Topic 2 – Cells and Control-Cell Division and Growth Flashcards
what is cell cycle?
series of events that take place in cell involving cell growth, DNA replication and cell division
described as lifecycle of cell
state 3 stages of cell cycle
stage 1- interphase
stage 2-mitosis
stage 3- cytokinesis
what is interphase?
longest stage of cell cycle that involves cell growth, synthesis of new organelles and DNA replication
what does DNA replication involve?
double helix ‘unzips’ exposing 2 strands
DNA bases align next to complementary bases on DNA strand
complementary base pair joins
2 identical DNA molecule formed
what is a chromosome
linear DNA molecule tightly coiled around proteins
what happens to chromosome during DNA replication?
DNA in arm of each chromosome is replicated.
what is mitosis?
form of cell division that produces 2 diploid daughter cells both genetically identical to parent cell.
why is mitosis important in organisms?
asexual reproduction
growth
repair of damaged cells
cell replacement
state 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 chromosomes pulled to opposite pole
chromatids seperated.
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 produced.
a cell divides by mitosis once each 2 minutes. calculate number of identical cells present after 10 minutes?
10/2=5
5 cells divisions have taken place
2^5=32
what is cancer?
non communicable disease
uncontrolled cell divison results in formation of a primary tumour
tumour 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 a certain age
what does 95th percentile mean?
95% of measurements will be below value of 95th percentile
what can doctors determine from percentile charts?
slower growth then normal
faster growth then normal
abnormal growth
describe growth in animals
cell division occurs in all body cells.occurs at slower rate in adults that in younger animals as growth stops and cell divison is only required for replacement and repair.
most cells differentiate at early age stage become specialised. some adult stem cells retain ability to differentiate.
describe growth in plants
cell division can occur in meristematic tissue. rate of cell division remains same throughout a plants life.
meristematic stem cells can differentiate into any cell type for as long as they live
cell elongation occurs in all plants. cells expand and enlarge enabling growth
what is meant by differentiation?
process which stem cells become specialised.
some genes switch on or off, determine cell type
why is cell differentiation important?
enables formation of specialised tissues with specific functions e.g. muscle tissue.
what are embryonic stem cells?
stem cells found in very early embryos that are unspecialised and capable of differentiating into any type of cell
what is function of embroyonic stem cells?
enable growth and development of tissues in human embryos.
what are adult stem cells?
stem cells that can differentiate into limited range of cell types
what is primary function of adult stem cells?
replacement of dead cells, e.g. replacement of red blood cells which live only 120 days.
where are stem cells found?
meristems
where is meristem tissue found?
regions of plant where cells are continuously dividing.
what are meristematic stem cells?
stem cells found in meristems that are not specialised, and capable of differentiating into any cell during 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 cell transplanted into patient
used to treat damage or disease
where can embryonic stem cells be collected from?
donor stem cells removed from embryos grown
patients own removed from umbilical blood before birth
what are benefits of using stem cells in medicine
treat damage or disease
treat diseases that are untreatable
used in scientific research
growing organs for transplant
what are risk of stem cell used medicine
transplanted stem cell can cause tumours.
finding suitable stem cell donors is difficult task
stem cells may be rejected by body
potential side effect
long term risks of using stem cells unkown
may become contaminated during preparation
what are ethical issues of stem cells?
embryos are destroyed, which is waste of human live.
may lead to reproductive cloning
