Glyceraldehyde
D-Erythrose
D-Ribose
D-Glucose
D- Mannose
D- Galactose
Dihydroxyacetone phosphate
D-Ribulose
D-Xylulose
D-Fructose fischer
D-mannose Chair conformation
D-ribulose-5-phosphatase fischer projection
Alpha-D-Fructose
Beta-D-glucose
sucrose
lactose
maltose
cellobiose
cellulose
starch
Sugar alcohols, such as maltitol, erythritol, sorbitol, mannitol
Maltodextrin
Dextrose
High fructose syrup
It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contain
glycogen
The main CHO storage in animals. Muscle and liver glycogen consists of Glc residues in a 1->4 links with lots of a 1->6 branches (many more branches than in starch). The polymer is synthesized on a protein primer called glycogenin (G)
chitin
the major substance in exoskeletons of anthropods and mollusks is a b 1->4 linked polymer of GlcNAc
cellulose bonded
lipid definition
A lipid is generally considered to be any molecule that is insoluble in water and soluble in organic solvents. Biological lipids usually refer to a broad grouping of naturally occurring molecules which includes fatty acids, waxes, eicosanoids, monoglyceri
lipid features
The lipids are a large and diverse group of naturally occurring organic compounds that are related by their solubility in nonpolar organic solvents (e.g. ether, chloroform, acetone & benzene) and general insolubility in water.
functions of lipids in the cell
The main biological functions of lipids include:
1. energy storage
2. structural components of cell membranes (phospholipids, sphingolipids)
3. and as important signaling molecule (sphingolipids - growth and differentiation)
know the two major kinds of cellular lipids and the subclasses that we discussed in class
Two structural groups
1) open chain structures (polar head groups) with long non-polar tails
includes: fatty acids, triacylglycerols, phosphoacylglycerols, sphingolipids glycolipids
2) fused ring compounds (steroids)
general structure of fatty acids
Fatty acids consist of a long hydrocarbon tail terminating with a carboxyl group
Fatty acids are merely carboxylic acids with long hydrocarbon chains. The hydrocarbon chain length may vary from 10-30 carbons (most usual is 12-18). The non-polar hydrocarbo
fatty acids are ________ at physiological pH. Why?
Since the pKa of the carboxyl group is approximately 4.5 to 5.0, fatty acids are anionic at physiological pH.
how fatty acids are named formally
Formally: IUPAC nomenclature, carbons are numbered beginning with the carboxyl carbon. In common nomenclature, the carbon atom adjacent to the carboxyl carbon is designated alpha, and the remaining carbons are lettered beta, gamma, delta, and so on. The c
saturated fatty acid properties
Unsaturated refers to the presence of one or more double bonds between carbons as in alkenes. A saturated fatty acid has all bonding positions between carbons occupied by hydrogens, no double bonds.
unsaturated fatty acids
Unsaturated refers to the presence of one or more double bonds between carbons as in alkenes. A saturated fatty acid has all bonding positions between carbons occupied by hydrogens.
saturated vs unsaturated contribution to melting point of chain length and cis-double bonds
1. As the molecular weight increases, the melting point increases.
2. Unsaturated fatty acids have lower melting points than the saturated fatty acids.
Melting point: Lower melting point of unsaturated fatty acids - The reason for this phenomenon can be f
structure of glycerol
also called glycerin
structure of triglyceride
Fatty Acid Chains can very in length!
Chains are always EVENLY numbered in length!
Fatty acid + glycerol = triglyceride
Glycerol (a) is the backbone to which three fatty acyl residues are esterified
(b). Although glycerol is not chiral, C-2 of a triacylgl
function of triglycerides in energy storage
Why do Triglycerides work for energy storage?
The advantages to using triacylglycerols as a source for metabolic fuel reside in:
1. Its highly reduced nature, as well as
2. Its hydrophobic state.
Since the carbons of fatty acids are more reduced (carbon i
function of triglyceride in thermal insulation inside cells (and bodies)
One of the functions of Triglycerides even more so, the related phospholipids is that they contribute to the structure of membranes by the formation of a lipid bilayer.
The lipid bilayer that Triglycerides form helps with insulation and storage.
