Friday, June 19, 2009
Acanthamoeba keratitis
Acanthamoeba keratitis: Infection of the cornea by acanthamoeba, a microscopic water-borne ameba. The disease tends to occur in people who wear contact lens. It can accompany a bacterial infection of the eye. Acanthamoeba keratitis can produce corneal ulceration and result in severe loss of vision and even blindness. Signs and symptoms are persistent redness and pain in the eye. Treatment is with multiple antibiotics, often including antifungal drugs, and sometimes surgery after the infection has subsided.
Abused inhalant
Abused inhalant: A breathable chemical vapor that is abused. All abused inhalants produce psychoactive (mind-altering) effects. Abused inhalants fall into the following categories:
Solvents
Industrial or household solvents or solvent-containing products, including paint thinners or removers, degreasers, dry-cleaning fluids, gasoline, and glue
Art or office supply solvents, including correction fluids, felt-tip-marker fluid, and electronic contact cleaners
Gases
Gases used in household or commercial products, including butane lighters and propane tanks, whipping cream aerosols or dispensers (whippets), and refrigerant gases
Household aerosol propellants and associated solvents in items such as spray paints, hair or deodorant sprays, and fabric protector sprays
Medical anesthetic gases, such as ether, chloroform, halothane, and nitrous oxide ("laughing gas")
Nitrites
Aliphatic nitrites, including cyclohexyl nitrite, an ingredient found in room odorizers; amyl nitrite, which is used for medical purposes; and butyl nitrite (previously used to manufacture perfumes and antifreeze), which is now an illegal substance.
Nearly all abused inhalants produce short-term effects similar to anesthetics, which act to slow down the body's functions. When inhaled via the nose or mouth into the lungs in sufficient concentrations, inhalants can cause intoxicating effects. Intoxication usually lasts only a few minutes. However, sometimes users extend this effect for several hours by breathing in inhalants repeatedly. Initially, users may feel slightly stimulated. Successive inhalations make them feel less inhibited and less in control. If use continues, users can lose consciousness.
Sniffing highly concentrated amounts of the chemicals in solvents or aerosol sprays can directly induce heart failure and death within minutes. This syndrome, known as "sudden sniffing death," can result from a single session of inhalant use by an otherwise healthy young person. Sudden sniffing death is particularly associated with the abuse of butane, propane, and chemicals in aerosols.
High concentrations of inhalants also can cause death from suffocation by displacing oxygen in the lungs and then in the central nervous system so that breathing ceases. Deliberately inhaling from an attached paper or plastic bag or in a closed area greatly increases the chances of suffocation. Even when using aerosols or volatile products for their legitimate purposes (such as painting, cleaning), it is wise to do so in a well-ventilated room or outdoors.
Chronic abuse of solvents can cause severe, long-term damage to the brain, the liver, and the kidneys. Other harmful irreversible effects may be caused by abuse of specific solvents.
Solvents
Industrial or household solvents or solvent-containing products, including paint thinners or removers, degreasers, dry-cleaning fluids, gasoline, and glue
Art or office supply solvents, including correction fluids, felt-tip-marker fluid, and electronic contact cleaners
Gases
Gases used in household or commercial products, including butane lighters and propane tanks, whipping cream aerosols or dispensers (whippets), and refrigerant gases
Household aerosol propellants and associated solvents in items such as spray paints, hair or deodorant sprays, and fabric protector sprays
Medical anesthetic gases, such as ether, chloroform, halothane, and nitrous oxide ("laughing gas")
Nitrites
Aliphatic nitrites, including cyclohexyl nitrite, an ingredient found in room odorizers; amyl nitrite, which is used for medical purposes; and butyl nitrite (previously used to manufacture perfumes and antifreeze), which is now an illegal substance.
Nearly all abused inhalants produce short-term effects similar to anesthetics, which act to slow down the body's functions. When inhaled via the nose or mouth into the lungs in sufficient concentrations, inhalants can cause intoxicating effects. Intoxication usually lasts only a few minutes. However, sometimes users extend this effect for several hours by breathing in inhalants repeatedly. Initially, users may feel slightly stimulated. Successive inhalations make them feel less inhibited and less in control. If use continues, users can lose consciousness.
