Topic 2 - Cells And Control Flashcards
What is the cell cycle?
Series of events taking place in a cell
Name some parts of the cell cycle
Cell growth
DNA replication
Cell division
State the three stages of the cell cycle
Interphase
Mitosis
Cytokinesis
What is interphase
Involves cell growth, synthesis of new organelles and DNA replication
What is the longest stage of the cell cycle?
Interphase
What does DNA replication involve?
Double helix unzips
DNA bases align next to complementary bases on strands
Complementary base pairs join
2 identical DNA molecules form
What’s a chromosome?
A DNA molecule tightly coiled around proteins
What happens to chromosomes during DNA replication?
DNA in arm of each chromosome is replicated
What are the arms of the chromosomes called?
Chromatids
What is mitosis?
Form of cell division - forms 2 diploid daughter cells
Genetically identical to parent cell
Why is mitosis important in organisms?
Asexual reproduction
Growth
Repair of damaged cells
Cell replacement
State the 4 stages of mitosis
Prophase
Metaphase
Anaphase
Telophase
Outline prophase
DNA condenses
Chromosomes become visible
Nuclear membrane disappears
Outline metaphase
Chromosomes line up along cell equator
Outline anaphase
Spindle fibres attach to each chromosome
Arms of each chromosome pulled to opposite poles
Chromatids separated
Outline telophase
Nucleus of cell divides
New membrane forms around each set of chromosomes
What does cytokinesis involve?
Division of cell membrane and cytoplasm
2 genetically identical daughter cells produces
A cell divides by mitosis once every 2 minutes. Calculate the number of identical cells present after 10 minutes
10/2=5
5 cell divisions taken place
2⁵ = 32 cells
What is cancer
Non communicable disease
Uncontrolled cell division (due to damaged DNA) results in formation of primary tumour
Tumour cells break off and spread to other tissues forming secondary tumours
What are percentile charts?
Chart used to monitor growth
Measurements can be compared to expected values at 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? (3)
Slower growth than normal (below bottom line)
Faster growth than normal (above top line)
Abnormal growth (irregular growth patterns)
Describe growth in animals
Cell division occurs in all body cells at slower rate in adults than younger animals - growth stops + cell division only required for repairs
Most cells differentiate at early stage + become specialised.
Describe growth in plants
Cell division only occurs in meristematic tissue. Rate remains same through life.
Meristematic stem cells can differentiate into any cell type.
Cell elongation occurs in all cells. They expand and enlarge = growth
What are stem cells?
Cells that are unspecialised and capable of differentiating into a range of different cell types.
What is meant by differentiation?
Process where stem cells become specialised
Why is cell differentiation important?
Enables formation of specialised tissues with specific funtions
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 growth and development of tissues in human embryos