Why stora
general structure of phospholipids
A phospholipid molecule consists of two main parts:
1. A hydrophilic polar head group and
2. A hydrophobic tail.
The polar head group has one or more phosphate groups while the hydrophobic tail has two fatty acyl chains. The polar head group is joined to
structural and functional role of phospholipids in the makeup of cell membranes
A lipid bilayer, also known as the phospholipid bilayer, is a sheet of lipids two molecules thick, arranged so that the hydrophilic phosphate heads point "out" to the water on either side of the bilayer and the hydrophobic tails point "in" to the core of
common phosphatidyl linked polar head groups (chart)
structure of phosphtidyl linked polar head groups
In one sense the polar lipids are like the anions of fatty acids, only more so. They contain two hydrophobic hydrocarbon tails and a head which may have several electrically charged sites.
structure of serine
structure of glycerol
also called glycerin
structure of ethanolamine
structure of choline
Quaternary ammonium salt with counter anion (X-) present (not in photo)
structure of myo-inositol
structure of phosphatidyl glycerol
The general structure of phosphatidylglycerol consists of a L-glycerol 3-phosphate backbone ester-bonded to either saturated or unsaturated fatty acids on carbons 1 and 2. The head group substituent glycerol is bonded through a phosphomonoester.
Four classes of phospholipases (including the selective bonds they hydrolyze)
Phospholipidase A1 - cleave Acyl-ester bonds at Sn-1
Phospholipidase A2 - cleave Acyl-ester bonds at Sn-2
Phospholipidase C - cleaves glycerophosphate bond
Phospholipidase D - removes head group, X
general structure of a wax (ester)
common functions of waxes in living organisms
In plants: Wax layer is microcrystalline in structure and forms the outer boundary of the cuticular membrane, i.e. it is the interface between the plant and the atmosphere.
It serves many purposes, for example:
1. to limit the diffusion of water and solut
structure of sphingosine
Sphingosine is an 18 Carbon long-chain, monounsaturated, aliphatic amino alcohol found in sphingolipids.
Sphingolipids are composed of sphingosine, a
fatty acid, and a mono or ogliosaccharide
general structure of eicosanoids and know the fact that they play a role in inflammation and immune response
Local Hormones". Prostaglandins and related compounds are collectively known as eicosanoids. Most are produced from arachidonic acid, a 20-carbon polyunsaturated fatty acid.
1. Rapidly degraded
2. Intra and Inter cellular signalling
Antiinflammatory: Cor
know the three functions of cholesterol in the animal cell membrane
1.Maintain ordered phase of membrane at High Temp
2. Maintain disordered phase of membrane at Low Temp
3. Formation of lipid rafts - In eukaryotic cells,
cholesterol ?lls the gaps among sphingomyelin molecules. The result is membrane regions with high con
Write fused ring structure of cholesterol and know closely related derivatives as steroids
understand the general structure and function of biological membranes (fluid-mosaic model)
. A lipid bilayer forms the basic matrix of biological membranes, and proteins (some of which are glycoproteins) are associated with it in various ways
The essence of their model is that membranes are two-dimensional solutions of oriented lipids and globu
early experiments discussed in class that validated fluid mosaic model
Diffusion of membrane proteins
Diffusion of membrane proteins. Human cells whose membrane proteins had been labeled with a red fluorescent marker were fused with mouse cells whose membrane proteins had been labeled with a green fluorescent marker. The ini
general properties of ?-helices and ?- sheets that allow proteins to span biological membranes
Alpha-helices - can be found in the inner membrane of bacterial cells or the plasma membrane of eukaryotes. Voltage-gated ion channels, such as potassium and chloride channels, are examples of alpha-helical transmembrane proteins.
Beta-helices - present i
simple diffusion (across biological membranes) vs facilitated diffusion
Simple diffusion: a Small, uncharged, substance moves directly through the membrane
Facilitated Diffusion: a substance moves through the membrane with the aid of a channel (pore) or carrier. A specific membrane protein lowers the activation energy for mov
3 types of facilitated transport
Uniport
Antiport
Symport
Differences between 3 types of facilitated transport (uniport, antiport, symport)
Uniport - carry only a single species across the membrane
Symport - carry more than one species in the same direction across the membrane
Antiport - carry more than one species but carry them in opposite directions across the membrane
difference between primary and secondary active transport
Primary active transport: ATP is used directly, and the energy comes from the breakage of a high energy phosphate bond
Secondary active transport: ATP is not used directly, and the energy comes from a gradient that was created by a primary active transpor
By using the energy from the
_____________ of _________ molecule of ATP, it transports ___________ Na+ out in exchange for ________ K+ that are taken in
By using the energy from the hydrolysis of one molecule of ATP, it transports three Na+out in exchange for two K+ that are taken in
Function of Na-K ATPase in Osmotic balance
The accumulation of sodium ions outside of the cell draws water out of the cell and thus enables it to maintain osmotic balance (otherwise it would swell and burst from the inward diffusion of water).
