bacteria shapes, structure, reproduction Bacteria are the smallest living organisms ­ they are much smaller than eukaryotic cells. They come in many shapes. There are three common bacteria shapes:
1. _______________ (coccus)
2. ____________ (bacillus)
­ shaped like spheres
­ example ­ Streptococcus
­ shaped like rods
­ many of Streptococcus bacteria are not harmful, but when they enter your body, they are ­ example ­ Escherichia coli
­ can cause strep throat, pneumonia, flesh­eating disease
­ many E. coli bacteria are not harmful ­ good E. coli lives in our guts and helps us digest food ­ there are some disease­
causing strains that can cause diarrhea, urinary tract infections, kidney failure ­ can contract this if you come into contact with feces 3. ______________ (spirillum)
­ winding spiral shape
­ example ­ Borrelia burgdorferi
­ Borrelia bacteria are found in ticks; when a tick bites, Borrelia can enter the blood stream of humans and cause Lyme disease ­ causes a bullseye rash and later can affect joints, heart, and nervous system 1
bacteria shapes, structure, reproduction Structure of a Bacterial Cell
Bacterial cells are much less complex than eukaryotic cells (which you learned in Unit 1)
Nucleoid region ­ Bacteria have one ____________ that is circular; its location is called the nucleoid region
Ribosome ­ where ______________ molecules are made
Flagellum ­ some bacteria have a tail­like structure that helps them _____________
Plasmid ­ small, circular pieces of extra DNA that are not needed for the bacteria cell to divide but contain important genes such as those for _______________________
Capsule ­ a _______________ outer envelope of many bacteria
Cell wall ­ inside the capsule, helps to give the cell shape and ________________
Plasma membrane ­ surrounds the cytoplasm and controls what goes in and out
Cytoplasm ­ the liquid inside the cell
protein
structure
protective
antibiotic resistance
DNA strand
move
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bacteria shapes, structure, reproduction Reproduction in Bacteria
Almost all bacteria reproduce ___________________, meaning that there is only one parent. Bacteria reproduce using a process called _________________________.
Watch the animation: http://www.classzone.com/books/hs/ca/sc/bio_07/
animated_biology/bio_ch05_0149_ab_fission.html
This reproduction results in two daughter cells that are _________________ to the single parent bacterial cell. Each of these replications is called a ________________. This process can happen very quickly or very slowly ­ some bacteria take 20 minutes to divide and some bacteria take several days.
For every one cell, ____________ cells are produced. For every two cells, _____________ cells are produced. For every four cells, ______________ cells are produced. This growth is called ____________________. four
generation
eight
identical
binary fission
exponential
two
asexually
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bacteria shapes, structure, reproduction Bacterial Recombination
Binary fission is an effective way for bacteria to reproduce, however it creates problems. Since the cells produced through this type of reproduction are _________________, they are all susceptible to the same types of ________________. In order to incorporate some genetic variation, bacteria use a process called recombination. Bacterial recombination can be accomplished through ______________________. Watch the animation: http://www.youtube.com/watch?v=7stZk6TesKk
Genes that encode for antibiotic resistance in bacteria are carried on ________________. These can be passed to bacteria of the same or different species to create more antibiotic resistant bacteria. conjugation
antibiotics
plasmids
identical
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bacteria shapes, structure, reproduction Antibiotic Resistance
Watch Understanding Bacteria (19:12 ­ 33:35) to understand antibiotic resistance.
­ Alexander Fleming accidentally discovered _________________, the first antibiotic
­ Antibiotics are actually produced by certain types of _______________. This is beneficial to them because they can kill off any invading bacteria species.
­ Antibiotics started to be mass produced in the 1940s, but they do not work on every type of bacteria. Some bacteria are __________________ to one or several kinds of antibiotics
­ If the parent bacteria is resistant to a certain antibiotic, the _________________ cells will also be resistant to the same antibiotic
­ Antibiotic resistance is passed to other bacteria through ___________________
­ When you are prescribed antibiotics, you must take them for several days to ensure all of the bad bacteria are killed off. If even one bacteria remains, it can reproduce and __________________. ­ It can be DANGEROUS to use antibiotics too often. For example, penicillin will kill off all bacteria that are susceptible, leaving any that are resistant. A single bacterium could have mutated to have a gene encoding for penicillin _________________. If it survives and repopulates, there will now be an entire population of penicillin resistant bacteria and penicillin will not work again.
­ Unfortunately, antibiotics are used WAY TOO OFTEN. They are used on livestock to keep them healthy and to promote __________________. They are also used on crops to kill bacteria. Therefore, we may accidentally _______________ antibiotics everyday. resistance
eat
resistant
repopulate
daughter
conjugation
growth
bacteria
penicillin
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bacteria shapes, structure, reproduction Homework
1. What are the three most common bacteria shapes?
2. List three features that are common between the eukaryotic and prokaryotic (bacteria) cells?
3. List 3 differences between mitosis and binary fission. 4. Why is it important that bacteria undergo conjugation (in your own words)?
5. E. coli has a generation time of 20 minutes. If an E. coli population begins with 5 bacteria, how many bacteria will there be in the population after:
a) 1 hour (60 minutes)
b) 5 hours (300)
c) After how much time will the population have 400 bacteria?
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bacteria shapes, structure, reproduction WORD SPLASH
Go through your notes and find an important word.
Come up to the front and write your word with your name ­ first come, first serve.
Cut out a "splash" from a coloured piece of paper.
On your splash, write your word, draw a picture, the "textbook" definition, "your own words" definition, use it in a sentence, and any related words.
Pair up with a partner and share your splash!
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