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Transcript of Bacteria
Bacteria are single-celled organisms. Bacteria are prokaryotes. The genetic material in their cells is not contained in nucleus.
Remember that a prokaryote is a cell without a nucleus and a eukaryote is a cell with a nucleus.
How do the cells of bacteria differ from those of eukaryotic cells?
Bacteria also lack many other structures that are found in eukaryotes. Bacterial cells have one of three basic shapes: spherical, rodlike, or spiral.
Most bacterial cells are surrounded by a rigid cell wall that helps to protect the cell. Inside the cell wall is the cell membrane that controls what enters and leaves the cell.
Bacterial cells contain cytoplasm, ribosomes, and the genetic material is located in the cytoplasm. Some bacteria have flagella.
A flagellum is a long, whip-like structure that extends from the cell membrane and out through the cell wall. A flagellum helps a cell to move.
All bacteria need certain things to survive. Bacteria must have a source of food and a way of breaking down the food to release its energy.
Some bacteria are autotrophs and make their own food in one of two ways. Some capture and use the sun's energy as plants do.
Others, such as bacteria that live deep in mud, do not use the sun's energy. Instead, these bacteria use the energy from chemical substances in their environment to make food.
Some bacteria are heterotrophs that obtain food by consuming autotrophs or other heterotrophs. They consume a variety of foods – from milk and meat to decaying leaves.
What do bacteria need to survive?
The process of breaking down food to release its energy is called
. Many bacteria need oxygen to break down their food. A few kinds of bacteria do not though. For them, oxygen can be a poison.
When bacteria have plenty of food, the right temperature, and other suitable conditions, they thrive and reproduce frequently.
Bacteria produce by
, a process in which one cell divides to form two identical cells. Binary fission is a form of asexual reproduction.
is a reproductive process that involves only one parent and produces offspring that are identical to the parent.
Some bacteria may undergo a simple form of sexual reproduction, which involves two parents who combine their genetic material to produce a new organism that differs from both parents.
One type of sexual reproduction that bacteria perform is called
. During conjugation, one bacterium transfers some of its genetic material into another.
Many bacteria can survive harsh conditions by forming
. An endospore is a small, rounded, thick-walled, resting cell that forms inside a bacterial cell.
Endospores contain the cell's genetic material and some of its cytoplasm. An endospore can resist freezing, heating, and drying, and can survive for many years.
Under what conditions do bacteria thrive and reproduce?
Bacteria in Nature
Some bacteria cause diseases and other harmful conditions. However, most bacteria are either harmless or helpful to people.
Bacteria are involved in oxygen and food production, environmental recycling and cleanup, and health maintenance and medicine production.
Helpful bacteria produce foods such as cheese and pickles. However, bacteria cause food to spoil when they break down the food's chemicals.
One method to slow down food spoilage is
, where food is heated to a temperature that is high enough to kill most harmful bacteria without changing the taste of the food.
Heterotrophic bacteria in the soil break down materials for reuse. These bacteria are decomposers – organisms that break down large chemicals in dead organisms into smaller chemicals.
Some bacteria help to clean up the environment. There are some bacteria that are used to clean up oil spills and gasoline leaks. The bacteria break down the chemicals.
There are bacteria living in your body and actually keep you healthy. Some help you digest your food. Some make vitamins that your body needs.
Other bacteria compete for space with disease causing organisms, preventing the harmful bacteria from attaching to your intestines and making you sick.
Scientists even use bacteria to make medicine. By manipulating the bacteria's genetic material, scientists engineered bacteria to produce human insulin.