Function of Na-K ATPase in Glucose and amino acid uptake
Symport Pumps
Indirect active transport, the driving ion (Na+) and the pumped molecule pass through the membrane pump in the same direction.
Examples:
The Na+/glucose transporter.
1. This transmembrane protein allows sodium ions and glucose to enter the c
Function of Na-K ATPase in Exciteable cells
At rest, there is a higher concentration of Na+ OUTSIDE the cell than inside.
At rest, there is a higher concentration of K+ INSIDE the cell than outside
This is maintained by the Na/K ATPase pump.
The electric. current in neurons is used to rapidly trans
General scheme involved in signal transduction pathways including the three types of receptors
Release of primary messenger
- from external stimulous
2) Reception of primary messenger-
Three types of receptors
a) 7TM receptors - 7 a-helical segments (G-protein-coupled) - bind ligands
b) receptors that dimerize
Example HGH
c) receptor tyrosine kinas
know the specific details (from the figures discussed in class) for G-protein coupled receptors
1.The first step in signal transduction is ligand binding.
2. Agonist binding is followed by a change in the conformation of the receptor that may involve disruption of a strong ionic interaction between the third and sixth transmembrane helices which fac
G-protein coupled receptors adenylate cyclase
Multiple signaling roles of a GPCR illustrated for the ?2-adrenergic receptor. Agonist occupancy of the receptor leads to activation of Gs and adenylyl cyclase (signal 1). PKA phosphorylation of the receptor uncouples it from Gs and facilitates its coupli
G-protein coupled receptors protein kinase A
See previous
PKA-catalyzed phosphorylation of the receptors contributes to controlling the specificity of G protein coupling.
G-protein coupled receptors that work through phospholipase C
The enzyme phospholipase C produces diacylglycerol (DAG) and inositol trisphosphate (IP3), which increases calcium ion permeability into the membrane. Active G-protein open up calcium channels to let calcium ions enter the plasma membrane.
The other produ
G-protein coupled receptors IP3
Release Ca 2+
IP3 (Inositol 1,4,5-triphosphate), also known as a second messenger, is a molecule that functions to transfer a chemical signal received by the cell, such as from a hormone, neurotransmitters, growth factors and hypertrophic stimuli to vario
G-protein coupled receptors DAG
...
built in features of the schemes discussed above to turn off signals from the receptors or to make the signals transient (temporary)
Several mechanisms cooperate in turning GPCRs off:
1. When activated, the G? subunit of the G protein swaps GDP for GTP. However, the G? subunit is a GTPase and quickly converts GTP back to GDP restoring the inactive state of the receptor.
2.The receptor
how tyrosine kinase receptors work
1. Binding of the ligand to two adjacent receptors forms an active homodimer.
2. This activated dimer is a tyrosine kinase; an enzyme that attaches phosphate groups to certain tyrosine (Tyr) residues � first on itself, then on other proteins converting th
tyrosine receptors that that are activated through dimerization (like human growth hormone)
These consist of 2 identical single-pass transmembrane proteins (i.e., homodimers) embedded in the plasma membrane. Each of their cytoplasmic ends binds a molecule of a Janus kinase ("JAK")
1. Binding of the ligand activates the JAK molecules which
2. Pho
tyrosine receptors that work covalently linked subunits (like the insulin receptor)
...
saponification
hydrolysis of animal fats under conditions of strong base (sodium hydroxide)- where we get the name soap
yields: fatty acid and glycerol
micelle
An aggregate of amphipathic molecules in water, with the nonpolar portions in the interior and the polar portions at the exterior surface, exposed to water. Happens in detergents
Micelles are favored when the polar head group has a greater cross-sectional
liposome
artificially formed lipid bilayer that has folded upon itself and is used to understand the dynamics of the cell membrane. Can be used to deliver genes into cells (transducement)
bilayer
The two phospholipid layers of the cell membrane
lipid raft
Microdomain, heavily enriched with cholesterol filling the space between the phospholipids packing them more tightly together than surrounding the membrane.
lateral vs transverse diffusion
In transverse diffusion, membrane asymmetry can be preserved for long period
ordered vs disordered phases of phospholipid bilayers
...
channel
...
carrier
...
selectivity filter
...
membrane receptor
...
transducer
...
second messenger
...
effector enzyme
...
