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Cell structure is correlated to cellular ____________.
Function
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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.
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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.
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What features do all cells possess?
- Ribosomes (make protein)
- Plasma membrane
- Semi-fluid substance called cytosol
- Chromosomes (carry genes)
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Where is the DNA stored in prokaryotic cells?
DNA is in an unbound region called the nucleoid.
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What is the difference between cytoplasm and cytosol?
- Cytoplasm: is the region that contains the organelles & cytosol.
- Cytosol: is the fluid in the cytoplasm
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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.
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What is the general structure of a biological membrane?
It's a double layer of phospholipids. (Phospholipid bi-layer)
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What properties would limit cells from being any smaller?
All the organelles and content will have to fit in the cell.
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What are the smallest known cells?
Mycloplasmas, a type of bacterial cell.
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Small cells have a ______________ relative to volume.
greater surface area.
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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
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What organelles are unique only to animal cells? (3)
- Lysosomes
- centrioles
- flagella
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What organelles are only unique to plant cells? (4)
- chloroplast
- cell wall
- central vacuole
- plasmodesmata
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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.
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What is the endosymbiont theory?
The theory that the mitochondria came first before the chloroplast.
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What is the lysosome's function?
Autophagy, macromolecules are hydrolyzed. (digestive organelle)
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Define cytoskeleton. (2)
- It's a network of fibers extending throughout the cytoplasm.
- It organizes cell's structure and activities, anchoring many organelles.
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What are the three molecular structures composed in the cytoskeleton?
- Microtubules
- microfilaments
- intermediate filaments
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What is a function of the cytoskeleton?
It helps to support the cell and maintain its shape.
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Cytoskeleton interacts with ___________ to produce motility.
Motor proteins
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What are microtubules?
They are hallow tubes that are composed of tubulin dimers.
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What are the functions of microtubules? (4)
- shaping the cell
- cell motility
- guiding movement of organelles
- separating chromosomes during cell division
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What is the centrosome?
It's a "microtubule organizing center" where microtubules grow out from, near the nucleus.
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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.
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How do microtubules move?
They move by growing and shrinking; adding and removing from each end.
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Microtubules control the beating of _______________, locomotor appendages.
Cilia and Flagella
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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
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What are microfilaments?
They are solid rods, built as a twisted double chain composed of actin subunits
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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
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What is the microvilli of intestinal cells composed of?
Bundles of microfilaments make up the core of microvilli
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Microfilaments that function in cellular motility contain the protein ________ in addition to actin.
Myosin
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Amoeboid movement is driven by __________
The contraction bought about by actin and myosin.
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What is pseudopodia?
cellular extensions.
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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.
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In plant cells, what drives cytoplasmic streaming?
actin-myosin interactions and sol-gel transformations.
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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
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What do extracellular structures include? (3)
- cell walls of plants
- Extracellular matrix (ECM) of animal cells
- intercellular junctions
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Extracellular components and connections between cells help ________________.
coordinate cellular activities.
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What is the function of a cell wall? (3)
- protects the plant cell
- maintains it's shape
- prevents excessive uptake of water
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What are plant cells made of?
Plant cells are made of cellulose fibers embedded in other polysaccharides and protein.
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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)
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Define plasmodesmata.
Are channels between adjacent plant cells. Helps plants communicate.
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Animal's lack a cell wall but are covered in _______________.
Extracellular matrix (ECM)
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What is the ECM made up of?
Made up of glycoproteins such as collagen, proteoglycans and fibronectin.
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What is the function of the ECM? (5)
- support
- adhesion
- movement
- regulation
- communication
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What is the function of intercellular junctions?
adhere, interact and communicate through direct physical contact between neighbouring cells.
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What are the 4 types of intercellular junctions ?
- plasmodesmata (plant cells)
- Tight junctions
- desmosomes
- gap junctions
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What is the function of tight junctions?
Membranes of neighbouring cells are pressed together, preventing leakage of extracellular fluid
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What is the function of desmosomes?
anchoring junctions, fasten cells together into strong sheets
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What is the function of gap junctions?
communication junctions, provide cytoplasmic channels between adjacent cells
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