Lipid Chemistry and Biology
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Questions and Answers

What is a characteristic of the double bond in the lipid?

  • Flexible structure
  • Harmful for the body
  • Rigid structure (correct)

    • Phosphatidyl inositol is a type of triglyceride.

    False

    All carbon-carbon bonds in fatty acids are single bonds.

    False

    Double bonds in fatty acids are always trans.

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

    Monounsaturated fatty acids always have a double bond at the fifth carbon.

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

    Triacylglycerols are a component of cell membranes.

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

    Lipases hydrolyze triglycerides into glycerol and one fatty acid.

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

    Bile salts increase the surface tension of fat droplets.

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

    Lipase digestion of triglycerides occurs in the stomach.

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

    Cholesterol is a type of sphingolipid.

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

    Gangliosides are the simplest form of sphingolipids.

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

    Phospholipids are found only in the nervous system.

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

    Lipid bilayers are crystalline in structure.

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

    Cholesterol increases fluidity in the crystalline state.

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

    Lipid rafts are fluid and disordered.

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

    Vitamin C is a fat-soluble vitamin.

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

    The hydroxyl group on the A-ring of a sterol is non-polar.

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

    Cerebrosides are found only in the nervous system.

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

    Lipid bilayer translocation requires protein for translocation.

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

    The Na+/K+-ATPase directly transports Na+ and K+ ions during action potential in axons.

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

    ABC transporters can transport material down their gradient.

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

    Symporters can move two substances in opposite directions at the same time.

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

    The β-subunit of Na+/K+-ATPase has binding sites for K+ ions.

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

    Facilitated diffusion requires energy input.

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

    Uniporters move two substances in the same direction at the same time.

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

    The 'piggyback mechanism' is a type of active transport.

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

    ABC transporters are involved in secondary active transport.

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

    Glucose can be transported out of the cell using the Na+/K+-ATPase.

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

    Acetylcholine is stored in the axon terminal.

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

    Amylopectin is a polymer present in glycogen

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

    Glycoproteins and glycolipids are common fuel-storage molecules

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

    Cellulose is a glucose polymer formed between #2 and #3C atoms

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

    Glycogen has a highly branched form that allows it to be rapidly assembled or disassembled

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

    Amylopectin has a linear chain structure

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

    Glycogen is typically stored in compact granules

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

    Cellulose has beta (1→3) glycosidic bonds

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

    Glycoproteins and glycolipids have a limited repertoire of complex molecules

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

    Chitin is a type of polysaccharide found in the cell walls of insects and crustaceans.

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

    N-acetylglucosamine is a type of sugar found in DNA.

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

    Animals can digest chitin.

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

    Glycosylation occurs in the Golgi apparatus.

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

    O-glycosylation occurs in the endoplasmic reticulum.

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

    Biofilms are composed of proteins and lipids.

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

    Glycoproteins are built one residue at a time in the ribosome.

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

    Disaccharides are the main components of biofilms.

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

    Study Notes

    Here are the study notes for the provided text:

    Lipids

    • Lipids are a type of biological molecule, including fats, waxes, and related compounds.
    • Examples of lipids include syhenul, plau, and waxtslid.

    Structure and Composition

    • Lipids are composed of fatty acid chains, which are long chains of carbon atoms with hydrogens attached.
    • The fatty acid chains can be single or double, with the double bonds forming a "kink" in the chain.
    • Lipids can also have a glycerol backbone, which is a three-carbon molecule that serves as the central structure of the lipid.

    Types of Lipids

    • Waxes are a type of lipid that consist of a long-chain fatty acid and a long-chain alcohol.
    • Fats are a type of lipid that consist of a glycerol backbone and three fatty acid chains.
    • Plau lipids are a type of lipid that is found in plant cells.

    Functions of Lipids

    • Lipids serve as a source of energy for cells.
    • They are also important for maintaining the structure and function of cell membranes.
    • Lipids can act as hormones or signaling molecules, helping to regulate various cellular processes.

    Other Important Concepts

    • Lipids are non-polar molecules, which means they are insoluble in water.
    • They are often stored in cells as droplets or as part of the cell membrane.
    • Lipids can be broken down into smaller molecules, such as fatty acids and glycerol, through a process called lipolysis.

    Phospholipids

    • Phosphatidyl inositol is a phospholipid present on the interface of the membrane, concentrated in lipid rafts.
    • Phospholipids are the major constituents of membranes and are responsible for the membrane being a bilayer.
    • Phospholipids have a complex structure consisting of a molecule of glycerol, attached to two fatty acids, a phosphate, and usually one other small molecule (X).

    Fatty Acids

    • Most carbon-carbon bonds in fatty acids are single, but they may contain one, two, or more carbon-carbon double bonds.
    • Double bonds in fatty acids are most often cis.
    • For monounsaturated fatty acids, the double bond is usually between carbon atoms 9 and 10.

    Triglycerides

    • Triglycerides are not part of the cell membrane and aggregate into globules, stored as an energy source.
    • Triglycerides are a component of oils and can be hydrolyzed to produce glycerol and three fatty acids.

    Lipases

    • Lipases hydrolyze triglycerides (fats) into their component fatty acid and glycerol molecules.
    • Initial lipase digestion occurs in the lumen of the small intestine, where bile salts reduce the surface tension of the fat droplets, allowing lipases to attack the triglyceride molecules.

    Glycerophospholipids

    • Glycerophospholipids are the major constituents of membranes and are responsible for the membrane being a bilayer.
    • Glycerophospholipids have a complex structure consisting of a molecule of glycerol, attached to two fatty acids, a phosphate, and usually one other small molecule (X).

