DNA
What Is DNA?
DNA (Deoxyribonucleic Acid) is the genetic material that carries the instructions to build and operate all living organisms.
💡 Key Concept: DNA is found in the nucleus of cells and is organised into chromosomes.
Structure of DNA
Feature | Description |
Double helix🧬 | DNA has two strands twisted into a spiral. |
Base pairs | Four bases: A (adenine), T (thymine), C (cytosine), G (guanine). A always pairs with T, C always pairs with G. |
Nucleotide | The building block of DNA: one sugar, one phosphate, one base. |
💡 Complementary base pairing:
- A – T
- C – G
Where Is DNA Found?
- DNA is stored in the nucleus of animal and plant cells.
- It is wrapped into structures called chromosomes.
- Humans have 46 chromosomes (23 pairs).
What Is a Gene?
A gene is a small section of DNA that codes for a specific protein.
✔ Different genes = different proteins = different functions in the body.
💡 One gene codes for one protein, which is made using amino acids in a specific order.
Why Is DNA Important?
✔ Carries the genetic code for all traits and characteristics.
✔ Involved in protein synthesis.
✔ Passed from parents to offspring during reproduction.
✔ Differences in DNA explain variation between individuals.
Human Genome Project
✔ Scientists have mapped the entire human genome.
✔ This helps in:
- Understanding inherited diseases.
- Developing targeted medicine.
- Tracing human ancestry and evolution.
Questions
- What does DNA stand for?
- Where in a cell is DNA found?
- What is the shape of the DNA molecule?
- What are the base pair rules?
- What does a gene do?
Summary
- DNA is a double helix made of base pairs: A-T and C-G.
- It carries the genetic code for building proteins.
- DNA is stored in chromosomes in the nucleus.
- Each gene codes for one protein, and understanding DNA helps us treat disease and study evolution.