OD 515 Chromosomes - Questions Exam 1 with
complete solutions.
What is the primary function of chromosomes?
To organize and compact large amounts of DNA to fit inside the cell nucleus.
What are the three learning objectives of this document?
Describe genetic material structure, explain human/mitochondrial DNA and enzymes, and
explain genetic regulation.
What is chromatin?
The combination of DNA and proteins that makes up chromosomes.
What are exons?
DNA segments that code for functional products, accounting for ~1.5% of human DNA.
What are introns?
DNA segments that do not code for a polypeptide product, rare in bacteria.
What are the five major classes of histones in eukaryotic cells?
H1, H2A, H2B, H3, and H4.
Which histone acts as a linker unit to stabilize DNA between nucleosomes?
Histone H1.
What subunits make up the histone octamer core?
Two copies each of H2A, H2B, H3, and H4.
, What is a nucleosome?
The fundamental unit of chromatin, consisting of ~200 bp of DNA wound around histones.
What local DNA sequence features facilitate binding to the histone core?
Abundance of A=T base pairs and staggered AA, AT, or TT dinucleotides at 10 bp intervals.
What is the physical state of the amino-terminal tails of histones?
Intrinsically disordered, serving as the primary site for histone modifications.
What is DNA underwinding?
Negative supercoiling that reduces helical turns, facilitating packaging and access to genetic
information.
Compare plectonemic and solenoidal supercoiling.
Plectonemic uses extended right-handed supercoils; solenoidal uses left-handed supercoils and
compacts DNA.
What is the topological linking number (Lk)?
The number of times a twisting DNA strand penetrates a surface.
What are cruciform structures in DNA?
Structures formed by unpaired bases under torsional stress that can stall transcription.
How do Type I and Type II topoisomerases differ in mechanism?
Type I breaks one strand (Lk steps of 1); Type II breaks both strands (Lk steps of 2).
What is a chromatid?
complete solutions.
What is the primary function of chromosomes?
To organize and compact large amounts of DNA to fit inside the cell nucleus.
What are the three learning objectives of this document?
Describe genetic material structure, explain human/mitochondrial DNA and enzymes, and
explain genetic regulation.
What is chromatin?
The combination of DNA and proteins that makes up chromosomes.
What are exons?
DNA segments that code for functional products, accounting for ~1.5% of human DNA.
What are introns?
DNA segments that do not code for a polypeptide product, rare in bacteria.
What are the five major classes of histones in eukaryotic cells?
H1, H2A, H2B, H3, and H4.
Which histone acts as a linker unit to stabilize DNA between nucleosomes?
Histone H1.
What subunits make up the histone octamer core?
Two copies each of H2A, H2B, H3, and H4.
, What is a nucleosome?
The fundamental unit of chromatin, consisting of ~200 bp of DNA wound around histones.
What local DNA sequence features facilitate binding to the histone core?
Abundance of A=T base pairs and staggered AA, AT, or TT dinucleotides at 10 bp intervals.
What is the physical state of the amino-terminal tails of histones?
Intrinsically disordered, serving as the primary site for histone modifications.
What is DNA underwinding?
Negative supercoiling that reduces helical turns, facilitating packaging and access to genetic
information.
Compare plectonemic and solenoidal supercoiling.
Plectonemic uses extended right-handed supercoils; solenoidal uses left-handed supercoils and
compacts DNA.
What is the topological linking number (Lk)?
The number of times a twisting DNA strand penetrates a surface.
What are cruciform structures in DNA?
Structures formed by unpaired bases under torsional stress that can stall transcription.
How do Type I and Type II topoisomerases differ in mechanism?
Type I breaks one strand (Lk steps of 1); Type II breaks both strands (Lk steps of 2).
What is a chromatid?