    Phospholipase Action

    • Phospholipases are enzymes that cleave ester bonds within phospholipids.
    • Phospholipases contribute to the stability and insulation of nerve cells.

    Sphingolipids

    • Sphingolipids are a type of lipid that contains a sphingoid base, a fatty acid, and a single sugar residue.
    • Cerebrosides are a type of sphingolipid that contains a sphingoid base, a fatty acid, and a single sugar residue, commonly found in the nervous system.
    • Gangliosides are the most complex sphingolipids, containing multiple sugar residues in addition to a sphingoid base and a fatty acid, predominantly present in the nervous system.

    Sterols

    • Sterols are a subgroup of steroids with a hydroxyl group at the 3-position of the A-ring.
    • Sterols are amphipathic lipids synthesized from acetyl-coenzyme A via the HMG-CoA reductase pathway.
    • The overall molecule is quite flat, with a hydroxyl group on the A-ring that is polar, while the rest of the aliphatic chain is non-polar.

    Ceramides

    • Ceramides are the simplest form of sphingolipids, composed of a sphingoid base and a single fatty acid linked by an amide bond.
    • Ceramides serve as precursors for more complex sphingolipids and are involved in cellular signaling pathways related to apoptosis and stress responses.

    Sphingomyelins

    • Sphingomyelins consist of a sphingoid base, a fatty acid, and a phosphorylcholine or phosphorylethanolamine head group.
    • Sphingomyelins are abundant in cell membranes, especially in myelin sheaths.

    Waxes

    • Waxes are esters made of long-chain alcohols and fatty acids.
    • Waxes provide protection, especially to plants, in which wax covers the leaves of plants.

    Fat-Soluble Vitamins

    • Fat-soluble vitamins include vitamins A, D, E, and K.
    • Fat-soluble vitamins play integral roles in a multitude of physiological processes, such as vision, bone health, immune function, and coagulation.

    Lipid Bilayer and Membrane Fluidity

    • The lipid bilayer is a 2D array of amphipathic molecules that forms spontaneously and is very fluid.
    • The lipid bilayer is formed from glycerophospholipids and sphingolipids.
    • Cholesterol is present in the lipid bilayer, which restricts lipid movement and serves as a fluidity buffer.

    Lipid Bilayer Translocation

    • Lipids move laterally easily while lipid movement between layers is less frequent.
    • Lipid movement between layers may require protein for translocation.
    • Interleaflet movement is essential for asymmetry.

    Lipid Bilayer Asymmetry

    • The two leaflets in the bilayer are not identical.
    • Some lipids have to do with the orientation of lipid-synthesizing enzymes.
    • Some lipids have to do with translocases or "flippases".
    • The function of the membrane is more than just as a "cell sack".

    Factors Affecting Melting Temperature

    • The degree of saturation affects the melting temperature.
    • The chain length affects the melting temperature.

    Cellular Membranes

    • Glucose transport works by a rocker mechanism.
    • Glucose binds on one side, eliciting a conformational change, which exposes the molecule to the other side.
    • Glucose transport moves in either direction and is an example of facilitated (passive) transport.

    Primary and Secondary Active Transport

    • Active transport requires energy input and moves against the gradient.
    • The Na, K-ATPase reaction cycle hydrolyzes 1 ATP to pump 3Na+ ions out of the cell and 2 K+ ions inside the cell.

    Secondary Active Transporter

    • The piggyback mechanism uses an established gradient to transport material.
    • Symporters can move glucose into the cell with Na+.
    • The Na+ gradient is already established by the Na+/K+ ATPase.

    ABC (ATP-Binding Cassette) Transporters

    • ABC transporters are composed of two membrane-integral domains and two ATP-hydrolyzing domains.
    • ABC transporters use ATP to transport material into the cell.
    • ABC transporters transport material against its gradient.

    Acetylcholine Release

    • Acetylcholine (ACh) is a neurotransmitter stored in synaptic vesicles.
    • When a nerve impulse reaches the axon terminal, Ca2+ ions from the ECF enter the cell, and ACh is released.

    Polysaccharides

    • Polysaccharides are common fuel-storage molecules.
    • Polysaccharides can be joined in a variety of ways.
    • Tremendous repertoire of complex molecules.

    Glycoproteins and Glycolipids

    • Glycoproteins and glycolipids are polysaccharides attached to proteins or lipids.
    • Amylopectin is a polymer present in starch.
    • Glycogen is a polymer that resembles amylopectin, but with branches every 12 residues.

    Structural Carbohydrates

    • Cellulose is a glucose polymer formed between #1 and #4C atoms.
    • Cellulose is a rigid and strong structure that provides rigidity and strength for plant cell walls.

    Disaccharides

    • Disaccharides occur in nature most commonly as breakdown products of polysaccharides.
    • Animals do not make cellulose and most cannot digest it.
    • Microbes do, and normal microflora for ruminants.

    O-Glycosylation

    • O-glycosylation is a highly specific process that gives tremendous variety and specificity to molecules.
    • O-glycosylation tends to be built one residue at a time in the Golgi apparatus.

    Purpose of Glycosylation

    • The purpose of glycosylation is to:
        1. Provide a specific signal for protein targeting
        1. Regulate protein function
        1. Modify the immune response
        1. Modulate cell-cell interactions
        1. Influence the degradation of proteins

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    This quiz covers the basics of lipid chemistry and biology, including their structure, functions, and importance in the human body.

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