Genetics Exam 3

Plasmid

 A small circular DNA molecule found in bacteria. Nonessential DNA in bacteria that are not part of the bacterial chromosomes.

Plasmids can be transferred through direct physical contact between bacteria in a process known as conjugation, which helps bacteria share their antibiotic resistance genes with their neighbors.

How does a plasmid work to spread antibiotic resistance?

Conjugation

the transfer of plasmids between joined bacterial cells

Transduction

when DNA is transferred from one bacterial cell to another by a bacterial virus

Transformation

alteration of a bacterial cell's genome by the uptake of foreign DNA from the surrounding environment

rapid reproduction & mutation

why is genetic recombination in bacteria high?

Plasmids

where are antibiotic resistance genes in bacteria?

Conjugative

the f plasmid is a _____________ plasmid

cell wall

why is transformation not very efficient?

false

true of false: transformation must occur with plasmids

CaCl2

compound added to a bacterial cell in the lab to make it "competent"; makes cell wall easier to break through

dead cells

what may be a source of genetic material to be transferred via transformation?

pilus

bridge-like structure that forms between bacterial cells; plasmids can be transferred through

r plasmids

resistance genes are located on ____________

conjugation

antibiotic resistance is spread through _____________

F+

cells that contain the F plasmids are described as ______

F-

cells that do NOT contain the F plasmids are described as ______

vaccines

there is no cure for viruses, but you can be protected from them through _____________

hfr cells

a bacterial cell with a conjugated F plasmid integrated into its DNA molecule. They are cells with a high frequency of recombination

genomic DNA

hfr cells are capable of inserting their own ________________ into F- cells, which can lead to more recombination

F+ cell

the cell that is responsible for forming the pilus to begin conjugation

Virus

consists of nucleic acid enclosed by a protein coat

host

viruses need a ______ to undergo replication, transcription, or translation

obligate parasite

a parasite that obtains its nourishment by living in or on another organism

Bacteriophage

a virus that infects bacteria

bacteriophage

transduction is made possible when host DNA accidentally ends up inside of a _______________

lytic cycle

viral reproductive cycle in which a virus injects its amino acids into the host, degrades its DNA, hijacks it to produce its own DNA, and then kills the host cell.

lysogenic cycle

viral reproductive cycle in which the viral nucleic acids are added to the host cell and are copied along with the host cell's nucleic acids. host does not die.

recombination

_________ may occur with host's nucleic acids during the lysogenic cycle

Many bacteria use a system known as CRISPR-Cas to defend themselves against infection by viruses called phages. This system protects the bacterial cell by taking a short length of DNA from the phage and inserting this 'spacer' into its own genome.

Describe bacterial defenses against viruses

Dead S cells burst open and absorb the dealy gene

What happens to a bacterial cell when it dies?

selective vs non-selective medium

**Selective media** are used for the growth of only selected microorganisms.

**Non-selective media** allows of the growth of several different bactarial species

1. The first is known as conjugation- involves a direct physical interaction between two bacterial cells. One bacterium acts as a donor and transfers genetic material to a recipient cell.
2. The second means of transfer is called transduction. This occurs when a virus infects a bacterium and then transfers bacterial genetic material from that bacterium to another.
3. The last mode of genetic transfer is transformation. In this case, genetic material is released into the environment when a bacterial cell dies. This material then binds to a living bacterial cell, which can take it up.

**Compare and contrast the major types of bacterial genetic transfer**

Hfr cells possess a plasmid that replaces the bacterial chromosome entirely. F plasmids are integrated to their chromosomes. 

**How is a Hfr cell different?**

**When a temperate phage undergoes lysogeny, the phage gene becomes a part of the bacterial chromosome. Most phage genes in prophage are kept in an inactive state by a phage repressor protein encoded in one of the phage genes.** 

**If a lysogen is infected with a phage of the same type as the prophage, then the repressor present within the cell from the prophage prevents expression of the genes of the infecting phage.**

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**What prevents a bacterial cell that is lysogenic for a temperate bacteriophage from being reinfected with a phage of the same type?**

Selective media are used to select for the growth of a particular "selected" microorganism. It is a medium that allows the selection of one or more types of microorganisms. For example, if a certain microbe is resistant to a particular antibiotic, then that antibiotic can be added to the medium in order to prevent other organisms, which are not resistant, from growing.

