Exam 2 Lecture 3 Flashcards
Most biological macromolecules in cells are
synthesized from about
20? 30 common small molecules
How many major classes of proteins are there
9
what are the 9 classes of proteins
Enzymes
structural Proteins
Motility
Regulatory
Transport
Signaling
receptor
defensive
storage
describe enzymes
serve as catalysts, increasing the rates of chemical reactions
Describe Structural proteins
physical support and shape
Describe Motility proteins —
contraction and movement
Regulatory proteins
control and coordinate cell function
What doesnt make protein
Intron
Transport proteins
move substances into and out of cells
Signaling proteins
communication between cells
Receptor proteins
enable cells to respond to chemical
stimuli from the environment
Defensive protein
protect against disease
Storage proteins
reservoirs of amino acids
do proteins ever have the same amino acid sequence?
No two different
proteins have the
same amino acid
sequence
Amino Acids
How many amino acids
20 amino acids
( technically there are 2 other found on archaea)
What is the structure of amino acids
Every amino acid has the same
basic structure
Each has a unique side chain,
called an R group
All amino acids except glycine
have an asymmetric α-carbon
atom
The specific properties of
amino acids depend on the
nature of their R groups
each amino acid is unique bc of its side chain
Which amino acid does not have an asymmetric α-carbon
atom
All amino acids except glycine
have an asymmetric α-carbon
atom
Group A amino acids
Nine amino acids have nonpolar, hydrophobic R
groups
Group B and C
The remaining eleven amino acids are hydrophilic, with R
groups that are either polar or charged at cellular pH
Polar amino acids tend to be found on the surfaces of
proteins
Cellular pH
7.4
Acidic amino acids are
negatively charged
basic
amino acids are
positively charged
Where are polar amino acids located
Polar amino acids tend to be found on the surfaces of
proteins
Amino acids are linked
together stepwise into
a….. ( and what reactions)
linear polymer by
dehydration (or
condensation)
reactions
As the three atoms
comprising the H2O are removed what type of bond is formed
Peptide bond ( convalent bond between the C-N)
two termini of polypeptides
N - Terminus
C- Terminus
Because of the way
peptide bonds are formed,
polypeptides have
Directionality
which side is the N -terminus
The end with the amino
group is called the N- (or
amino) terminus
Which side is the C - terminus
The end with the
carboxyl group is called
the C- (or carboxyl)
terminus
Protein synthesis
The process of elongating a chain of amino acids is
called protein synthesis
what is the name of the immediate product amino acid polymerization
Polypeptide
When does a polypeptide become a protein
A polypeptide does not become a protein until it
has assumed a unique, stable, three-dimensional
shape and is biologically active
Proteins that consist of a single polypeptide are
monomeric
proteins
multimeric proteins
consist of two or
more polypeptides
homomultimeric vs heteromultimeric protein
different vs same subunits
If the chains are identical, it would be homomultimer. If the chains were different, it would be a heteromultimer. Hemoglobin is an example of a heteromultimer having two alpha and two beta chains making up a tetrameric structure.
Dimers
proteins consisting of two polypeptides
trimers
proteins consisting of three polypeptides
what type of bonds are needed for protein to adopt its proper shape or conformation?
