Study Notes
Chromosomes are made of DNA, which contains genetic information in the form of genes. A gene is a length of DNA that codes for a protein, and an allele is an alternative form of a gene. The sequence of bases in a gene determines the sequence of amino acids used to make a specific protein.
- Chromosome — a thread-like structure of DNA carrying genetic information in the form of genes Example: Humans have 23 pairs of chromosomes.
- Gene — a small section of DNA that codes for one specific protein Example: A gene might code for a structural protein like collagen.
- Allele — an alternative form of a gene Example: Alleles determine variations in traits, such as eye color.
- Diploid — containing two sets of chromosomes Example: Human diploid cells have 46 chromosomes.
- Haploid — containing a single set of chromosomes Example: Human gametes (sperm and egg cells) are haploid with 23 chromosomes.
- Protein Synthesis — the process by which proteins are made from amino acids based on the sequence of bases in DNA Example: Ribosomes read mRNA to assemble amino acids into proteins.
Exam Tips
Key Definitions to Remember
- Chromosome: a thread-like structure of DNA
- Gene: a section of DNA that codes for a protein
- Allele: an alternative form of a gene
- Diploid: a cell with two sets of chromosomes
- Haploid: a cell with one set of chromosomes
Common Confusions
- Confusing the sequence of amino acids with the sequence of bases in DNA and RNA
- Mixing up the terms diploid and haploid
Typical Exam Questions
- What is the role of a gene? A gene codes for a specific protein.
- How is sex determined in humans? Sex is determined by the X and Y chromosomes.
- What is the difference between a diploid and a haploid cell? A diploid cell has two sets of chromosomes, while a haploid cell has one.
What Examiners Usually Test
- Understanding of how genes code for proteins
- The process of protein synthesis
- The difference between diploid and haploid cells