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**What is selective media and provide an example of how it is used.**

CRISPR

technological advancement that has made DNA manipulation significantly faster and cheaper

replica plating

when cells are grown on one plate and transferred to another; was done to prove that mutations occur randomly and unrelated to stimuli

one

prokaryotes have \______ RNA polymerase(s)

rna polymerase II

the rna polymerase that is used primarily in transcription

three

eukaryotes have \_______ rna polymerase(s)

promoter

specific region of a gene where RNA polymerase can bind and begin transcription

initiation protein

binds to RNA strand; recruits RNA polymerase to come in and begin transcription

sigma factor

initiation protein in prokaryotes

promoter region

in prokaryotes, two consensus sequences make up the \______________

-10 and -35

where are the consensus sequences for the promoter region in prokaryotes?

TATA box

the very AT-rich middle of the promoter region in eukaryotes

-10 region

this part of the promoter region in prokaryotes is usually very A/T rich

26

the number of initiation factors that must bind to the promotor region in eukaryotes

enhancer

activator protein binds to \___________

the activator protein binds to the enhancer

in eukaryotes, the transcription factors cannot bind to the promoter region until...

eukaryotes

enhancer region is exclusive to \___________

5' to 3'

the direction in which RNA polymerase builds

promoter

each DNA strand has its own \___________ region for transcription

gene

the template strand can vary depending on the \_________

terminator

in prokaryotes, this sequence causes a hairpin loop that dissociates RNA polymerase

hairpin loop and run of Us

key factors of termination in prokaryotes

rho-dependent termination

in prokaryotes, this is when the rho protein runs along the DNA strand in the opposite direction as the RNA polymerase, knocking it off the strand

prokaryote

eukaryote or prokaryote? no further processing is done to the mRNA following termination

AAUAAA

the polyadenylation sequence in eukaryotic termination

endonuclease

cuts the RNA polymerase out of the DNA strand 10-35 nucleotides after it reads the termination sequence

pre-mRNA

the product of transcription in eukaryotes

collinearity

when the linear order of the nucleotides in a gene \= the linear order of amino acids to produce a gene

prokaryotes

collinearity is only associated with \_____________

introns

sequence of DNA that is not involved in coding for a protein

exons

Coding segments of eukaryotic DNA

rna processing

in eukaryotes, when a 5' cap and 3' poly-A tail are added, and the introns are spliced out

mRNA

after processing following eukaryotic transcription, the result is \________

spliceosome

where RNA splicing takes place

snRNAs

found inside of the spliceosome; direct protein to recognize introns that must be cut out

untranslated regions

regions always left on the ends of the coding segment after mRNA processing

domain

part of the tertiary structure of the protein

independently

domains of a protein can exist \__________ of one another

one gene one enzyme hypothesis

states that each gene is responsible for one enzyme, which affects a single step in a metabolic pathway

alternative splicing

the way in which selective introns can be cut out during the splicing process, resulting in various polypeptides that could be formed as a result

tRNA

type of RNA that translates each codon and brings the correct amino acid into the polypeptide sequence

anti-codon

each tRNA has an \_________ that matches with the codon in sequence

aminoacyl-tRNA synthetase

enzyme that catalyzes the attachment of amino acids to the corresponding tRNA; reattaches amino acids to tRNA after they've lost them

ATP

used by aminoacyl-tRNA syntheyase to attach amino acids to tRNA molecules

wobble

flexibility in the base-pairing rules when it comes to the third nucleotide of a codon, in which a change in the base does not change the amino acid in sequence

ribosome

where protein synthesis occurs

monocistronic

eukaryotes are \_____________, meaning that they can only translate one gene on one mRNA at one time

polycistronic

prokaryotes are \__________, meaning they can translate multiple genes on one mRNA copy

5' cap

what elongation factors bind to to begin the translation process in eukaryotes

elongation factors

responsible for recruiting the ribosomal subunit and initiator tRNA in translation

AUG

where translation actually begins, and the large ribosomal unit is recruited

reading frame

the way in which codons are read in translation, 3 bases at a time; set by methionine

exit site

e site of a ribosome; where discharged tRNAs leave the ribosome

peptidyl site

p site of a ribosome; holds the tRNA that is carrying the growing polypeptide chain

aminoacyl site

a site in ribosome; holds the tRNA carrying the next amino acid in sequence

exit tunnel

part of the ribosome where the polypeptide chain is released

amino to carboxyl end

direction in which polypeptide chains are built

GTP hydrolysis

where the energy used to form peptide bonds comes from

dehydration synthesis

how new peptide bonds are made

stop codon

what causes release factors to stop translation

one

eukaryotes have \_____ release factor(s)

three

prokaryotes have \_______ release factor(s)

chaperone proteins

proteins that bind and release to hydrophobic regions of folding proteins to prevent them from folding onto themselves

chaperonin proteins

proteins that form cylindrical chambers where a folding protein can enter and form in an isolated region

GTP hydrolysis

when a mismatched anticodon is present at the A site, \________ is delayed