Cell specialisation and Stem Cells Flashcards
What is a Specialised Cell
When cells or tissues become adapted to carry out their specific function
How much time is it before cells become specialised
After fertilisation all of the cells are identical for the first 3-5 days then they start to specialise to do a particular job and what the specialise into is then fixed.
What is Differentiation
When cells become specialised, we say they have undergone differentiation
Root Hair Cell Function & Adaptions
Found Where - Underground in the roots of a plant
Function - Absorb water & nutrients from soil to provide to rest of plant
Appearance - Has a long thin extension protruding from box-like structure (root hair). Large Vacuole and normal Organelles found in plant cells. No Chloroplasts.
Specialisation - Root Hair - larger SA to absorb. Very thin cell wall - easier for water to pass into cell. Large vacuole - temporary water storage until it is transported up through the plant.
Nerve Cell / Neuron Function & Adaptions
Found Where - Nervous System across whole body, mostly in brain & spinal column
Function - Send & Receive electrical messages to & from the brain and nervous system.
Appearance - Cytoplasm stretched to form long, thin axon. Axon covered in fatty sheath (myelin sheath). Millions of Nerve Endings (dendrites) at both ends which look like branches on a tree.
Specialisation - Long, thin shape - faster to send electrical messages. Axon covered by rings of myelin sheath - stops the electrical signal from travelling down axon - electrical insulator. Faster electrical message - electrical signal has to jump between gaps in the myelin sheath.
Sperm Cell Function & Adaptions
Found Where - Males only. Produced in testicles, during sexual intercourse released out of penis into the woman’s vagina where it swims to find the woman’s egg.
Function - Male sex cell - fertilise a female egg cell - can develop into a foetus. Contains father’s genes and pass these onto the offspring.
Appearance - Smallest cell in a man’s body - streamline shape & flagellum. Head has an acrosome which contains many digestive enzymes. Has lots of mitochondria.
Specialisation - Flagellum - swimming. Lots of mitochondria which carry out respiration - release energy.
Nucleus contains half a set of genes from the father.
Acrosome head containing digestive enzymes - digest the cell membrane of the egg cell to swim inside.
Muscle Cell Function & Adaptions
Found Where - Makes up all of the muscles in the body including heart.
Function - Contract - gets shorter. Relax - gets longer. Controls all of the movements in the body.
Appearance - Relaxed - Long, thin shape. Contracted - the filaments inside tighten - becomes a short, fat cell.
Specialisation - Many Mitochondria - Site of respiration - energy released - always working very hard so needs energy.
Xylem Cell Function & Adaptions
Found Where - Vascular Bundles inside Plants
Function - Movement of water through a plant - from its roots to its leaves via the stem.
Appearance - Made from dead xylem cells which have the cell walls removed at the end of the cells - tubes - water & dissolved mineral ions flow
Specialisation - Tubes are dead and hollow - water can move in a continuous column through the plant. Walls contain lignin - waterproofing & strengthening material.
Phloem Cell Function & Adaptions
Found Where - Vascular Bundles inside Plants
Function - translocation - movement of dissolved sugars & amino acids
Appearance - Columns of living cells. Small holes at the ends of the cell referred to as sieve plates. Connection of phloem cells forms tube - dissolved sugars transport.
Specialisation - Sieve Plates - continuous movement of water with sugars & dissolved minerals. Cells next to the phloem vessels called companion cells have lots of mitochondria for loading sugar into the vessels.
Guard Cell Function & Adaptions
Found Where - Leaf epidermis on underside of leaf.
Function - Pairs of guard cells surround and form stomatal pores, which regulate CO2 intake from atmosphere into leaves & also regulate water loss of plants via transpiration to the atmosphere.
Appearance - A relatively thick cuticle on the pore-side and a thin one opposite it. As water enters the cell, the thin side bulges outward like a balloon and draws the thick side along with it, forming a crescent; the combined crescents form the opening of the pore.
Specialisation - When environmental conditions change, guard cells can rapidly change shape so that the pores open or close to control leaf gas exchange and water transpiration.
Egg Cell / Ovum Function & Adaptions
Found Where - Females only. Ovaries, or less often - fallopian tubes.
Function - Female sex cell - fertilisation by a male sperm cell - can develop into a foetus. Contains mother’s genes and pass these onto offspring.
Appearance - One of the largest cells in the female body. Round & has a nucleus. Lots of mitochondria & cytoplasm.
Specialisation - Lots of Mitochondria - carry out respiration - release energy.
Nucleus contains half a set of genes from the mother.
Cone Cell / Cones Function & Adaptions
Found Where - retina - around the fovea
Function - Colour Vision
Appearance - Cone-like shape at one end which tune going to other end where is splays out.
Specialisation - Less sensitive to light. Can perceive finer detail & more rapid changes in images - response times to stimuli are fast.
Fat / Adipose Cell Function & Adaptions
Found Where - All over the body. It can be found under the skin (subcutaneous fat), packed around internal organs (visceral fat), between muscles, within bone marrow and in breast tissue.
Function - storage of energy in the form of triglycerides and helps conserve the heat of the body.
Appearance - bulbous little spheres
Specialisation - Enzymes - specialize in the hydrolysis of triglycerides in order to generate fatty acids and glycerol for physiological processes.
