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In a study published Thursday in the journal Science, they report that they've pinpointed the bit of finch DNA behind the swift transition: a gene called HMGA2. In finches, HMGA2 seems to be the primary factor in beak size - like a really good group project leader, it orchestrates the expression of a number of other genes, each of which tweaks the size of the bird's beak. The same gene also appears in dogs, horses, even humans, holding sway over body size and stature.

The short film opens with two questions: "So what determines how many species live in a given place? Or how many individuals of the species can live somewhere?" The research that provided answers to these questions was set in motion by key experiments by ecologists Robert Paine and James Estes. Robert Paine's starfish exclusion experiments on the coast of Washington state showed that removing starfish from this marine ecosystem has a big impact on the population sizes of other species, establishing the starfish as a keystone species. James Estes and colleague John Palmisano discovered that the kelp forest ecosystems of the North Pacific are regulated by the presence or absence of sea otters, which feed on sea urchins that consume kelp. These direct and indirect effects of sea otters on other species describe a trophic cascade. These early studies were the inspiration for hundreds of investigations on other keystone species and trophic cascades, as well as ongoing studies into the regulation of population sizes and species numbers.

In their study of the medium ground finches, evolutionary biologists Peter and Rosemary Grant were able to track the evolution of beak size twice in an amazingly short period of time due to two major droughts that occurred in the 1970s and 1980s. This activity simulates the food availability during these droughts and demonstrates how rapidly natural selection can act when the environment changes. Students use two different types of tools to represent different beak types to see which is best adapted to collect and "eat" seeds of different sizes. Students collect and analyze data and draw conclusions about traits that offer a selective advantage under different environmental conditions. They have the option of using an Excel spreadsheet to calculate different descriptive statistics and interpret graphs.

Reference page cellular facts: cell size, lenth, division, concentration, energy, diffusion, genomic information, and mutation rates.

You will learn about "Dalton's Atomic Theory" in this video. John Dalton was an English chemist who is very well known today for his work in the development of atomic theory. Let us learn the postulates of Dalton's atomic theory. All matter, whether an element, a compound or a mixture are made up of very tiny particles called atoms. All atoms of a given element are identical in size, mass and chemical properties. Atoms of different elements differ in size, mass and chemical properties. Atoms are indivisible particles which can neither be created nor destroyed in a chemical reaction. Atoms combine together in fixed whole number ratios to form compounds. In a chemical reaction, atoms only get rearranged. An atom of an element does not change into the atom of another element.

video with relative sizes of objects arranged on a single scale.

The researchers isolated different subpopulations of human brain stem cells and precisely identified, which genes are active in which cell type. In doing so, they noticed the gene ARHGAP11B: it is only found in humans and in our closest relatives, the Neanderthals and Denisova-Humans, but not in chimpanzees. This gene manages to trigger brain stem cells to form a bigger pool of stem cells. In that way, during brain development more neurons can arise and the cerebrum can expand. The cerebrum is responsible for cognitive functions like speaking and thinking.

Sure, we know insufficient serotonin levels get a bad rap when it comes to depression, but that's like blaming one person in a full-scale riot. Depression isn't caused by only one factor. In fact, study co-author Elyse Aurbach says we're probably not getting to the core of why people are depressed because "the brain is immensely complex." In this study, the research team conducted eight experiments (four on animal brains, four on brains of the deceased human kind) of varying sample sizes - from 20 to 90 brains in each - and found that the brains of deceased humans who'd been depressed had increased levels of hippocampal FGF9 and that live animals with increased FGF9 levels demonstrated depressive, anxious behavior. "This is not just a correlation," study leader Huda Akil of the University of Michigan says. Less really may be more, at least when it comes to FGF9.

Stress isn't always a bad thing; it can be handy for a burst of extra energy and focus, like when you're playing a competitive sport or have to speak in public. But when it's continuous, it actually begins to change your brain. Madhumita Murgia shows how chronic stress can affect brain size, its structure, and how it functions, right down to the level of your genes.

