Topic 14 Flashcards
Normally the rate of mutation can be affected by which of the following?
genome size, exposure to mutagens, ionizing radiation, & infections
Is a type of regulatory protein that decreases the frequency of transcription when binding to DNA?
repressors
The control of gene expression occur through which of the following?
regulatory proteins & promoters
Gene expression is converting information from the genotype into the ____?
phenotype
Is a type of regulatory protein that increases the frequency of transcription when binding to DNA?
activators
Is a type of mutation that causes conversion to a STOP codon?
nonsense mutations
Is a type of mutation that is changes the amino acid of a protein?
missense mutation
Is a type of mutation that causes a shift in the codons, and thus changes a large amount of the amino acids downstream?
frameshift mutation
What is the relationship between mutations and evolution?
mutations can create new alleles
Is a type of mutation that does NOT cause any change to the amino acid?
silent mutation
Regulatory proteins
act by modulating the ability of RNA polymerase to bind to the promoter.
RNA polymerase binding to the promoter is the key to transcription creating the mRNA and protein synthesis.
Regulatory proteins can either block or facilitate the binding of RNA polymerase.
Regulatory proteins are able to interact with specific sequences of bases.
Repressor/Downregulation
Negative control – decreases the frequency of initiating transcription, mediated by proteins called repressors that bind to regulator sites on DNA.
Activator/Upregulation
Positive control – increases the frequency of initiating transcription, mediated by proteins called Activators
DNA-binding motifs
are the key structure within the DNA-binding domains of these proteins, most common motif is the helix-turn helix motif
Helix-turn helix motif – is the most common DNA-binding motifs, contructured from two alpha-helical segments of protein, linked by a short, nonhelical segment.
Interacts with the major groove.
Zinc finger motif – protein structural motif containing zinc ions, which interacts with the major groove, with multiple finger-like protrusions that make tandem contacts with the DNA molecule.
Leucine Zipper motifs – is created where a region on one subunit containing several hydrophobic amino acids (usually leucines) interacts with a similar region on the other subunit
locus
A specific fixed position on a chromosome, where a particular gene or genetic marker is located. The plural form is loci
Initiation/Transcription factor complex
Transcription factor complexes – bind to promoter regions upstream from genes, in the genetic code itself.
RNA polymerase I transcribes rRNA (Ribosome RNA)
RNA polymerase II transcribes mRNA (Messenger RNA)
RNA polymerase III transcribes tRNA (Transfer RNA)
operons
consisting of a single promoter, and multiple genes that are transcribed together
lac operon
consists of the regulatory region with promoter, repressor and Operator, and genes necessary to utilize lactose
consist of a Regulatory region, and Coding region with multiple genes coding for enzymes necessary for Lactose utilization
Operator – Binding site for repressor protein (lac repressor), controlling the transcription of the coding region by blocking RNA polymerase (Negative regulator
TRP Operon
consists of the promoter, repressor, and Operator, and genes necessary to synthesize tryptophan
consist of a Regulatory region, and Coding region with multiple genes coding for enzymes necessary for tryptophan synthesize
Operator – Binding site for repressor protein (Trp repressor), controlling the transcription of the coding region by blocking RNA polymerase (Negative regulator)
lac repressor (protein)
is removed by the binding of allolactose, allowing for a conformational change in structure.
trp repressor
binds to the operator under the presence of Trypotophan, and is removed in the absence of tryptophan
promoter regions
binding site for RNA polymerase.
CAP (catabolite activator protein)
affects RNA polymerase from binding to the promoter, and activated by increasing levels of cAMP (Positive regulator), becomes available in low-glucose levels in the cell/Environment.
regulatory regions
a segment of a nucleic acid molecule which is capable of increasing or decreasing the expression of specific genes within an organism
coding region
also known as the coding sequence (CDS), is the portion of a gene’s DNA or RNA that codes for protein
epigenetics
the study of how your behaviors and environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.
DNA methylation
affect the structure of the chromatin
epigenetic alteration, affecting gene expression, by using methylase, to add a methyl group to cytosine.
High level of DNA methylation correlates with inactive genes and is seen in genomic imprinting in allele-specific expression, as DNA methylation is heritable, as the semiconservative replication of DNA, produces hemi-methylated DNA that becomes fully methylated by methylase.
histone modification
affect the structure of the chromatin
changing the conformation of histones and altering the structure of chromatin, includes forms of acetylation, and methylation of lysine, and phosphorylation of serine, threonine, and tyrosine.
Depends on the type of modification and location, can activate or deactivate the transcription of gene expression.
X-Chromosome Inactivation
in female mammals, one X chromosome will become inactivated, due to proper dosage compensation, having equal genes being expression between males and females.
X-inactivation-specific transcript – a specific region of the X Chromosome that inactivates process.
Post-translation regulation
protein degradation through proteases and ubiquitin
proteins are turned over in a controlled manner, as proteins are continually being synthesized and degraded.
Ubiquitin
(76-amino acid protein), is used by eukaryotic cells for marking proteins for destruction by proteases, ubiquitin can be added in chains, with ubiquitin ligase, creating polyubiquitinated chain, to signal to destroy protein
Compare and contrast the types transcription factors
General Transcription factors – are factors necessary to recruit RNA polymerase II to a promoter region and assemble of an initiation complex for productive initiation.
Specific Transcription factors – are tissue specific or time dependent factors that stimulate higher levels of transcription than the base level.
Proteases
is an enzyme that breaks down proteins into smaller polypeptides or single amino acids
Understand the difference in gene expression in Prokaryotes and Eukaryotes, with respect to number of genes per translation, and regulatory regions within DNA
In prokaryotes, the processes of transcription and translation occur almost simultaneously in the cytoplasm. The regulation of gene expression occurs primarily at the transcriptional level. Prokaryotic transcription often covers more than one gene and produces polycistronic mRNAs that specify more than one protein.
In eukaryotes the processes of transcription and translation are physically separated by the nuclear membrane; transcription occurs only within the nucleus, and translation occurs only outside the nucleus in the cytoplasm. The regulation of gene expression can occur at all stages of the process, including transcriptional, post-transcriptional, translational, and post-translational levels.
In prokaryotes, the number of genes involved in translation is relatively small, with only about 55 genes required for the process. In contrast, eukaryotes have a much larger number of genes involved in translation, with estimates ranging from 2000 to 3000 genes.
Compare and contrast the types of regulatory factors
activators, repressors, enhancers (DNA sequences that bind to activator & increase the rate of transcription of genes), silencers (DNA sequencers that bind to repressor & decrease the rate of transcription of genes, and Transcription factors (are necessary for initiation of transcription, required for RNA polymerase enzyme to bind to the promoter region, and initiate gene expression.
Transcription factors interact with RNA polymerase to form the initiation/transcription complex at the promoter region (TATA box) upstream from a gene)
