Bac Path Test Cards

Preparation for Exam 2

What are the growth requirements for microbes?

Nutrients, Energy, Temperature, pH, and Osmotic pressure

What is an obligate aerobe?

A microorganism that requires oxygen to grow and survive

What is an anaerobe?

An organism that grows without requiring oxygen

What is an aerotolerant anaerobe?

An organism that can grow without oxygen, but can tolerate it.

What is a facultative anaerobe?

An organism that can grow with or without oxygen, but usually grows better when oxygen is present.

What is an obligate anaerobe?

An organism that can not grow in the presence of oxygen because it is toxic

What are the four phases of bacterial growth?

Lag phase, log phase, stationary phase, and death phase

What is the lag phase?

Cells synthesize enzymes and adjust to growth conditions

What is the log phase?

Bacteria grow and divide rapidly + the population grows exponentially

What is the stationary phase?

The rate of new bacterial cells = rate of cells dying.

What is the death phase?

Bacteria cells die faster than new ones are made

What is a symbiotic relationship?

Individuals cooperate and become interdependent

What is an antagonistic relationship?

Individuals that harm or kill one another

What is a discrete colony?

A group of cells arising from a single parent

What are planktonic cells?

Cells that are free in liquid

What is an aggregate colony?

A collection of microbes living in a complex community

What is a biofilm?

microorganisms that attach to a surface and are surrounded by a protective, self-produced matrix

What is the five steps of biofilm formation?

1. Attachment

2. EPS formation

3. Quorum sensing

4. Maturation

5. Dispersal

What is the first step of biofilm formation?

Microbes land on a surface + attach

What is extracellular polymeric substance (EPS)?

A protective matrix used to hold a biofilm together; can contain DNA, protein, and sugar.

What is quorum sensing?

Cell to cell communication in which microbes release and detect signaling molecules to coordinate changes in biochemistry and shape.

What happens as a biofilm matures?

More microbes join, the biofilm becomes more complex, and water channels may form to help transport nutrients and remove waste.

What happens when microbes disperse from the film?

Microbes leave the biofilm and return to a free-living, planktonic state. May start a new biofilm.

What is a complex media?

media with exact chemical composition is not completely known, such as yeast extract, beef extract, or peptones.

What is a defined medium?

A growth medium in which the exact chemical identity and amount of every ingredient are known.

What is selective media?

A growth medium that only allows the growth of certain microorganisms and inhibiting the growth of others.

What is differential media?

Distinguishes between microorganisms based on visible differences in their biochemical activities, such as color changes

What is DNA replication?

The process of copying DNA to produce two DNA molecules

What does helicase do during DNA replication?

Unwinds and separates the two DNA strands by breaking the hydrogen bonds

What does topoisomerase do during DNA replication?

Relieves twisting and supercoiling ahead of the replication fork by temporarily cutting and rejoining DNA

What is DNA gyrase?

A type of topoisomerase found in bacteria that helps relive DNA supercoiling

What does DNA polymerase do?

Synthesizes a new DNA strand by adding complementary DNA nucleotides to a template strand

What is transcription?

The process of using DNA as a template to synthesize RNA

What enzyme carries out transcription?

RNA polymerase

What does RNA polymerase do during transcription?

Opens a small section of DNA and uses one strand as a template to synthesize a complementary RNA strand

What is the difference between replication and transcription?

DNA replication copies DNA into more DNA. Transcription uses DNA as a template to make RNA

What is translation?

The process in which ribosomes read mRNA and use its codons to assemble a protein from amino acids

What is the function of a ribosome?

reads mRNA and joins amino acids together to build a protein

What type of ribosomes do prokaryotes have?

70S ribosomes

What type of ribosomes do eukaryotic cells have?

80s ribosomes

What is 16S rRNA and why is it important?

Found in the small subunit of bacterial ribosomes, it is used to identify and classify bacteria

What is 18S rRNA?

Ribosomal RNA found in the small subunit of eukaryotic cytoplasmic ribosomes, used for studying and identification

What is the central dogma of molecular biology?

Genetic information generally flows from DNA → RNA → protein.

Which enzyme synthesizes DNA, and which synthesizes RNA?

DNA polymerase and RNA polymerase

What happens during initiation of translation?

The ribosome assembles on the mRNA, and the initiator tRNA binds at the start codon, usually AUG.

What happens during elongation of translation?

tRNAs bring amino acids to the ribosome, which joins them together to lengthen the growing protein chain (polypeptide)

What happens during termination of translation?

Ribosome reaches a stop codon and releases the completed polypeptide

What is the function of mRNA?

Carries genetic instructions copied from DNA to the ribosome, where they are read to make a protein

What is the function of tRNA?

Carries a specific amino acid to a specific codon

What is the function of rRNA?

Forms the structural and catalytic core of ribosomes, helping position mRNA and tRNAs and catalyze peptide bond formation.