Cells & Control Flashcards
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What is Cancer?
+ A disease caused by an uncontrolled division of abnormal cells in a part of the body + A malignant growth or tumour resulting from an uncontrolled division of cells.
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What is a tumour?
+ A swelling of a part of the body, generally without inflammation, caused by an abnormal growth of tissue, whether benign or malignant.
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What is mitosis?
+A type of cell division that results in two cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth
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What is a benign tumour?
A tumour that does not invade its surrounding tissue or spread around the body.
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What is a malignant tumour?
A tumour that may invade its surrounding tissue or spread around the body
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Why do cancer cells keep dividing?
They do not have hayflick limits
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Why doesn’t normal cells keep dividing?
Because they have hayflick limits
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What is Metastasis?
Growth of a secondary tumour
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What does the nucleus contain?
DNA and genetic material in the form of chromosomes.
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What are chromosomes?
Coiled up lengths of DNA molecules
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What do body cells normally have?
+Two copies of each chromosome +This makes them diploid cells [One comes from the organisms mother and one comes from its father]
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What happens when a cell divides by mitosis?
+It makes two identical cells to the original cell +The nucleus of each new cell contains the same number of chromosomes as the original cell.
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When do cells divide?
+When an organism grows +An organism becomes damaged and need to produce new cells for repair
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What does Mitosis produce?
Two daughter cells
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What is mitosis?
+A type of cell division in which a diploid body cell copies itself.
+It then finally divides into two identical diploid daughter cells.
+The daughter cells are clones of each other [Every base pair of their DNA is identical.]
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What are the stages of mitosis?
+Interphase +Prophase +Metaphase +Anaphase +Telophase +Cytokinesis
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What is interphase?
+The DNA in chromosomes copies itself to get ready for mitosis. +The cell spends most of its life in this phase
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What is prophase?
+The DNA in chromosomes and their copies condenses to become more visible +The membrane around the nucleus disappears
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What is Metaphase?
+Chromosomes and their copies line up in the middle of the cell.
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What is Anaphase?
+Chromosomes and their copies are pulled to different ends of the cell.
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What is Telophase?
+New membranes form around the chromosomes at each end of the cell.
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What is mitosis?
+A type of cell division in which a diploid body cell copies itself. +It then finally divides into two identical diploid daughter cells. +The daughter cells are clones of each other [Every base pair of their DNA is identical.
What happens when a cell becomes cancerous?
It begins to grow and divide uncontrollably
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What are the two types of tumour?
Benign and Malignant
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What type of cells are cancer cells?
+Undifferentiated- they do not carry out their normal function
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What causes cancer?
Carcinogens
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What are carcinogens?
+Carcinogens cause cancer by damaging DNA.-Carcinogens cause mutations to occur. +A single mutation will not cause cancer. Several are required for this to occur. +For this reason, we are more likely to develop cancer as we get older
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What are the lifestyle risk factors of carcinogens?
+Viruses +Chemical carcinogens in cigarette smoke [increases lung cancer] +Alcohol +Exposure to ultraviolet radiation [leads to development of skin cancers] +Diet [including fat and salt intake]
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What are the industrial and environmental risk factors of carcinogens?
+Exposure to ionising radiation +Exposure to chemical carcinogens +[There are also genetic risk factors for some cancers]
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How do animals and plants begin life?
+They begin life as a single cell, fertilised egg or zygote +These cells must divide by mitosis to produce a multicellular organism
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Where does mitosis happen in plants and animals?
+Mitosis happens throughout the bodies of animals +But it only occurs in specific regions of plants +These are called meristems and are found in the tips of roots and shoots [here new cells are formed]
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What are meristems?
+Specific areas of plants where mitosis occurs +Meristems produce unspecialised cells that are able to divide and form any cell type in the plant +The unspecialised cells go on to form specialised tissues like xylem and phloem
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What is cell elongation?
+Where plants are able to become longer as they grow +This process occurs throughout the plant not just the meristems +[Cell elongation does not occur in animals]
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What is cell differentiation?
+Where the cells of multicellular animals and plants develop features that enable them to fulfil specific roles +Cells that have differentiated have become specialised. +Without this specialisation, complex multicellular animals and plants would not exist.
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What are some specialised systems in animals?
+Circulatory system +Excretory system +Muscular system +Nervous system +Respiratory system +Reproductive system +Skeletal system
What are some specialised cells of plants?
+Palisade mesophyll +Spongy mesophyll +Guard cells +Sieve tubes +Companion cells +Xylem vessels +Meristem
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What are some specialised cells of animals?
+Egg cell +Sperm cell +Ciliated epithelial cells
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How are the growth of babies measured?
+Mass [kg] +Length [cm] +Head circumference [cm]
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What are percentile growth charts?
Charts that measure the growth of a baby over a period of time
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What are stem cells?
+Stem cells are cells that have not undergone differentiation.
+ A cell which has not yet become specialised is called undifferentiated.
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What are embryonic stem cells?
+Stem cells found in the embryo that can differentiate into any cell type
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What are adult stem cells?
+Stem cells that can only differentiate into specific cell types +Mainly found in the bone marrow +Used to replace damaged cells
What happens in a growing shoot?
+New cells are being continuously produced near the tip +As cells become older, further away from the tip, they become differentiated +They enlarge and develop a vacuole
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How do you obtain embryonic stem cells?
+The best source is a five day old embryo [although there are clinical ethical and social issues with their use]
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Give an example of an adult stem cell transplant
Bone marrow transplants
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When are bone marrow transplants carried out
+In cases of blood cell cancer such as leukaemia and lymphoma +When blood cells have been destroyed by cancer treatment
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What do stem cells have great potential for?
+Treating patients with currently untreatable conditions +Growing organs for transplants +Medical research
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What are the clinical issues of stem cells?
+There is no guarantee how successful treatment will be +The difficulty in finding suitable stem cell donors
+The difficulty in obtaining and storing a patients embryonic stem cells +Stem cells could mutate (causes cancer) +Cultured stem cells could be contaminated with viruses
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What are the ethical issues of stem cells?
+A source of embryonic stem cell is unused embryos produced by in vitro fertilisation (IVF) +Is is right to create embryos for therapy and destroy them in the process? +Embryos could come to be viewed as a commodity, not as an embryo that could develop into a person
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What are the social issues of stem cells?
+It is important to educate the public about what stem cells can and can’t do +Whether benefits of stem cell research outweigh the objections +Patients could be exploited by paying for expensive treatments and being given false hope of a cure [as stem cell therapies are only in their developmental stages]
