Shared Flashcard Set

Details

Exam 3 Review
BIO 325 - Mohantey
156
Biology
Undergraduate 3
04/23/2013

Additional Biology Flashcards

 


 

Cards

Term
mutation
Definition
alteration in DNA sequence
Term
spontaneous mutations
Definition
happen naturally and randomly
Term
induce mutations
Definition
happens from some type of influence
Term
Somatic mutations
Definition
occur in any cell except germ cells and aren't heritable
Term
Germ-line mutations
Definition
occur in gametes and are inherited
Term
Autosomal mutations
Definition
occur within genes on the autosomes
Term
X-linked mutations
Definition
occur within genes located on the X chromosome
Term
Recessive autosomal mutation
Definition
often doesn't result in a detectable phenotype. In other words, the mutation rarely has an effect
Term
Dominant autosomal mutations
Definition
expresses phenotypically
Term
Point mutations
Definition
a single base is altered
Term
Frameshift mutations
Definition
inserting or deleting a base causes the frameshift to change. If 3 bases are added or deleted, the frame of reading stays the same because the other amino acids in other positions will still translate the same as it would've before the mutation occurred
Term
Missense mutation
Definition
a triplet is changed which changes resulting in a different amino acid being translated. this ultimately results in a different protein
Term
Nonsense mutation
Definition
a codon gets changed into a stop codon which results in premature translation
Term
Silent mutation
Definition
changes the codon but the same amino acid gets translated so the resulting protein is unchanged
Term
Transition
Definition
When a pyrimidine replaces a pyrimidine or a purine replaces a purine (same replaces same)
Term
Transversion
Definition
A purine replaces a pyrimidine or vice versa (replaces opposite)
Term
Lethal mutations
Definition
obviously result in death
Term
Conditional mutations
Definition
the effect of the mutation is only noticed under certain conditions
Term
Neutral mutations
Definition
happens in the part of the genome that don't contain genes so they have no effect
Term
Slippage
Definition
the misalignment of the complementary DNA strands which leads to repeats
Term
Tautomeric shift
Definition
when one of the 4 bases switches to an alternative form of itself, such as thymine switching from the keto form to enol form. This causes T to bind with G and A to bind with C
Term
Depurination
Definition
the process of where a purine is loss leading to a spontaneous mutation
Term
Deamination
Definition
the process where an amine group is removed leading to a spontaneous mutation
Term
Oxidative damage
Definition
when the DNA is exposed to too much oxidation
Term
transposons
Definition
are DNA sequences that move from one location to another. These can thus act like mutagens
Term
Mutagens
Definition
any agents that induce mutations
Term
Base analogs
Definition
a chemical that can substitute for purines or pyrimidines during replication causing an obvious mutation
Term
Alkylating agents
Definition
agents that add alkyl groups to to nucleotides to change how the success of base pairing
Term
Acridine dyes
Definition
cause frameshift mutations by inserting themselves purines and pyrimidines
Term
UV radiation
Definition
creates pyrimidine dimers that changes the conformation of DNA that leads to errors during replication
Term
Ionizing radiation
Definition
X rays, gamma rays, and cosmic rays which can all cause mutations
Term
Two causes of spontaneous mutations
Definition
replication errors and base modifications
Term
Three causes of replication errors
Definition
point mutation, deletion and insertion
Term
Three causes of base modification
Definition
tautomeric shift, depurination, deamination
Term
Three cuases of induced mutations
Definition
oxidative damage, transposons, radiation and chemicals
Term
4 kinds of radiation and chemical agents that causes induced mutations
Definition
Base analogs, alkylating agents and acridine dyes, UV light, ionizing radiation (rays)
Term
Duchenne muscular dystrophy
Definition
caused by a frameshift in the dystrophin gene, more severe
Term
Becker muscular dystrophy
Definition
caused by an alteration in protein sequence, less severe
Term
Trinucleotide repeat sequences
Definition
are abnormal amounts of trinucleotide repeats and can cause disorders such as Huntington disease and fragile X syndrome
Term
Genetic anticipation
Definition
the phenomenon where the number of trinucleotide repeats in someone with a disorder may increase in each subsequent generation
Term
Ames test
Definition
a test used to determine if a certain chemical is mutagenic
Term
Ames test procedure
Definition
Autotrophs that are missing histidine is combined with the chemical to test. If after plating the bacteria survive then you know the chemical is a mutagen because it caused a mutation in the bacteria that allowed it to grow histidine and thus survive. If very little amounts of bacteria survive then the chemical isn't a mutagen.
Term
Proofreading
Definition
The process of recognizing and correcting errors during replication. keyword during
Term
Mismatch repair
Definition
corrects errors AFTER proofreading, keyword after
Term
Postreplication repair
Definition
occurs when DNA replication skips over a lesion and requires homologous recombination mediated by the RecA protein.