define amino residiues
both covalent and noncovalent interactions
^ also required for polypeptides to form multimeric proteins
The interactions involve carboxyl,
amino, and R groups of the amino
acids, called amino acid residues
once incorporated into a
polypeptide
disulfide Bonds
how to form and break
type of bond
Covalent disulfide bonds form between the sulfur
atoms of two cysteine residues
They form through the removal of two hydrogen ions
(oxidation) and can be broken only by the addition of
two hydrogens (reduction)
Once formed, disulfide bonds confer considerable
stability to the protein conformation
categories of disulfide Bonds
Intramolecular disulfide bonds
Intermolecular disulfide bonds
they link the two polypeptides together
Intramolecular disulfide bonds
form between cysteines
in the same polypeptide
Intermolecular disulfide bonds
form between cysteines
in two different polypeptides
what types of bonds are Noncovalent bonds and
interactions
include hydrogen
bonds, ionic bonds, van der
Waals interactions, and
hydrophobic interactions
These are individually weaker
than covalent bonds but
collectively can strongly
influence protein structure and
stability
what type of bond forms between amino acids via the R chain
hydrogen Bonds Form in water and between amino
acids in a polypeptide chain via their R groups
Hydrogen bond donors
(e.g., hydroxyl or amino
groups) have hydrogen atoms covalently linked to
more electronegative atoms
Hydrogen bond acceptors
(e.g., carbonyl or sulfhydryl
groups) have an electronegative atom that attracts the
donor hydrogen
Ionic Bonds
Ionic bonds, or electrostatic interactions, form
between positively and negatively charged R groups
They exert attractive forces over longer distances than
some of the other noncovalent interactions
Because they depend on the charge on the R groups,
changes in pH can disrupt ionic bonds
Van Der Waals Interactions
Molecules with nonpolar covalent bonds may have
transient positively and negatively charged regions
These are called dipoles, and two molecules with
dipoles will be attracted to one another if they are
close enough
This transient interaction is called a van der Waals
interaction or van der Waals force
Hydrophobic Interactions
A hydrophobic interaction is the tendency of
hydrophobic molecules or parts of molecules to be
excluded from interactions with water
Protein folding is a balance between the tendency of
hydrophilic groups to interact with water and of
hydrophobic groups to avoid interaction with water
Amino acids with hydrophobic side chains tend to be found
within proteins
Primary protein structure
amino acid sequence
secondary Protein structure
local folding of polypeptide
tertiary Protein structure
three dimensional conformation
quaternary structure
interactions between
monomeric proteins to form a multimeric unit
Table 3-3
slide 8
amino acid residues
The interactions involve carboxyl,
amino, and R groups of the amino
acids, are called amino acid residues
once incorporated into a
polypeptide
what is an amino acid residue
a residue refers to a single unit that makes up a polymer, such as an amino acid in a polypeptide or protein
oxidation
Disulfied Bonds form through the removal of two hydrogen ions
(oxidation)
reduction
the addition of
two hydrogens (reduction)breaks disulfied bonds
why are disulfide bonds important ?
they help proteins fold into their three dimensional protein structure
why is cysteine important
Cysteine residues often play essential roles in protein structure and function by conferring stability through disulfide bond formation, maintaining proper maturation and localization through protein-protein intermolecular interactions, or providing a thiol group for reactions with molecular substrates
How does pH affect ionic bonds
Because they depend on the charge on the R groups,
changes in pH can disrupt ionic bonds
What type of bond and interactions are involved in the primary structure of protein folding
( state structure too)
strucutre: amino acid sequence
B/I: covalent peptide bonds
What type of bond and interactions are involved in the secondary structure of protein folding
( state structure too)
Structure: folding into alpha helix and beta sheets or random coil
B/I = Hydrogen bonds between NH and CO groups of peptide bond in the backbone
What type of bond and interactions are involved in the tertiary structure of protein folding
( state structure too)
structure: three dimensional folding of a single polypeptide chain
B/I disulfide bonds, hydrogen bonds, ionic, van der wall interactions, hydrophobic interactions
What type of bond and interactions are involved in the quaternary structure of protein folding
( state structure too)
Structure: association of multiple polypeptides to form a multimeric protein
B/I disulfide bonds, hydrogen bonds, ionic, van der wall interactions, hydrophobic interactions
By convention, amino acid sequences are written from
the N-
terminus to the C-terminus, the direction in which the
polypeptide was synthesized
The first protein to have its amino acid sequence determined
was
the hormone insulin
Insulin consists of
one A and one B subunit with 21 and 30
amino acids, respectively
Primary structure refers to
the amino acid sequence
who is Sanger
Sanger obtained the Nobel Prize for his work on
the insulin protein sequence
He cleaved the protein into smaller fragments and
analyzed the amino acid order within individual
overlapping fragments
Sanger’s work paved the way for the sequencing of
hundreds of other proteins and for advancements
in the methods used for sequencing proteins
what is the importance of the primary structure
Genetically and Structurally
Primary structure is important genetically because
the sequence is specified by the order of
nucleotides in the corresponding messenger RNA
It is important structurally because the order and
identity of amino acids directs the formation of the
higher-order (secondary and tertiary) structures
describe The secondary structure
The secondary structure of a protein describes
local regions of structure that result from hydrogen
bonding between NH and CO groups along the
polypeptide backbone
These result in two major patterns, the α helix and
the β sheet
The α helix
what does it consist of ?
