BIOL 331 Final Exam with correct
answers 100% 2026
Mechanism of cellular differentiation - Correct Answerchromatin closure
Heterochromatin - Correct AnswerHighly compacted chromatin that is not accessible for
transcription (especially after mitosis)
Euchromatin - Correct AnswerLess condensed, transcriptionally active (Eu = true, "truly
transcribed")
Nucleosome - Correct AnswerA length of DNA wound twice around a histone heterooctamer
6 Chemical Modifications Comprising the Histone Code - Correct Answer1. Acetylation +
2. DNA Methylation -
3. Histone Methylation -
4. Phosphorylation
5. Ubiquitination
6. small RNA silencing
HAT - Correct AnswerHistone Acetyl Transferase (opens chromatin)
HDAC - Correct AnswerHistone Deacetylase (closes chromatin)
HP-1 - Correct AnswerHeterochromatin Protein-1. Recruited by methylation of lysine 9 on H3
Impact of small RNAs on chromatin - Correct AnswerBinds to a gene and promotes methylation
,Only totipotent cell in mammals - Correct AnswerZygote
Pluripotent - Correct AnswerCells that are capable of developing into any cell type except extra-
embryonic cells
Totipotent - Correct AnswerStem cells with the potential to differentiate into any type of cell
(including extra-embryonic cells)
Multipotent - Correct AnswerStem cells that can form a limited range of cells within a tissue
Protoamines - Correct Answersmall, arginine-rich, nuclear proteins that replace histones late in
the haploid phase of spermatogenesis
Induced Pluripotent stem cells - Correct AnswerInduce differentiated cells back to an
undifferentiated state; can make many cell types
Self-renewal - Correct AnswerDivision of a stem cell to produce two more stem cells
Cadherins - Correct Answercalcium-dependent glycoproteins that hold similar cells together
Selectin - Correct AnswerCell adhesion transmembrane glycoproteins that bind sugar moieties
L-selectin - Correct AnswerSelectins found on leukocytes
E-selectin - Correct AnswerSelectin molecule on endothelial cells
, P-selectin - Correct Answerselectin found on platelets and endothelial cells
Integrin - Correct AnswerTransmembrane receptors that facilitate cell-extracellular matrix
adhesion. Upon ligand binding, integrins activate signal transduction pathways that mediate
cellular signals such as regulation of the cell cycle, organization of the intracellular cytoskeleton
Immunoglobulin Superfamily - Correct AnswerCell adhesion molecules that contain
immunoglobulin domains that attach to another IgSF member or integrin on another cell.
Steps in Neutrophil Extravasation - Correct Answer1. Upregulation of selectins at sight of
infection
2. These selectins bind sugar moieties on neutrophils
3. Platlet activating factor (IL8) on endothelial cells activate a GPCR on neutrophil that activates
integrins
4. Activated neutrophil integrins bind ICAM on endothelial cells which allows transendothelial
migration
ICAM - Correct AnswerIgSF Intercellular adhesion molecule. An endothelial cell surface
glycoprotein that binds integrins (especially on neutrophils)
PAF (IL8) - Correct AnswerPlatlet activating factor. Endothelial PAFs activate a GPCR on
neutrophils that activates neutrophil integrins that bind ICAM
Order of Cell Junctions (Top to Bottom) - Correct Answer1. Tight
2. Adherins
3. Desmosomes
Functions of Tight Junctions - Correct Answer1. Gate Function
answers 100% 2026
Mechanism of cellular differentiation - Correct Answerchromatin closure
Heterochromatin - Correct AnswerHighly compacted chromatin that is not accessible for
transcription (especially after mitosis)
Euchromatin - Correct AnswerLess condensed, transcriptionally active (Eu = true, "truly
transcribed")
Nucleosome - Correct AnswerA length of DNA wound twice around a histone heterooctamer
6 Chemical Modifications Comprising the Histone Code - Correct Answer1. Acetylation +
2. DNA Methylation -
3. Histone Methylation -
4. Phosphorylation
5. Ubiquitination
6. small RNA silencing
HAT - Correct AnswerHistone Acetyl Transferase (opens chromatin)
HDAC - Correct AnswerHistone Deacetylase (closes chromatin)
HP-1 - Correct AnswerHeterochromatin Protein-1. Recruited by methylation of lysine 9 on H3
Impact of small RNAs on chromatin - Correct AnswerBinds to a gene and promotes methylation
,Only totipotent cell in mammals - Correct AnswerZygote
Pluripotent - Correct AnswerCells that are capable of developing into any cell type except extra-
embryonic cells
Totipotent - Correct AnswerStem cells with the potential to differentiate into any type of cell
(including extra-embryonic cells)
Multipotent - Correct AnswerStem cells that can form a limited range of cells within a tissue
Protoamines - Correct Answersmall, arginine-rich, nuclear proteins that replace histones late in
the haploid phase of spermatogenesis
Induced Pluripotent stem cells - Correct AnswerInduce differentiated cells back to an
undifferentiated state; can make many cell types
Self-renewal - Correct AnswerDivision of a stem cell to produce two more stem cells
Cadherins - Correct Answercalcium-dependent glycoproteins that hold similar cells together
Selectin - Correct AnswerCell adhesion transmembrane glycoproteins that bind sugar moieties
L-selectin - Correct AnswerSelectins found on leukocytes
E-selectin - Correct AnswerSelectin molecule on endothelial cells
, P-selectin - Correct Answerselectin found on platelets and endothelial cells
Integrin - Correct AnswerTransmembrane receptors that facilitate cell-extracellular matrix
adhesion. Upon ligand binding, integrins activate signal transduction pathways that mediate
cellular signals such as regulation of the cell cycle, organization of the intracellular cytoskeleton
Immunoglobulin Superfamily - Correct AnswerCell adhesion molecules that contain
immunoglobulin domains that attach to another IgSF member or integrin on another cell.
Steps in Neutrophil Extravasation - Correct Answer1. Upregulation of selectins at sight of
infection
2. These selectins bind sugar moieties on neutrophils
3. Platlet activating factor (IL8) on endothelial cells activate a GPCR on neutrophil that activates
integrins
4. Activated neutrophil integrins bind ICAM on endothelial cells which allows transendothelial
migration
ICAM - Correct AnswerIgSF Intercellular adhesion molecule. An endothelial cell surface
glycoprotein that binds integrins (especially on neutrophils)
PAF (IL8) - Correct AnswerPlatlet activating factor. Endothelial PAFs activate a GPCR on
neutrophils that activates neutrophil integrins that bind ICAM
Order of Cell Junctions (Top to Bottom) - Correct Answer1. Tight
2. Adherins
3. Desmosomes
Functions of Tight Junctions - Correct Answer1. Gate Function
