cell division cell differentiation

Erythrocytes specialisation - shape

(RBC) flattened biconcave shape increases SA:V

erythrocytes specialisation - nuclei

no nucleus increases volume for haemoglobin

erythrocytes specialisation - flexibility

flexible so it can squeeze through narrow capillaries

neutrophils specialisation - nuclei

(WBC) multi lobed nucleus so it can squeeze through small gaps to reach infection sites

neutrophils specialisation - cytoplasm

granular cytoplasm contains lysosomes which contain enzymes used to attack pathogens

neutrophils specialisation - flexibility

flexible so they can form psuedopodia that engulf microorganisms

Sperm cell specialisation - movement

tail or flagellum aids movement, many mitochondria supply energy needed to swim

sperm cell specialisation - digestive

acrosome contains digestive enzymes released to digest protective layers of the ovum allowing sperm to penetrate and fertalise

Palisade cell specialisation - chloroplasts

contain chloroplasts which can move so they can absorb large amounts of light for photosynthesis

Palisade cell specialisation - vacuole

large vacuole maintains turgor pressure

Palisade cell specialisation - cell wall

thin cell wall so there is a short diffusion distance increasing rate of diffusion of CO2

Palisade cell specialisation - shape

rectangular box shaped so they can be tightly packed and form a continuous layer

Root hair cell specialisation (SA, thin, permanent, active, no)

- long extensions increase SA and maximises uptake of water and minerals
- Thinner walls than other plant cells so that water can move through easily (due to shorter diffusion distance)
- Permanent vacuole contains cell sap which is more concentrated than soil water, maintaining a water potential gradient
- Mitochondria for active transport of mineral ions
- no chloroplasts because of no sunlight underground

Guard cell specialisation

cell wall is thicker on one side than the other so when the volume changes the cell can bend

Squamous epithelium specialisation

very thin (flat and one cell thick) means there is a rapid diffusion of oxygen into the blood, permeable so gases can easily diffuse

Ciliated epithelium specialisation

cilia sweep mucus away from the lungs, goblet cells release mucus that traps unwanted particles stopping them reaching alveoli

cartilage specialisation

strong and resists pressure so prevents damage to bones for example. (form tracheal rings which hold the trachea open)

Muscle tissue specialisation (layers, high)

layers of protein filaments which can slide over each other causing muscle contraction, a high density of mitochondria to provide sufficient energy for muscle contraction

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muscle tissue specialisation - skeletal muscle tissues

Skeletal muscle cells fuse together during development to form multinucleated cells that contract in unison

Epidermis specialisation

covered by waxy cuticle to prevent water loss, stomata are present allowing CO2, O2 and H20 vapour in and out

Xylem tissue specialisation (no, cells, outer)

- No top and bottom walls between cells to form continuous hollow tubes through which water is drawn upwards towards the leaves by transpiration
- Cells are essentially dead, without organelles or cytoplasm, to allow free movement of water
- Outer walls are thickened with a substance called lignin, strengthening the tubes, which helps support the plant

Phloem tissue specialisation (made, joined, cells)

- Made of living cells which are supported by companion cells
- Cells are joined end-to-end and contain holes in the end cell walls (sieve plates) forming tubes that allow sugars and amino acids to flow easily through (by translocation)
- Cells also have very few subcellular structures to aid the flow of materials

specialised cell

A cell adapted to carry out specific functions. (differentiated)

tissue

A group of similar cells that perform the same function.

organ

A collection of tissues that carry out a specialized function of the body

organ system

A group of organs that work together in performing vital body functions.

stem cell

undifferentiated cells that are capable of becoming differentiated to a number of possible cell types. (all cells come from stem cells)

totipotent stem cells

can differentiate into any type of cell, early embryonic cells have the capacity to differentiate into cells that produce the embryo and placenta

pluripotent stem cells

form all tissue types but not whole organisms, present in early embryos and are the origin of different types of tissue in the organism

multipotent stem cells

Can only form a range of cells within a certain type of tissue, found in bone marrow (haematopoetic stem cells give rise to types of blood cells)

source of stem cells in animals

embryonic stem cells, tissue stem cells

making embryonic stem cells

fertilized egg, divides and forms a blastocyst, stem cells are harvested and embryo destroyed

Harvesting adult stem cells

may be extracted from the bone marrow or peripheral blood

Stem Cells in Umbilical Cord Blood

after birth cord is cut and clumped, cord blood is collected, examined in a lab, stem cells yielded and stored at -196 degrees C for 21 years

source of stem cells in plants

meristems (shoots, roots and cambium)

uses of stem cells

stem cells transplants can help a number of diseases : heart disease, alzheimers, type 1 diabetes, parkinsons, spinal injuries
already used in some areas such as: burn treatment, drug trials and developmental biology