Questions and Answers
Which of the following are examples of lipids? (Select all that apply)
Lipids have _____ _____ in water.
low solubility
Name four steroids.
Cholesterol, Estradiol, Testosterone, Vitamin D
What is cholesterol?
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What is estradiol?
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What is testosterone?
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What is vitamin D?
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What is the structure of a phospholipid?
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What functional features does the phosphate group contribute to the structure of a phospholipid?
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What holds phospholipids together in a bilayer formation?
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Which molecule is less soluble in water—a fat or a phospholipid? Why?
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The characteristic that all lipids have in common is that _________.
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Hydrophobic substances like salad oil are?
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What cannot rapidly pass directly through the phospholipids of the plasma membrane?
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Non-polar molecules are?
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Polar molecules are?
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Ions (Na+, K+, etc) are?
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When molecules move down their concentration gradient, they move from where they are ______ to where they are _____
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Diffusion across a biological membrane is called _____
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Which of the following factors does not affect membrane permeability?
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How are lipids distinguished from sugars?
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What property of dishwashing liquid makes it useful to wash grease from pans?
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Facilitated diffusion is a type of ____.
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Osmosis is defined as?
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Lysed refers to?
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Turgid refers to?
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During osmosis, water diffuses across a selectively permeable membrane from the region of higher ____ concentration and lower ____ to the side with lower ____ concentration and higher ___ concentration.
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A human cell placed into a hypertonic solution is likely to?
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When a person is dehydrated, his or her IV fluids should be?
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Transport channels do what?
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Transport carriers do what?
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Both channels and carriers do what?
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The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by?
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Active and passive transport of solutes across a membrane typically differ in what way?
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Co-transport refers to?
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Endocytosis moves materials ____ a cell via ______.
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Pinocytosis is defined as?
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Phagocytosis describes?
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What describes some aspect of exocytosis and endocytosis?
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Exocytosis is defined as?
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Endocytosis involves?
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Both exocytosis and endocytosis require what?
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In what way do membranes vary among eukaryotic cells?
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According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly?
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What factor would tend to increase membrane fluidity?
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Study Notes
Lipids Overview
- Primary types of lipids include fats, phospholipids, waxes, and steroids such as cholesterol.
- Lipids exhibit low solubility in water due to their hydrophobic nature.
Steroids
- Notable steroids include cholesterol, estradiol, testosterone, and vitamin D.
- Cholesterol is vital for maintaining animal cell membrane integrity.
- Estradiol is the main female sex hormone produced in the ovaries.
- Testosterone is the principal male sex hormone produced in the testes.
- Vitamin D is crucial for calcium and phosphate metabolism.
Phospholipid Structure
- Composed of a glycerol backbone (three carbon chain).
- Contains two fatty acid tails and a phosphate group that carries a negative charge, allowing interaction with water.
- Phosphate groups facilitate attachment of small charged molecules.
Membrane Dynamics
- Phospholipids arrange into a bilayer through hydrophilic (water-attracting) and hydrophobic (water-repelling) interactions.
- Fats have lower solubility than phospholipids due to the absence of polar regions.
- Common lipid characteristic is that they do not dissolve in water, making them hydrophobic.
Transport Mechanisms
- Water, glucose, and ions cannot quickly pass through phospholipid membranes.
- Non-polar molecules can easily cross lipid bilayers without transport proteins.
- Polar molecules and ions struggle to cross and require transport proteins.
Diffusion and Concentration Gradients
- Molecules move down their concentration gradient from areas of high to low concentration.
- Diffusion across membranes is classified as passive transport.
- Membrane permeability is influenced by the properties of lipids, excluding lipid polarity.
Role of Detergents
- Dishwashing liquid is effective in removing grease due to its amphipathic nature, forming micelles that encapsulate grease particles.
Osmosis
- Defined as passive transport of water across selectively permeable membranes.
- Involves movement from higher free water concentration and lower solute concentration to the opposite side.
Cell Responses to Solutions
- Plant cells swell (turgid) in hypotonic solutions and animal cells may burst (lysed).
- In hypertonic solutions, human cells lose water by osmosis.
- Isotonic IV fluids are recommended for dehydrated individuals to prevent harm to red blood cells.
Transport Proteins
- Transport channels provide continuous pathways for water and small ions across membranes.
- Transport carriers change shape to assist polar organic molecules across the membrane.
- Both channels and carriers are integral membrane proteins that enable hydrophilic pathways and facilitate solute transport.
Active vs Passive Transport
- Active transport requires cellular energy, while passive transport does not.
- Cotransport couples the movement of one ion down its gradient with another solute against its gradient using ATP energy.
Endocytosis and Exocytosis
- Endocytosis draws materials into cells using membranous vesicles; it decreases plasma membrane surface area.
- Exocytosis expels large molecules from cells and increases plasma membrane surface area by merging vesicles.
- Both processes necessitate cellular energy and alter the surface area of the plasma membrane.
Membrane Characteristics
- Eukaryotic membranes vary with unique protein compositions.
- According to the fluid mosaic model, membrane proteins are primarily embedded in lipid bilayers.
- Increased fluidity in membranes is associated with a higher proportion of unsaturated phospholipids.
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Description
Test your knowledge of lipids with these flashcards from Chapter 7. Define different types of lipids, their properties, and specific examples such as steroids. This quiz will help reinforce your understanding of their functions and significance in biology.