ch 2 cell divison and differentiation Flashcards
when do cells divide
when the body needs to
-grow
-replace worn out cells
-repair damaged tissue
how many pairs of chromosomes do we have
23 - 46 in total
what does homologous mean
identical
what are chromosomes
long strands of dna found in nucleus
whats the difference between mitosis and meiosis
mitosis produces 2 genetically identical daughter cells while meiosis occurs after mitosis and produces 4 differentiated daughter cells
what are the stages of mitosis
1- interphase where dna is replicated
2-chromosome migrates to opposite ends of cell
3- cell divides in 2 with same number of chromosomes
4- end up with 2 identical daughter cells
in which cells does mitosis not occur
all cells except gametes (sex cells)
what happens when cells divide uncontrollably
causes tumor then cancer
what is the cell cycle
the process a cell goes through each time it divides
-chromosome doubles
-cell divides into 2 daughter cells and receives 1 copy of doubled material
what are the 3 main phases of the cell cycle
-interphase
-mitosis
-cytokinesis
what happens in interphase
organelles double and dna replicates to form 2 coppies
what happens in mitosis
the chromosomes move apart and nucleus divides
what happens in cytokinesis
the cell membrane splits in 2 to finally give 2 identical daughter cells
what happens in meiosis
4 differentiated daughter cells are created (haploids)
what happens in the stages of meiosis
-chromosomes are doubled
-mitosis
-cell divides again which forms 4 gametes (sex cells)
what are the main features of meiosis
-cell divides twice and forms 4 gametes
-gametes are genetically different
what are stem cells
cell that hasnt become differentiated or specialised yet
what are the features of stem cells
-can replicate many times by mitosis
-can become different types of cells
what happens to stem cells during the development of an embryo
most cells become specialised
cell differentiation is a ____ process
irreversable
what are plant stem cells called
meristem cells
where are meristem cells found
root and shoot tipes
what are the 2 functions of stem cells
-growth and development
-repair and replacement
what happens to cells over time
they die or get too old to function properly
why are adult stem cells needed
for growth
eg:bone marrow
why are embryonic stem cells needed
to develop- they come from discarded embryos
why are adult stem cells resistricted in types of cells they can become
because genes are turned off
what are the features of embryonic stem cells
-they can differentiate into any cell
-usually removed from human embryos
-unspecialised
what are the features of adult stem cells
-specialised
-can only differentiate into skin or blood cells
name 3 organs where adult stem cells can be found
-brain to treat neurological diseases
-skin cells repair damaged or worn out cells
-intestines to replace worn out cells
what is therapeutic cloning
the process of creating stem cells with the same genes as the patient
what are the 4 steps of therapeutic cloning
1- nucleus taken out of human egg cell
2- nucleus put into egg cell
3- egg cell stimulated to develop into an embryo
4- stem cells grow
what are the advantages of therapeutic cloning
- helps create vital organs
-can help prevent or cure diseases
-small chance of rejection
what are the disadvantages of therapeutic cloning
-stem cells kept in labs show similarities to cancer cells
-virus transfer is possible
-its very expensive to extract eggs
-raises ethical issues
whatre the advantages of adult stem cells
-since cells are from the same body they wouldnt get rejected
-no embryos envolved so adults give permision
whatre the disadvantages of adult stem cells
-cells grown in labs can cause cancer
-only a few stem cells remain in the human body
-they can only differentiate into specific cells
whatre the advantages of embryonic stem cells
-lots of stem cells are avalible
-can differentiate into any cell
-can be used to replace damaged or destroyed cells
what are the disadvantages of embryonic stem cells
-ethical issues
-transplants can be rejected by the patients immune system
-difficult to obtain and store patatients stem cells
-patient can be scammed becaue stem cells are only in their developmental stage
a cell that has 2 sets of chromosomes
diploids
cells that have only 1 set of chromosomes
haploid
mass of abnormal cells caused by mutation that invade and destroy surrounding tissue
tumor
what are the features of a benign tumor
grow slowly, harmless but can cause blockage and pressure organs
what are the features of malignant tumors
they grow rapidly,invade and destroy tissue,spread in blood
what can cause cancer
-carcingogens
-raadiation
-inhertiance
-obestity
-age
how does chemotherapy treat cancer
chemicals are used to stop cells from dividing or making those cells distruct
how does radiotherapy help treat cancer
cancer cells are destroyed by targeted doses of radiation