Dodecanoate
Laurate CH3(CH2)10COO-
fatty acid
Myristate
Tetradecanoate
fatty acid
Palmitate
Hexadecanoate
fatty acid
Stearate
Octadecanoate
fatty acid
Arachidate
Eicosanoate
fatty acid
Behenate
Docosanoate
fatty acid
Lignocerate
Tetracosanoate
fatty acid
Palmitoleate
cis-delta 9-Hexadecenoate (has 1 double bond)
fatty acid
Oleate
cis-delta 9-Octadecenoate (has 1 double bond)
fatty acid
Linoleate
cis,cis-delta9,12- octadecadeinoate (has 2 double bonds)
fatty acid
Linolenate
all cis-delta9,12,15-octadecatrienoate (has 3 double bonds)
fatty acid
Arachidonate
all cis-delta5,8,11,14-Eicosatetraenoate (has 4 double bonds)
fatty acid
The __________ of glycoproteins and glycolipids are on the ________ surface of
the _________.
oligosaccharides, exterior
Function of biological membrane
1. Passive diffusion and osmosis
2. Transmembrane protein channels and transporters
3. Endocytosis
4. Exocytosis
Active Diffusion
Active: a substance moves through the membrane against with the aid of a carrier and up a concentration gradient
Passive Diffusion
A substance (s) moves through the membrane down a concentration gradient
Channel (facilitated transport)
channels - open to both sides of membrane
Carriers (facilitated transport)
carriers - open to only one side of the membrane (change in conformation)
Channels are ________ ________, follow _________ kinetics, are ____ saturated
Channels are weakly selective, follow linear kinetics, are not saturated
Carriers are _______selective, follow ________ kinetics,
are __________
Carriers are highly selective, follow hyperbolic kinetics, are saturated
Amylose structure
Amylose
Amylopectin structure
Amylopectin
polysaccharides
These contain many monosaccharides in glycosidic links, and may contain many branches. They serve as either structural components or energy storage molecules.
Glycogen Chair Conformation
Cellulose Chair Conformation
Triglycerides conversion to energy (steps)
The process of breaking down of triglycerides is known as Lipolysis.
In this process, a single triglyceride is broken down to one molecule of glycerol and three molecules of fatty acids.
Conversion To Acetyl-CoA
The glycerol and fatty acids follow differe
Homeostatic regulation of energy balance in mammals (overview)
Signals from sites of fat storage communicate the energetic state of the body to the nervous system, which also receives environmental and sensory inputs. The nervous system integrates these signals and responds to alter behavior, physiology and energy up
Lipid Bilayer
Triglycerides (phospholipids) form it. The membranes serve as a barrier to keep separate the inside of a cell and the outside of a cell. The triglycerides and the phospholipids help to achieve this by having the polar head of the molecule facing the insid
polar fatty acids vs nonpolar fatty acids
As was true of most nonpolar lipids, the structures of polar lipids are based on condensation of fatty acids with glycerol.
MAIN DIFFERENCE is that only two of the three OH groups on glycerol are involved. The third is combined with a highly polar molecul
Lipid Metabolism (General Overview)
Lipid Digestion (overview)
1. Emulsification of Fats
Fatty acids can be liberated by simple hydrolysis of the ester bonds
in triglycerides, but the INSOLUBILITY OF TRIGLYCERIDES PRESENTS A PROBLEM FOR DIGESTION ; digestion
occurs following dispersion of dietary fat into small parti
The enzyme involved in hydrolyzing emulsified fats is specific for which linkages?
1. Pancreatic lipase is
virtually specific for the hydrolysis of primary ester linkages, the 1 or the 3 ester bonds, but not the bond in the central 2 position (see below).
As a result of this conversion, 2-monoglycerides (2-monoacylglycerols) are major e
Instead, the great majority of absorbed lipids, including triglycerides, phospholipids, cholesterol
esters, and cholesterol, appear in the form of
chylomicrons (that pass to the lymphatic vessels of the abdominal region and later to the systemic blood
Informal lipid naming
There are also other notations for a person to read fatty acids. One case is denoting the number of carbon atoms versus the number of double bonds. For example 14:2 states that there are 14 carbon atoms and 2 double bonds within the molecule.
