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Cell Structure and Function
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Cell Structure and Function
Cell Structure and Function
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1
Question
Why are lipids considered hydrophobic?
Answer
Lipids consist mostly of hydrocarbons, which form nonpolar covalent bonds, making them repel water and thus hydrophobic.
2
Question
What does it mean for a substance to be hydrophobic?
Answer
A hydrophobic substance is one that does not have an affinity for water and tends to repel or fail to mix with water.
3
Question
What type of molecule is water, and how are its charges distributed?
Answer
Water is a polar molecule, with the oxygen region having a partial negative charge (δ–) and the hydrogen region a partial positive charge (δ+).
4
Question
What are amino acids, and what role do they play in proteins?
Answer
Amino acids are organic molecules containing both carboxyl and amino groups and serve as the monomers of proteins.
5
Question
How does the cytoskeleton contribute to the movement of cilia and flagella?
Answer
Motor proteins cause microtubules within cilia and flagella to move relative to each other, enabling movement.
6
Question
Which eukaryotic organelle is thought to have evolved as part of the endomembrane system?
Answer
The nuclear envelope is believed to have evolved as part of, or an elaboration of, the endomembrane system.
7
Question
What is the endosymbiont theory regarding the origin of mitochondria?
Answer
The theory states that mitochondria evolved from an oxygen-using bacterium that entered into endosymbiosis within a larger host cell.
8
Question
In what order does a potassium ion (K+) pass through cellular structures when moving from soil into a vacuole in a plant root cell?
Answer
Primary cell wall → plasma membrane → cytoplasm → vacuole.
9
Question
Which organelle produces and modifies polysaccharides for secretion?
Answer
The Golgi apparatus produces and modifies polysaccharides that will be secreted.
10
Question
In which organelle are thylakoids, DNA, and ribosomes found?
Answer
Thylakoids, DNA, and ribosomes are found in chloroplasts.
11
Question
Do archaea have membrane-enclosed organelles or nuclei like bacteria?
Answer
No, both archaea and bacteria lack a membrane-bound nucleus; however, DNA is present in both archaea and bacteria.
12
Question
What is the correct pathway of a protein destined for secretion from an animal cell?
Answer
Rough ER → transport vesicle → Golgi apparatus → transport vesicle → plasma membrane.
13
Question
Where are mitochondrial proteins synthesized?
Answer
Mitochondrial proteins are synthesized somewhere other than the rough ER, typically by free ribosomes in the cytoplasm.
14
Question
What primary function does the Golgi apparatus perform?
Answer
It modifies and sorts proteins for their proper destinations.
15
Question
What plant cell structure is functionally similar to gap junctions in animal cells?
Answer
Plasmodesmata are similar in function to gap junctions, facilitating communication between cells.
16
Question
Which organelle is mainly involved in the synthesis of oils, phospholipids, and steroids?
Answer
The smooth endoplasmic reticulum (smooth ER) synthesizes oils, phospholipids, and steroids.
17
Question
Which plant organelles contain their own DNA and ribosomes?
Answer
Mitochondria and chloroplasts contain their own DNA and ribosomes.
18
Question
Which organelle is abundant in liver cells due to its role in detoxification?
Answer
The smooth endoplasmic reticulum (smooth ER) is abundant in liver cells for detoxifying poisons and drugs.
19
Question
Which type of intercellular junction prevents fluid leakage between animal cells?
Answer
Tight junctions prevent passive movement of fluids and bacteria through spaces between cells.
20
Question
Where does most ATP synthesis occur in prokaryotic cells, according to the endosymbiont theory?
Answer
Most ATP synthesis occurs on the plasma membrane of prokaryotic cells.
21
Question
Which cellular components are shared by both eukaryotic cells and their prokaryotic ancestors?
Answer
Ribosomes are common components shared by both eukaryotic cells and prokaryotes.
22
Question
Why is the mitochondrion not considered part of the endomembrane system?
Answer
Because it is not derived from the endoplasmic reticulum or Golgi apparatus.
23
Question
What advantage does light microscopy have over transmission electron microscopy?
Answer
Light microscopy allows viewing of dynamic processes in living cells.
24
Question
Which organelle often occupies much of the volume of a plant cell?
Answer
The vacuole often takes up much of the volume of a plant cell.
25
Question
How do prokaryotes synthesize secreted proteins without an endomembrane system?
Answer
Proteins secreted by prokaryotes are synthesized on ribosomes bound to the cytoplasmic surface of the plasma membrane.
26
Question
What common characteristic is shared by the cell walls of bacteria, fungi, and plants and the extracellular matrix of animal cells?
Answer
They are constructed of polymers synthesized in the cytoplasm and then transported out for assembly.
27
Question
Where are extracellular matrix proteins produced in eukaryotic cells?
Answer
Extracellular matrix proteins are produced by ribosomes on the rough endoplasmic reticulum.
28
Question
Why is the volume enclosed by the plasma membrane often larger in plant cells compared to animal cells?
Answer
Because plant cells contain a large vacuole that reduces the volume of the cytoplasm.
29
Question
With what cellular structures do motor proteins interact to transport materials?
Answer
Motor proteins interact with cytoskeletal structures to transport materials within cells.
30
Question
Which microscopy technique provides the finest resolution for studying internal ultrastructure of cells?
Answer
Transmission electron microscopy (TEM) provides the finest resolution for internal ultrastructure.