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BACTERIA - PowerPoint PPT Presentation

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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.

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Ch. 2.2

I the bacterial cell
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
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
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
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
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
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).


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

Iii reproduction
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.


  • 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.

Iv the role of bacteria in nature
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
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_.