Sniffing highly concentrated amounts of the chemicals in solvents or aerosol sprays can directly induce heart failure and death within minutes. This syndrome, known as "sudden sniffing death," can result from a single session of inhalant use by an otherwise healthy young person. Sudden sniffing death is particularly associated with the abuse of butane, propane, and chemicals in aerosols.
High concentrations of inhalants also can cause death from suffocation by displacing oxygen in the lungs and then in the central nervous system so that breathing ceases. Deliberately inhaling from an attached paper or plastic bag or in a closed area greatly increases the chances of suffocation. Even when using aerosols or volatile products for their legitimate purposes (such as painting, cleaning), it is wise to do so in a well-ventilated room or outdoors.
Chronic abuse of solvents can cause severe, long-term damage to the brain, the liver, and the kidneys. Other harmful irreversible effects may be caused by abuse of specific solvents.
Thursday, June 18, 2009
Abductor muscle
Abductor muscle: Any muscle used to pull a body part away from the midline of the body. For example, the abductor muscles of the legs spread the legs away from the midline and away from one another.
The word "abductor" comes from the Latin prefix "ab-" meaning "away from" + "ducere" meaning "to draw or lead" = "to draw away from."
The prefix "ab-" is opposed to the prefix "ad-". Therefore, the opposite of "abductor" is "adductor." An abductor muscle opposes an adductor muscle.
The word "abductor" comes from the Latin prefix "ab-" meaning "away from" + "ducere" meaning "to draw or lead" = "to draw away from."
The prefix "ab-" is opposed to the prefix "ad-". Therefore, the opposite of "abductor" is "adductor." An abductor muscle opposes an adductor muscle.
Abduction
Abduction: In medicine, the movement of a limb away from the midline of the body. Abduction of both legs spreads the legs. The opposite of abduction is adduction. Adduction of the legs brings them together.
From the Latin "ab-" meaning "away from" + "ducere" meaning "to draw or lead" = "to draw away from."
From the Latin "ab-" meaning "away from" + "ducere" meaning "to draw or lead" = "to draw away from."
Abducent nerve
Abducent nerve: A small motor nerve that has one task: to supply a muscle called the lateral rectus muscle that moves the eye outward.
Paralysis of the abducent nerve causes inward turning of the eye (internal strabismus) leading to double vision.
The abducent nerve is the sixth cranial nerve. All 12 cranial nerves, the abducent nerve included, emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
The word "abducent" comes from the Latin "ab-", away from + "ducere", to draw = to draw away. The abducent (or abducens) operates the lateral rectus muscle that draws the eye toward the side of the head. The abducent nerve is also called the abducens nerve.
Paralysis of the abducent nerve causes inward turning of the eye (internal strabismus) leading to double vision.
The abducent nerve is the sixth cranial nerve. All 12 cranial nerves, the abducent nerve included, emerge from or enter the skull (the cranium), as opposed to the spinal nerves which emerge from the vertebral column.
The word "abducent" comes from the Latin "ab-", away from + "ducere", to draw = to draw away. The abducent (or abducens) operates the lateral rectus muscle that draws the eye toward the side of the head. The abducent nerve is also called the abducens nerve.
Abdominal pain
Definition of Abdominal pain
Abdominal pain: Pain in the belly (the abdomen). Abdominal pain can come from conditions affecting a variety of organs. The abdomen is an anatomical area that is bounded by the lower margin of the ribs above, the pelvic bone (pubic ramus) below, and the flanks on each side. Although abdominal pain can arise from the tissues of the abdominal wall that surround the abdominal cavity (the skin and abdominal wall muscles), the term abdominal pain generally is used to describe pain originating from organs within the abdominal cavity (from beneath the skin and muscles). These organs include the stomach, small intestine, colon, liver, gallbladder, and pancreas.
Occasionally, pain may be felt in the abdomen even though it is arising from organs that are close to but not within the abdominal cavity, for example, the lower lungs, the kidneys, and the uterus or ovaries. This latter type of pain is called "referred" pain because the pain, though originating outside the abdomen, is being referred to (felt) in the abdominal area.
Abdominal pain can be acute and sudden in onset, or the pain can be chronic and longstanding. Abdominal pain may be minor and of no great significance, or it can reflect a major problem involving one of the organs in the abdomen. The characteristics of the pain--location, timing, duration, etc. are important in diagnosing its cause. Persistent or severe abdominal pain should be evaluated by a physician.
