Looking inside a cell
If you magnify food even more, you can see the parts inside cells. Earlier, we looked at DNA inside a bacterial cell. Although DNA is unimaginably tiny, it is important. DNA is a molecule that controls what a cell becomes.
This is the nucleus of a cell in animal liver, magnified thousands of times. The blue areas inside the nucleus are chromosomes.
DNA and genes
Every cell in plants and animals also has DNA inside its nucleus. Long strings of DNA are packaged into microscopic units called chromosomes. The DNA in chromosomes forms sets of instructions, called genes, for the cell to follow. Because of genes, tomato cells form a tomato, and chicken cells turn into a chicken. Because of genes, the tomatoes might be bright red or pale orange.
Glossary
- antibiotic—medicine used to fight infections and illnesses caused by bacteria
- bacteria—microorganisms with only one cell that are the smallest and most numerous life-forms on Earth
- cell—tiny unit that all livings things are made of contaminated—infected with harmful organisms or chemicals
- cyst—dormant (inactive) stage of a parasite that becomes active when it finds its way into a living host
- fermentation—process during which microbes feed on sugars and release products such as alcohol
- fungi—organisms similar to plants but with no ability to make food, so they live on other organisms (living or dead).
- hyphae—threads that most fungi use to grow and spread through their food source
- larva—stage of an insect after it has hatched from an egg but is not yet an adult. Larvae is the plural of larva.
- microanimal—tiny bug or other animal too small to be seen clearly without a microscope
- microbe—microorganism that is not a microanimal. Microbes also include viruses even though they are not really organisms.
- microfungi—fungi that are microscopic or are made up mostly of microscopic parts
- micrometer—measurement of length that is one-thousandth of a millimeter
- microorganism—any living thing that is too small to be seen clearly without a microscope
- mites—tiny creatures related to spiders, many of which live on animals, plants, or food
- molecule—microscopic part that makes up all living and nonliving things. All cells are made of molecules.
- nanometer—measurement of length that is one-millionth of a millimeter
- nucleus—part of a cell that controls the cell’s form and functions
- organism—any living thing, such as a plant, animal, or bacterium
- parasite—organism that lives on or in another living thing and feeds off it
- protist—usually single-celled microorganism that lives in water or damp places. Protists can be plant-like (algae) or animal-like (protozoa).
- species—group of living things of the same kind. For example, bears are a kind of animal, but grizzly bears are a species.
- spore—reproductive part of a fungus
- starch—form of carbohydrate found in plants
- virus—microbe that can only multiply by infecting living cells
