Cell differentiation & Specialisation

Created by

Aisha

Cards (22)

The process by which a cell changes to become specialised for its job.
What is differentiation?
Different subcellular structures and turn into different types of cells. This allows them to carry out specific functions. 
As cells change they develop what?
When an organism develops. 
When does most differentiation occur?
In most animal cells, the ability to differentiate is lost at an early stage. 
Do animal cells lose the ability to differentiate?
Lots of plant cells don't ever lose the ability to differentiate. 
Do plant cells lose the ability to differentiate?
Stem cells 
What are undifferentiated cells called?
To get the male DNA to the female DNA

1) It has a long tail and streamlined head to help it swim to the egg.
2) There are a lot of mitochondria in the cell to provide the energy needed.
3) Contains enzymes to digest through the egg cell membrane. 
What is the function of sperm? What are some of the things sperm has to help it do this?
The function of nerve cells is to carry electrical signals from one part of the body to another.

1) These cells are long (to cover more distance) and have branched connections at their ends to connect to other nerve cells and for a network throughout the body. 
What is the function of nerve cells? What are some of the things it has to help it do this?
The function of muscle cells is to contract quickly.

2) These cells are long (so they have space to contract) and contain lots of mitochondria to generate the energy needed for contraction 
What is the function of muscle cells? What are some of the things it has to help it do this?
Root hair cells are specialised for absorbing water and minerals.

1) Root hair cells are on the surface of plant roots, which grow into long "hairs" that stick out into the soil.
2) This gives the plant a big surface area for absorbing water and mineral ions from the soil. 
What is the function of root hair cells? What are some of the things it has to help it do this?
Phloem and xylem cells are specialised for transporting substances.

1) Phloem and xylem cells form phloem and xylem tubes, which transport substances such as food and water around the plant.
2) To form the tubes, the cells are long and joined end to end.
3) Xylem cells are hollow in the centre and phloem cells have very few subcellular structures, so that stuff can flow through them. 
What is the function of phloem and xylem cells? What are some of the things it has to help it do this?
Name one adaptation for each of the following specialised animal cells. Describe how this adaptation helps to carry out its function.

A) Nerve cell
B) Muscle cell
C) Sperm cell
[6]
A) Any one from: [2]
• lots of dendrites - to make connections to other nerve cells
• long axons - to carry nerve impulse
• synapses - to pass impulse to another cell or between nerve cell and muscle using transmitter chemicals.
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B) Any one from: [2]
• special proteins - that slide over each other to contract fibres
• many mitochondria - to produce energy for movement
• glycogen storage - for cellular respiration.
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C) Any one from: [2]
• Any one from long tail - to move sperm towards egg
• many mitochondria - to produce energy for movement
• acrosome - stores digestive enzymes for breaking down outside layers of egg
• large nucleus - to contain genetic material to be passed on.
Cone cells are specialised nerve cells in the eye. They contain a chemical that changes in coloured light. As a result of change, an impulse is sent along another nerve to the brain. Cone cells usually contain many mitochondria. Suggest why this is an important adaptation.
[4]
Transmitter chemicals [1] are required to pass impulse from cone cell to another nerve cell and then on to the brain. [1] The many mitochondria [1] supply energy from cellular respiration needed to make transmitter chemicals.[1]
Describe the features you would look for to decide on the function of an unknown specialised animal cell.
[6]
Any three from: [6]
• number of mitochondria indicates how much energy cell uses.
• flagella or cilia - presence indicates whether cell moves around or moves substances such as mucus.
• nucleus - presence indicates whether cell is capable of reproduction.
• storage materials such as fat or starch - presence indicates whether cell stores materials it can use for respiration.
Name one adaptation for each of the following specialised plant cells. Describe how this adaptation helps to carry out its function.

A) Root hair cell
B) Xylem cell
C) Phloem cell
D) Photosynthetic cell
[6] 
A) Any one from: [2]
• increased surface area - to promote water uptake
• large permanent vacuole - to speed up movement of water by osmosis
• many mitochondria - to produce energy for active transport of minerals.
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B) Any one from: [2]
• cells die forming long hollow tubes - to allow water and mineral ions to move easily through them
• lignin spirals formed - to help cells withstand pressure of water moving up plant and to support plant stem.
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C) Any one from: [2]
• cell walls break down to form sieve plates - to enable water and dissolved food to pass through
• companion cells - to support phloem cells and provide energy to move substances up and down in phloem.
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D) Any one from: [2]
• chloroplasts - contain chlorophyll to trap light needed for photosynthesis
• positioned in leaves and outer layers of stem - to absorb as much light as possible
• large permanent vacuole - to keep cell rigid and support leaf and stem to capture light.
Suggest why a cell in a trunk of a tree can not carry out photosynthesis. [2]
Cell not exposed to sunlight [1]
and therefore not adapted to photosynthesise (not photosynthetic).[1]
Describe the features you would look for to decide on the function of an unknown specialised plant cell. [6]
Any three from: [6]
• chloroplasts - presence indicates whether cell is photosynthetic
• large vacuole - presence indicates role in osmosis/rigid support
• lignin spirals - presence indicates strengthening and transport of water
• sieve plates/companion cells - presence indicates transport of dissolved food
• mitochondria - presence indicates active movement of substances
Define differentiation. [1] 
Process by which cells become specialised and adapted to carry out a particular function. [1]
Describe why differentiation is important in living organisms. [2]
- All cells in an early animal or plant embryo are unspecialised (stem cells). [1]
- Differentiation fulfils organisms' requirements for different cells to carry out different roles (e.g., muscle cells, sperm cells, gut lining cells). [1]
Explain how differentiation differs in animal and plant cells. [4] 
In animals, differentiation occurs during embryo development [1]
and is permanent. [1]
In plants, it occurs throughout life [1]
and can be reversed or changed [1]
Calculate by what order of magnitude an adult is bigger than the original fertilised ovum. [4]
order of magnitude = factor of 10 [1]
adult human has approximately 3.72 × 1013^13 cells [1] fertilised ovum is one cell [1]
adult human is around 13 orders of magnitude bigger than the original cell. [1]
Explain how the difference in differentiation patterns affect our ability to clone plants and animals. [6]
In plants differentiation can be reversed and mitosis induced. [1]
Conditions can be changed to induce more mitosis. [1]
Cells redifferentiate into different plant tissues needed to form a new clone plant, [1]
so plants can be cloned relatively easily. [1]
In animals differentiation cannot be reversed (cells differentiate permanently), [1]
so clones cannot be made easily. [1]
In order to make animal clones, embryos have to be cloned [1]