BIO 260 exam 3 - the same generation time? Be able to use the fo...

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BIO 260 exam 3

• Understand what is meant by generation time, and binary fission. Do all organisms have

the same generation time? Be able to use the formula on p. 93 to calculate the number of cells in a population after a given amount of time.–Answer -generation time the time it takes for a cell to divide once -Binary fission the way in which bacteria split to multiply -Organisms differ in the generation time -N^t=Nv0X2^n example starting with 10 cells with a generation time of 20 minutes. calculate how many there will be after two hours.10x2^6=640

• What is a biofilm? What are some medical applications/examples of biofilms? Are all

biofilms damaging –Answer Biofilm

slimy matrix in which multiple bac- terium live.biofilms can cause persistent ear infections and tooth decay biofilms are encouraged in sewer treatment facilities.

• What is the definition of a pure culture? What are some techniques used to determine if a

sample is pure? How are stock cultures maintained?–Answer -pure culture

a sample consisting only of one type of bacteria.-streak plate is a technique used for pure samples.

• pure cultures that you want to keep for future use. They are refrigerated on and agar slant or

frozen for long-term storage

• Explain how physical conditions such as temperature, pH, and oxygen can influence 1 / 2

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bacterial growth.–Answer Temp

can have an influence on the speed of growth (including optimum growth), and too hot of temp can kill some bacteria. pH

bacteria that are not adapted to live in acidic conditions will die when their proteins denature.O2

some bacteria require O2, some require the absence of O2, and others can survive in either anaerobic or aerobic conditions.H20 –Answer some bacteria require a specific water condition (less or more osmotic) to survive.

• What is the optimum temperature for growth of psychrophiles, psy- chrotrophs,

mesophiles, and thermophiles?–Answer psychophiles

-5-15 C psychotrophs

15-30 C

mesophile

25-45 C

thermophile

45-70 C

Hyperthermophile

70+ C

• What are the basic chemical requirements for bacterial growth?

–Answer

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