Palisade Cell Function & Adaptions
Found Where - Only in top half of a plant leaf.
Function - Photosynthesis
Appearance - Box-like, tall, narrow shape with many chloroplasts. Large vacuole and all of the organelles that you would expect to find in a plant.
Specialisation - Many chloroplasts - Photosynthesis happens in chloroplasts. Tall, thin shape to pack as many of these cells in a small area - more Photosynthesis.
I am found on the top half of the leaf to get sunlight easily.
Red Blood / Erythrocytes Cell Function & Adaptions
Found Where - Circulatory system - travels around inside blood vessels. There are 3 types of blood vessels; arteries, veins and capillaries.
Function - Collect oxygen from lungs & carry it around the body to cells - respiration. Collect CO2 from cells & carry it back to lungs to be removed.
Appearance - V. small & bright red - contains haemoglobin. Round, biconcave shape. No nucleus.
Specialisation - Contains haemoglobin which sticks to oxygen molecules. Biconcave shape - can travel through small blood vessels without becoming stuck - can bend.
Ciliated Epithelial Cell Function & Adaptions
Found Where - Lining in the nose, the trachea and the bronchi in the respiratory system. Also in reproductive system - fallopian tubes lining.
Function - Tiny hairs (cilia) wave & help move things. Respiratory system - cilia are covered in mucus (snot) & trap any dust & bacteria that are trying to enter the body. Wave back and forth - carries mucus containing the dust & bacteria - mouth - swallowed. Cilia lining in the fallopian tubes move the egg cell through the female reproductive system to the uterus (womb).
Appearance - Tiny hairs (cilia) on surface. Contains many of the organelles that you would expect to see in an animal cell.
Specialisation - Tiny hairs (cilia) move & help to carry things along inside of the body.
How is the body organised
Made up of different organ systems working together to carry out all the functions of a living organism Many Cells = Tissue Many Tissue = Organ Many Organs = Organ System Many Organ Systems = Organism
What are Stem Cells
an undifferentiated cell whichis capable of self-renewal to produce more stem cells or differentiate into specific specialised cells
What are the two purposes of Stem Cells
Self-Renewal (copying) (Identical Stem Cell)
OR…
Differentiation (specialising) (Specialised Cells)
Plant Stem Cells
Usually retain the ability to differentiate throughout their lives.
Where do plants have a layer of unspecialised, stem cells
In the Meristem layer (roots and shoots) (these stem calls can become any type of plant cell)
Advantages of Plant Stem Cells
Clones can be made quickly & efficiently - large numbers of rare plants can be grown quickly - could prevent extinction.
Large numbers of plants can be produced to sell – economic benefit.
Crops with ideal features like disease resistance can be cloned so more crops survive
Identical plants can be made for research
Food?
What can Specialised Cells differentiate into
They can only divide to make its own type of cell
In mature animal cells, division restricted to repair & replacement
Where are the 4 places we can find human stem cells
Embryonic Stem Cells
Umbilical Cord Stem Cells
Adult Stem Cells
Therapeutic Stem Cells
Where are Embryonic Stem Cells found and what can they differentiate into
Where - Human Embryos (3-5 days old) (e.g. unused embryos left over from fertility treatment)
Differentiation - Any type of cell found in the body
Note - As the new cells are used to treat a different individual – immunosuppressants (a tablet taken to weaken immune system so it doesn’t reject transplants) needed
Where are Adult Stem Cells found and what can they differentiate into
Where - Certain locations in adult humans (brain, eyes, blood, heart, liver, bone marrow, skin, muscle, intestine)
Differentiation - Only into cells from the type of tissue where they are found. Their role is to replace body cells that die through injury and disease. (e.g. bone marrow cells can differentiate into blood cells & cells of the immune system, but not other cell types)
Where are Umbilical Cord Stem Cells found and what can they differentiate into
Where - Umbilical Cord just after birth of a baby (can be frozen & stored for future use but only of that child)
Differentiation - different blood cells (Can be used to treat a variety of blood disorders)
Therapeutic Cloning
Nuclear transfer - nucleus of a body cell from patient transferred to egg cell (nucleus removed)
Produces Stem Cells w/sm genes as patient so no need for immunosuppressants/anti-rejection drugs
Advantages of Embryonic Stem Cells
Many available
All types of tissues can be grown
Replace cells that have been damaged or destroyed e.g. paralysis
Disadvantages of Embryonic Stem Cells
Ethical issues (use of embryos)
Risk of immuno-rejection
Expensive
Lack of donors
Advantages of Adult Stem Cells
Cells from sm body - minimal rejection
No embryos involved
Adults can give their own consent
Treatment of serious diseases e.g. cancer
Disadvantages of Adult Stem Cells
Can only differentiate into the type of tissues where they are found
Painful to extract
Very few available
Advantages of Umbilical Cord Stem Cells
Stored for later use
No rejection
No ethical issues
Treat blood diseases
Disadvantages of Umbilical Cord Stem Cells
Expensive
Can only treat blood disorders
Can only help that particular child whose umbilical cord was stored.
Advantages of Therapeutic Stem Cells
Many available
Can differentiate into any type of cell
Fewer immunosuppressants needed as stem cells from patient are used
Disadvantages of Therapeutic Stem Cells
Ethical issues (use of embryos) Technology still developing