Essential features of fatty acids (3)
Essential components that define fatty acids:
1. Hydrocarbon chain(s)
2. Saturated (pure C-C bonds) or unsaturated (contains one or more C=C bonds)
3. Carboxylic acid at one terminus
Two main parts of any phospholipid
A phospholipid molecule consists of two main parts:
1. A hydrophilic polar head group with 1 or more phosphate groups and
2. A hydrophobic tail with two fatty acyl chains.
The polar head group has one or more phosphate groups while the hydrophobic tail ha
4 components to build a phospholipid
A phospholipid molecule is constructed from four components:
1. One or more fatty acids
2. A platform to which the fatty acids are attached
3. A phosphate
4. An alcohol attached to the phosphate.
The platform on which phospholipids are built may be glycer
Why is there a great amount of phospholipid diversity?
A phospholipid can have many different phosphitidyl 'head groups' as a substituent to the phosphate group. Examples of these head groups include serine, ethanolamine, choline, glycerol, inositol.
2 main forms phospholipid can exist in
Phospholipids exist in two forms:
1. Phosphoglycerides - Lipids of glycerol groups bonded to two fat-soluble fatty acids and one charged, water-soluble phosphate group; the compound is known as phosphatidic acid.
2. Sphingomyelin - Sphingomyelins are unli
Glycolipid (general definition)
Glycolipids are lipids that have a covalently attached carbohydrate (sugar-containing lipids). Glycolipids aid in providing energy as well as serving as genetic markers for cell recognition.
2 types of glycolipids (name 1, know the other)
There are two types of glycolipids: sphingolipids and galactolipids.
The sphingolipid is made up of one sphingosine, a fatty acid, and a mono or oligosaccharide.
Structure of sphingolipid
The structure of the glycolipid sphingolipid are formed by:
Carbohydrate chains bonded to phospholipids on extracellular side of cell membrane of phospholipid bilayer. These structures serve as recognition markers for chemicals and also stabilize the memb
Structure of sphingolipid (detailed)
How do alpha-helix and beta-helix proteins span membranes?
Why do they span membranes?
Because the peptide bonds themselves are polar and because water is absent, all peptide bonds in the bilayer are driven to form hydrogen bonds with one another. The hydrogen bonding between peptide bonds is maximized if the pol
Passive and active transporters
Although the transport proteins are depicted as having an open central pore, passive and active transporters actually undergo conformational changes when transporting their solutes
Three types of receptors for Signal Transduction
Three types of receptors
1. 7TM receptors - 7 a-helical segments (G-protein-coupled) - bind ligands
2. receptors that dimerize - Example HGH (dimeraize - consisting of two identical simpler molecules)
3. receptor tyrosine kinases (covalent) -receptor bind
________________ are the source of the lipids involved in signal transduction
Cell membranes
Lipid classes chart
The presence in a given cell of one __________________________ versus another determines whether a parent lipid molecule such as phosphatidylcholine gives rise to arachidonic acid (AA), phosphatidic acid (PA), or platelet-activating factor (PAF).
phospholipase enzyme (PL)
Cholesterol structure
Fatty chains in blue. hydrophobic regions to the top, polar (hydrophilic) region towards bottom
The presence of a double bond in a fatty acid adds a kink. Fatty acids that have more double bonds have more kinks in their structure and take up more space. Thus, as the number of double bonds increases, the membrane becomes _____ ?uid because the fatty
The presence of a double bond in a fatty acid adds a kink. Fatty acids that have more double bonds have more kinks in their structure and take up more space. Thus, as the number of double bonds increases, the membrane becomes more ?uid because the fatty a
Also, the identity of a lipid is determined by its ______________ and not by its _____________, since the _____________ may vary.
parent structure, not by its fatty acids which may vary
Lipid naming (informal)
#carbons: #double bonds
Lauric
12:0
Palmitoleic
16:1
Myristic
14:0
Oleic
18:1
Palmitic
16:0
Linoleic
18:2
Stearic
18:0
Linolenic
18:3
Arachidic
20:0
Arachodonic
20:4
spontaneously form micelles, liposomes, and bilayers (chain length and other properties determine structures that form
phospholipid
Sphingolipid structure (again)
Hydropathy plot purpose
predict whether a given protein sequence contains membrane-spanning segments.
Sodium Potassium ATPase is example of
Primary active transport
Sodium Potassium ATPase function
Exclusive transporter in animal cells
Three functions:
1. Keeping water out of cell
2. Driving secondary active transport
3. Excitable cells
In order to maintain the cell potential, cells must keep a low concentration of sodium ions and high levels of pot
Sodium Potassium ATPase mechanism
1. The pump, with bound ATP, binds 3 intracellular Na+ ions.
2. ATP is hydrolyzed, leading to phosphorylation of the pump at a highly conserved aspartate residue and subsequent release of ADP.
