Chromatin Structure
This enzyme acetylates histones.
What is a HAT (histone acetyltransferase)
What are point mutations?
A single nucleotide change in DNA sequence.
Examples: silent, missense, nonsense; transversions and transitions
Tumor suppressor, determining factor in DNA damage sensing pathway.
What are examples of heterochromatin?
Looking for at least 2!
Barr body (inactivated X chromosome)
Centromeric DNA
telomeric DNA
repetitive DNA
Repetitive DNA is often associated with heterochromatin.
At the centromere, these heterochromatic repetitive sequences facilitate binding of spindle fibers during segregation of homologous chromosomes and sister chromatids.
Telomeric repetitive sequences are involved in the maintenance of the chromosome's structural integrity.
In order to create the possibility of generating a trisomy, nondisjunction must occur during meiosis II.
True or False.
False, this happens during meiosis I!
This is the tightly compacted form of chromatin.
What is heterochromatin
What non-coding regions of eukaryotic DNA have we discussed that might influence gene expression?
promoter, splice sites, polyadenylation, 5’ and 3’ UTR
Which of the following statements is true of non-homologous end joining (NHEJ)?
A) it is a double-strand repair pathway
B) it is error-prone
C) it is error-free
D) it utilizes the sister chromatid as a template for repair
E) it is both error-prone and is a double-strand repair pathway
E) it is both error-prone and is a double-strand repair pathway
What are the 5 categories of eukaryotic gene regulation?
Transcriptional
mRNA processing
mature mRNA regulation
translation regulation
post-translational regulation
Which of the following statements about allopolyploid individuals is true?
A. They can be formed when two sperm simultaneously fertilize an ovum within the same species.
B. They may be sterile and unable to produce offspring.
C. They result from a mating between individuals of the same species.
D. They are generated from exposure to colchicine.
B. They may be sterile and unable to produce offspring.
Think about the ploidy of the offspring and then there cycle of reproduction.
What compromises a nucleosome? Be specific!
DNA and linker DNA
Histones - H2A, H2B, H3, H4 (linker histone - H1)
What are tautomers?
Altered base pairing, will be fixed
What fixes thymidine dimers in bacteria? in eukaryotes?
Bacteria: photoreactive repair
Eukaryotes: UV excision repair
What are 2 purposes of mRNA processing (5'cap, 3'polyA tail, splicing)?
Looking for commonality between all 3 processes.
Protect mRNA from degradability
Facilitate transport of mature mRNA
Which of the following accurately describes a possible meiotic nondisjunction event?
A. Meiosis fails to proceed to completion.
B. Fusion of gametes results in trisomy.
C. Homologs fail to separate during meiosis I.
D. Sister chromatids fail to separate during meiosis I.
C. Homologs fail to separate during meiosis I.
How does DNA methylation affect transcription?
Silences or represses transcription
More specifically, makes promoter regions inaccessible.
Give 3 differences of DNA mutation vs repair
DNA damage compared to DNA mutation
•DNA non-viable
•No flow of info; central dogma halted
•DNA repair occurs
What are three types of reversions and how do they differ from one another?
True reversion: wild-type DNA sequence is restored by a SECOND mutation within the SAME codon
Intragenic reversion: SECOND mutation at a different site within the SAME gene restores the WT phenotype
Second site/intergenic reversion: SECOND mutation in a DIFFERENT gene restores the WT phenotype
You want to design a repressor protein mutant. Which protein domain is the best target for preventing binding of the corepressor?
All of the following events occur during normal meiosis except _______.
A. two haploid gametes fuse to form a diploid cell
B. one diploid cell produces four haploid cells
C. homologous chromosomes separate from one another during meiosis I
D. sister chromatids separate from one another during meiosis II
A. two haploid gametes fuse to form a diploid cell
Name 4 exogenous damages to DNA
UV and ionizing radiation: T-T dimer, distorts structure; induces ROS that can lead to ds breaks
Nucleotide modifying agents: modify base pairing via alkylating, deaminating, and hydroxylating
Nucleotide base analogs: different structure of base
Intercalating agents: obstructs DNA structure, ex: EtBR
DNA damage signaling processes are essential for regulating the ________ transition within the cell cycle.
G1/S