background preloader


Facebook Twitter

Why do our cell’s power plants have their own DNA? It’s one of the big mysteries of cell biology.

Why do our cell’s power plants have their own DNA?

Why do mitochondria—the oval-shaped structures that power our cells—have their own DNA, and why have they kept it when the cell itself has plenty of its own genetic material? A new study may have found an answer. Scientists think that mitochondria were once independent single-celled organisms until, more than a billion years ago, they were swallowed by larger cells. Instead of being digested, they settled down and developed a mutually beneficial relationship developed with their hosts that eventually enabled the rise of more complex life, like today’s plants and animals. Over the years, the mitochondrial genome has shrunk. Scientists have tossed around some ideas, but there haven't been hard data to pick one over another. “Keeping those genes locally in the mitochondria gives the cell a way to individually control mitochondria,” Johnston says, because pivotal proteins are created in the mitochondria themselves. Mitosis and Meiosis. Animations. How cells divide.

How do we smell? - Rose Eveleth. All you ever wanted to know about Germs. What would happen to your body without water? Muscular System: Facts, Functions & Diseases. While most people associate muscles with strength, they do more than assist in lifting heavy objects.

Muscular System: Facts, Functions & Diseases

The 650 muscles in the body not only support movement — controlling walking, talking, sitting, standing, eating and other daily functions that people consciously perform — but also help to maintain posture and circulate blood and other substances throughout the body, among other functions. Muscles are often associated with activities of the legs, arms and other appendages, but muscles also produce more subtle movements, such as facial expressions, eye movements and respiration, according to the National Institutes of Health (NIH).

Three types of muscles The muscular system can be broken down into three types of muscles: skeletal, smooth and cardiac, according to the NIH. Skeletal muscles are the only voluntary muscle tissue in the human body and control every action that a person consciously performs. Muscle shapes Size can be used to differentiate similar muscles in the same region. Nervous System: Facts, Function & Diseases. The nervous system is a complex collection of nerves and specialized cells known as neurons that transmit signals between different parts of the body.

Nervous System: Facts, Function & Diseases

Vertebrates — animals with backbones and spinal columns — have central and peripheral nervous systems. The central nervous system is made up of the brain, spinal cord and retina. The Human Body: Anatomy, Facts & Functions. Human body systems.Credit: Image via Shutterstock The human body is everything that makes up, well, you.

The Human Body: Anatomy, Facts & Functions

The basic parts of the human body are the head, neck, torso, arms and legs. Body systems Our bodies consist of a number of biological systems that carry out specific functions necessary for everyday living. Skin: Facts, Diseases & Conditions. While it may not immediately come to mind when asked to name the body’s major organs, the integumentary system, or skin, is its largest organ.

Skin: Facts, Diseases & Conditions

It comprises the skin as well as hair and nails, which are appendages of the skin. In humans, this system accounts for about 15 percent of total body weight. Urinary System: Facts, Functions & Diseases. The urinary system – also known as the renal system – produces, stores and eliminates urine, the fluid waste excreted by the kidneys.

Urinary System: Facts, Functions & Diseases

The urinary system includes two kidneys, two ureters, the bladder, two sphincter muscles and the urethra. Description of the urinary system The urinary system works with the lungs, skin and intestines to maintain the balance of chemicals and water in the body. Adults eliminate about a quart and a half (1.42 liters) of urine each day, depending on the amount of fluid consumed and fluid lost through perspiring and breathing. Certain types of medications, such as diuretics that are sometimes used to treat high blood pressure, can also affect the amount of urine a person produces and eliminates. Respiratory System: Facts, Function and Diseases.

The human respiratory system is a series of organs responsible for taking in oxygen and expelling carbon dioxide.

Respiratory System: Facts, Function and Diseases

The primary organs of the respiratory system are lungs, which carry out this exchange of gases as we breathe. Red blood cells collect the oxygen from the lungs and carry it to the parts of the body where it is needed, according to the American Lung Association. During the process, the red blood cells collect the carbon dioxide and transport it back to the lungs, where it leaves the body when we exhale. The human body needs oxygen to sustain itself. A decrease in oxygen is known as hypoxia and a complete lack of oxygen is known as anoxia and, according to MedLine Plus. Skeletal System: Facts, Function & Diseases. The adult human skeletal system consists of 206 bones, as well as a network of tendons, ligaments and cartilage that connects them.

Skeletal System: Facts, Function & Diseases

The skeletal system performs vital functions — support, movement, protection, blood cell production, calcium storage and endocrine regulation — that enable us to move through our daily lives. Animals with internal skeletons made of bone, called vertebrates, are actually the minority, as 98 percent of all animals are invertebrates, meaning they do not have internal skeletons or backbones. Human infants are born with 300 to 350 bones, some of which fuse together as the body develops. Reproductive System: Facts, Functions and Diseases. The reproductive system is a collection of organs that work together for the purpose of producing a new life.

Reproductive System: Facts, Functions and Diseases

Scientists argue that the reproductive system is among the most important systems in the entire body. Without the ability to reproduce, a species dies. Lymphatic System: Facts, Functions & Diseases. Immune System: Diseases, Disorders & Function. Endocrine System: Facts, Functions and Diseases. Digestive System: Facts, Function & Diseases. The human digestive system is a series of organs that converts food into essential nutrients that are absorbed into the body and moves the unused waste material out of the body.

Digestive System: Facts, Function & Diseases

It is essential to good health because if the digestive system shuts down, the body cannot be nourished or rid itself of waste. Description of the digestive system The digestive tract, also known as the gastrointestinal (GI) tract, starts at the mouth, continues to the esophagus, stomach, small intestine, large intestine (commonly referred to as the colon) and rectum, and ends at the anus. The entire system — from mouth to anus — is about 30 feet (9 meters) long. CellCraft. Six myths about vaccination – and why they’re wrong.

A pear has 600 times more formaldehyde in it than a vaccine does, writes Rachael Dunlop. Image: Oksana Kuzmina/Shutterstock Recently released government figures show levels of childhood vaccination have fallen to dangerously low levels in some areas of Australia, resulting in some corners of the media claiming re-ignition of “the vaccine debate”. You can check how your postcode rates here.

Well, scientifically, there’s no debate. In combination with clean water and sanitation, vaccines are one of the most effective public health measures ever introduced, saving millions of lives every year. Those who claim there is a “debate” will cite a series of canards designed to scare people away from vaccinating, but, if you’re not familiar with their claims, you could easily be convinced by anti-vaccine rhetoric.

So what is true and what is not? Let’s address just a few of the common vaccine myths and explain why they’re wrong. 1. 2. 3. 4. 5. 6. Melting Glaciers Liberate Ancient Microbes. Editor's Note: This article is an extended version of "Bugs in the Ice Sheet" from the May 2012 Issue of Scientific American. BOZEMAN, Mont. —Locked in frozen vaults on Antarctica and Greenland, a lost world of ancient creatures awaits another chance at life. Like a time-capsule from the distant past, the polar ice sheets offer a glimpse of tiny organisms that may have been trapped there longer than modern humans have walked the planet, biding their time until conditions change and set them free again.

With that ice melting at an alarming rate, those conditions could soon be at hand. GMO - What Is It? After Life: The Science Of Decay (BBC Documentary) Interactive Tutorials and Quizzes On Human Anatomy and Physiology. Human Anatomy Model, Anatomy Chart, Anatomical Chart. Interactive 3D Human Anatomy. Home of CELLS alive!