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78 Cards in this Set

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The ____ strand encodes the genetic info while the ______ strand is read by RNA pol to make mRNA. ________ base pairing allows this.
Plus, Minus, Complementary
The promotor region is _______ of all genes.
Upstream
Upstream vs Downstream
Upstream = towards the 5' end
Downstream = towards the 3' end
Transcription Factors
Sequences of DNA within the promotor that are recognized by regulatory proteins.
TF's are analogous to a _________ switch.
Dimmer
Some promote, some repress
During initiation of transcription, the _______ ________ on the RNA pol recognizes the _________ region.
Sigma Factor, Promotor
After the RNA pol binds to the promotor region, the _______ _______ falls off, leaving the RNA pol _______ ________.
Sigma Factor
Core enzyme
mRNA is synthesized _____ to ____.
5' to 3'
A _________ sequence in the DNA displaces the RNA pol from the gene, ending transcription.
Termination
Define UTR's. What does it stand for, what do they do and where are they located on the mRNA?
Untranslated regions. Each mRNA has a short 5' UTR and a long 3' UTR. They contain regulatory elements that control several aspects of mRNA activities including the 1/2 life.
The genetic code is __________ because more then one codon can encode some aa. The _____ position is where the degeneracy occurs.
Degenerate, 3rd
__________, composed of RNA's and proteins, are the site of polypeptide synthesis.
Ribosomes
The ________-_________ sequence is found in the __' UTR of bacterial RNA's.
Shine-Delgarno
5'
Define the Shine-Delgarno sequence.
It assures proper alignment of the mRNA on the ribosome, allowing the ribosoe to find the AUG start codon.
tRNA's have two important features:
1. The anti-codon that is complementary to the codon
2. An amino acid that is specific for the codon.
Define the wobble hypothesis:
The reason why the 3rd position is degenerate is because the 3rd position can't make as close contact between the tRNA and the mRNA and can therefore be misread fairly easily.
A ribozyme is a __________ RNA molecule.
Catalytic
A ribozyme called ________ _________ forms a peptide bond between the COOH of the 2st amino acid and the NH2 of the 2nd amino acid.
Peptidyl transferase
Eukaryotic mRNA is usually _______cistronic while prokaryotic mRNA is usually _______cistronic.
Monocistronic
Polycistronic
When a gene is continually expressed, it is said to be __________ expressed.
Constituatively
A _________ gene is one that is affected by repression or activation.
Modulated
Define repressors:
They bind to the DNA between the promotor and the transcriptional start site, thus blocking RNA pol.
Define activators:
They interact with the promotor region to facilitate RNA pol binding.
The lac operon is a sensing pathway for __________.
Lactose
Define the lac operon:
The presence of lactose and the absense of glucose in a culture media stimulates the expression of genes that metabolize lactose.
Describe the first step of the lac operon pathway:
1. As glucose levels drop, cyclic AMP increases (cAMP)
Describe the second step of the lac operon pathway:
2. cAMP binds to catabolite activating protein (CAP), allowing it to bind to the promotor. It can't bind without cAMP.
Describe the third step of the lac operon pathway:
3. Allolactose, an isomer of lactose, binds to the lac repressor, preventing it from binding to the DNA.
Ligation to specific macromolecular receptors on the surface of cells creates what kind of response within the cell?
This induces a series of signal transduction events inside the cell that results in a change in gene expression profile.
Staphylococcus aureus is a common Gram ________ bacteria
Positive
There are multi-drug resistant strains of Staph in hospitals, how do they survive the antibiotics and what are these strains called?
They are called methicillin-resistant Staphylococcus aureaus (MRSA), they evolved a pump system to export the antibody.
True or False:
Antibiotic resistance is a genetic event.
True
What are the two mechanisms of mutagenesis?
1. Spontaneous mutation of the DNA
2. Horizontal gene transfer (bacteria sex)
What are the two main causes of mutagenesis?
1. Chemicals and radiation
2. Mutases
What are mutases?
Enzymes that are expressd during times of stress that increase rates of mutations. They are modified DNA polymerases, this is a last ditch effort.
