BACTERIA7th Grade Biology

Obtaining Food

Bacteria must have a source of food and a way of breaking down the food to release energy.

Some bacteria are autotrophs and make their own food.

They make food in one of two ways. Some capture the sun’s energy like plants. Others use the energy from chemical

substances in their environment.

Obtaining food

Some bacteria are heterotrophs and cannot make their own food.

They must consume other organisms or the food that other organisms make.

Heterotrophic bacteria may consume a variety of foods- from milk and meat, to decaying leaves on a forest floor.

Respiration Like all organisms, bacteria need a

constant supply of energy to carry out their functions.

This energy comes from food. The process of breaking down food to

release energy is called respiration. Like many other organisms, most bacteria

need oxygen to break down their food. Some bacteria do not need oxygen, in fact,

for them oxygen is a poison.

Reproduction

When bacteria have plenty of food, the right temperature, and other suitable conditions, they thrive and reproduce frequently.

Some can reproduce every 20 min.

Brain Check What is an autotroph? Makes it own food-

similar to a plant. What is a heterotroph? Must consume other

organisms The process of

breaking down food to release energy is called __________.

respiration

Asexual Reproduction Bacteria reproduce by a process called binary

fission, in which one cell divides to form two identical cells.

Binary fission is a form of asexual reproduction. Asexual reproduction is a process that involves

only one parent and produces offspring that are identical to the parent.

During this process, a cell duplicates its genetic material and then divides into two separate cells.

Each new cell gets its own complete copy of the parent cell’s genetic material as well as some of the parent’s ribosomes and cytoplasm.

Sexual Reproduction Sexual reproduction involves two parents who

combine their genetic material to produce a new organism, which differs from both parents.

During a process called conjugation, one bacterium transfers some of its genetic material into another.

Using a thin, threadlike bridge that joins the two cells. When these bacterium divide by binary fission, the

new genetic material passes to a the new cells. Conjugation does not increase the number of

bacteria. It does result in new bacteria that are genetically

different from the parent cells.

Endospore Formation Sometimes, conditions in the environment become

unfavorable for the growth of bacteria. Some bacteria can survive harsh conditions by forming

endospores. An endospore is a small, rounded, thick-walled, resting cell

that forms inside a bacterial cell. It contains the cell’s genetic material and some of its

cytoplasm. Because endospores can resist freezing, heating, and

drying, they can survive for many years. The bacteria that causes botulism, produce heat resistant

endospores that can survive improperly canned food. They are very light, and can be carried off by a breeze,

moving it to a better place to open up and multiply.

Words

Pasteurization-the food is heated to a temperature high enough to kill most harmful bacteria without changing the taste of the food.

Louis Pasteur, is its inventor. Decomposers- organisms that break

down large chemicals in dead organisms into small chemicals.

They are nature’s recyclers.