When it skips over the legion, the complementary sequence is cut from the opposite strand and is inserted into the gap that formed. The new gap that is formed is then filled. The RecA protein allows for the recombinational exchange.
Term
SOS repair system
Definition
Is a last resort, it will just insert A's into any gaps or mismatches it finds
Term
Photoreactivation repair
Definition
removes thymine dimers caused by UV light. Depends on photoreactivation enzyme (PRE)
Term
Base Excision repair
Definition
removes mutation by a nuclease
fills gap by DNA pol
seals the gap by DNA ligase

It first has to recognize the incorrect base by DNA glycosylase which removes the base
The DNA backbone at this point is then cut out by AP endonuclease. DNA pol adds the correct base, ligase seals the gap
Term
Nucleotide excision repair
Definition
removes bulky lesions (like dimers). Is very similiar to base excision except it removes who legions instead of a single base
Term
Xeroderma pigmentosum
Definition
when you lose the ability to undergo nucleotide excision repair
Term
DNA double-strand break repair
Definition
Happens when both DNA strands get broken due to some type of damage. Repairs both strands at the same time (homologous recombinational repair)

The 5' ends of the broken strands get digested and the 3' ends uses a nondamaged sister chromatid as a template to reproduce the broken strand
Term
Nutritional mutations
Definition
mutations that do not allow an organism to grow on minimal medium, but do allow the organism to grow on complete medium.
Term
Muscular Dystrophy
Definition
results from a mutation in the gene encoding dystrophin
Term
Cockayne Syndrome
Definition
defect in nucleotide-excision repair
Term
Cis-acting elements
Definition
Term
Trans-acting elements
Definition
Term
lac operon
Definition
Has a regulatory region (promoter plus operator) and a structural region (lazC, lacY, and lacA)

Operon is required to metabolize lactose
Term
lacZ gene
Definition
encodes for B-galactosidase, which converts lactose to glucose and galactose
Term
lacY gene
Definition
specifies structure of permease, which facilitates entry of lactose into the cell
Term
lacA gene
Definition
codes for transacetylase, which removes toxi by-products from lactose digestion
Term
Negative control of lac operon
Definition
in this system, transcription of the operon will only occur when the repressor fails to bind to the operator region. This occurs when there's lactose present so the operon can be transcribed and lactose can get broken down. The lactose will bind to the repressor changing it shape. Essentially, you only make the enzymes to break lactose down when you have lactose available.

Transcription will not occur when the repressor binds to the operator (ie, when there's no lactose present). You don't want to make enzymes to break down lactose when you don't have any available to break down.
Term
Positive control of lac operon
Definition
Based on the CAP protein.

When there's lactose available but no glucose, there's lots of cAMP available. CAP-cAMP binds to the CAP binding site making it easier for RNA pol to bind and thus easier transcription

When there is glucose present, CAP can't bind because of low cCAMP levels (can't make that binding complex) so the repressor is able to bind and thus no transcription
Term
trp Operon
Definition
produces tryptophan

When there's trp present, the operon is repressed. Trp will bind to the repressor and both together will bind to the operon blocking transcription

When there's no tryp, the repressor can't bind because it needs tryp so transcription will occur
Term
Attenuator
Definition
a leader sequence containing a regulatory site that precedes trp structural genes
Term
Attenuation
Definition
a mechanism where expression of the rest of the trp operon is repressed after transcription of the leader sequence

In the presence of tryptophan, the hairpin structures formed act as a transcriptional terminator.

