Tut 12 - Stem Cells (Teacher)

St Andrew’s Junior College The Cell and Biomolecules of Life / Stem Cells 2022 H1 Biology 1 Full Name: Civics group: 21S Index no.: Date: Core Idea 1: Cells and Biomolecules of Life Stem Cells Tutorial 12 MCQ 1 2 3 4 5 6 7 D A C D B A D 1 Which of the following shows the correct developmental potency of the following stem cells. Zygotic stem cells ➔ can differentiate into all types of cells to form a whole organism i.e. totipotent Embryonic stem cells ➔ can differentiate into most types of cells except extra-embryonic tissues i.e. pluripotent Myeloid stem cells ➔ can differentiate into specific lineage of cells found in the blood eg. RBCs, neutrophils, basophils i.e. multipotent Neural stem cells➔ can differentiate into specific lineage of cells that make the nervous system eg. neurons, oligodendrocytes, astrocytes i.e. multipotent A Pluripotent Totipotent Multipotent Unipotent B Totipotent Pluripotent Multipotent Unipotent C Pluripotent Totipotent Pluripotent Multipotent D Totipotent Pluripotent Multipotent Multipotent 2 Which of the following best illustrates totipotency? A A somatic cell isolated from a root tip develops into a normal adult plant. ➔ only totipotent cells can divide and differentiate into any cell type to form a whole organism. B Stem cells are able to divide indefinitely. ➔ This is characteristic of all stem cells, not just totipotent stem cells. C Mesenchymal stem cells can differentiate into an extensive range of cell types, including bone cells, cartilage cells, muscle cells and fat cells. ➔ This suggests that mesenchymal stem cells are multipotent as they can differentiate to form specific types of cells (albeit extensive)

St Andrew’s Junior College The Cell and Biomolecules of Life / Stem Cells 2022 H1 Biology 2 D The replacement of the nucleus of an unfertilised egg with that of a pancreatic cell converts the egg into a pancreatic cell. ➔ This does not illustrate totipotency as a pancreatic cell is a specialised cell. A totipotent stem cell is unspecialised. 3 Which of the following statements is/are true regarding zygotic stem cells and cancer cells? 1 Both are able to move from one location to another. ➔ only cancer cells can undergo metastasis 2 Both are able to divide by mitotic division. ➔ True; both are eukaryotic cells capable of mitosis 3 Both are specialised cells and capable to differentiate further. ➔ False, both stem cells and cancer cells are not specialised (not playing a particular function) and are capable of differentiating further given the right environmental conditions 4 Both are capable of indefinite replication. ➔ True, telomerase gene is activated in both stem cells and cancer cells A 2 only B 1 and 3 only C 2 and 4 only D 1, 2 and 4 only 4 What is the role of stem cells with regard to the function of adult tissues and organs? A Stem cells are fully differentiated cells that reside under the surface of epithelial tissue, in position to take over the function of the tissue when the overlying cells become damaged or worn out. ➔ False, stem cells are undifferentiated (not having any specific structures to play any function) B Stem cells are embryonic stem cells that persist in the adult, and can give rise to all of the cell types in the body. ➔ False, stem cells that persist in adult are already called adult stem cells, which gives rise to limited cell types (e.g. rbc, wbc, platelets) of specific lineage e.g. blood cell line C Stem cells are differentiated cells that have yet to express the genes and produce proteins characteristic of their differentiated state, and do so when needed for repair of tissues and organs. ➔ False, stem cells are undifferentiated (not having any specific structures to play any function) D Stem cells are undifferentiated cells that divide asymmetrically, giving rise to one daughter cell that remains a stem cell and one daughter that will differentiate to replace damaged and worn out cells in the adult tissue or organ. 5 [9648/2013/01/38] Stem cells are found in many tissues that require frequent cell replacement such as the skin, the intestine and the blood. However, within their own environments, a bone marrow cell cannot be induced to produce a skin cell and a skin cell cannot be induced to produce a blood cell. Which statement explains this?

St Andrew’s Junior College The Cell and Biomolecules of Life / Stem Cells 2022 H1 Biology 3 A Different stem cells have only the genes requ ired for their particular cell line. ➔ False. All stem cells of the same organism, should have the same genome B Genes not required for the differentiation of a particular cell line are methylated. ➔ True, these genes are silenced in a long term. C Binding of repressor molecules prevents the expression of genes not required for a particular cell line ➔ this mode of silencing is short term and is not used in stem cell’s long term silencing, as the types of cells that each stem cell and its progenitors can eventually give rise to, are fixed, and a certain group of genes will not be needed to be expressed in the long run. D Expression of genes not required for a particular cell line is controlled at translational level. ➔ Control is normally done at transcriptional level Examiner’s comments: Those selecting option C may have confused repression of genes in active cells with deactivation of genes not required by a particular cell line. 6 All the following statements about stem cells are true except A Cord blood stem cells will only give rise to blood cells . ➔ False. Haematopoietic stem cells found in the cord blood are pluripotent. They have the ability to differentiate into any cell type except those found in extra-embryonic tissue. B Cord blood from the newborn is a source of adult stem cells. ➔ True. Cord blood is rich in haematopoietic stem cells as well as other types of adult stem cells. C Adult somatic cells can be reprogrammed to behave like embryonic stem cells. ➔ True. This is how induced pluripotent stem cells (iPSCs) are created. D Cord blood stem cells are pluripotent. ➔ True. Haematopoietic stem cells found in the cord blood are pluripotent. 7 Which of the following is a valid ethical concern on the use of stem cells? A Use of adult stem cells could result in the formation of new organism. ➔ adult stem cells are multipotent and cannot give rise to the entire new organism B Totipotent stem cells should be recommended as they are in huge abundance. ➔ totipotent stem cells are not in huge abundance as they lasts for a short time only before differentiating into embryonic stem cells. Most research involves the usage of embryonic stem cells C Skin stem cells usage should be prohibited as they are limited in quantities. ➔ not an ethical concern; skin stem cells are easily harvested. D Embryonic stem cells retrieval results in the destruction of human embryos. ➔ human embryos might be regarded as alive.

St Andrew’s Junior College The Cell and Biomolecules of Life / Stem Cells 2022 H1 Biology 4 STQ QUESTION 1 (a) Describe the features of myeloid and lymphoid stem cells and discuss their use in the treatment of leukemia. ……………………………………………………………………………………………….[6] Features (max 3) General features 1 Self-renewal ability / divide continuously by mitosis to produce new stem cells; 2 Unspecialized and undifferentiated; Specific features 3 Derived from specialized tissues.g. from the bone marrow / peripheral stem cells suspended in the blood / cord blood; 4 Multipotent as they are able to differentiate into a limited range of cell type by differential gene expression and produce only cells of a specific lineage; [E.g. Myeloid stem cells can differentiate into red blood cells, platelets as well as various types of white blood cells (monocytes,