mutation
Reading Passage 1
Mutations in The Body
A mutation is a change in the DNA of a living thing. DNA is inside every cell and gives instructions to the body. These instructions are made up of a code using four different bases. The sequence, or order, of the bases tells the body how to build proteins. Proteins help the body work and grow.
Sometimes, this sequence can change. That change is called a mutation. A mutation can happen when something like sunlight or chemicals affects the DNA. One base might get changed, or a base might be added or taken out. This makes the instructions different.
Not every mutation causes a problem. Some changes don’t affect the organism at all. But some mutations can change how something looks or works. For example, a mutation might change the color of an animal’s fur or make a plant grow faster.
When a mutation happens in just one cell, it usually stays there. But if it gets passed on to a new organism, the mutation will be in every cell of that organism. This means the new sequence is part of the body from the start.
Over time, helpful mutations can become common in a group of organisms. If a mutation helps an organism survive and have babies, that trait can spread. But harmful mutations may go away if the organism doesn’t survive.
Scientists study mutations to learn how living things grow, change, and pass traits to the next generation.
Reading Passage 2
Mutations in The Body
A mutation is a change in the DNA of an organism. DNA is found inside a cell and contains instructions for how the body functions. These instructions are written in a code made up of four chemical units called bases. The specific sequence of these bases determines how proteins are made, and proteins control many parts of how an organism looks and behaves.
Sometimes, the order of bases in a sequence can be changed. This change is called a mutation. Mutations can happen in many ways. For example, radiation from the Sun or certain chemicals can cause the DNA inside a cell to change. In one case, a single base might be swapped for another. In other cases, one or more bases might be added or deleted from the sequence. The result is a new set of instructions.
Not all mutations matter. Some happen in parts of the DNA that do not affect the organism. Others may cause small or big changes. For example, a mutation might cause a plant to have slightly different-colored flowers, or it could make an animal better able to survive in its environment.
A mutation usually begins in just one cell. That change might stay in that single cell and have little effect. But if the mutation is passed to the next generation, something different happens. The offspring will not just have the mutation in one cell—it will be in all the cells of that new organism. This means the changed sequence becomes a permanent part of that individual's DNA.
This process is one way that traits can spread through a population over time. A mutation that helps an organism survive or reproduce may become more common, especially if it is passed on to many offspring. On the other hand, harmful mutations may disappear if the organism does not survive or reproduce.
Scientists study mutations to understand how organisms change and evolve. They also look at how certain mutations may lead to diseases or other conditions. Understanding the way DNA works, and how mutations affect it, helps researchers develop medicines and treatments.
In short, a mutation begins with a small change in a sequence of bases in a cell. But if that change happens in the right kind of cell and leads to a new trait, it can be carried forward into future generations.
Reading Passage 3
Mutations in The Body
A mutation refers to a change in the DNA of an organism. Located in every cell, DNA contains coded instructions that direct the functions and development of life. These instructions are made up of four different bases arranged in a specific sequence, which determines how proteins are formed—essential components that influence an organism’s structure and behavior.
Mutations occur when the usual sequence of these bases is altered. External factors like radiation or chemicals can damage DNA, causing a base to be replaced, removed, or added. This disrupts the original instructions and may result in different traits.
The effects of mutations vary widely. Some have no observable impact, while others lead to significant changes. A mutation might slightly change a flower's petal color or lead to advantages in survival, such as resistance to disease. These changes can affect an organism's traits in visible or hidden ways.
When a mutation arises in a single cell, it may have little effect unless it occurs in a reproductive cell. If passed to an offspring, the mutation will appear in every cell of that new individual, permanently embedding the new sequence in its genetic material.
This process contributes to how traits spread within populations. A mutation that improves survival or reproduction is more likely to be passed on, while detrimental changes may be naturally filtered out. Over generations, this contributes to genetic diversity and evolutionary change.
By examining mutations, scientists gain insight into genetic processes, disease mechanisms, and the ways species adapt over time.