The three main types of mutations are:
1. Nucleotide base substitution (AKA point mutation)
2. Deletion or insertion of nucleotides
3. Transposable elements ("jumping genes")
Mutations are a _________ game with rates that usually fall between:
Numbers
10^-4 and 10^-12
Silent Mutation
A base substitution mutation that has no effect on which amino acid is added to the polypeptide
Missense Mutation
A base substitution mutation resulting in an amino acid change (can be dramatic
________ mutations can alter the 3D shape of a protein or compromise a critical amino acid.
Missense
Nonsense Mutation
Results in a premature stop codon.
Deletions or insertion mutations alter the _________ ________ of DNA.
Reading frame
Mutations that shift the reading frame on DNA are termed _________ mutations.
Frameshift
__________ elements are common in plants and often carry genes that alter the __________ of recipient bacteria, including antibiotic resistance.
Transposable
Phenotype
_______ are used to discover gene functions.
Mutagens
______ _________ change cases that are misread during DNA replication.
Base modifiers
______ _________ resemble normal bases but have different ___-_______ characteristics and are mismatched during replication
Base analogs
H-Bond
________ _______, such as ethidium bromide, insert btwn adjacent baes on a strand, which can lead to the __________ of a base pair
Intercalating agents
Insertion
Radiation thru UV light can create ________ ________ while X-rays induce ________ ________ _____ ________.
Thymine dimers
Double strand DNA breaks
What is proofreading?
Some DNA polymerases can step backward and remove a misincorporated base.
True or False:
Viruses can proofread their DNA looking for mutated DNA.
False, viruses cannot proofread.
_________ are enzymes that recognize inappropriate ____ _______ of DNA and remove mutant bases, which are corrected by DNA pol
Endonucleases
3D structure
The process of endonucleases removing mutant bases so DNA pol can replace them is called __________ repair.
Mismatch
After endonucleases recognize and remove a mismatched base, _____ _____ repairs it.
DNA pol
Thymine dimers can be repaired through ____________, which recognizes buldges in the DNA.
Photoreactivation
Photoreactivation harness light energy to break the _________ bonds btwn adjacent ___________.
Covalent
Thymines
The two types of thymine dimer repair are:
1. Photoreactivation
2. Excision repair
Explain excision repair:
-Repairs thymine dimers
-Removes several adjacent bases
-DNA pol refills the gaps
-DNA ligase forms phosphodiester bonds
________-_______ __________ recognize modified bases and remove them.
Lesion-specific glycosylases
Explain SOS repair:
-System of 30+ genes for repair of highly damaged DNA
-System of desperation
-Highly prone to error
What are the three events that evolution requires:
1. Genetic variation
2. These variations must be inheritable
3. Natural selection of those traits most suitable for an environment
Isolating a mutant is a ________-________ event.
Statistically-unlikely
List three important microbes that have been developed using artificial seletion:
1. Oil-consuming bacteria
2. Heavy metal decompisition
3. Wines
Cells that are receptive to DNA transfer are termed _________.
Competent
Competent cells allow DNA to pass through their _________ and ______ ______, this process is termed __________.
Membranes
Cell walls
Transformation
___________ are bacterial viruses.
Bacteriophages
The process of new genes in a bacterial genome "spread" by a bacteriophage is termed __________.
Transduction
Plasmids
-Circular molecules of DNA
-They can be 100-1000 nucleotides long
-They often contain virulence factors
Define virulence factors
Often contained in plasmids and contribute to disease suseptibility with antibiotics and toxins.
Plasmids are considered __________ because they can disseminate btwn species of bacteria.
Promiscuous
Competent cells acquire plasmids by ___________ __________.
Random chance
__________ is the direct transfer of plasmids (or chromosomes) btwn bacteria.
Conjugation
A recipient cell is denoted as _____, while a donor cell is donated _____
Recipient = F-
Donor = F+
Define a sex pilus
A tubular structure that mediates contact btwn a donor cell and a reciepient
A plasmid becomes __________ when an enzyme cleaves it.
Mobilized
At the end of conjugation both bacteria are F__.
+
Transposons
Self replicating DNA molecules. AKA transposable elements, jumping genes
All transposons encode DNA and/or RNA polymerase, termed ___________, that mediates jumping.
Transposases