Lipids Flashcards
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Questions and Answers

What do all lipids have in common?

All lipids are nonpolar and hydrophobic, thus all lipids are insoluble in water and are linked by nonpolar covalent bonds.

What elements make up lipids?

Carbon, hydrogen, and oxygen

What are the four major groups of lipids?

Fats or triglycerides, phospholipids, steroids, and waxes

What are the functions of fats?

<p>Long term energy storage, insulation, body cushioning</p> Signup and view all the answers

What two molecules are lipids made from?

<p>Glycerol and fatty acids</p> Signup and view all the answers

What is the structure of glycerol?

<p>A three carbon chain molecule with each carbon containing a hydroxyl group and all the other open bonds containing hydrogen</p> Signup and view all the answers

What is a hydrocarbon chain?

<p>A chain of carbon with hydrogens attached</p> Signup and view all the answers

What type of bond forms between carbon and hydrogen?

<p>Nonpolar</p> Signup and view all the answers

What is the structure of a fatty acid?

<p>A hydrocarbon chain with about 15 carbons and a carboxyl group attached at one end</p> Signup and view all the answers

To make a fat, what must combine together?

<p>Three fatty acids must link to one glycerol molecule to make a fat.</p> Signup and view all the answers

What is a fatty acid with no double bond called?

<p>Saturated</p> Signup and view all the answers

What is a fatty acid with one or more double bonds called?

<p>Unsaturated</p> Signup and view all the answers

What are the characteristics of unsaturated fatty acids?

<p>They have less than the maximum number of hydrogens, which causes kinks in the chain and keeps them liquid at room temperature.</p> Signup and view all the answers

What are the characteristics of saturated fatty acids?

<p>They contain the maximum number of hydrogen atoms, making them solid at room temperature and often unhealthy.</p> Signup and view all the answers

What is the difference between mono and polyunsaturated?

<p>Monounsaturated means only one double bond between carbons, while polyunsaturated has more than one double bond.</p> Signup and view all the answers

What is the major component of cell membranes?

<p>Phospholipids</p> Signup and view all the answers

What are phospholipids?

<p>Two fatty acids linked to a glycerol molecule, with a phosphate group attached to the third hydroxyl group.</p> Signup and view all the answers

What are steroids?

<p>Lipids whose carbon skeleton is bent to form four fused rings.</p> Signup and view all the answers

Is cholesterol a component of animal cell membranes?

<p>True</p> Signup and view all the answers

Is cholesterol a component of plant cell membranes?

<p>False</p> Signup and view all the answers

What type of hormone is made from steroid lipids?

<p>Sex hormones</p> Signup and view all the answers

What is the most hydrophobic lipid that serves as a waxy coat to prevent drying out?

<p>Waxes</p> Signup and view all the answers

Study Notes

Lipid Characteristics

  • All lipids are nonpolar and hydrophobic, making them insoluble in water.
  • Lipids are linked by nonpolar covalent bonds.

Composition of Lipids

  • Lipids consist of carbon, hydrogen, and oxygen.

Major Groups of Lipids

  • Four main categories include:
    • Fats (triglycerides)
    • Phospholipids
    • Steroids
    • Waxes

Functions of Fats

  • Provide long-term energy storage.
  • Act as insulation (e.g., blubber).
  • Offer cushioning for the body.

Building Blocks of Lipids

  • Composed of glycerol and fatty acids.

Glycerol Structure

  • Structure is a three-carbon chain with hydroxyl groups and hydrogen atoms.

Hydrocarbon Chain

  • Formed by a chain of carbon atoms with hydrogen atoms attached.

Bonding in Lipids

  • Carbon and hydrogen form nonpolar bonds due to equal electronegativity, contributing to hydrophobicity.

Fatty Acid Structure

  • Consists of a hydrocarbon chain typically with around 15 carbons and a carboxyl group at one end.

Formation of Fats

  • Fats are created when three fatty acids link to one glycerol through dehydration synthesis.

Types of Fatty Acids

  • Saturated fatty acids:
    • No double bonds, maximum hydrogen atoms, solid at room temperature, often from animals (e.g., butter, lard).
  • Unsaturated fatty acids:
    • Contain one or more double bonds, liquid at room temperature, primarily sourced from plants (e.g., vegetable oil), healthier option.

Mono vs. Polyunsaturated Fatty Acids

  • Monounsaturated: one double bond between carbons, considered the healthiest.
  • Polyunsaturated: more than one double bond between carbons.

Phospholipids

  • Major components of cell membranes, composed of two fatty acids linked to glycerol, with a phosphate group attached.
  • Have a dual nature; the phosphate group (polar, hydrophilic) and fatty acids (nonpolar, hydrophobic).

Steroids

  • Characterized by a carbon skeleton that forms four fused rings, consisting of three six-sided rings and one five-sided ring.
  • Cholesterol serves as the precursor for all steroids.

Cholesterol and Cell Membranes

  • Cholesterol is found in animal cell membranes but not in plant cell membranes.

Steroid Hormones

  • Sex hormones are synthesized from steroid lipids.

Waxes

  • The most hydrophobic lipid, providing a waxy coat to prevent organisms from drying out.

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Test your knowledge on lipids with these flashcards. Each card focuses on a key concept, such as the common characteristics of lipids, their elemental composition, and the major groups of lipids. Perfect for students studying biology or biochemistry.

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