DNA, Genes, Chromosomes and Patterns of Inheritance
With Sophie and Marcus, Biology & Physiology Specialist
Key Takeaways
- Because midwives are often the first professional to have conversations about family history, genetic risk, and screening options.
- Understanding the basic science allows you to explain conditions clearly and support women in making informed decisions.
- DNA is the molecule that carries genetic information, made of four bases — adenine, thymine, cytosine, guanine — arranged in a double helix.
- It is packaged into chromosomes inside the cell nucleus.
- A gene is a specific sequence of DNA that codes for a particular protein.
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Full Transcript
Sophie: Today we're exploring DNA, Genes, Chromosomes and Patterns of Inheritance. I'm Sophie, and with me is Marcus, our Biology and Physiology Specialist. Marcus, why does genetics matter in midwifery practice?
Marcus: Because midwives are often the first professional to have conversations about family history, genetic risk, and screening options. Understanding the basic science allows you to explain conditions clearly and support women in making informed decisions.
Sophie: How is DNA organised in human cells?
Marcus: DNA is the molecule that carries genetic information, made of four bases — adenine, thymine, cytosine, guanine — arranged in a double helix. It is packaged into chromosomes inside the cell nucleus. Humans have 46 chromosomes in 23 pairs.
Sophie: What is a gene?
What is dna, genes, chromosomes and patterns of inheritance and why does it matter?
Marcus: A gene is a specific sequence of DNA that codes for a particular protein. We have around 20,000 genes. Each gene has two alleles — one inherited from each parent — and the combination of alleles determines traits and genetic risk.
Sophie: What are dominant and recessive patterns of inheritance?
Marcus: In dominant inheritance, only one altered copy of a gene is needed to cause a condition — Huntington's disease follows this pattern. In recessive inheritance, two altered copies are needed. Cystic fibrosis is recessive — a carrier with one copy is unaffected.
Sophie: How does sex-linked inheritance work?
Marcus: Genes on the X chromosome are inherited differently between males and females. Haemophilia is X-linked recessive — females with one affected X are carriers, but males with one affected X will have the condition as they have no second X to compensate.
How does dna, genes, chromosomes and patterns of inheritance work in a healthcare context?
Sophie: What is a karyotype and when would a midwife encounter one?
Marcus: A karyotype is a visual representation of an individual's chromosomes, arranged by size and shape. Midwives encounter karyotype results when discussing Down's syndrome — caused by trisomy 21, three copies of chromosome 21 — following prenatal screening.
Sophie: How should midwives approach genetic conversations with families?
Marcus: With sensitivity and without judgement. Genetic risk is complex and emotionally loaded. Your role is to provide accurate information, facilitate access to specialist genetic counselling when appropriate, and support whatever decision the family makes.