In the absence of tryptophan, a different hairpin forms and acts as an antiterminator, and transcription proceeds
Term
antiterminator hairpin
Definition
forms in the absence of tryptophan and stalls the ribosome because there isn't the correct tRNA available. this will allow for transcription to proceed
Term
TRAP
Definition
a protein used by a bacteria that during attenuation of the trp operon, binds and forms a terminator hairpin. transcription stops

However if there's uncharged tRNA available, anti-TRAP will form which will induce transcription
Term
ara Operon
Definition
has both positive and negative control controlled by the AraC protein.

AraC binds to the araI region in the presence of arabinose and CAP-cAMP inducing expression

In the absense of arabinose and CAP-cAMP, AraC binds to both the araI and araO2 region forming a loop that represses the gene
Term
inducible
Definition
one that requires a substrate to "turn on" (RNA polymerase only binds in the presence of lactose)
Term
repressible
Definition
one that requires a substrate to "turn off" (RNA polymerase is always bound unless there is a high concentration of tryp)
Term
Basal (general transcription factors)
Definition
are required for RNA pol 2 to bind to the promoter
Term
TFIID
Definition
a general transcription factor that binds to the TATA box with the help of TATA binding protein
Term
Two domains of transcription factors
Definition
DNA binding domain
trans-activating domain that activates or represses transcription through protein-protein interactions
Term
3 domains of DNA-binding proteins
Definition
helix-turn-helix
zinc finger
basic leucine zipper motifs
Term
Enhanceosome
Definition
a group of activators that bind to enhancers and interacts with the transcription complex
Term
GAl genes
Definition
genes of yeast that are inducible by the presence of galactose but only when the presence of glucose is low
Term
Posttranscriptional regulation
Definition
Obviously regulation that occurs after transcription. Includes
alternative splicing
mRNA stability
translation
protein stability
Term
Alternative splicing
Definition
generates different forms of mRNA from a pre-mRNA which leads to different kinds of proteins being created
Term
Proteome
Definition
the number of proteins that a cell can make. Is not related to the number of genes because multiple proteins can arise from one gene through alternative splicing
Term
Genes that a part of gene regulation for Drosophilia
Definition
Sxl, tra, and dsx. These are all genes that regulate sex determination

Sxl gene acts as a switch that selects the pathway of sexual development by controlling splicing of dsx
Term
Autoregulation
Definition
the type of regulation where translation plays a role in mRNA stability
Term
RNA interference
Definition
uses the protein Dicer to cut double stranded RNA moleculues into small interfering RNAs (siRNAs) that bind to the RNA-induced silencing complex for unwinding
Term
DNA methylation
Definition
addition of methyl groups to the cytosine of CG doublets
Term
3 reasons why gene regulation in eukaryotes is more complex than in prokaryotes
Definition
larger amount of DNA
larger number of chromosomes
mRNA processing
Term
chromosome territories
Definition
the area that each chromosome occupies which separates them from other chromosomes

the edges of the territories contain transcriptionally active genes
Term
interchromosomal domain
Definition
areas between chromosome territories that contain little to no DNA
Term
Chromatin remodeling
Definition
involves the repositioning or removal of nucleosomes on DNA
Term
HATs
Definition
enzyme that catalyzes histone acetylation of the nucleosome which increases transcription
Term
HDACs
Definition
remove acetate groups from histone tails which decreases transcription
Term
SWI/SNF
Definition
remodels nucleosome structure in several ways such as loosening the attachment between histones and DNA or by loosening DNA from the nucleosome core. This allows for different chromosomal regions to be accessible to transcription proteins
Term
DNA methlyation
Definition
decreases gene expression because the methyl groups stick out?
Term
Promoters
Definition
nucleotide sequences that serve as recognition sites for transcription to take place such as the TATA box
Term
TATA box
Definition
region where RNA pol 2 binds for transcription
Term
Enhancers
Definition
several short DNA sequences that increase transcription rates
Term
Silencers
Definition
cis-acting elements that repress the level of transcription
Term
Transcription factors
Definition
proteins that bind to cis acting sites to regulate expression
Term
hMTIIA gene
Definition
provides an example of how a gene can be transcriptionally regulated through the interplay of multiple promoter and enhancer elements and the transcription factors that bind to them
Term
Cancer cells share two fundamental properties:
Definition
unregulated cell proliferation
metastatic spread
Term
Clonal
Definition
the property of cancer cells where they all originated from a common ancestral cell that went through many mutations
Term
Tumorigenesis
Definition
the formation of a tumor. each successive step results from a genetic alteration that makes the cell progressively lose control on its growth and proliferation
Term
Mutator phenotype
Definition
the high level of genomic instability in cancer cells