Acute abdominal pain may require urgent surgery such as for a twisted ovarian cyst, ectopic pregnancy, intestinal obstruction, appendicitis, peritonitis, perforated peptic ulcer, perforated diverticulitis, or abdominal aortic aneurysm. Patients with gallbladder disease, pancreatitis, or a kidney stone may also need urgent treatment. Acute or chronic abdominal pain may also call for medical (nonsurgical) therapy.
The causes of abdominal pain depend on sex and age of the patient. A woman may have a twisted ovarian cyst while a man may have testicular torsion with a twisted testis. Abdominal pain in infants and small children may be due to intestinal obstruction from atresia or stenosis of the intestine, esophageal webs, intussusception, volvulus, imperforate anus, and Hirschsprung disease. These causes of abdominal pain are rarely, if ever, encountered in adults
Abdominal pain: Pain in the belly (the abdomen). Abdominal pain can come from conditions affecting a variety of organs. The abdomen is an anatomical area that is bounded by the lower margin of the ribs above, the pelvic bone (pubic ramus) below, and the flanks on each side. Although abdominal pain can arise from the tissues of the abdominal wall that surround the abdominal cavity (the skin and abdominal wall muscles), the term abdominal pain generally is used to describe pain originating from organs within the abdominal cavity (from beneath the skin and muscles). These organs include the stomach, small intestine, colon, liver, gallbladder, and pancreas.
Occasionally, pain may be felt in the abdomen even though it is arising from organs that are close to but not within the abdominal cavity, for example, the lower lungs, the kidneys, and the uterus or ovaries. This latter type of pain is called "referred" pain because the pain, though originating outside the abdomen, is being referred to (felt) in the abdominal area.
Abdominal pain can be acute and sudden in onset, or the pain can be chronic and longstanding. Abdominal pain may be minor and of no great significance, or it can reflect a major problem involving one of the organs in the abdomen. The characteristics of the pain--location, timing, duration, etc. are important in diagnosing its cause. Persistent or severe abdominal pain should be evaluated by a physician.
Acute abdominal pain may require urgent surgery such as for a twisted ovarian cyst, ectopic pregnancy, intestinal obstruction, appendicitis, peritonitis, perforated peptic ulcer, perforated diverticulitis, or abdominal aortic aneurysm. Patients with gallbladder disease, pancreatitis, or a kidney stone may also need urgent treatment. Acute or chronic abdominal pain may also call for medical (nonsurgical) therapy.
The causes of abdominal pain depend on sex and age of the patient. A woman may have a twisted ovarian cyst while a man may have testicular torsion with a twisted testis. Abdominal pain in infants and small children may be due to intestinal obstruction from atresia or stenosis of the intestine, esophageal webs, intussusception, volvulus, imperforate anus, and Hirschsprung disease. These causes of abdominal pain are rarely, if ever, encountered in adults
Abdominal muscles
Abdominal muscles: A large group of muscles in the front of the abdomen that assists in the regular breathing movement and supports the muscles of the spine while lifting and keeping abdominal organs such as the intestines in place. Abdominal muscles play a key role in exercises such as "sit-ups." They are informally called the "abs".
Abdominal hysterectomy
Abdominal hysterectomy: Surgical removal of the uterus (a hysterectomy) done through an incision made in the abdominal wall. As opposed to a vaginal hysterectomy in which the incision is made within the vagina.
Abdominal guarding
Abdominal guarding: Tensing of the abdominal wall muscles to guard inflamed organs within the abdomen from the pain of pressure upon them. The tensing is detected when the abdomen wall is pressed.
Guarding is a characteristic finding in the physical examination for an abruptly painful abdomen (an acute abdomen) with inflammation of the inner abdominal (peritoneal) surface due, for example, to appendicitis or diverticulitis. The tensed muscles of the abdominal wall automatically go into spasm to keep the tender underlying tissues from being touched.
Guarding is a characteristic finding in the physical examination for an abruptly painful abdomen (an acute abdomen) with inflammation of the inner abdominal (peritoneal) surface due, for example, to appendicitis or diverticulitis. The tensed muscles of the abdominal wall automatically go into spasm to keep the tender underlying tissues from being touched.
Abdominal cavity
Abdominal cavity: The cavity within the abdomen, the space between the abdominal wall and the spine.
