Module One, Lecture Eight Flashcards
Cell Walls and Their Role in Regulating Plant Cell Shape (19 cards)
What are the components of a Plant Cell? ( 6 )
- A rigid cell wall composed of cellulose
- A cell membrane surrounding the cell
- A nucleus housing genetic material
- Chloroplasts responsible for photosynthesis
- A large vacuole for storage and support
- A cytoplasm containing various organelles
What is the primary function of the plant wall?
Gives structural strength to plant cell
What are the functions of the Cell Wall? ( 7 )
- Give plants a clear shape, strength, and rigidity
- Offers protection against mechanical stress and physical shock
- Influences cell morphology
- Aids in limiting cell growth brought on by water intake
- Assists in preventing cell water loss
- Moves material inside and outside the cell
- Serves as a barrier between the internal cellular components and the outside world
What are the two phases of the Cell Wall?
- Microfibrils ( Crystalline Phase )
- Matrix ( Non-crystalline Matrix )
What is the Matrix ( Non-crystalline Matrix )?
A material lacking long-range, ordered atomic structure
What is the Microfibrils ( Crystalline Phase )?
A state of matter highly characterised by a highly ordered, repeating three-dimensional arrangement of atoms or molecules within a solid structure
What is Hemicellulose?
A heterogeneous group of polysaccharides. Long chains of one type of sugar and short side chains form a rigid structure.
What is Pectin?
Branched, negatively charged polysaccharides. Bind water and have gel-like properties
Describe the synthesis of the Primary Cell Wall? ( 3 )
- Cellulose microfibrils synthesised at the plasma membrane ( outside the cell as its produced )
- Polysaccharides ( pectin and hemicellulose ) are synthesised in the Golgi complex and are transported to the plasma membrane in vesicles
- Extensis ( cell wall proteins ) synthesised in the rough ER and transported via Golgi to plasma membrane in vesicles. The vesicles fuse with the plasma membrane and are released through exocytosis
What are the functions of Exocytosis? ( 2 )
- Transport material out of the cell or delivers it to the cell surface
- Constitutive exocytosis releases extracellular matrix proteins
What is the structure / function of the Cytoskeleton? ( 2 )
- A network of microtubules, microfilaments that extend throughout the cytoplasm
- Including maintaining the position of organelles, providing structural support
What are the three layers of the Plant Cell Wall? ( 3 )
- Primary
- Middle Lamella
- Secondary
What are the three main types of carbohydrates found in the Primary Cell Wall? ( 3 )
- Cellulose
- Hemicellulose
- Pectin
Describe the structure of the Primary Cell Wall…
Is a flexible and extensible layer, is primarily composed of cellulose, microfibrils embedded in a matrix of pectin and hemicelluloses, with structural proteins also present
Describe the structure of the Secondary Cell Wall…
Formed after the Primary Cell Wall has reached completion and cell expansion ceases, the secondary cell wall acts as a rigid structure composed of cellulose, hemicelluloses, and lignin providing strength and support to the cell
Describe the structure of the Lamella…
A thin, plate-like structure, often one of many closely packed together, with spaces between them
Describe the structure of the Vacuoles…
A vacuole is an organelle surrounded by a single membrane. It is highly selective, controlling much of what enters and leaves the vacuole. Water moves in the vacuoles by osmosis ( passive transport )
What is the Lignin? ( 3 )
- Lignin is the second most abundant organic macromolecule
- Lignin is a complex polymer
- Confers strength and rigidity to the secondary cell wall and acts to exclude water
What is Plasmodesmata?
Microscopic channels that connect plant cells, allowing for the movement of molecules and communication between them
