Biology Chapter 7 Flashcards

Questions and Answers

Which of the following are examples of lipids? (Select all that apply)

Phospholipids (correct)

Fats (correct)

Steroids (e.g., cholesterol) (correct)

Waxes (correct)

Lipids have _ _ in water.

low solubility

Name four steroids.

Cholesterol, Estradiol, Testosterone, Vitamin D

What is cholesterol?

An important component of animal cell membranes. Signup and view all the answers

What is estradiol?

The primary female sex hormone, produced in ovaries. Signup and view all the answers

What is testosterone?

The most abundant male sex hormone, produced in the testes. Signup and view all the answers

What is vitamin D?

Aids in calcium and phosphate metabolism. Signup and view all the answers

What is the structure of a phospholipid?

<ul> <li>A three carbon chain glycerol.- Fatty acids (2 tails)- Phosphate group (negative charge) and attached to another charged molecule.</li> </ul> Signup and view all the answers

What functional features does the phosphate group contribute to the structure of a phospholipid?

It has a place to attach another small charged molecule and it has a negative charge to interact with water. Signup and view all the answers

What holds phospholipids together in a bilayer formation?

Hydrophilic and hydrophobic interactions with water. Signup and view all the answers

Which molecule is less soluble in water—a fat or a phospholipid? Why?

A fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has. Signup and view all the answers

The characteristic that all lipids have in common is that _________.

none of them dissolve in water Signup and view all the answers

Hydrophobic substances like salad oil are?

Nonpolar molecules that repel water molecules. Signup and view all the answers

What cannot rapidly pass directly through the phospholipids of the plasma membrane?

Water, glucose, ions Signup and view all the answers

Non-polar molecules are?

Hydrophobic, can cross easily through a lipid bilayer, and no transport protein is required. Signup and view all the answers

Polar molecules are?

Hydrophilic, have difficulty crossing a lipid bilayer, and require a transport protein. Signup and view all the answers

Ions (Na+, K+, etc) are?

Hydrophilic, have difficulty crossing a lipid bilayer, and require a transport protein. Signup and view all the answers

When molecules move down their concentration gradient, they move from where they are __ to where they are _

high concentration, less concentrated Signup and view all the answers

Diffusion across a biological membrane is called _____

passive transport Signup and view all the answers

Which of the following factors does not affect membrane permeability?

The polarity of membrane phospholipids. Signup and view all the answers

How are lipids distinguished from sugars?

Lipids are mostly nonpolar. Signup and view all the answers

What property of dishwashing liquid makes it useful to wash grease from pans?

Amphipathic nature Signup and view all the answers

Facilitated diffusion is a type of ____.

passive transport Signup and view all the answers

Osmosis is defined as?

Passive transport of water. Signup and view all the answers

Lysed refers to?

The bursting of the cell. Signup and view all the answers

Turgid refers to?

The swelling of plant cells. Signup and view all the answers

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.

free water, solute, free water, solute Signup and view all the answers

A human cell placed into a hypertonic solution is likely to?

lose water by osmosis. Signup and view all the answers

When a person is dehydrated, his or her IV fluids should be?

Isotonic, because either a hypertonic or hypotonic IV would damage red blood cells. Signup and view all the answers

Transport channels do what?

<ul> <li>Provide a continuous path across the membrane.- Allow water molecules and small ions to flow quickly across the membrane.</li> </ul> Signup and view all the answers

Transport carriers do what?

<ul> <li>Transport primarily small polar organic molecules.- Undergo a change in shape to transport solutes across the membrane.</li> </ul> Signup and view all the answers

Both channels and carriers do what?

<ul> <li>Are integral membrane proteins.- Provide a hydrophilic path across the membrane.- Transport solutes down a concentration or electrochemical gradient.</li> </ul> Signup and view all the answers

The movement of glucose into a cell against a concentration gradient is most likely to be accomplished by?

Co-transport of the glucose with a proton or sodium ion that was pumped across the membrane using the energy of ATP hydrolysis. Signup and view all the answers

Active and passive transport of solutes across a membrane typically differ in what way?

Active transport always involves the utilization of cellular energy, whereas passive transport does not require cellular energy. Signup and view all the answers

Co-transport refers to?

A type of active transport, where the energy from an ion moving through a transport protein down its electrochemical gradient is coupled with the movement of another solute against its gradient. Signup and view all the answers

Endocytosis moves materials a cell via __.

into, membranous vesicles Signup and view all the answers

Pinocytosis is defined as?

The cell is engulfing extracellular fluid. Signup and view all the answers

Phagocytosis describes?

When the cell engulfs a large particle. Signup and view all the answers

What describes some aspect of exocytosis and endocytosis?

Both temporarily change the surface area of the plasma membrane. Signup and view all the answers

Exocytosis is defined as?

<ul> <li>Requires fusion of vesicles with the plasma membrane.- Increases the surface area of the plasma membrane.- Secretes large molecules out of the cell.</li> </ul> Signup and view all the answers

Endocytosis involves?

<ul> <li>Forms vesicles from inward folding of the plasma membrane.- Decreases the surface area of the plasma membrane.</li> </ul> Signup and view all the answers

Both exocytosis and endocytosis require what?

Cellular energy. Signup and view all the answers

In what way do membranes vary among eukaryotic cells?

Certain proteins are unique to each membrane. Signup and view all the answers

According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly?

Embedded in a lipid bilayer. Signup and view all the answers

What factor would tend to increase membrane fluidity?

A greater proportion of unsaturated phospholipids. Signup and view all the answers

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.