What is Biology?

Biology is the study of life.

What properties of life help us distinguish living things, or organisms, from nonliving things. In general, organisms:

There are several properties of life that help us distinguish living things, or organisms, from nonliving things. In general, organisms: - reproduce, grow, and develop, obtain and use matter and energy for life’s functions - respond to their environment - maintain a stable internal environment - are based on a universal genetic code - undergo evolution at the population level -are made up of basic units called cells.

What are cells?

Cells are small, living, membrane-enclosed structures that form the basis of life on Earth. All organisms are made up of one or more cells.

What can organisms be classified as based on cells?

- Multicellular organisms are made up of many cells. The cells in multicellular organisms are often specialized to carry out specific functions. - Unicellular organisms are made up of one cell. Most unicellular organisms live their entire lives as a single cell. However, some types of unicellular organisms (such as Volvox algae) cluster together to form a colonial organism in which certain cells take on specialized functions.

What is the smallest unit of life?

The cell is the smallest unit of organization that can perform all the activities required for life. For example, cells use and copy genetic material, communicate with other cells in their environments, and are the sites of life’s chemical reactions.

What do cells contain?

Cells contain a variety of molecules and subcellular structures (organelles) which allow them to carry out these processes.

What do new cells come from?

All new cells are produced from existing cells. Cell reproduction occurs through the process of cell division. ​​During cell division, one cell grows in size, copies its parts, and then splits into two independent cells that have the same genetic material.

What is cell theory?

Cell theory summarizes the cellular basis of life, it explains what scientists have observed over time to be true for all cells.

What main concepts does cell theory include?

Cell theory includes three main concepts: - All living organisms are made up of one or more cells. - Cells are the smallest unit of structure and function for an organism. - All cells come from other cells.

What is cell biology?

Cell biology is the study of cells.

What does cell biology focus on?

Cell biology is an area of study that focuses on: - the structure - function - behavior of cells Cell biology allows scientists to connect the processes happening at the cellular level to the impacts these processes have on the organism as a whole. Cell biology research has led to important breakthroughs in areas such as cancer treatment and vaccine development.

What can cells be viewed with?

To see and study cells, scientists use microscopes. These powerful tools magnify objects, allowing them to be seen up close. Microscopes can also capture images, called micrographs.

What are cells typically measured in?

Cells are tiny! - Cell diameters are typically measured in micrometers (µm) - cell’s internal structures are often measured in nanometers (nm). Objects of this size are too small to be seen with the unaided eye. For reference, 1micrometer (µm) is roughly 1/70 the width of a human hair, and 1 nanometer (nm) is 1,000 x smaller than that!

What are some types of microscopes used to view and study cells?

- Light microscopes - Fluorescence microscopes - Electron microscopes

Light Microscope

A light microscope shines light through a specimen (such as a cell), and then through a series of lenses. These lenses refract (bend) the light in such a way that the image of the specimen is made larger.

What is a light microscope magnification?

Light microscopes can magnify objects up to about 1,000 times their actual size! Specimens are often stained with chemical dyes to make cell parts visible.

What are light microscopes mostly used for specifically?

Light microscopes can be used to visualize living cells. Scientists use light microscopes to study cell structures and to observe cell movements and interactions. For example, light microscopes can be used to observe cell division, the behavior of microorganisms, or changes in cancer cells.

What is a fluorescence microscope?

A fluorescence microscope is a type of light microscope that creates brightly-colored images. The colors come from fluorescent (light-producing) dyes that are used to label different molecules in the specimen.

What do scientists use fluorescence microscopes for?

Scientists use fluorescence microscopes to observe the role of specific cell components in cellular processes, and to locate specific proteins in the cell.

What is an electron microscope?

An electron microscope focuses beams of electrons on specimens instead of visible light. Electron microscopes can visualize details at a much smaller scale compared to light microscopes. For example, electron microscopes can capture detailed images of the structures inside of cells.

What is the limitation of electron microscopes?

Because of the way specimens have to be prepared for viewing, electron microscopy can only be used to see nonliving cells.

What types of electron microscopes are there?

There are two types of electron microscopes: - scanning electron microscopes (SEMs) - transmission electron microscopes (TEMs).

What are SEMs used for?

SEMs are used to show 3D images of a specimen’s surface. SEMs allow scientists to observe the overall shape and surface features of cells. For example, with an SEM, scientists can see outer cell structures such as the flagella of bacteria.

What are TEMs used for?

TEMs are used to visualize a thin cross section (slice) of a specimen. TEMs allow scientists to see detailed images of organelles and other structures inside of cells. For example, with a TEM, scientists can see: - the inner membranes of mitochondria - details of the nucleus - parts of the cytoskeleton