practice questions Flashcards
Which of the following is an example of a pluripotent stem cell?
Embryonic stem cell
Explain the role of transcription factors in maintaining stem cell pluripotency
Oct4- maintaining pluripotency in stem cells
tightly regulated transcription factor associated with a number of target genes implicated in pluripotency maintenance. Regulatory elements in target genes are in close vicinity of Sox2 binding sites
Many ES cell pluripotency-associated genes are coregulated by SOX2 and Oct4.
What is the significance of the inner cell mass in embryonic development?
The inner cell mass (ICM) is a group of cells present within the blastocyst stage of embryonic development. It is significant because it contains pluripotent cells that will give rise to all the cell types in the body. The ICM is the source of embryonic stem cells, which have the potential to differentiate into any cell type, making them valuable for research and regenerative medicine.
hypoblast and epiblast –> ectodern, mesoderm and endoderm
Briefly explain the process of homologous recombination and its role in genetic inheritance
DNA DSB repair
requires a homologous template - only occurs when the genome has been replicated (late S/G2-phase)
high degree of accuracy - low frequency of mistakes
essential for cell viability
defects in HRR are associated with hereditary breast cancer and neurodegenerative disorders e.g. A-T/A-TLD/NBS/FA
pathway:
DSB
recognised by the MRN complex
MRN complex binds to CltP - activation of endonuclease activity
creates nicks in the DNA - resect away from the DSB
53BP1 complex functions to limit resection and HR
RPA binds to resected DNA
BRCA2-BRCA1-POUB2 complex removes RPA and load on Rad51
Rad51 forms a nucleofilament along the ssDNA
promotes invasion of the non-damaged DNA
invasion allows DNA polymerase to uses this as a template - DNA synthesis across the DSB - forms a double holiday junction
resolved by either
- topoisomerase/helicase complex resulting in non-crossover
- structure-specific nuclease complex which depending on the direction of cutting results in cross over/non-cross over
Discuss the potential applications of induced pluripotent stem cells (iPSCs) in regenerative medicine
Induced pluripotent stem cells (iPSCs) have significant potential in regenerative medicine. iPSCs are generated by reprogramming adult somatic cells to a pluripotent state, resembling embryonic stem cells. They offer an ethical alternative to embryonic stem cells and can be derived from a patient’s own cells, reducing the risk of immune rejection. iPSCs can be differentiated into various cell types, allowing for the potential regeneration of damaged or diseased tissues and organs. This holds promise for treating conditions such as heart disease, neurodegenerative disorders, and diabetes, as well as facilitating drug development and personalized medicine.
examples of a monogenic disorder
cystic fibrosis
Explain the difference between totipotent and multipotent stem cells.
Totipotent stem cells have the ability to differentiate into any cell type, including both embryonic and extraembryonic tissues. They can give rise to an entire organism. Multipotent stem cells, on the other hand, can differentiate into a limited range of cell types within a particular lineage or tissue. They are more specialized compared to totipotent stem cells.
Describe the process of somatic cell nuclear transfer (SCNT) and its potential applications.
Somatic cell nuclear transfer involves the transfer of the nucleus of a somatic cell into an enucleated egg cell. The resulting reconstructed egg contains the genetic material of the somatic cell donor. This technique can be used to create cloned embryos for various purposes, such as studying embryonic development, generating patient-specific embryonic stem cells, and potentially producing organs for transplantation through therapeutic cloning. SCNT has the potential to advance research in regenerative medicine and personalized medicine.
What is the role of microRNAs in gene regulation?
MicroRNAs degrade mRNA molecules and inhibit translation.
Describe the role of the Notch signaling pathway in stem cell maintenance and differentiation
When activated, the Notch receptor binds to its ligand on neighboring cells, leading to the cleavage and release of the Notch intracellular domain (NICD). The NICD then translocates to the nucleus, where it interacts with transcription factors to regulate gene expression. In stem cells, Notch signaling helps maintain an undifferentiated state and self-renewal by inhibiting differentiation-promoting genes. It also plays a role in cell fate determination, as activation of Notch can lead to the differentiation of stem cells into specific lineages.
Discuss the potential applications of gene editing technologies, such as CRISPR-Cas9, in stem cell research and therapy
. They enable precise modification of the genome, allowing scientists to edit specific genes or introduce desired changes. In stem cell research, gene editing can be used to study gene function, create disease models, and improve the efficiency of reprogramming somatic cells into pluripotent stem cells. In therapy, gene editing holds promise for correcting genetic mutations in patient-specific stem cells, which can be used for cell-based therapies or organ regeneration. However, it is important to consider ethical and safety considerations when using gene editing technologies.
Explain the concept of genomic imprinting and provide an example of an imprinted gene
Genomic imprinting is an epigenetic phenomenon where certain genes are expressed in a parent-of-origin-specific manner. It involves the addition of methyl groups to the DNA or modification of histones in a way that affects gene expression. Imprinted genes are typically marked in either the paternal or maternal allele and remain epigenetically silenced or activated. One example of an imprinted gene is the insulin-like growth factor 2 (IGF2) gene. In humans, the IGF2 gene is normally expressed from the paternal allele, while the maternal allele is imprinted and silenced. This imprinted gene plays a role in fetal growth and development
give an example of a multipotent stem cell
Hematopoietic stem cell
Explain the concept of epigenetic inheritance and provide an example of an epigenetic modification that can be inherited across generations
Epigenetic inheritance refers to the transmission of epigenetic modifications from one generation to the next without changes in the underlying DNA sequence. Epigenetic modifications, such as DNA methylation or histone modifications, can influence gene expression patterns and cellular identity. An example of an epigenetic modification that can be inherited across generations is genomic imprinting, where specific genes are marked by epigenetic modifications in a parent-of-origin-specific manner and maintain their imprinting status through multiple
what is a stem cell niche
specialized microenvironment in which stem cells reside. It provides the necessary signals, support, and interactions that regulate the behavior and maintenance of stem cells. The niche may consist of surrounding cells, extracellular matrix components, and factors secreted by nearby cells.