The abdominal cavity is hardly an empty space. It contains a number of crucial organs including the lower part of the esophagus, the stomach, small intestine, colon, rectum, liver, gallbladder, pancreas, spleen, kidneys, and bladder.
The abdominal cavity is hardly an empty space. It contains a number of crucial organs including the lower part of the esophagus, the stomach, small intestine, colon, rectum, liver, gallbladder, pancreas, spleen, kidneys, and bladder.
Abdominal aortic aneurysm
Abdominal aortic aneurysm: A ballooning or widening of the main artery (the aorta) as it courses down through the abdomen. At the point of the aneurysm, the aneurysm usually measures 3 cm or more in diameter. The aneurysm weakens the wall of the aorta and can end in the aorta rupturing with catastrophic consequences. As the diameter of the aorta increases, the chances of an abdominal aortic aneurysm rupturing rise. A measurement of 5 cm is often used to recommend surgery. Persons with AAA tend to be 60 or over. Men are 5 times more likely than women to have an AAA.
Abdominal aorta
Abdominal aorta: The abdominal aorta is the final section of the aorta, the largest artery in the body. It is a continuation of the thoracic aorta. It begins at the diaphragm, and runs down to the point where it ends (by splitting in two to form the common iliac arteries).
The abdominal aorta supplies oxygenated blood to all of the abdominal and pelvic organs and the legs.
Like the other sections of the aorta (the ascending aorta, aortic arch and thoracic aorta), the abdominal aorta is an arbitrary anatomic entity. The aorta is one continuous conduit that arises out of the left ventricle of the heart to carry blood to the body. Nonetheless, the abdominal aorta is a hallowed and convenient subdivision of the aorta.
The abdominal aorta is also known in medical Latin as the aorta abdominalis or the pars abdominalis aortae (under which it is often hidden in standard print medical dictionaries).
The abdominal aorta supplies oxygenated blood to all of the abdominal and pelvic organs and the legs.
Like the other sections of the aorta (the ascending aorta, aortic arch and thoracic aorta), the abdominal aorta is an arbitrary anatomic entity. The aorta is one continuous conduit that arises out of the left ventricle of the heart to carry blood to the body. Nonetheless, the abdominal aorta is a hallowed and convenient subdivision of the aorta.
The abdominal aorta is also known in medical Latin as the aorta abdominalis or the pars abdominalis aortae (under which it is often hidden in standard print medical dictionaries).
Abdominal aneurysm
Abdominal aneurysm: An aneurysm situated within the abdomen (belly). An aneurysm is a localized widening (dilatation) of an artery, vein, or the heart. At the area of an aneurysm, there is typically a bulge and the wall is weakened and may rupture. The word "aneurysm" comes from the Greek "aneurysma" meaning "a widening." An aneurysm may involve the aorta, the largest artery in the body, as it courses down through the abdomen. Because of the great volume of blood flowing under high pressure in the aorta, rupture of an abdominal aortic aneurysm is a surefire catastrophe.
Abdominal
Abdominal: Relating to the abdomen, the belly, that part of the body that contains all of the structures between the chest and the pelvis. The abdomen is separated anatomically from the chest by the diaphragm, the powerful muscle spanning the body cavity below the lungs.
The abdomen includes a host of organs including the stomach, small intestine, colon, rectum, liver, spleen, pancreas, kidneys, appendix, gallbladder, and bladder.
The word "abdomen" has a curious story behind it. It comes from the Latin "abdodere", to hide. The idea was that whatever was eaten was hidden in the abdomen
The abdomen includes a host of organs including the stomach, small intestine, colon, rectum, liver, spleen, pancreas, kidneys, appendix, gallbladder, and bladder.
The word "abdomen" has a curious story behind it. It comes from the Latin "abdodere", to hide. The idea was that whatever was eaten was hidden in the abdomen
acute
Abdomen, acute:The abrupt (acute) onset of abdominal pain. A potential medical emergency, an acute abdomen may reflect a major problem with one of the organs in the abdomen such as the appendix (being inflamed = appendicitis), the gallbladder (inflamed = cholecystitis), the intestine (an ulcer that has perforated), the spleen (that has ruptured), etc. The term "acute abdomen" is medical shorthand. It has nonetheless come into common usage in medical parlance.
Abdomen
Abdomen: The belly, that part of the body that contains all of the structures between the chest and the pelvis. The abdomen is separated anatomically from the chest by the diaphragm, the powerful muscle spanning the body cavity below the lungs.
