Test Questions on chapter 7 – Microbiology – Flashcards

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genome
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all DNA present (chromosome + plasmids) the cells entire genetic component including both its genes and the nucleotide sequences that link genes together.
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nucleic acids are polymers of basic building blocks called ______________.
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nucleotides
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each nucleotide is made up of a __________ attached to a __________ which is intern made up of a pentose sugar.
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phosphate attached to a nucleoside
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comp base pairs
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DNA
thymine-adenine
guanine-cytosine

RNA
uracil- adenine
guanine-cytosine
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each new DaughterDNA is composed of
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one original strand
one new strand
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dan polymerase replication adds in one direction
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5' to 3'
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laggin strand vs leading strand
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laggin strand synthesized in segments
lead- all at once
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DNA>complement DNA>mRNA>TrNA> codons
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1.dna template is converted to complement DNA
2. the original dNA template is used to code mRNA (opposites, T is now U)
3. now use the mRNA to code the tRNA (opposites, T is still U)
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plasmids
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extra chromosomal pieces of DNA
1. replicate independently of the chromosome
2. nonessential genetic material
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the central dogma
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explains the flow of information in a cell (info exists in DNA)
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transcription
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uses DNA and makes RNA
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translation
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process of translation uses RNA and produces the protein
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what determines the genotype
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all DNA in cell determines the genotype
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what determines phenotype
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all protein in cell determines phenotype of cell (their abilities)
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phenotype is determined by _____________
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genotype
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the abilities of a cell determines its
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phenotype
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we can see a different phenotype without genotype being altered by ?
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regulating gene expression
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what does it mean to say that a gene is being expressed?
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transcription and translation are taking place *if the gene is expressed we are seeing evidence of the phenotype *
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when transcription and translation are taking place this means the __________ is being _______________
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gene is being expressed
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what can alter the phenotype without changing genotype?
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gene expression
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importance of regulation of genes (gene expression)
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energy is conserved when a cell does not need to make a particular protein
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quorum sensing
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cells secrete quorum sensing molecules into their environment and other cells detect these signals so as to measure their density. when population size reaches a particular density, gene expression is turned on.
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vibrio vulnificus
why is it necessary for v vulnificus to turn on different genes when the microbe invades a human?
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a gram negative pathogen found in estuarine environments (prefers to grow where salt meets freshwater) it causes wound infection and food bourne infections SHELLFISH

it is necessary for them to turn on different genes when the microbe invades humans because the host is different now so it must turn on genes allowing it to survive. (ex of chaningin phenotype without genotype)
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mutations
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changes to the DNA
spontaneous, or induced (caused by exposure to something),
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mutagens
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cause induced mutations (UV light or radiation for example)
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pyrimidine dimers (thymine dimers)
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caused by UV light exposure
-wherever there are adjacent thymines, UV light causes thymines to bond to each other instead and breaks bond to adenine
-BOND BETWEEN A AND T ARE BROKEN
-T BONDS TO ANOTHER T INSTEAD
-can result in death, or simple change of phenotype
-depends what part of info is interrupted
-THIS OCCURS IN HUMAN CELLS!
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DNA repair
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most cells have DNA repair mechanisms so we do not always see phenotypic change or cell death when a mutation occurs

1. light repair- enzyme activated in light that will go in and cut out thiamine dimer and fix it

2. dark repair- could occur in light or dark, not light activated, enzyme comes in and cuts out dmaged DNA and fixes thiamine dimer
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gene transfer types
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vertical- process of asexual binary fission, parent cell gives genetic material to offspring it forms. offspring identical genetically to parent.

horizontal- once cells have been made, these cells have the potential to exchange genetic material. there are three types.
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vertical gene transfer
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process of asexual binary fission, parent cell gives genetic material to offspring it forms. offspring has identical genetic material
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horizontal gene exchange (3 types)
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horizontal- once cells have been made they may exchange genetic material

1. transformation- recipient cell take up DNA from environment such as DNA released by dead organisms. transformations from harmless to deadly are possible. smooth cells of donor make a capsule and rough cells of recipient does not make capsule so the rough cells take in dan from smooth cells and incorporate it into its own data.

recipient cell/smooth cell binds to a piece of DNA and take DNA into cel and incorporate that DNA into its own (GENETICALLY ALTERED)


requirements for transformation: DONOR CELL MUST BE DEAD, dan fragments in environment. RECIPIENT CELL MUST BE COMPETENT/able to bind to DNA and take DNA in (THIS IS CALLED COMPETENCY)
experiment: streptococcus (one has capsule, one does not) (this is a genetic difference) the encapsulated cells will kill mouse, cell without capsule will not kill cell. when dead encapsulated cells are given to a mouse, mouse lives. when he mixes dead encapsulated cell with living non encapsulated cell and gives it to the mouse, mouse dies DUE TO TRANSFORMATION (recipient cell is genetically altered by donor cell DNA even though the donor cell is dead)


2. transduction- a mistake in the lytic cycle (performed by bacteriophage). in transduction the first cell infected is the donor cell because the lytic cycle results in the rupture of the donor cell. in lytic cycle to host cell chromosome gets degraded and synthesis of viral parts begin, then assembly (cytoplasm contains donor cell and viral DNA so sometimes the bacterial DNA accidentally gets put into the capsid instead of the viral DNA. *mistake one has bacterial DNA (host cell) *at end of transduction recipient cell possesses donor cell DNA* bacteriphage must be present so it will take place

3. conjugation- conjugation requires contact between donor and recipient cell. It is mediated by pili which are thin protinaceous tubes on surface of cell. Gene that codes for pili is located on a plasmid called an F fertility plasmid. cells containing this are called F+ cells and they are the DONORS in conjugation. F- cells lack an F plasmid and therefor have no pili.1. sex pills attaches donor and recipient2.single strand of F plasmid DNA transfers to the recipient beginning with a section called origin of transfer. The F- recipient then synthesizes complementary strand of F plasmid DNA, becoming F+ cell. the donor also synthesizes a complementary strand restoring its complete plasmid.

