Test #2 Flashcards
Types of Genomes
Genomes can be Single Stranded DNA, Double Stranded DNA, Single Stranded RNA, Double Stranded RNA
RetroVirus
Virus with an RNA Genome
BAC Cloning
Computer searches for common sequences in DNA by finding tagged sites or sequences. These are found in fragments. Computer finds overlaps and combines them to map genome
Synteny
Similar genes in a similar pattern among different species
Introns and Extrons
Introns: non coded regions in between coded regions.
Exons: the expressed genes
Alternative splicing
Removal of Introns and adding Exons together to form multiple proteins made from one gene
Human Genome DNA (Protein)
Only 1.5% of DNA codes for proteins
Genomic Alterations
Gene duplication: Duplication of gene next to it on the same chromosome
Transposition: moving a gene from one spot on the chromosome to another
Inversion: ???
Single Nucleotide Polymorphism
Single base variation in certain areas of the genome that are different across different people.
Haplotype
set of SNP’s
Linkage Analysis
Mapping heritable trait genes to their chromosome locations. Can examine inheritance pattern of DNA markers within families to determine if there is a relationship between a particular region of genome and phenotype
First Dimension Gel Electrophoresis
Proteins are separated according to isoelectric point
2D Dimension Gel Electrophoresis
SDS-Page to separate protein according to size. Used to compare two or more different samples (Cancer vs. no cancer) to identify proteins expressed
Supercoiling
Tight coiling of DNA for DNA packing and regulation
Supercoiling effect on transcription and replication
strand separation leads to added stress and super-coiling. As a result, the DNA becomes over-wound ahead of the polymerase, and under-wound behind.
Topoisomerase I
Relaxes negative supercoils.
Chancges linking # by 1 in positive direction. Nicking 1 stand and passing unbroken strand through the break
Topoisomerase II
DNA Gyrase
Introduces Negative supercoils, needs ATP. Changes linking # by 2 in negative direction. One intact duplex DNA segment passes through a double-strand break in another segment (breaks 2 strands)
Topoisomerase IV
Resolves Catenanes that arise in DNA replication. Passing one duplex thorough a double strand break. No ATP Required
Catenanes
Intertwined Bacterial DNA because of replication
Cohesins
Bind to Chromosomes during G1 Phase. Keep sister chromatids together during S phase DNA replication until anaphase
Condensins
Bind during Mitosis and keep chromatids condensed until separation during anaphase
SMC Proteins
Structural Maintenance of Chromosomes. Include Cohesins and Condensins. Homodimers in Bacteria. Heterodimers in eukaryotes
Histone core (histone octamer)
made of 2 sets of H2A, H2B, H4 and H3.
Histone Proteins
DNA wraps around nearly twice for each histone octamer. Histone has Lysine and Arginine so it is positively charged.
H1
Completely blocks gene expression by locking in the nucleosome
Chromatin Remodeling Complexes
Can move a histone by reposition. Eject a Histone.
Or replace Histones with altered histone for different interactions.
Acetylation:
Phosphorylation:
Methylation:
Neutralizes Charge
Decreases charge
NO change in charge
Epigenetics
During replication H3-H4 are distributed between old strand and New strand (every-other to one). H2A-H2B are then added to make full octamer. Epigentic markers fill in gaps with new histones that match original.
DNA replication method
Semi-conservatively. always goes 5’—>3’. Needs a free OH on the 3’ for proper replication. Replication is bidirectional
Replication Fork
Replication is coordinated in both direction 5’-3’ Lagging strand creates Okazaki Fragments. Continuous strand continually goes
DNA Polymerase
Needs template strand, Synthesizes in the 5’-3’, Many have 3’-5’ proofreading exonuclease activity to back up and fix something.
Polymerase I
Okazaki fragment Processing and DNA repair. 3’-5’ and 5’-3’
Polymerase III
Chromosome replication. 3’-5’ exonuclease
Enzymes required at the DNA replication Fork
Beta clamp, Helicase, Topoisomerase, DNA Primase, Ligase, SSB
Polymerase II
Transleasion repair. It has a 3’—5’ exonuclease
Polymerase IV
Transleasion synthesis . It has no exonuclease ability
Polymerase V
Transleasion synthesis. It has no exonuclease ability
Processivity
number of nucleotide that a polymerase can incorporate into DNA during a template-binding event before dissociation from the DNA. (B Clamp increases processivity by keeping polymerase on DNA)
How can we take samples every second
Mg2+ is needed for the DNA polymerase, Adding a chelating agent can stop the binding of Mg2+ and thus stop the reaction.
DAM methylase
adds methyl groups to the origin of replication. Adds after replication begins to regulate only one DNA process.
DnaA-ATP
Promotes an open complex in chromosome, closes when losing a phosphate group. (E.Coli)
Tus/Ter sites
Tus proteins bind to Ter sites
Tus Ter system prevents a replication fork from extending much beyond the halfway point around the chromosome. ensures that the fork moves in the same direction as transcription.
ORC
Origin recognition complex (eukaryotic)
Telomeres
buffer at the end of eukaryotic chromosomes. Each time replication happens, small part of the telomere is left out.
Also form T-loop to protect the chromosomes from nucleases