The abdomen includes a host of organs including the stomach, small intestine, colon, rectum, liver, spleen, pancreas, kidneys, appendix, gallbladder, and bladder.
The word "abdomen" has a curious story behind it. It comes from the Latin "abdodere", to hide. The idea was that whatever was eaten was hidden in the abdomen.
The abdomen includes a host of organs including the stomach, small intestine, colon, rectum, liver, spleen, pancreas, kidneys, appendix, gallbladder, and bladder.
The word "abdomen" has a curious story behind it. It comes from the Latin "abdodere", to hide. The idea was that whatever was eaten was hidden in the abdomen.
Abbreviations
Abbreviations, prescription: A prescription, as is well known, is a physician's order for the preparation and administration of a drug or device for a patient. What may be less well known is that a prescription has several parts:
The superscription (or heading) with the symbol R or Rx which stands for the word Recipe, meaning (in Latin) to take;
The inscription which contains the names and quantities of the ingredients;
The subscription or directions for compounding the drug; and
The signature which is often preceded by the sign s. standing for signa, mark, giving the directions to be marked on the container.
You may see some chicken scrawl marks on a prescription. For example, b.i.d. It means twice (two times) a day and is an abbreviation for "bis in die" which in Latin means, not too surprisingly, twice a day. It is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken.
Some of the abbreviations of terms commonly used in prescriptions with their meanings are:
a.c. = before meals (from "ante cibum," before meals)
ad lib: use as much as one desires (from "ad libitum")
b.i.d. = twice a day
caps = capsules
da or daw = dispense as written
g (or gm or GM) = gram
gtt. = drops (from "guttae," drops)
h. = hour
mg = milligram
ml = milliliter
p.c. = after meals (from "post cibum," after meals)
p.o. = by mouth, orally (from "per os," by mouth)
p.r.n. = when necessary (from "pro re nata," for an occasion that has arisen, as circumstances require, as needed)
q.d. = once a day (from "quaque die," once a day)
q.i.d. = four times a day (from "quater in die," 4 times a day)
q._h.: If a medicine is to be taken every so-many hours (from "quaque," every and the "h" indicating the number of hours)
q.h. = every hour
q.2h. = every 2 hours
q.3h. = every 3 hours
q.4h. = every 4 hours
t.i.d. = three times a day (from "ter in die," 3 times a day)
ut dict. = as directed (from "ut dictum," as directed)
The word "prescription" also comes from the Latin "praescriptus" and is made up of "prae," before + "scribere," to write, so that prescription meant "to write before." This reflected the historic fact that a prescription had traditionally to be written before a drug could be prepared and then administered to a patient.
The superscription (or heading) with the symbol R or Rx which stands for the word Recipe, meaning (in Latin) to take;
The inscription which contains the names and quantities of the ingredients;
The subscription or directions for compounding the drug; and
The signature which is often preceded by the sign s. standing for signa, mark, giving the directions to be marked on the container.
You may see some chicken scrawl marks on a prescription. For example, b.i.d. It means twice (two times) a day and is an abbreviation for "bis in die" which in Latin means, not too surprisingly, twice a day. It is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken.
Some of the abbreviations of terms commonly used in prescriptions with their meanings are:
a.c. = before meals (from "ante cibum," before meals)
ad lib: use as much as one desires (from "ad libitum")
b.i.d. = twice a day
caps = capsules
da or daw = dispense as written
g (or gm or GM) = gram
gtt. = drops (from "guttae," drops)
h. = hour
mg = milligram
ml = milliliter
p.c. = after meals (from "post cibum," after meals)
p.o. = by mouth, orally (from "per os," by mouth)
p.r.n. = when necessary (from "pro re nata," for an occasion that has arisen, as circumstances require, as needed)
q.d. = once a day (from "quaque die," once a day)
q.i.d. = four times a day (from "quater in die," 4 times a day)
q._h.: If a medicine is to be taken every so-many hours (from "quaque," every and the "h" indicating the number of hours)
q.h. = every hour
q.2h. = every 2 hours
q.3h. = every 3 hours
q.4h. = every 4 hours
t.i.d. = three times a day (from "ter in die," 3 times a day)
ut dict. = as directed (from "ut dictum," as directed)
The word "prescription" also comes from the Latin "praescriptus" and is made up of "prae," before + "scribere," to write, so that prescription meant "to write before." This reflected the historic fact that a prescription had traditionally to be written before a drug could be prepared and then administered to a patient.
