DNA and The Genome
Laura Armstrong
Teacher
Contents
Recall Questions
This topic requires prior knowledge of cell structure and DNA.
What is DNA made of?
DNA is a polymer made of two strands forming a double helix
Where is DNA found in a eukaryotic cell?
In the nucleus, inside structures called chromosomes
How many chromosomes are found in a human body cell?
46
Topic Explainer Video
Check out this @lauradoesbiology video that explains DNA and the genome, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!
DNA And The Genome
DNA: The Molecule of Life
- DNA stands for Deoxyribonucleic Acid.
- It is the genetic material found in the nucleus of animal and plant cells.
- DNA is a polymer made up of two strands twisted into a double helix shape.
- The two strands are made up of sugar and phosphate.
- There are bases in the middle (you do not need to know the names of the bases!).
Chromosomes
- DNA is packaged into structures called chromosomes.
- Humans have 46 chromosomes (23 pairs) in their body cells.
- They have 23 chromosomes in their gametes (as these cells are made by meiosis).
Genes and Proteins
- A gene is a small section of DNA found on a chromosome.
- Each gene codes for a sequence of amino acids, which are the building blocks of a specific protein.
- These proteins determine how our bodies develop and function.
The Genome
- The genome is the entire genetic material of an organism.
- The human genome project has identified all the genes in human DNA.
Why is understanding the human genome important?
1. Disease Detection
- Identifies genes linked to inherited diseases (e.g., cancer, cystic fibrosis).
2. Medical Advances
- Leads to better diagnosis, treatment, and personalised medicine.
3. Human Migration
- Helps scientists trace the migration patterns of ancient humans across the globe.
Key Terms
- DNA – Genetic material in the nucleus; polymer of two strands in a double helix.
- Gene – A section of DNA that codes for a protein.
- Chromosome – A thread-like structure made of DNA found in the nucleus.
- Genome – The complete set of genetic material in an organism.
- Protein – A molecule made of amino acids that performs specific functions in the body.
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Exam Tips
When describing DNA, always include:
- It is a polymer
- Made of two strands
- Shaped as a double helix
Make sure you learn the definition of a gene as provided in this study note.
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Practice Question
What is the genome, and give three reasons why understanding the human genome is important?
(4 marks)
Model Answer:
- The genome is the entire genetic material of an organism.
- Understanding the genome helps identify genes linked to inherited diseases.
- It also helps develop new treatments and personalised medicine.
- It can be used to trace human migration patterns from the past.
More Practice
Try to answer these practice questions from the TikTok videos on your own, then watch the videos to see how well you did!