Genomic instability comes in the form of:
translocations, aneuploidy, chromosome loss, chromosomal deletions
Term
Inherited cancers caused by defects in genes
Definition
xeroderma pigmentosum
chronic myelogenous leukemia
hereditary nonpolyposis colorectal cancer
Term
Philadelpha chromosome
Definition
a specific chromosomal abnormality that is associated with chronic myelogenous leukemia (CML). It is the result of a reciprocal translocation between chromosome 9 and 22
Term
Epigenetics
Definition
the study of factors that cause DNA modifications in a heritable way without affecting the nucleotide sequence of DNA. This includes methylation and histone acetylaion
Term
G0
Definition
the cell cycle phase where metabolically active cells go even though they aren't growing or dividing. Cancer cells bypass G0 and just keep growing and dividing
Term
Signal transduction
Definition
initiates a program of gene expression that propels the cell out of G0 and back into the cell cycle. Cancer cells however often have defects in signa; transduction pathways
Term
Cyclin/CDK system
Definition
when a cyclin is present, it binds to a specific CDK triggering a CDK/cyclin complex. The complex activates the changes necessary for the cell to advance through the cell cycle.
Term
Apoptosis
Definition
programmed cell death. Will occur when the DNA is so fucked up
Term
Caspases
Definition
a series of proteases responsible for initiating apoptosis and digesting intracellular components
Term
Proto-oncogenes
Definition
genes whose products promote cell growth and division
Includes transcription factors, signal transduction molecules, and cell-cycle regulators
Term
Oncogene
Definition
a proto-oncogene that is mutated and contributes to the development of cancer
Term
Tumor suppressor genes
Definition
genes who products normally regulate cell-cycle checkpoints or initiate apoptosis
Term
ras genes
Definition
encode signal transduction molecules that regulate cell growth and division

When these get mutated, they get frozen into their active state which will constantly stimulate the cell to divide
Term
Two cyclins that are protooncogenes
Definition
D1 and E
Term
p53 tumor suppressor gene
Definition
encodes for a protein that acts as a transcription factor that represses or stimulates transcription of more than 50 different genes

Cells that lack p53 are unable to arrest the cell at specific points in the cell cycle.

Bound to MDM2
Term
mutation of the RB1 tumor suppressor gene
Definition
contributes to the development of many cancers
Term
Familial retinoblastoma
Definition
a mutated RB1 allele is inherited
Term
Sporadic retinoblastoma
Definition
requires two independent mutations of RB1 within the same cell
Term
retinoblastoma protein
Definition
a tumor suppressor protein that controls the G1/S cell cycle checkpoint
Term
Proteolytic enzymes
Definition
enzymes that break down protein? are present at high levels in malignant tumors
Term
TIMPs
Definition
regulatory molecules that control proteolytic enzymes
Term
FAP
Definition
a genetic predisposition to colon cancer. Individuals inherit just one mutant copy of the APC gene
Term
retroviruses
Definition
viruses that cause cancer
Term
Acute transforming retroviruses
Definition
viruses that cause cancer in animals by transforming normal cells into cancer cells
Term
Carcinogenic
Definition
any substance or event that damages DNA
Term
Gene pool
Definition
all the alleles present in the population
Term
Hardy-Weinberg model
Definition
describes what happens to alleles and genotypes in an "ideal" population that is infinitely large with random mating.

