Skip navigation
National Institutes of HealthNational Library of Medicine
MedlinePlus Trusted Health Information for You
Search MedlinePlus
Search MedlinePlus
GO
About MedlinePlus What's New Site Map Customer Support
Health TopicsDrugs & SupplementsGeneticsMedical TestsVideos & Tools
Español
You Are Here:Home → Genetics → Help Me Understand Genetics → Cells and DNA → What is DNA?
What is DNA?
Email this page to a friend Facebook Twitter Pinterest Download PDF
DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria are structures within cells that convert the energy from food into a form that cells can use.
The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.
DNA is a double helix formed by base pairs attached to a sugar-phosphate backbone.
DNA is made up of base pairs and a sugar phosphate backbone.
Credit: U.S. National Library of Medicine
For more information about DNA:
The National Human Genome Research Institute (NHGRI), a part of the National Institutes of Health (NIH), provides a fact sheet Deoxyribonucleic Acid (DNA) that gives an introduction to this molecule.From the National Institutes of Health
StatedClearly offers a video introduction to DNA and how it works.
The New Genetics, a publication of the National Institute of General Medical Sciences, part of the NIH, discusses the structure of DNA and how it was discovered.From the National Institutes of Health
4. CLASS RULES
1. OPEN your cameras
2. MUTE your microphones
3. UTILIZED chat box
4. UNMUTE microphone if
teacher calls you
5. UPPER RESPIRATORY TRACT
INFECTION
•Most common infections of
the respiratory system which
affect sinuses, nasal passages,
pharynx and larynx.
•Bacteria and viruses are the
typical causes of such infection
6. UPPER RESPIRATORY TRACT
INFECTION
• Nasal cavity inflammation – rhinitis
• Common cold – acute
nasopharyngitis
• Inflammation of the pharynx –
pharyngitis
• Inflammation of the Larynx –
Laryngitis
7. SYMPTOMS:
• Sneezing
• Runny nose
• Cough with or without phlegm
• Sore throat
• Fever
• Headache
• Chills
• Feeling of weakness or lethargy
8. TREATMENT :
• Rest
• Stay hydrated
• Intake over-the-counter medications like
• Antipyretic – can lower fever
• Analgesic – relieve headache and other pain
• Decongestant – clear nasal cavity of mucus
• Antitussive – relieve cough
• Some serious URTI may require antibiotic and even
hospitalization
9. WAYS TO PREVENT URTI
•Wash your hands properly before
touching your nose, mouth or eyes
•Close your mouth and nose when
sneezing or coughing
•Boost your immune system by eating
fruits rich in vitamin C such as citrus
fruits and green leafy vegetable
10. INFLUENZA OR FLU
• Is a virus –induced illness that has similar
symptoms to common cold but in a more
severe degree
• It is usually most prevalent during cold and
rainy months
• Consult your doctor for proper diagnosis
• Antibiotics should never be taken
• Flu vaccine is widely available for more robust
protection against the disease
11. CORONAVIRUS DISEASE 2019
• WHO declared as COVID 19 as a global
epidemic or pandemic
• first clusters of infection were reported in
Wuhan City in China last December 2019.
• A flue like disease
• Novel corona virus said to be originated
from bats
12. SERIOUS COVID-19 SYMPTOMS
• Shortness of breath/ difficulty in breathing
• Loss of speech or mobility or confusion
• Chest pain
Seek medical attention as soon as
possible !!
14. LESS COMMON SYMPTOMS
• Sore throat
• Headache
• Aches and pains
• Diarrhea
• A rash on the skin or discoloration of
fingers or toes
• Red or irritated eyes
15. Asthma:
- Condition in which breathing is
impaired by constriction of bronchi and
bronchioles, cough, and thick mucus
secretions. The severity and incidence
of asthma has risen dramatically in
recent years, especially in children. May
be fatal if not treated.
16. Causes: Attacks may be precipitated
by inhalation of allergens (e.g.:
pollen, cats, and cockroach proteins),
pollutants, infection, or emotional
stress.
Treatment: Alleviates symptoms
(e.g.: immuno-suppressors,
bronchodilators), but is not a cure.
17. • Tuberculosis – is an infectious disease caused
by mycobacterium tuberculosis
18. • Bronchitis: Inflammation of the mucous
membranes of the bronchi. May present
with cough, fever, chest or back pain, and
fatigue.
Causes: Associated with smoking, pollution,
and bacterial or viral infections.
• Pneumonia: Acute inflammation of the
lungs. Symptoms include high fever, chills,
headache, cough, and chest pain.
Causes: Bacterial, fungal, or viral infections.
Treatment: Antibiotics or other
antimicrobials.
19. • Lung Cancer: Cancerous growth that invades
and destroys lung tissue. Very high fatality
rate.
Symptoms include bloody sputum, persistent
cough, difficulty breathing, chest pain, and
repeated attacks of bronchitis or pneumonia.
Causes: Smoking (50% of all cases) and
pollution (radon, asbestos). Smokers are 10
times more likely to develop lung cancer than
nonsmokers.
Treatment: Surgery is most effective, but only
50% of all lung cancers are operable by time
of detection. Other treatments include
radiation and chemotherapy.
20.
21. CARDIOVASCULAR DISORDERS
• Cardiovascular disease (CVD) is the leading
cause of death in Western countries.
• Modern research efforts have improved
diagnosis, treatment, and prevention.
• Major cardiovascular disorders include
atherosclerosis, stroke, heart attack,
aneurysm, and hypertension.
22. HEMOPHILIA
• Hemophilia is an inherited clotting
disorder due to a deficiency in a clotting
factor that produces abnormal bleeding.
• Bumps and falls cause bleeding in the
joints; cartilage degeneration and
resorption of bone can follow.
• The most frequent cause of death is
bleeding into the brain with
accompanying neurological damage.
23. ATHEROSCLEROSIS
• Atherosclerosis is due to a build-up of
fatty material (plaque), mainly
cholesterol, under the inner lining of
arteries.
• The plaque can cause a thrombus (blood
clot) to form.
•The thrombus can dislodge and lead to
the bursting of a blood vessel.
24. STROKE, HEART ATTACK, AND
ANEURYSM
• Stroke results when an embolus lodges in
a cerebral blood vessel or a cerebral
blood vessel bursts; a portion of the brain
dies due to lack of oxygen.
• Heart attack occurs when a portion of
heart muscle dies due to lack of oxygen.
25. • Aneurysm is a ballooning of a blood
vessel, usually in the abdominal aorta or
arteries leading to the brain.
• Death results if the aneurysm is in a large
vessel and the vessel bursts.
• Atherosclerosis and hypertension weaken
blood vessels over time, increasing the risk
of aneurysm.
26. CORONARY BYPASS OPERATIONS
• A coronary bypass operation involves
removing a segment of another blood
vessel and replacing a clogged
coronary artery.
• It may be possible to replace this
surgery with gene therapy that
stimulates new blood vessels to grow
where the heart needs more blood flow.
28. CLEARING CLOGGED ARTERIES
• Angioplasty uses a long tube threaded
through an arm or leg vessel to the point
where the coronary artery is blocked;
inflating the tube forces the vessel open.
Stents are put in place to keep it open.
• Stents are small metal pieces that are
expanded inside the artery to keep it open.
• Stents are coated with heparin to prevent
blood clotting and with chemicals to prevent
arterial closing.
