Specialised Cells and Stem Cells Flashcards
Outline the levels of organisation of a multicellular organism (in order).
Organelle, Cell, Tissue, Organ, Organ system, Organism
Define specialised
Having a particular structure to serve a specific function.
Define differentiation
The process of a cell becoming differentiated. Involves the selective expression of genes in a cell’s genome.
Define the term cell
A basic unit of life. Consists of cellular contents surrounded by a plasma membrane . All life is composed of these basic units whether it is unicellular or multicellular
Define the term tissue
A collection of differentiated cells that work together to perform a specialised function or functions.
Define the term organ
A collection of tissues that work together to perform a particular function in an organism
Define the term organ system
A number of organs working together to carry out a major function in the body.
Describe how neutrophils are specialised for their funciton
Functions- Defend the body from disease
Structure:
1. They have a flexible shape- allows them to engulf foreign particles or pathogens.
2. Multi-lobed nucleus- easier to squeeze through small gaps to get to site of infections.
3. Cytoplasm contain many lysosomes- they contain digestive enzymes to break down the engulfed particles
Describe how sperm cells are specialised for their funciton
Function- deliver genetic information to the female gamete
Structure:
1. Have a flagellum- capable of movement
2. They have lots mitochondria- to provide energy to swim
3. Acrosome on the head contains digestive enzymes- released to digest the protective layers around the ovum, allowing the sperm to penetrate.
Describe how palisade cells are specialised for their function
Function- to do most of the Photosynthesis
Structure:
1. Contain many chloroplasts- absorb large amounts of energy for photosynthesis
2. The cells are a rectangular box shape- can be closely packed to form a continuous layer.
3. Have thin cell walls- increase the rate of diffusion of CO2
Describe how root hair cells are specialised for their funciton
Function- Absorb mineral ions and water from the soil
Structure:
1. Have lots of root hairs (long extensions)- increase SA of cell, to maximise uptake of water and minerals
2. Thin permeable cell wall- for entry of water and ions
3. Cytoplasm contain extra mitochondria to provide the energy needed for active transport.
Describe how guard cells are specialised for their funciton
Function- control the release and entry of gases.
Structure:
1. Found in pairs with a gap between them to form a stoma- necessary for CO2 to enter plants
2. One side of the cell wall is thicker than the other- In the light, guard cells take up water into their vacuoles and become turgid- thin outer walls and thickened inner walls force them to bend outwards, opening the stomata.
3. When they lose water- less swollen- change shape and stoma close to prevent further water loss.
State the 4 main categories of tissues in animals.
- Nervous tissue- adapted to support transmission of electrical impulses
- Epithelial tissue- adapted to cover body surfaces, internal and external
- Muscle tissue- adapted to contract
- Connective tissue- adapted either to hold other tissues together or as a transport medium.
Describe how squamos epithelium tissues are specialised for their function
- Made of specialised squamous epithelial cells
- Very thin (contains flat cells) and is one cell thick- allow efficient diffusion
- Present when rapid diffusion across a surface is essential.
- Forms lining of lungs and allows rapid diffusion of O2 into blood
Describe how Ciliated epithelium are specialised for their function
- Made of ciliated epithelial cells
- Have hair like structures- cilia- which move in rhythmic manner
- Line the trachea- cause mucus to be swept away from the lungs
- Goblet cells are present- release mucus to trap unwanted particles present in the air and stops them reaching the lungs
Describe how cartilage is specialised for its function
- Connective tissue found in ears, nose and ends of bones.
- Contains fibres of the proteins elastin and collagen.
- It is a firm, flexible connective tissue composed of chondrocyte cells embedded in extracellular matrix.
- Prevents the ends of bones from rubbing together and causing damage.