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Diversity in cells, specialised cells & stem cells - Coggle Diagram
Diversity in cells, specialised cells & stem cells
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stem cell
= unspecified cell able to express all of its genes & divide by mitosis, from which all cells originate from
pluripotent
they are undifferentiated but are capable of differentiating into any type of specialised cell in that organism (capable of expressing all their genes)
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differentiation
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during differentiation of stem cells certain genes are switched off & other genes may be expressed so that;
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owing to this differentiation, each cell type is specialised for a particular function
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Neutrophils
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adaptations for function
contains a multilobed nucleus - makes easier for them to squeeze through small gaps to get to sight of infections & travel through tiny blood capillaries
flexible shape - allows them to pass through cell junctions & extend pseudopodia (sections which surround the pathogen)
have nucleus, ER & ribosomes - can synthesise toxic chemicals to kill pathogens & also make proteins tat can pierce & rupture the pathogen ell membrane
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Sperm (spermatozoa)
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adaptations for function
acrosome - specialised lysosome which released digestive enzyme to digestive the protective layer of egg cell
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streamlined shape - small ,long & thin so they can swim faster
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Palisade cells
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adaptation for function
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long & rectangular shape -allows cells to pack closely together, but little space between cells for air to circulate (allowing CO2 to diffuse into the cells for photosynthesis)
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large vacuole - so chloroplasts are positioned nearer edge of cell reducing distance for CO2 to diffuse to chloroplasts & making it easier for them to absorb sunlight
contain cytoskeleton treads & motor proteins - move chloroplasts nearer to upper surface of the leaf when sunlight is low but further down when it is high
Guard cells
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function
control opening of stomata, when stomata are open, water vapour is lost from the leaf by transpiration & gaseous exchange can occur for respiration & photosynthesis
adaptation for function
cellulose cell wall - more flexible & thinner at tips of guard cells & more rigid & thicker sides meaning when cells swell in a curved shape to allow opening of stomata
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Root hair cells
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adaptation for function
have hair-like projection - greatly increases SA for absorption of water & mineral ions, such as nitrates from the soil
have special carrier proteins in plasma membrane - in order to actively transport the mineral ions in
contain lots of mitochondria - produce ATP, needed for active transport
plants die when roots are waterlogged cause airspaces in soil are filled with water, therefore roots cannot take in O2 for aerobic respiration & cannot produce enough ATP to transport in mineral ions or for other metabolic activities
sources of stem cells
embryonic stem cells
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grown in a petri dish using fluid that contains all the nutrients they need to undergo differentiation
this fluid will contain growth factors which will express particular genes in order to form particular specialised cells
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adult tissue stem cells
can be found in variety of locations in the body, including the bone marrow, brain & skin
are multipotent
they can differentiate to produce multiple types of specialised cells but not all types of specialised cells
can only make kinds of cells found in tissues they can belong to, e.g. blood stem cells can only make different types of cells found in the blood
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