[MACRO Academy] H2 Biology Stem Cells Cheat Sheet

Stem Cells H2 BIOLOGY A stem cell is an (1) unspecialised cell which has (2) long-term self-renewal capability via mitosis and (3) can differentiate to give rise to specialised cells, comprising tissues and organs. POTENCY Potency is the range of cell types that a stem cell can differentiate into. Itis determined by the number of possible developmental pathways the cellpossesses. TOTIPOTENT PLURIPOTENT MULTIPOTENT Can differentiate into allcell types in an organism& any cell in the extra-embryonic membrane Can differentiate into allcell types in an organismbut not any cell in theextra-embryonicmembrane (e.g. placentalcells) Can differentiate into alimited number of celllines and types e.g. Zygotic Stem Cell(ZSC) e.g. Embryonic Stem Cell(ESC) e.g. Adult Stem Cell(ASC) Within 5 days offertlisation Between 5-7 days offertilisation More than 7 days afterfertilisation Taken from the zygote Taken from cells in theinner cell mass (ICM) ofthe blastocyst Taken from maturetissue zygote blastocyst tissue embryo zygote (ZSC) morulablastocyst (ESC) Day 1 Day 2 Day 3 Day 4 Day 5 The blastocyst will eventually develop into cells of the threegerm layers - mesoderm, endoderm, ectoderm (i.e. all cells in theorganism) Mesoderm - skin and central nervous system cells.Endoderm - gut, lungs, liverEctoderm - brain, epidermis, peripheral nervous system cells DEVELOPMENT CYCLE

Stem Cells Summary H2 BIOLOGY ADULT STEM CELLS ASCs are located in mature tissueand (1) maintain and repair thetissue in which they are located &(2) replace cells that die due toinjury or disease. e.g. BLOOD STEM CELLS Blood stem cells (BSCs), aka haemopoietic stem cells (HSCs) and can differentiate intothree cellular elements that form blood plasma. The main role of BSCs are to replaceblood cells. Red Blood Cells (erythrocytes)1. White Blood Cells (leukocytes and lymphocytes)2. Platelets (megakaryocytes)3. There are four principles governing bioethics Respect for Persons - Respecting the choice of people1. Maximizing Benefit, Minimizing Harm - Emphasisingbeneficence and non-maleficence2. Justice - Emphasising fairness3. Care - Respect for relationships between people4. Due to the ethical implications of using ESCs, scientistshave discovered a way to turn somatic cells into inducedpluripotent stem cells (iPSCs). BIOETHICS FOR IPSC AGAINST IPSC Made with patient cells - lowerchance of rejection Time consuming, Expensive - onlyavailable to select few Do not have ethical implications ofusing ESCs from humans May be tumorigenic - lack ofresearch on iPSCs Readily accessible Difficult to standardize - patientspecific HSC lymphoid progenitor cellmyeloid progenitor cell plateletsred blood cells lymphocytesleukocytes(white blood cells) erythroid lineage myeloid lineage lymphoid lineage For FREE notes, join our Telegram @macroacademy www.macroacademy.org