Assumes:

there is no selection
no new alleles arise from mutation
there is no migration into or out of the population
the population is infinitely large
random mating occurs


Predicts that the frequency of alleles in the gene pool doesn't change over time (they remain constant)
Term
Hardy-Weinberg equation
Definition
p^2 + 2pq + q^2 = 1

where p is the frequency of A and q is the frequency of a
Term
CCR5 gene
Definition
codes for the CCR5 protein that is a receptor for HIV. The mutant version is nonfunctional and so individuals will not get HIV because it won't have anything to bind to

Normal allele: CCR5-1
Mutant allele: CCR5-32

So if an individual is homozygous for CCR5-1, they are susceptible to HIV
If they are heterozygous, they are susceptible but may progress to AIDS slowly
If they are homozygous to CCR5-32, they're in the clear!!
Term
Hardy-Weinberg for X-linked traits
Definition
the frequency of X-linked alleles in the the gene pool is equal to the frequency of males expressing the X-linked trait

For females, the allele will be q^2 instead of q
Term
Natural selection
Definition
causes allele frequencies to change from one generation to the next
Term
Fitness
Definition
An individual's genetic contribution to future generations
Term
Directional
Definition
geneotype that represents a phenotypic extreme is selected and this shifts the population mean towards it
Term
stabilizing
Definition
the intermediate types are preferred over extremes
Term
disruptive
Definition
extremes are preferred over intermediate types
Term
How are new alleles created?
Definition
mutations
Term
Mutation rate
Definition
the frequency at which mutations take place
Term
Migration and gene flow alter allele frequencies, not mutations
Definition
Term
Genetic drift
Definition
occurs when the number of reproducing individuals in a population is too small to ensure that all the alleles in the gene pool will be passed on to the next generation in their existing frequencies so the genes "drift away"
Term
Founder effect
Definition
the genetic consequences seen when a population originates from a small number of individuals.
Term
Nonrandom Mating Changes Genotype Frequency but Not Allele Frequency
Definition
Term
positive assortive mating
Definition
genotypes are more likely to mate than dissimilar ones
Term
negative assortive mating
Definition
which dissimilar genotypes are more likely to mate than similar ones
Term
Coefficient of inbreeding
Definition
give the probability that two alleles of a given gene in an individual are identical because they are descended from the same single copy of the allele in an ancestor.
Term
inbreeding depression
Definition
inbred populations have a lowered mean fitness
Term
Epigenetic trait
Definition
a stable, and heritable phenotype that results from changes in gene expression without alterations in the DNA sequence
Term
Epigenators
Definition
by the cell and that stimulate a response via an intracellular pathway
Term
epigenetic initiators
Definition
Responses to epigenator signals
Term
epigenetic maintainers
Definition
maintains epigentic modifications
Term
Methylation of DNA is one major epigenetic mechanism
Definition
adds methyl groups to CpG islands which will block transcription because the islands are located near the promoter

Mostly found in repetitive DNA
Term
Histone modification is another major epigenetic mechanism
Definition
Occurs at the N-terminus site of amino acids
Includes methylation, acetylation, and phosphorylation
Can either make genes transcribable or not depending on the structure of the histone after it is modified
Term
HAT
Definition
makes genes available for DNA by adding acetyl group to histones which opens up the chromatin structure
Term
HDAC
Definition
does the opposite of hat, like the exact opposite....will deacetylize which closes the configuration. also adds methyl groups to DNA
Term
RNA interference is the last major epigenetic mechanism
Definition
siRNAs interfere with transcription initiation by associationg with protein complexes to form RISCs which blocks the promoter region?

sRNAs bind with protein complexes to form RITS which forms heterochromatin
Term
Imprinted genes
Definition
show expression of only the maternal allele or the paternal allele
Term
DNA hypomethylation reverses the inactivation of genes, leading to unrestricted transcription of many gene sets including oncogenes
Definition
Supporting users have an ad free experience!