Exam 2 - Review Flashcards
What conclusions did Beadle and Tatum make pertaining to the gene-protein relation?
A single gene encodes a single enzyme
What is the region of repetitive nucleotide sequences at the end of chromosomes termed?
Telomeres
What is the region on the chromosome where there spindle fiber attaches via the kinetochore? Essential for chromosome separation.
Centromere structure
What is the funciton of telomeres?
Protects the end of the chromosome from deterioration or from fusion with neighboring chromosome
What biological outcomes are associated with shorter telomeres?
Shorter life span and increased incidence of disease
What complex of proteins assoicated with centromeres of a chromosome aloow the spindle to attach during cell division?
Kinitochore
Cylindrical cell organelle, located near the nucleus in the cytoplasm of most eukaryotic cells, that divides in perpendicular fashion during mitosis.
Centriole
If a chromosome where to break and one of the fragments did not have a centromere what would occur?
The fragment without the centromere would degrade
Enzyme responsible for adding and removing turns in the coil (i.e. DNA coil).
Topoisomerase
What permits the attaction of histones to DNA?
Histones are positively charged and DNA is negatively charged
Complex formed by DNA wrapped around eight histone proteins.
Nucleosome
What is the difference in chromatin condensation between euchromatin and heterochromatin?
Euchromatin is less condensed and heterochromatin is more condensed
DNase I sensitivity sites tend to be at accesible chromatin. What can this be used to determine?
Gene expression
By testing DNase I sensitivity throughout a embryo’s lifetime researchers were able to conclude what?
Chromatin structure changes in the course of transcription
A heritable alteration of phenotype because of altered chromatin structure without changing DNA sequence.
Epigenetics
Tract of tandemly repeated DNA motif that ranges in length from two to five nucleotides typically repeated 5-50 times.
Microsatellite DNA
What is the goal of amplifying microsatellite DNA sequences?
Can help determine a persons “DNA fingerprint” as well as DNA profiling in cancer diagnosis
What would occur if the positive charges on the histone proteins was neutralized?
They would separate from DNA and the would not be attracted to each other
Proposes that mitochondria and chloroplasts were once free-living bacteria.
Endosymbiotic theory
What evidence supports the endosymbiotic theory?
Mitochondria/Chloroplast are similiar to eubacteria (i.e. circulat DNA, no histones, 70s ribosomal subunit, and grow via binary fission)
What is a popular example of uniparental inheritance of organelle-encoded traits in mammals?
Mitochondrial DNA is nearly exclusively inherited from female parent
The presence of more than one type of organellar genome.
Heteroplasmy
Seperation of organlles in heteroplasmic cells is guided/random.
Random
What has a higher mutaiton rate in vertebrates mitochondrial DNA or nuclear DNA?
Mitochondrial DNA
Most copies of mitochondrial DNA are different/identical.
Identical
What is the association with aging and mitocondrial damge?
Proportional
What is the purpose of pronuclear transfer?
Prevent transmission of mitochondrial DNA disease (i.e. note this is not a flawless process)
Why is pronuclear transfer not perfect?
There is some carry over from the mother with damaged mitochondria
What were the conclusions of the Beadle and Tatum experiments?
Each enzyme is encoded by a single gene
What is meant by a degenerate code?
AA may be specified by more than more codon
What are synonymous codons?
Codons that specify the same AA
What are isoaccepting tRNAs?
Different tRNAs that accept the same AA however they have different anticodons
What are sense codons?
Encoding AA
What is the Wobble hypothesis?
Essentially states that pair rules are flexible at the third nucleotide of a codon
What is meant by nonoverlapping in genetics?
A single nucleotide may not be included in more than one codon
Term for binding of AA to tRNA?
Charging
What part of a tRNA does an AA bind to?
3’ (i.e. to an adenine)
True/False: For each tRNA there is a specific aminoacyl-tRNA synthase that facilitates that attachment of AA to tRNA.
True
What are Kozak Sequences?
Consensus sequences that signal the beginning of the coding sequence
What components are required during initation of translation?
Initiation factors and GTP
What proteins are recruited in the presence of a stop codon, they bind to the ribosome, and facilitate release of the polypeptide?
Release factors
Generally what processes are involved in translation?
tRNA charging, initiation, elongation, and termination
What is a polyribosome?
An mRNA with several ribosomes attached
What are structural genes?
Genes that encode for non-regulatory proteins
What are regulatory genes?
Genes that encode for proteins that interact with other sequences thus affecting transcription and translation of those sequences such as transcription factors
What are regulatory elements?
DNA sequences that are not transcribed but regulate other nucleotide sequences
What is constitutive expression?
Gene that are always expressed under normal cellular conditions
What is positive control?
Control that stimulates gene expression
What is negative control?
Control that inhibits gene expression
60-90 AA responsible for binding to DNA, forming hydrogen bonds with DNA.
Domains
Within a binding domain, a simple structure that fits into the major groove of the DNA.
Motif
A DNA sequence encoding products that affect the operon function but are not part of the operon.
Regulator gene
List some difference in gene expression control in eukaroytes and prokaryotes.
Eukaryotes - Structural genes have their own promoter and are transcribed indiviually, histone unwinding is required, and transcription and translation occur at seperate times and in different spaces
Examples of histone modifications
Addition of methy group to histone protein tail and addition of acetyl groups to histone proteins
What can be concluded using chromatin immunoprecipitation (ChIP)?
ID DNA-binding sites for a specific protein and locations of modified histone proteins
A DNA sequence that stimulates transcription at a distance away from the promoter.
Enhancer
DNA sequence that prevents or insulates that effects of an enhancer.
Insulator
A multiprotein complex that acts as a transcriptional coactivator in all eukaryotes. Transmits signals from transcription factors to polymerases.
Mediator
Common regulatory elements upstream of the start sites of a collective group of genes in response to a common environmental stimulus
Response elements
Small non-coding RNA that functions in RNA silencing and post-transcriptional regulation of gene expression.
microRNA
siRNAs and miRNAs usually bind to what part of the mRNA molecule?
3’ UTR
