BACTERIA

Ch. 2.2

Anton van Leeuwenhoek

I. The Bacterial Cell

• A. Anton _van_ _Leeuwenhoek_ first discovered bacteria by accident.

• He made _microscopes_ as a hobby. He liked to look at scrapings from his _teeth_ to look at tiny, _wormlike_ organisms.

B. Cell Structures

• 1. _Bacteria_ are prokaryotes ( Cells _without_ a nucleus)

• 2. The genetic material in bacterial cells is _NOT_ found in a nucleus.

• 3. Bacteria _lack_ many other structures found in cells of eukaryotes (cells _with_ a nucleus)

• 4. Most bacterial cells are surrounded by a rigid _cell_ _wall_, which protects the cell.

Cell Structures

• 5. Inside the Cell Wall is a _cell_ _membrane_, which controls what material moves in and out of the cell.

• 6. Inside the cell is the _cytoplasm_, a gel-like material.

• 7. _Ribosomes_ are chemical factories where proteins are produced.

• 8. _Genetic_ material is found in the cytoplasm.• 9. A bacterial cell may have a _flagella_, a long whip-

like structure used for movement. (plural is flagellum)

C. Cell Shapes

• 1. Three basic shapes _spherical_ , _rodlike_ and _spiral_.

• 2. It is the _chemical_ make-up of the cell that determines the shape of the bacterial cell.

D. Cell Sizes

• 1. Bacteria vary greatly in _size_. They are measured in _microns_.

• 2. One micrometer is one _millionth_ of a meter.

II. Obtaining Food and Energy

• A. Bacteria must have a source of _food_ and a way of breaking down the food to release its _energy_.

• 1. Some bacteria are _autotrophs_ (make their own food).

• 2. Some bacteria use _energy_ from the chemicals in the environment.

• 3. Some bacteria are _heterotrophs_ (cannot make their own food).

Respiration

• B. The process of breaking down food to release energy is called _respiration_.

III. Reproduction

• A. When _bacteria_ have plenty of _food_, the right temperature and other suitable conditions they thrive and _reproduce_ frequently.

• B. _Binary_ _fission_ is when 1 bacterial cell becomes 2.

• C. _Asexual_ reproduction involves only 1 parent and produces offspring identical to the parent.

Binary Fission

Reproduction

• D. _Sexual_ reproduction involves 2 parents who combine their genetic material to produce a new offspring

• E. _Conjugation_ is a process where 1 bacterial cell transfers genetic material into another bacterial cell.

• F. Some bacteria can survive harsh conditions to form an _endospore_, a small rounded thick-walled resting cell that forms inside a bacterial cell.

Conjugation

IV. The Role of Bacteria in Nature

• A .Most Bacteria are either _harmless_ or _helpful_ (Some cause diseases).

• B. Bacteria release _oxygen_ into the air to help keep oxygen levels in the air stable.

• C. Helpful bacteria make food. List some foods bacteria help make: Cheese, pickles, apple cider, yogurt, sour cream, dried meat, soy sauce, chocolate beverages, sourdough bread.

• D. Some bacteria spoil food but refrigerating/heating food _slows_ down food spoilage.

Helpful Bacteria

• E. _Pasteurization_ = food is heated to a temperature that is high enough to kill most harmful bacteria without changing the taste of the food (Named after Louis Pasteur).

• F. _Decomposers_ are organisms that break down large chemicals in dead organisms into small chemicals. They are “nature’s recyclers”.

• G. Some bacteria help to clean up Earth’s _land_ and _water_.

• H. Bacteria in your _intestines_ help you digest food. Scientists use bacteria to make _medicine_.

Decomposers