In part one of this series, we looked at basic genetics concepts such as DNA, inheritance, and cells and cell division, and in part two we examined more difficult ideas, such as dominance and recessivity, sex-linked traits, genetic pathways, development and environmental effects. From here on, I'm going to assume you're comfortable with all of this, so please review if necessary.
So far, we've just considered situations where everything goes to plan, focussing mostly on theoretical concepts. But real life is messy, so let's conclude this series by switching our attention to some practical applications of genetics, by taking a brief look at chromosome variations, genetic mutation, cancer, selective breeding and disease genetics.
This is the second article in a three-part series on genetics. In part one, we began with some basic concepts: looking at cells, the structure and replication of DNA, genes and what they do, and how cell division and genetic inheritance work. This article will delve a little deeper into some slightly more challenging concepts.
Let's go back to the genes. We have two copies of each gene, one from each parent. But what if these copies are different from one another? How does this change things? In fact, this is often the case. Most genes come in several different forms, called alleles. If genes were cars, then alleles could be Honda, Tesla or Lamborghini. Although affecting the same trait or traits, different alleles have differing DNA sequences, resulting in variations in the proteins they produce. Each of our 20,000 genes is located in a specific position (called a locus) on one of our chromosomes. All the alleles for a given gene can thus be found in the same position on the same chromosome as one another, but there can only be one of the possible alleles on any particular chromosome.
Why do some traits appear in grandparents and grandchildren, skipping the intervening generation? Are there really genes for intelligence, running, mental arithmetic? More broadly, are we in any sense controlled by our genes? How far has our understanding of genetics advanced in recent years, and where is the field heading? What about ethical issues raised by new genetic technologies?
A conceptual understanding of genetics is mandatory for anyone wishing to truly understand questions like these. And, if we don't want to be misled by grandiose or unfounded claims that are regularly made about genetics, we need a solid grasp of how genetics works. This is today more vital than ever, given the ever-accelerating pace of research.
This is the first of a three-part series that collectively aims to cover all the major concepts required for a solid understanding of modern genetics. This article will give you a tour of the basics, with no prior knowledge required. In part two I'll expand on this foundation by covering more complex concepts, and part three will conclude the series by discussing some human-specific areas of genetics in greater detail.
After reading this series, you should have a much more sophisticated understanding of genetics, and you'll be able to utilize this as I plan to write more specialized articles on diseases and other genetics-related stories in the news, several of which will be critiques of a few of the many dubious claims propagated by the media.
Let's start the discussion with three somewhat familiar concepts: cells, genes and DNA.
This article is aimed at poker novices and casual players: maybe you've watched a few episodes of televised poker and you want to know why the players did what they did, or maybe you play in an occasional home game and wonder why you rarely win. Absorb the ideas in this tutorial and you'll improve markedly. For those of you who do play in a home game, I'll let you in on a little secret: even if the stakes you play for are modest, it's much more fun if you understand what you're doing, and why you're doing it. Not only will you win more often, but appreciating the strategy of poker makes playing the game much more engaging (even when you're simply watching those hands you're not involved in).
The form of poker I'm going to focus on is No Limit Texas Hold'Em (NLHE), which has long since eclipsed the other forms of the game in popularity. Note: I'm not going to go over the rules of NLHE here; if you need to, you can read the Wikipedia article and then come back.
Film Review: Carlito's Way
This is a magnificent (and somewhat underrated) film, directed by Brian De Palma. More nuanced than Scarface and The Untouchables, it's also better acted. All the main cast are fantastic: Pacino, seemingly relishing his role, is much better here than he was in his previous film Scent of a Woman; Penelope Ann Miller as disenchanted old flame Gail; Luis Guzman and John Leguizamo as colourful gangsters; and not least Sean Penn, who does a stunning job as the utterly unscrupulous, sleazy, flash underworld lawyer Kleinfeld. Set in the '70s, the period is believably depicted via clothing, vehicles and hairstyles. Pacino's character is Carlito Brigante, a gang member in Spanish Harlem who was sent down for life five years previously for murder and drug running.
In the opening sequence, we see Brigante executing a rambling monologue to a resolutely unimpressed judge, about how he's a changed, and vindicated, man. Warming to his theme, he gives an increasingly overblown speech about his childhood, life chances, and how he's now “rehabilitated, reinvigorated and re-assimilated”. He thanks the chief investigator for supplying tainted evidence, the appeals court for reversing the judge's sentence, and the Almighty for allowing all this to come to pass. Brigante's smirking lawyer, Kleinfeld, has got him freed on a technicality, and along with the judge and everyone else in the courtroom, believes that Carlito's diatribe is merely so much bluster.
It is a Sunday evening in early December 2014 in the northern English city of York. In front of a rapt audience and several million TV viewers, two men are playing the deciding frame of the final of the annual UK Snooker Championship (the second of three snooker 'majors'). The winner will receive £150,000 in addition to the title of UK Champion.
It has already been an incredible match. The favourite is snooker's number one draw, 39-year-old Ronnie The Rocket O'Sullivan, a prodigious and mercurial talent who, amazingly, first won the UK Championship aged 17 way back in 1993. O'Sullivan, from Essex, got his nickname due to his rapid and flamboyant playing style, which offered a stark contrast to the more deliberate approach employed by most of his contemporaries. Considered by many to be the most talented player in history, he holds endless snooker records and has career earnings approaching 8 figures.