Abate
Abate: To lessen or decrease. After a boil is lanced, the pus can drain and the pain and tenderness abate. From the French abbatre, to beat down.
Abatement
Abatement: A diminution, decrease or easing. In medicine there may be abatement of pain or any other symptom or sign. In the environment there may abatement in the degree of pollution. See also: Abate.
Smith syndrome
syndrome of congenital malformations (birth defects) characterized by hydrocephalus, cleft palate, and severe arthrogryposis (joint contractures). Other anomalies may include deformed ears, ptosis (drooping) of the eyelids, inability to open the mouth fully, heart defects, and clubfoot. The fingers are thin with absent knuckles, reduced creases over the joints and inability to make a full fist.
The syndrome is inherited as an autosomal dominant trait, transmitted from generation to generation, affecting both males and females. It is named for the American dysmorphologists (birth-defect experts) Jon Aase and David W. Smith.
The syndrome is inherited as an autosomal dominant trait, transmitted from generation to generation, affecting both males and females. It is named for the American dysmorphologists (birth-defect experts) Jon Aase and David W. Smith.
Scott syndrome
Aarskog-Scott syndrome: A syndrome of wide spaced eyes (ocular hypertelorism), front-facing (anteverted) nostrils, a broad upper lip, a malformed ("saddle-bag") scrotum, and laxity of the ligaments resulting in bending back of the knees (genu recurvatum), flat feet, and overly extensible fingers. There are X-linked and autosomal forms of the disease. The gene for the X-linked form has been mapped to chromosome band Xp11.21 and identified as the FGD1 gene.
The disease is named for DJ Aarskog (1928-) and CI Scott, Jr. (1934-), Norwegian and American pediatricians, who described it in 1970 and 1971. It is also known as Aarskog syndrome, faciodigitogenital dysplasia, and faciogenital dysplasia
The disease is named for DJ Aarskog (1928-) and CI Scott, Jr. (1934-), Norwegian and American pediatricians, who described it in 1970 and 1971. It is also known as Aarskog syndrome, faciodigitogenital dysplasia, and faciogenital dysplasia
Aarskog syndrome
Aarskog-Scott syndrome: A syndrome of wide spaced eyes (ocular hypertelorism), front-facing (anteverted) nostrils, a broad upper lip, a malformed ("saddle-bag") scrotum, and laxity of the ligaments resulting in bending back of the knees (genu recurvatum), flat feet, and overly extensible fingers. There are X-linked and autosomal forms of the disease. The gene for the X-linked form has been mapped to chromosome band Xp11.21 and identified as the FGD1 gene.
The disease is named for DJ Aarskog (1928-) and CI Scott, Jr. (1934-), Norwegian and American pediatricians, who described it in 1970 and 1971. It is also known as Aarskog syndrome, faciodigitogenital dysplasia, and faciogenital dysplasia.
The disease is named for DJ Aarskog (1928-) and CI Scott, Jr. (1934-), Norwegian and American pediatricians, who described it in 1970 and 1971. It is also known as Aarskog syndrome, faciodigitogenital dysplasia, and faciogenital dysplasia.
adenine
A (adenine): In genetics, A stands for adenine, one member of the A-T (adenine-thymine) base pair in DNA. The other base pair in DNA is G-C (guanine-cytosine).
Each base pair forms a "rung of the DNA ladder." A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the "letters" that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In DNA base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.
Adenine is also one of the bases in RNA. There it always pairs with uracil (U). The base pairs in RNA are therefore A-U and G-C.
Each base pair forms a "rung of the DNA ladder." A DNA nucleotide is made of a molecule of sugar, a molecule of phosphoric acid, and a molecule called a base. The bases are the "letters" that spell out the genetic code. In DNA, the code letters are A, T, G, and C, which stand for the chemicals adenine, thymine, guanine, and cytosine, respectively. In DNA base pairing, adenine always pairs with thymine, and guanine always pairs with cytosine.
Adenine is also one of the bases in RNA. There it always pairs with uracil (U). The base pairs in RNA are therefore A-U and G-C.
Subscribe to:
Posts (Atom)