Topic 2: Cells and Control Flashcards
What is the cell cycle?
A series of events that take place in a cell involving cell growth, DNA replication and cell division. It’s described as the lifecycle of a cell
What are the three stages of the cell cycle?
Interphase, mitosis and cytokines
What is interphase?
The longest stage of the cell cycle that involves cell growth, the synthesis of new organelles and DNA replication
What does DNA replication involve?
Double helix ’unzips’ exposing two strands, DNA bases align next to complementary bases on the DNA strand, complementary base pairs join and two identical DNA molecules formed
What is a chromosome?
A linear DNA molecule tightly coiled around proteins
What happens to chromosomes during DNA replication?
The DNA in the ‘arm’ of each chromosome (chromatid) is replicated
What is mitosis?
A form of cell division that produces two diploid ‘daughter’ cells, both genetically identical to the parent cell
Why is mitosis important in organisms?
Asexual production, growth, repair of damaged cells and cell replacement
What are the four stages of mitosis?
Prophase, Metaphase, Anaphase and Telophase
What happens in Prophase?
DNA condenses, chromosomes become visible and nuclear membrane disappears
What happens in Metaphase?
Chromosomes line up along the cell equator
What happens in Anaphase?
Spindle fibres attach to each chromosome, ‘arms’ of each chromosome pulled to opposite poles and chromatids separated
What happens in Telophase?
Nucleus of the cell divides and new membrane forms around each set of chromosomes
What does cytokines involve?
Division of the cell membrane and cytoplasm and two genetically identical ‘daughter’ cells produced
What is cancer?
Non-communicable disease, uncontrolled cell division results in the formation of a primary tumour
What are percentile charts?
A chart used to monitor growth and measurements can be compared to the expected values at a certain age
What can doctors determine from percentile charts?
Slower growth and faster growth than normal and abnormal growth
What is growth in animals?
Cell division occurs in all body cells, it occurs at a slower rate in adults that in younger animals as growth stops and cell division is only required for replacement and repair. Most cells differentiate at an early stage and become specialised and some adult stem cells retain their ability to differentiate
What is growth in plants?
Cell division can only occur in meristematic tissue and the rate of cell division remains the same throughout a plants life. Meristematic stem cells can differentiate into ant cell type for as long as the plant lives. Cell elongation occurs in all cells and cells expand and enlarge enabling grown of the plant
What are stem cells?
Cells that are unspecialised and capable of differentiating into a range of different cell types
What is meant by ‘differentiation’?
The process by which stem cells become specialised and some genes switch on or off, determining cell type
Why is cell differentiation important?
It enables the formation of specialised tissues with specific functions
What are embryonic stem cells?
Stem cells found in very early embryos that are unspecialised and capable of differentiating into any cell type
What is the function of embryonic stem cells?
Enables the growth and development of tissues in human embryos
What are adult stem cells?
Stems cells that can differentiate into a limited range of cell types
What is the primary function of adult stem cells?
Replacement of dead cells
Where are stem cells found in plants?
Meristems
Where is meristem tissue found?
In regions of the plant where cells are continuously dividing
What are meristematic stem cells?
Stem cells found in meristems that are unspecialised and capable of differentiating into any cell type during the life of a plant
How can stem cells be used in medicine?
Stem cells collected, stem cells stimulated to differentiate into specific cell types, specialised cells transplanted into the patient and used to treat damage or disease
Where can embryonic stem cells be collected from?
Donor stem cells removed from embryos growth in vitro and patients own stem cells removed from the umbilical blood before birth
What are the benefits of using stem cells in medicine?
Treat damage or disease, treat diseases that would otherwise be untreatable, used in scientific research and growing organs for transplant
What are the risks of stem cell use in medicine?
Transplanted stem cells could cause damage, finding suitable stem cells donors is a difficult task, stem cells may be rejected by the body, potential side effects, long term risks of using stem cells unknown and stem cells may become contaminated during preparation and when transplanted transmit infection to the patient
What are the ethical issues related to the use of stem cells in medicine?
May lead to the production of human cloning and the embryos that were used to provide stem cells are destroyed which is seen as unethical and a waste of potential human life
What is the function and structure of the cornea?
Transparent outer covering or the eye and refracts light entering the eye
What is the function and structure of the iris?
Pigmented ring of circular muscles and radial muscles and controls the size of the pupil to alter how much light enters they eye