What defines a prokaryotic cell's DNA structure and organelles?
It has circular DNA in a nucleoid and lacks membrane-bound organelles.
What characterizes a eukaryotic cell's chromosomes and organelles?
It has linear chromosomes in a nucleus and membrane-bound organelles.
Which components are common to both prokaryotic and eukaryotic cells?
Genetic material, ribosomes, cytosol, and a plasma membrane.
Where is prokaryotic DNA located and what form does it take?
In the nucleoid as a circular chromosome, sometimes with plasmids.
How is eukaryotic DNA organized and enclosed?
Into linear chromosomes inside a membrane-bound nucleus.
What is a ribosome made of?
Proteins and ribosomal RNA.
What is the function of rough endoplasmic reticulum?
Protein synthesis.
What is the function of smooth endoplasmic reticulum?
Lipid synthesis and detoxification.
What does the Golgi complex do to proteins?
Modifies them into their final conformation.
What enzymes do lysosomes contain?
Hydrolytic enzymes.
What is the main function of mitochondria?
Produce energy.
What structures do chloroplasts contain for photosynthesis?
Thylakoids stacked into grana and stroma.
What role does the centrosome play in animal cells?
Organizes spindle fibers during cell division.
What does the endosymbiosis hypothesis state about mitochondria and chloroplasts?
They evolved from free-living prokaryotes engulfed by larger prokaryotes.
Why do mitochondria and chloroplasts support the endosymbiosis hypothesis?
They contain circular DNA and ribosomes similar to prokaryotes.
How do mitochondria and chloroplasts reproduce?
By binary fission, like bacteria.
How does compartmentalization increase cell efficiency?
By separating enzymes of different metabolic processes and reducing harmful cross-reactions.
What is the formula for the surface area of a spherical cell?
What is the formula for the volume of a spherical cell?
What is the surface-area-to-volume ratio formula for a spherical cell?
How does cell size affect surface-area-to-volume ratio?
A larger cell has a lower surface-area-to-volume ratio.
How does a lower surface-area-to-volume ratio affect cell exchange efficiency?
It reduces efficiency of exchanging nutrients, wastes, chemicals, and energy.
What effect do folding membranes have on surface area?
They increase the surface area available for reactions or absorption.
What does the fluid mosaic model describe about plasma membranes?
It describes a plasma membrane with mobile phospholipids, proteins, glycoproteins, glycolipids, and steroids moving within the membrane surface.
What is the structure of the plasma membrane?
It is a phospholipid bilayer with hydrophilic heads facing aqueous environments and hydrophobic tails facing inward.
What roles do plasma-membrane proteins perform?
They transport materials, participate in signaling, anchor cells, and catalyze chemical reactions.
What is the function of glycoproteins and glycolipids in the plasma membrane?
They function in cell recognition.
How do steroids affect the plasma membrane?
They adjust membrane fluidity according to environmental conditions and cellular needs.
Which molecules cross the phospholipid bilayer easily?
Small hydrophobic molecules like O2, CO2, and N2.
What is passive transport?
Movement of molecules down their concentration gradient without energy input.
What distinguishes osmosis from facilitated diffusion?
Osmosis is water diffusion across a membrane; facilitated diffusion uses proteins for polar molecules or ions.
How does the Na+/K+ pump use ATP?
It moves three Na+ out and two K+ into the cell against gradients.
What process brings water and macromolecules into the cell?
Endocytosis.
What process expels molecules by fusing vesicles with the plasma membrane?
Exocytosis.
What does water potential predict in a solution?
The direction of water movement.
From which water potential does water move?
From higher water potential.
What is the formula for total water potential?
How is solute potential calculated?
What does the ionization constant represent in solute potential?
The number of particles a substance forms in solution.
What is the ionization constant for NaCl?
2
How do you calculate temperature in Kelvin from Celsius?
What is osmolarity?
The total concentration of solutes in a solution.
Why does water enter a freshwater paramecium?
Because it has higher internal solute concentration and lower water potential than its environment.
What role does the contractile vacuole play in freshwater paramecia?
It pumps excess water out of the cell.
Why do saltwater-fish cells have lower solute concentration than seawater?
Their cells have lower solute concentration and higher water potential than seawater.
How do saltwater fish manage excess solutes?
They excrete excess solute through specialized salt-secreting organs.
What happens if water enters a cell unregulated?
The cell can burst.
What is a risk of excessive dehydration for an organism?
It can cause the organism to die.
Test your knowledge with 27 questions on Cell Structure and Function.
1. Which feature best identifies a prokaryotic cell?
2. What distinguishes a eukaryotic cell from a prokaryotic cell?
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