At the annual meeting of the American Association for Cancer Research in Washington DC this week, Wolchok and other researchers will report on their search for immunotherapy markers - ways to predict a patient's response to an immunotherapy or to show whether a given treatment is working. The work is hampered by the complexity of the immune system, but early results are converging on one point: that patients' own immune responses to cancer are crucial in determining outcomes.

Staging describes the severity of a person's cancer based on the size and/or extent (reach) of the original (primary) tumor and whether or not cancer has spread in the body.

Article summarizing cell division with time lapse cell division video of 30hours pro vs eukaryotic division.

Questions about the nature of viruses remain quite vexing. Recent studies of the giant Mimivirus illustrate this point. Its large size and correspondingly large genome test our general ideas of viruses as small, simple entities. The existence of genes associated with translation, metabolism, DNA repair, and protein folding raises questions about the evolutionary history of viruses. Further studies of this virus, and the search for other giant viruses, may shed light on these issues.

For at least 10,000 years, humans have been cultivating plants and selectively breeding them for fast growth, pest resistance, long-term survival in storage, and bigger and better fruit. We've been domesticating animals for just as long, selecting for traits that suited our needs, such as size, appearance, or even personality. For a few decades, we've also had genetic engineering methods for getting the characteristics we want in plants, animals, and microorganisms.

In the animal kingdom, humans are known for our big brains. But not all brains are created equal, and now we have new clues as to why that is. Researchers have uncovered eight genetic variations that help determine the size of key brain regions. These variants may represent "the genetic essence of humanity," says Stephan Sanders, a geneticist and pediatrician at the University of California, San Francisco, who was not involved in the study. These results are among the first to come out of the ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) collaboration, involving some 300 scientists from 33 countries. They contributed MRI scans of more than 30,000 people, along with genetic and other information, most of which had been collected for other reasons. "This paper represents a herculean effort," Sanders says.

Problem-based learning (PBL) is an exciting way to learn biology and is readily incorporated into large classes in a lecture hall environment. PBL engages students in solving authentic biological case problems, stimulating discussion among students and reinforcing learning. A problem-based learning environment emulates the workplace and develops self-directed learners. This is preferable to a mimetic learning environment in which students only watch, memorize, and repeat what they have been told. The examples given here are suitable for use in a first year college biology lecture theater, but the method is applicable to any class size and educational level. [A more detailed explanation of PBL in Biology may be found in Chapter Four of INSPIRING STUDENTS, published in 1999 by Kogan Page.]

High on Bolivia's semiarid Andean plains at more than 12,000 feet and subject to climatic whims, the shallow saline lake has dried up before only to rebound to a size twice the area of Los Angeles. But recovery may no longer be possible, scientists say. "This is a picture of the future of climate change," said Dirk Hoffman, a German glaciologist who studies how rising temperatures from the burning of fossil fuels has accelerated glacial melting in Bolivia.

The Y chromosome is only one-third the size of the X. Although the Y has a partner in X, only the tips of these chromosomes are able to recombine. Thus, most of the Y chromosome is inherited from father to son in a pattern resembling asexual, not sexual, reproduction. No recombination means no reassortment, so deleterious mutations have no opportunity to be independently selected against. The Y chromosome therefore tends to accumulate changes and deletions faster than the X. Degradation doesn't occur in X chromosomes because during female meiosis, the X has the other X as a full partner in recombination.

In the end, Darwin came up with an entirely new theory to explain the extraordinary lengths many animals will go to in order to woo a potential mate. He called it sexual selection. Simply put, sexual selection is the evolutionary process that favors adaptations that increase an animal's chances of mating. Darwin identified two kinds. In the first, males compete fiercely with each other for access to females. This kind favors the evolution of secondary sexual characters, such as large size and armaments like horns, that enhance a male's ability to fight. In the second, males compete to win over a female.

A new treatment for pancreatic cancer could significantly increase survival rates, Ulster University has claimed. It said the treatment could lead to a five-fold reduction in tumour size. It involves injecting tumours with oxygen micro bubbles that are coated with a drug which is then activated by ultrasound.