DNA Structure
What type of bond binds nucleotides together in a single strand?
Phosphodiester bonds
Which of the following would be found as heterochromatin, not euchromatin?(multiple answers are correct)
A) Heteromeres
B) Telomeres
C) Centromeres
D) Highly expressed regions of DNA
E) Mitotic chromosomes
Telomeres, centromeres, and mitotic chromosomes
(B, C, and E)
What is the main word that describes how DNA replication takes place?
I.E: DNA replication is ____________
DNA replication is SEMICONSERVATIVE
What are the 3 main aspects that differ in DNA and RNA?
1.) RNA is typically single stranded while DNA is double stranded
2.) RNA nucleotides are ribonucleotides that contain a ribose sugar instead of deoxyribose sugar
3.)RNA nucleotides include uracil instead of thymine
Across the rungs of the DNA ladder, nitrogenous bases are ALWAYS bound in what fashion?
Purines are always bound to pyrimidines
What is the difference between interphase and mitosis?
Interphase duplicates chromosomes, mitosis segregates these duplicated chromosomes into daughter cells.
What base pairs are replication origins typically composed of?(bonus point if you can tell me why?)
Replication origins are rich in AT base pairs because AT pairs are double bound, rather than triple bound like CG pairs, making them easier for enzymes to pull apart at the start of replication
What is the main difference between functioning of RNA Polymerase and DNA polymerase?
RNA polymerase does not need a primer to initiate transcription
What type of bond holds the 2 DNA strands of the double helix together?(Bonus point if you can tell me why?)
H bonds, because they are weak individually it makes it easier for enzymes to pull the strands apart during replication.
What is the function of the histone linker protein H1?
Presence of H1 causes DNA in the nucleosome core to be further packaged into a chromatin fiber
What characteristic of DNA allows each strand of the molecule to act as a template that specifies the exact sequence of nucleotides to the other strand?
The complimentarity of the bases
(A with T, U with G)
What sequences tell RNA when to start and stop transcription?
Promoter and terminator sequences
*Start and stop codons are used in translation, NOT transcription
In what fashion must strands be oriented in the DNA double helix?
Strands must be oriented in Antiparallel fashion
What is the order of DNA folding in mitosis?
DNA -> Chromatin(beads on a string) -> Nucleosomes -> Chromatin fiber -> Mitotic chromosome
What differentiates the 3' end of DNA from the 5' end of DNA?
The 3' end contains a hydroxyl group while the 5' end contains a phosphate group
What 4 types of RNA are produced during transcription?(bonus if you can tell me what each type is used for)
1.) mRNA: direct protein synthesis
2.) rRNA: Form structural and catalytic components of ribosomes
3.) tRNA: Directs amino acids to ribosome for incorporation into proteins
4.) miRNA: Regulate gene expression
What proteins are present in the histone octamer in the nucleosome?
2 H2A, 2 H2B, 2 H3, 2 H4
What are the 2 modifying enzymes that change nucleosome structure to allow for access to DNA?
1.) Chromatin Remodeling Complex: uses atp to change position of DNA wrapped around nucleosomes
2.) Histone-Modifying Enzymes: Catalyze addition of an acetyl group, phosphate group, or methyl group to histone tails
Name the function of each of these enzymes:
1.) Primase
2.) Nuclease
3.) Ligase
4.) Helicase
5.) Topoisomerase
6.) DNA Pol. III
7.) DNA Pol. I
1.) Primase creates the RNA primer that allows DNA Pol. III to bind to a double helix
2.) Nuclease cleaves the primer from the strand and degrades it
3.) Ligase seals the nick left from RNA primer in newly synthesized DNA via phosphodiester bonds
4.) Helicase unwinds the DNA during replication
5.) Topoisomerase relieves tension caused by unwinding by placing nicks on single strands and sealing them
6.) DNA Pol. III synthesizes new strands of DNA using the template strand via phosphate hydrolysis
7.) DNA pol. I, the repair polymerase, replaces RNA with DNA
What assists RNA Pol. in binding and initiating transcription?
General transcription factors
Specifically TFIID that binds to TATA box and distortsthe double helix and TFIIH that phosphorylates the tail fo RNA Pol releasing it from the promoter and dissociating the complex