3. A conformational change in the pump exposes the Na+ ions to
Which ion is responsible for the chemical gradient?
Potassium
As the plasma membrane is far less permeable to sodium than it is to potassium ions, an electric potential (negative intracellularly) is the eventual result
Export of ______ from the cell provides the driving force for several facilitated transport processes that:
import glucose, amino acids and other nutrients into the cell
Translocation of sodium from one side of an epithelium to the other side creates
An osmotic gradient which drive the absorption of water
Why do beta sheet "barrels" form?
because of unsatisfied hydrogen-bond donor and acceptor groups in their backbones.
Hydrophobic side chains cover the exterior, polar/charged side chains aim into the interior
Function: To permit water or ions to diffuse into the membrane
Why no mix of alpha and beta?
the need to hydrogen bond polar groups on the edge strands of the beta sheets would be difficult to satisfy in a mixed structure
Electrochemical Gradient functions
Theelectrochemical gradient the Na-K-ATPase generates is critical in maintaining the osmotic balance of the cell, the resting membrane potential of most tissues, and the excitable properties of muscle and nerve cells. In addition, the Na+ gradient provide
alpha subunit in Na/K ATPase function/mass
The a-subunit is a multispanning membrane protein with a molecular mass of 112,000 Da that is responsible for :
catalytic and transport properties of the enzyme.
Alpha subunit binding sites (Na/K ATPase)
The a-subunit contains the
binding sites for the cations, ATP, and the inhibitor,
ouabain
Beta subunit function (Na/K ATPase)
Theb-subunit is a polypeptide that crosses the membrane once and, depending on the degree of glycosylation in different tissues, has a molecular weight between 40,000 and 60,000 Da.
The b-subunit is essential for the
1. normal activity of the enzyme
2. in
G Coupled Protein Basic Mechanism Activation
1. In the inactive state, G? has GDP in its binding site.
2. When a hormone or other ligand binds to the associated GPCR, an allosteric change takes place in the receptor (that is, its tertiary structure changes).
3. This triggers an allosteric change in
Count Delta from
Methyl End
Many membrane processes, such as _________ or ______________, depend on the fluidity of the membrane lipids, which in turn depends on the properties of fatty acid chains, which can exist in an ordered, rigid state or in a relatively disordered, fluid stat
Many membrane processes, such as transport or signal transduction, depend on the fluidity of the membrane lipids, which in turn depends on the properties of fatty acid chains, which can exist in an ordered, rigid state or in a relatively disordered, fluid
The presence of ____________ fatty acyl residues favors the rigid state because their straight hydrocarbon chains interact very favorably with each other. On the other hand, a _______________ produces a bend in the hydrocarbon chain. This bend interferes
The presence of saturated fatty acyl residues favors the rigid state because their straight hydrocarbon chains interact very favorably with each other. On the other hand, a cis double bond produces a bend in the hydrocarbon chain. This bend interferes wit
Vitamin C
glycosidic bond
Type of covalent bond that joins a carbohydrate (sugar) molecule to another group, which may or may not be another carbohydrate.
A glycosidic bond is formed between the hemiacetal group of a saccharide (or a molecule derived from a saccharide) and the hyd
Hemiacetal
Anomer
It is one of two stereoisomers of a cyclic saccharide that differs only in its configuration at the hemiacetal or hemiketal carbon, also called the anomeric carbon.
Two anomers are designated alpha (?) or beta (?), according to the configurational relatio
Anomeric Center
The anomeric carbon or the anomeric center can be recognised by looking for the C that is attached to two O atoms by single bonds
Membrane proteins
1. are sometimes covalently attached to lipid moieties.
2. are sometimes covalently attached to carbohydrate moieties.
3. are composed of the same 20 amino acids found in soluble proteins.
4. diffuse laterally in the membrane unless they are anchored
Glycosphingolipids and cholesterol cluster together in membrane regions known as "__________".
These microdomains are more __________ than the surrounding phospholipid-rich membrane due to a high content of __________ fatty acids.
rafts, ordered, saturated
Amphipathic molecules, with both hydrophobic and hydrophilic domains, when placed in water
tend to arrange themselves in a way that minimizes contact of their hydrophobic domains with water.
One structure that accomplishes this is the lipid bilayer where
...