosity. We examined preferences for manipulated face shape associated with different populations in both Europeans \(Britain\) and Africans \(Guinea-Bissau\). We found that mixed-ethnicity face shapes were more attractive than enhanced single-ethnicity face shape across both populations. These results are consistent with evolutionary theories suggesting individuals should prefer heterozygosity in partners because facial cues to mixed-ethnicity are likely to indicate diverse genes compared to cues that indicate a face belongs to a single particular culture or population.\#attractiveness \#genetics \#heterozygosity\#populationgenetics\#evolutionarypsychologyYoutube video: https://lnkd.in/daVjY-6e\#nikolays_genetics_lessons

How many times does a restriction enzyme cut a double stranded DNA?A restriction enzyme is able to cut a segment of DNA several times. The number of times the DNA is cut \(4n\) depends on the length of the recognition site \(n\).A restriction enzyme cuts how many times?According to statistics, an enzyme makes an average of one cut per 4n base pairs, where n is the length of the recognition site. As a result, a DNA molecule's likelihood of containing one or more restriction sites increases with length.Where on the double-stranded DNA are restriction enzymes active?Restriction enzymes \(RE\) are endonucleases that recognize particular DNA sequences between four and eight base pairs in length and normally break the strands at a specified and constant point within or before the recognition site.You can get a much more accurate estimate if you take into account the probability of GC and AT pairs independently. If the GC content of the organism is \(say\) 70%, and the recognition site of the enzyme is GAATTC \(EcoRI site\), then the probability of its presence will be \(.35\)\(.15\)\(.15\)\(.15\)\(.15\)\(.35\) = 6.2e-5, since the probability of G is half of the probability of GC, and the probability of A is half of the probability of AT.Instead of the naively calculated 4096 bp between sites on average, the 70% GC content version will have an expected distance of 1/6.2e-5 = 16,129 bp.Youtube video: https://lnkd.in/d2j4sKvc\#nikolays_genetics_lessons

Where Indo-European languages originated from?The Aryans or Noble Ones were thought to have remained together on the Caucasian steppes from about 4500 BCE until about 2500 BCE when groups began to migrate. Their single language, known by linguists as Proto-Indo-European, evolved into many of the Asiatic and European languages such as Sanskrit, Persian, German, Gaelic, Latin, Greek, Russian, and English. The Indo-European language family has the largest number of speakers of all language families as well as the widest dispersion around the world.Recent ancient DNA studies indicate that the Proto-Indo-European language likely traveled first with the Yamnaya steppe pastoralists when they migrated from the vast grasslands of the Eurasian steppes into Europe around 4,000\_3,000 BCE. They were one of the earliest peoples to train horses and to have wheeled carts that allowed them to manage large herds comprising sheep, goats and cattle. Bringing their Corded Ware Complex culture with them, they spoke a language linked to Proto-German, from which all of today s 400 Indo-European languages spring. They interbred with local Europeans, descendants of local hunter-gatherers and farmers who had come from Anatolia. Within a few hundred years, the Yamnaya contributed to at least half of central Europeans genetic ancestry.Youtube video: https://lnkd.in/d8pSdCM6\#nikolays_genetics_lessons

Smoking and cardiovascular diseasesCurrent smokers faced nearly three times the risk of premature death from cardiovascular disease compared with people who never smoked, with the risk being higher among those who began smoking during childhood, according to new research published today in the Journal of the American Heart Association, an open access journal of the American Heart Association.Smoking continues to cause an estimated 100,000 deaths from cardiovascular disease every year in the U.S. Currently, there are about 25 million people who smoke daily including 5 million who became regular smokers before the age of 15.Earlier research in Cuba found a correlation between childhood smoking and a higher risk for premature death overall. In this new study, investigators set out to determine if the findings were generalizable in other populations by conducting a similar analysis of U.S. data focused on death from cardiovascular disease. It was surprising to see how consistent these findings were with our earlier research and with other studies from around the world, including from the U.K., Australia and Japan, among others, both in terms of the substantial risks associated with smoking and with the health benefits of quitting smoking, said lead study author Blake Thomson, M.Phil., D.Phil., an epidemiologist at the University of Oxford in Oxford, England. The age at which a person begins smoking is an important and often overlooked factor, and those who start smoking at a young age are at especially high risk of dying prematurely from cardiovascular disease. However, quitting can substantially reduce that risk, especially for those who quit at younger ages. Getting people to quit smoking remains one of the greatest health priorities globally. Using data collected between 1997 and 2014, from the annual U.S. National Health Interview Survey, researchers examined the medical histories, lifestyle habits and demographics of smokers and nonsmokers. The study included 390,929 adults, ages 25 to 74 years \(average age of 47\), 56% female. Occasional smokers were excluded from the study. Current smokers were grouped by the age at which they began smoking.During the follow-up period, 4,479 people died before the age of 75 from heart disease or stroke. After adjusting for potential confounding variables, such as age, education, alcohol consumption, region and race, researchers found:58% were never smokers; 23% were ex-smokers; and 19% were current smokers;Among current smokers, 2% had started smoking before age 10, and 19% began smoking between ages 10 and 14; andThose who quit smoking by the age of 40 reduced their excess risk of premature death from cardiovascular disease by about 90%.Youtube video: https://lnkd.in/deUVg8dB\#nikolays_genetics_lessons

This animal is truly immortalDid you know that some of the animals are truly immortal? Here is one such animal - Backward-aging jellyfish - it is a tiny variety of jellyfish known as Turritopsis doohmii, or more commonly, the immortal jellyfish. It has found a way to cheat death by actually reversing its aging process. If the jellyfish is injured or sick, it returns to its polyp stage over a three-day period, transforming its cells into a younger state that will eventually grow into adulthood all over again.This remarkable ability has fascinated scientists and researchers for years, as it challenges our understanding of the aging process and has raised hopes for potential breakthroughs in regenerative medicine. Studying these unique creatures may hold the key to unlocking new insights into longevity and regeneration, offering hope for advancements in human health and longevity research.Youtube video: https://lnkd.in/dbKccdUA\#nikolays_genetics_lessons