* in some bacterial cells an F plasmid does not remain independent in the cytosol but instated integrates at a specific DNA sequence in the cellular chromosome. they are called HfR (high frequency of recombination) cells. they can conjugate with an F- cell. After the F plasmid has integrated and Hfr and F- cells join via pilus, DNA transfer begins at the origin of transfer of the F plasmid, carrying with it one copy of the donor's chromosome. **** in most cases movement breaks the intercellular connection before an entire donor chromosome is transferred. when the recipient only receives a portion of the F plasmid, it remains an F- cell but it also squires some chromosomal genes from the donor. recombination can integrate the donor DNA into the recipient's chromosome. the recipient is now a recombinant cell that contains its own genes as well as some donor genes. ***conjugation ENDS with pieces of F PLASMID and donor DNA in recipient cell, cells synthesize complementary DNA strands.
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competency
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ability to bring in DNA fragment
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what do nucleotides form together to make?
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nucleic acids (polymers of nucleotides) (RNA AND DNA)
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how is a nucleotide structured
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it is made up of a phosphate attached to a nucleoside (which is made up of pentose sugar)
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nucleotides are the basic building blocks of
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nucleic acids/ RNA DNA
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nucleic acids types
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RNA AND DNA
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a nucleoside is made up of
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pentose sugar
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competency
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the recipient cells ability to bind to DNA from the donor cell (in transformation)
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is it the template or complementary strand of DNA which is used to make the mRNA?
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template
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point mutations, silent mutations,(also inversion, duplication, or transposition)
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point- just a single nucleotide base pair affected (substitution and frame shifts) (also known as insertions and deletions) (substitution is changing the letter, insertion and deletion produce more drastic affects on multiple codons

silence- no change because of redundancy in the genetic code
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smooth cells have _____________ and are the _____ cell
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capsule (rough cells don't)
DONOR CELL
(rough cell=recipient)
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what is the one requirement for transduction
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bacteriophage must be present
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what is the one requirement of transformation
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donor cell must be dead
recipient must be competent
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conjugation requirements
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3 requirements for conjucation:
one cell must posses F factor
two cells (donor and recipient) are opposite mating types (F+ and F-)
two cells must be in contact with eachother/ attach
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in HFR cell conjugation what does the recipient cell receive first ?
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1/2 the F factor, then some genetic material
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how can you interrupt conjugation?
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keep flask shaking, remove F factor
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what happens in horizontal gene transfer, transformationwhich cell is genetically altered
what are the requirements
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a capsulated smooth cell DONATES dna to a non encapsulated Recipient rough cell that brings it in and incorporates it into its own DNA

the recipient is genetical altered

requirements:
1. donor cell must be dead with DNA fragments in environment
2. recipient cell must be competent
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what is transduction? (horizontal gene transfer)
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a mistake in the lytic cycle resulting in bacterial DNA being placed in capsid instead of the intended viral DNA, this allows bacterial DNA to be transferred from one bacterial cell to another via a virus. (it can become integrated into recipient bacterial cell chromosome thereby transferring genes to the recipient)

*this is how antibiotics become useless due to transfer of resistant genes between bacterial cells

requirements:
1. bacteriophage must be present
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what is conjugation? (F+ F- type)
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the transferring of DNA between bacterial cells by use of pili. A plasmid known as the F factor, or fertility factor, is required by the donor cell for conjugation to happen. The F+ donor cell produces a pilus which attaches it to the F- recipient cell .(F factor codes for pilus) F factor initiates its own replication once cells are attached and sends it to the recipient cell. Now it has become F+ cell.
*if conjugation is interrupted not all of F factor will be transferred and the recipient cell will contain some F factor but will still be F-

F+= contains F factor
F-= doesn't have F factor

requirements1. one cell must posses F factor
2. two cells (donor and recipient) are opposite mating types (F+ and F-)
3. two cells must be in contact with each other/ attach
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what does the F factor genetic material allow for
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the creating on a pilus
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what is the phenotypic change for the recipient cell in conjugation?
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it has gained the F factor
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what is the HFr and F- conjugation?
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Same as F+ F- conjugation except the F factor DOES NOT EXIST AS PLASMID! it is part of the host cell chromosome and has integrated. F factor still initiates replication when cells attach, but the f factor is in the chromosome so its origin of replication is in the center meaning what is transferred first is the first 1/2of the F factor and then the chromosome gets replicated. The recipient cell remains F- because not whole F factor was received. (rarely becomes F+)(still can be future recipient in conjugation again)
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what are cells called with F factor as part of the chromosome?
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HFR cells
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