Topic 2 - cells and control Flashcards
What is the cell cycle?
A series of event that take place in a cell involving cell growth, DNA replication and cell division
It is described as the life cycle of a cell
What is interphase?
The cell grows. New organelles are synth sized and the DNA is replicated
What are the stages of mitosis?
Interphase Prophase Metaphase Anaphase Telophase Cytokinesis
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 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 reproduction
Growth
Repair of damaged cells
Cell replacement
Outline prophase
DNA condenses, chromosomes become visible
Nuclear membrane disappears
Outline metaphase
Chromosomes line up along the cell equator
Outline anaphase
Spindle fibres attach to each chromosome
‘Arms’ of each chromosome pulled to opposite poles
Chromatids separated
Outline telophase
Nucleus of the cell divides
New membrane forms around each set of chromosomes
What does cytokinesis involve?
Division of the cell membrane and cytoplasm
Two genetically identical ‘daughter’ cells produced
What is cancer?
Non-communicable disease
Uncontrolled cell division which results in the formation of a primary tumour
Tumour cells break off and spread to other tissues forming secondary tumours
What are percentile charts?
A chart used to monitor growth
Measurements can be compared to the expected values at a certain age
What does the 95th percentile mean?
95% of measurements will be below the value of the 95th percentile
What can doctors determine from percentile charts?
Slower growth than normal
Faster growth than normal
Abnormal growth
Describe growth in animals
Cell division occurs in 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 some adult stem cells retain their ability to differentiate
Describe growth in plants
Cell division can only occur in meristemic tissue. The rate of cell division remains the same throughout a plant’s life
Meristematic stem cells can differentiate into any cell type for as long as the plant lives
Cell elongation occurs in all cells. Cells expand and enlarge
What are stem cells?
Cells that are unspecialised and capable of differentiating into a range of different cell types
What is meant be differentiation?
The process by which stem cells become specialised
Some genes switch on or off determining cell types
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?
Enable the growth and development of tissues in human embryos
What are adult stem cells?
Stem cells that can differentiate into a limited range of cell types e.g bone marrow stem cells
What is the primary function of adult stem cells?
Replacement of dead cells
Where are stem cells found in plants?
Meristem