| What is a stem cell? | An undifferentiated cell that is capable of becoming another cell type |
| What happens when a cell differentiate? | It produces certain subcellular structures to become a specialised cell that is adapted for its function |
| What is an example of a specialised cell? | Muscle cells as it has mitochondria as its subcellular structure like any other cell, but instead it has many of mitochondria because it is a higher energy demand than most cells. |
| There are different ways of getting stem cell. Name one example. If unsure, look at the diagram. | Embryonic stem cells |
| What happens during embryonic stem cell? Look carefully at the diagram then explain what is happening during it. (DIFFICULT) | A sperm cell meets a human egg. Then, a sperm fertilises the egg to form a fertilised zygote or egg with a full set of human chromosomes, which is 46. Then, the zygote starts dividing by mitosis to form an embryo. None of the cells would have specialised as undifferentiated cells. They have the choice to become any cell type e.g nerve cells, brain cell or muscle cells. The cell then undergoes its first wave of differentiation to form two cell types in a structure called the blastocyst. |
| Zoom in at the diagram. How many chromosomes do a sperm cell have? | Half the full set of chromosome |
| Zoom in at the diagram. How many chromosomes do a egg cell have? | Half the full set of chromosome |
| What is the number of full set of chromosomes? | 46 |
| What is an embryo? | A ball of cells that are each clone of one another. Every single one of the cells would have 46 chromosomes and contain same genes. |
| What is a zygote? | A fertillised egg with a full set of chromosomes |
| How would the zygote into an embryo during embryonic stem cell? | By mitosis |
| What is a blastocyst? | A hollow ball of cells. The outer cells would have the choice to become cells that form the women's placenta, and umbilical cord for the foetus. |
| What are the purple cells clustered inside the blastocyst called? | Inner cell mass cell. |
| What is the purple cells clustered inside the blastocyst job? | Has genes that allow the cell to form a placenta or umbilical cord switched off or deactivated. |
| All the other genes that can make the cell in the foetus is active in where? | The adult human |
| What is the purple cells clustered inside the blastocyst important? | To treat someone, who has got an illness to the cells not working properly and can't be replaced by the body. It gets extracted from the blastocyst as they would not need a new plecenta or umbilical cord, then grown in a lab into cell of choice. |
| What is the human being post birth called? | Adult stem cells |
| What is an adult stem cell? | A newborn baby, which is not an embryo anymore, and has the ability to differentiate and form new cells. |
| Give example of stem cells where cells and tissues have to be replaced | Skin cell |
| Why do skin cells constantly have to be replaced and how it is also effective at this? | Skin cell's upper layer is constantly shedding as dead cells. Below them, there are live, nearly formed skin cells ready to be replaced so it can do its job effectively. |
| Why do bone marrows constantly have to be replaced and how is it effective at this? | The cells in our blood are constantly being replaced, so it has a source of stem cells found in the softer tissue part of our bone called bone marrow. |
| Give a name of an example in which there are problems with the blood cell in the bone marrow. | leukaemia and they would need to have their defective blood cells killed off by kinesitherapy with bone marrow transplant. |
| How would leukaemia work? | You would insert a long needle through the hip of a donor, and bone marrow stem cells get extracted then injected to patient. |
| What is the disadvantages of adult stem cells? | They have a limited potential cell type to become (multipotent) |
| Why would they use a very close relative for leukaemia? | The new cells need to match as much as possible |
| Why would they take someone who has been paralysed during their life for adult stem cell? | Nerve cells in their spine has become sievert |
| Why would some people think using embryonic stem cells is unethical? | It has a right to life |
| Where does the source of these embryonic cells come from? | IVF patients |
| When people have IVF, sperm and egg is removed and is put on and tested where? | On a petri dish in a lab |
| What reasons are there that agree for embryonic stem cells? | Totipotent |
| What is therapeutic cloning? | Cloning a human embryo to be genetically identical to the patient so you can harvest stem cells from it to treat the patient |
| What are the steps to therapeutic cloning? Use the images to help you. | You get the patient's cell ideally one healthy one. Inside, would be a nucleus with a full set of chromosomes of 46. You would then remove the nucleus and put an empty egg cell into it. So, you get an egg from the donor with half the full set of 23. You would only need the cell membrane of the cell - nothing else nor the DNA associated with the egg cell, so you would remove the nucleus and put in into the bin. You would have an empty egg without a nucleus. You put the patient's nucleus with the donor's empty egg cell. The cell is tricked to become a zygote. There is then the fertilised egg.
You then give the cell a small and slight electic shock to get the cell to start dividing into an embryo or a ball of cells. All the cells are identical and have the potential to become totipotent. So, for example, the patient had spinal paralysis, you would separate them with a petri dish. If there was the right cocktail of hormones, you would then program it to differentiate to start making extra or less sub-cellular structures. A nerve cell could be produced by nerve cells to treat paralysis. Cells that give insulin could also be formed for people with diabetes. A brain chemical, dopamini, could also be formed in the brain. The embryo does not get implanted into a uterus of umbilical cord though. |
| What is different to plants than mammals when it comes to differentiation? | They have to ability to differentiate throughout their entire life unlike mammals |
| What is different in stem cells in plants compared to stem cells in animals? | They have the ability to regain totipotency |
| What would gardeners do for stem cells in a plant during gardening? Give the full steps | They would take a snip of the plant. All the cells in the exposed part of the plant of the stem of the leaf would revert back into being in a state in which they form back into a meristem. You dip the end into a powder, which is a hormone and growth factor. You then place it into a compost/ soil and some of the cells would differentiate and switch on genes into cells that form the root. It then gets water and minerals from the soil over time. It would change into a plant identicaL TO THE PARENT. |
| What is a cutting? | It is when a gardener during gardening takes a snip or cut off a plant. |
| Where would you find meristems? | In the growing tips of the roots and shoots |
| What are meristems? | Unspecialised stem cells in plants are grouped together and are found in the root and shoot tips |
