Biology 1115 chapter. 6
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Cell structure is correlated to cellular ____________.
What are prokaryotic cells and what do they include?
Prokaryotic cells are single-celled organisms with no nucleus and no membrane-bound organelles. They include bacteria and archae.
What are eukaryotic cells and what do they include?
Eukaryotic cells are multi-celled organisms with a nucleus and membrane-bound organelles. They include plants, animals, protists, and fungi.
What features do all cells possess?
- Ribosomes (make protein)
- Plasma membrane
- Semi-fluid substance called cytosol
- Chromosomes (carry genes)
Where is the DNA stored in prokaryotic cells?
DNA is in an unbound region called the nucleoid.
What is the difference between cytoplasm and cytosol?
- Cytoplasm: is the region that contains the organelles & cytosol.
- Cytosol: is the fluid in the cytoplasm
What is the plasma membrane?
It's a selective barrier that allows sufficient passage of oxygen, nutrients and waste to enter in and out of the cell.
What is the general structure of a biological membrane?
It's a double layer of phospholipids. (Phospholipid bi-layer)
What properties would limit cells from being any smaller?
All the organelles and content will have to fit in the cell.
What are the smallest known cells?
Mycloplasmas, a type of bacterial cell.
Small cells have a ______________ relative to volume.
greater surface area.
What is the biological importance of having high surface area to volume ratio? (2)
- The logistics of carrying nutrients in and wastes out of the cell
- Cellular Metabolism
What organelles are unique only to animal cells? (3)
What organelles are only unique to plant cells? (4)
- cell wall
- central vacuole
What are the organelles in order for the endomembrane system?
nucleus to nuclear membrane to ribosomes in rough ER to a vesicle that's transported to the Cis Golgi body (modified) to trans Golgi to plasma membrane where it's secreted out or sent to another part in the cell.
What is the endosymbiont theory?
The theory that the mitochondria came first before the chloroplast.
What is the lysosome's function?
Autophagy, macromolecules are hydrolyzed. (digestive organelle)
Define cytoskeleton. (2)
- It's a network of fibers extending throughout the cytoplasm.
- It organizes cell's structure and activities, anchoring many organelles.
What are the three molecular structures composed in the cytoskeleton?
- intermediate filaments
What is a function of the cytoskeleton?
It helps to support the cell and maintain its shape.
Cytoskeleton interacts with ___________ to produce motility.
What are microtubules?
They are hallow tubes that are composed of tubulin dimers.
What are the functions of microtubules? (4)
- shaping the cell
- cell motility
- guiding movement of organelles
- separating chromosomes during cell division
What is the centrosome?
It's a "microtubule organizing center" where microtubules grow out from, near the nucleus.
What do the centrosomes in animal cells contain?
In animal cells, the centrosome has a pair of centrioles each with nine triplets of microtubules arranged in a ring.
How do microtubules move?
They move by growing and shrinking; adding and removing from each end.
Microtubules control the beating of _______________, locomotor appendages.
Cilia and Flagella
What are the common ultrastructure's that cilia and flagella share? (3)
- Core of microtubules sheathed by the plasma membrane. (9 + 2 pattern)
- A basal body that anchors the cilium or flagellum.
- A motor protein called dynein, which drives the bending movements
What are microfilaments?
They are solid rods, built as a twisted double chain composed of actin subunits
What are the functions of microfilaments? (2)
- Structural role of microfilaments is to bear tension, resisting pulling forces within the cell.
- They form a 3-D network called the cortex just inside the plasma membrane to help support the cell's shape
What is the microvilli of intestinal cells composed of?
Bundles of microfilaments make up the core of microvilli
Microfilaments that function in cellular motility contain the protein ________ in addition to actin.
Amoeboid movement is driven by __________
The contraction bought about by actin and myosin.
What is pseudopodia?
What is cytoplasmic streaming? What is it's function?
It's a circular flow of cytoplasm within the cells. This streaming speeds distribution of materials within the cell.
In plant cells, what drives cytoplasmic streaming?
actin-myosin interactions and sol-gel transformations.
What are intermediate filaments? (3)
- Larger than microfilaments but smaller than microtubules
- Composed of proteins in the keratin family.
- More permanent cytoskeleton fixtures than the other two classes
What do extracellular structures include? (3)
- cell walls of plants
- Extracellular matrix (ECM) of animal cells
- intercellular junctions
Extracellular components and connections between cells help ________________.
coordinate cellular activities.
What is the function of a cell wall? (3)
- protects the plant cell
- maintains it's shape
- prevents excessive uptake of water
What are plant cells made of?
Plant cells are made of cellulose fibers embedded in other polysaccharides and protein.
Where is the cell wall located and what are its three layers?
- The cell wall is located outside the plasma membrane. It includes:
- Primary cell wall (thin and flexible)
- Middle lamella
- Secondary cell wall(thicker, rigid layer)
Are channels between adjacent plant cells. Helps plants communicate.
Animal's lack a cell wall but are covered in _______________.
Extracellular matrix (ECM)
What is the ECM made up of?
Made up of glycoproteins such as collagen, proteoglycans and fibronectin.
What is the function of the ECM? (5)
What is the function of intercellular junctions?
adhere, interact and communicate through direct physical contact between neighbouring cells.
What are the 4 types of intercellular junctions ?
- plasmodesmata (plant cells)
- Tight junctions
- gap junctions
What is the function of tight junctions?
Membranes of neighbouring cells are pressed together, preventing leakage of extracellular fluid
What is the function of desmosomes?
anchoring junctions, fasten cells together into strong sheets
What is the function of gap junctions?
communication junctions, provide cytoplasmic channels between adjacent cells
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