Cell divisions

Created by

Sophie Barker

Cards (46)

What type of cell division occurs in eukaryotic cells ?
mitosis or meiosis
What type of cell division occurs in prokaryotic cells ?
binary fission
Haploid cell = one copy of each chromosome
diploid = two copies of each chromosome
example of haploid cell ?
gametes
what happens in G1?
protein synthesis occurs and organelles replicate
What happens at g1 checkpoint ?
checks cell is correct size and no DNA has been damaged
What happens in s phase ?
DNA is replicated
G2 = cell grows and energy stores are replenished
G2 checkpoint = check for copying errors in DNA
Cytokinesis = cytoplasm splits inot two genetically identical cells
Prophase = chromatin condenses into visible chromosomes, centrioles move to opposite poles of nucleus and spindle fibres form between them
Metaphase = chromosomes line up along equator of cell
Telophase = nuclear envelope reforms around new sets of chromosomes, mitotic spindles break down and cytokinesis begins
Anaphase = sister chromatids separate from each other and pulled towards the poles by microtubules
Meiosis = reductional division - produces haploid gametes with half the number of chromosomes as parent cell
Mitosis is important because it allows organisms to grow and repair damaged tissues
Meiosis has two rounds of division with one round of DNA replication
What is the result of meiosis ?
4 genetically different haploid daughter cells
Which processes cause variation in meiosis ?
Crossing over and independant assortment
Crossing Over = Exchange of genetic material between non-sister chromatids (chromosomes) during prophase I
independant assortment = random position of paternal/maternal chromosomes when lining up at the equator of the cell in anaphase 1
stem cells = undifferentiated cells
Tolipotent cells = divide and produce any type of body cells, including the placenta. They occur for a limited time and can be found the embryo
Pluripotent cells = can form most types of cells in the body, found in the embryo.
Multipotent = form limited number of cells. E.g if found in bone marrow can form any type of blood cell
Unipotent cell = form one type of specific cell
Name 3 uses of stem cells ?
repairing damaged tissues
treatment of neurological conditions
research into developmental biology
What is an ethical issue surrounding the use of stem cells ?
People consider embryos as alive beings, so when they are extracted and used for research of treatment it is argued they are murdering them
Name 2 ways the erythrocytes are specilised ?
Biconcave shape to increase surface area for more efficient diffusion
No nucleus to increase the space to hold more haemoglobin to increase oxygen transport.
Where are neutrophils made ?
Bone marrow
Name 3 adaptations of neutrophils ?
Lobed nucleus to help surround and engulf the pathogen
Flexible, surround the pathogen and fit through small capillaries
Lysosomes filled with digestive enzymes to destroy pathogens
Name 2 adaptations of the sperm cell ?
Many mitochondria in the flagella to release energy for locomotion of the tail to move towards the egg faster
Digestive enzymes in the acrosome of the head to digest the wall of the egg cell so the sperm can penetrate it and fertilise the egg
Where are palisade cells located ? 
In the mesophyll tissue layer of the leaves
Name 3 adaptations of the palisade cell?
Thin cell wall to reduce the diffusion distance of carbon dioxide
Many chloroplasts to maximise light absorption and photosynthesis
Rectangular, so can tighly pack together to maximise photosynthesis
Name an adaptation of guard cells?
Walls are uneven thickness on each side to allow it to open/close when turgid/flaccid.
Give an example of squamous epithelial cells? 
lining of the lungs
Name 1 adaptation of squamous epithelial cells ?
Single layer of flattened cells to provide a short diffusion distance
Goblet cells = produce mucus to trap dust and bacteria
Ciliated epithelial cells = hairlike projections to sweep dust and debris away from airways or move eggs along the oviduct.