Learn: DNA, Genes and Alleles

Welcome!Today we'll explore DNA, genes, and alleles. You'll learn what they are, how they work, and why they're essential for life. Let's get started!

What is DNA?DNA (deoxyribonucleic acid) is the molecule that carries genetic information in living organisms. It’s made of two strands twisted into a double helix, and is a polymer built from smaller units called nucleotides. DNA is found in the nucleus of eukaryotic cells and contains the instructions for making proteins that determine an organism's characteristics.

What are Genes?Genes are sections of DNA that contain instructions to make specific proteins. These proteins determine traits like eye colour or height. Genes are located on chromosomes, which are long strands of DNA found in the nucleus of eukaryotic cells.

What are Alleles?An allele is a variant form of a gene. For example, a gene for eye colour might have alleles for blue or brown eyes. Alleles are responsible for differences in traits among individuals. Each person inherits one allele of each gene from each parent.

Genotype and PhenotypeGenotype refers to the genetic makeup of an organism—the combination of alleles it has. Phenotype is the physical expression of the genotype, influenced by both genetics and the environment. For example, a genotype for tallness might result in a tall phenotype, but only if the organism has access to proper nutrition.

MutationsMutations are changes in DNA that create genetic variants. These can affect phenotype by altering how proteins are made. Some mutations occur in coding DNA directly related to proteins, while others occur in non-coding DNA that regulates gene activity. Mutations can be beneficial, harmful, or neutral.

Protein SynthesisProtein synthesis is the process where genetic information in DNA is used to make proteins. This involves two main steps: transcription, where DNA is copied into mRNA; and translation, where ribosomes use mRNA to assemble amino acids into proteins. Proteins are essential for functions like growth and repair.

Review Time!Great work! You've learned about DNA, genes, alleles, genotype, phenotype, mutations, and protein synthesis. Now let’s test your knowledge with some review questions.