The α helix is spiral in shape,
consisting of the peptide
backbone, with R groups
jutting out from the spiral
There are 3.6 amino acids
per turn of the helix
A hydrogen bond forms
between the NH group of one
amino acid and the CO group
of a second amino acid that is
one turn away from the first
the b sheet
The β sheet is an
extended sheet-like
conformation with
successive atoms of the
polypeptide chain located
at “peaks” or “troughs”
The R groups jut out on
alternating sides of the
sheet
Because of the formation
of peaks and troughs, it is
sometimes referred to as
a β-pleated sheet
The β sheet is characterized by a maximum of
hydrogen bonding, but β sheet formation may
involve different polypeptides or different regions of
a single polypeptide
If the parts of polypeptides forming the β sheet
have the same polarity (relative to the N- and C-
termini), they are called parallel
If the parts of polypeptides forming the β sheet
have opposite polarity, they are called antiparallel
If the parts of polypeptides forming the β sheet
have the same polarity they are called
parallel
C. C
|. |
|. |
N N
If the parts of polypeptides forming the β sheet
have opposite polarity, they are called
antiparallel
C. N
|. |
|. |
N C
do all amino acids form the same Secondary Structure? If not which form alpha and which form beta?
Certain amino acids (e.g., leucine, methionine,
glutamate) tend to form α helices, whereas others
(e.g., isoleucine, valine, phenylalanine) tend to form
β sheets
Proline cannot form
hydrogen bonds and tends to
disrupt α helix structures by introducing a bend in
the helix
What are motifs
Certain combinations of α
helices and β sheets have been
identified in many proteins
These units of secondary
structure consist of short
stretches of α helices and β
sheets and are called motifs
Examples include the β–α–β,
the hairpin loop, and the helix-
turn-helix motifs
Describe tertiary structure
The tertiary structure reflects the unique aspect of
the amino acid sequence because it depends on
interactions of the R groups
Tertiary structure is neither repetitive nor easy to
predict
It results from the sum of hydrophobic residues
avoiding water, hydrophilic residues interacting with
water, the repulsion of similarly charged residues,
and attraction between oppositely charged residues
Native Conformation
The most stable possible three-dimensional
structure of a particular polypeptide is called the
native conformation
always active
Proteins can be divided into two broad categories
Fibrous proteins
Globular proteins
describe Fibrous proteins
Fibrous proteins have extensive
regions of secondary structure,
giving them a highly ordered,
repetitive structure
Some examples include
Fibroin proteins of silk
Keratin proteins of hair and wool
Collagen found in tendons and
skin
Elastin found in ligaments and
blood vessels
describe globular proteins
Most proteins are
globular proteins that
are folded into
compact structures
Each type of globular
protein has its own
unique tertiary
structure
Most enzymes are
globular proteins
how are peptide bonds broken
hydrolysis
how many amino acids are there per turn of the helix
3.6 amino acids
β sheet aka
β-pleated sheet
our hair is mostly
alpha helices
a protein can have a similar sequence but different folding =
different function
Globular proteins havea secondary structure that can be mainly
α helical, mainly β
sheet, or a mixture of both structures
Many globular proteins consists of a number of segments called
domains
What is a domain in a protein
A domain is a discrete, locally folded unit of tertiary structure,
usually with a specific function
A domain is typically 50–350 amino acids long, with regions of
α helices and β sheets packed together
Proteins with similar functions often
share
a common domain
Proteins with multiple functions
usually have
a separate domain for each function, like modular units
from which globular proteins are
constructed
How can the primary structure help predict tertiary structure
primary structure determines the
final folded shape of a protein
can we predict all aspects of protein folding
we are still not able to predict exactly
how a given protein will fold, especially for larger proteins
what is the quaternary structure
The quaternary structure of a protein is the level
of organization concerned with subunit interactions
and assembly
The term applies specifically to multimeric proteins
Some proteins consist of multiple identical subunits;
others, such as hemoglobin, contain two or more
types of polypeptides
quaternary strucutre applies specifically to
multimeric proteins
( 2 or more polypeptides - one would j be tertiary structure)
the process of creating a quaternary structure is usually
spontaneous however smt molecular chaperones are required to assist the process
Higher Levels of Assembly in proteins ( fix card)
A higher level of assembly is possible in the case of
proteins (often enzymes) that are organized into
multiprotein complexes
Each protein in the complex may be involved
sequentially in a common multistep process
An example is the pyruvate dehydrogenase
complex, in which three enzymes and five other
proteins form a multienzyme complex
function of nucleic acids
store, transmit, and express genetic info
structure of nucleic acids
linear polymers of nucleotides
DNA stands for
deoxyribonucleic acid
RNA stands for
ribonucleic acid
DNA and RNA differences
DNA and RNA differ chemically and in their role in
the cell
RNA contains the five-carbon sugar ribose, and
DNA contains the related sugar deoxyribose
DNA serves as the repository of genetic
information, whereas RNA plays several roles in
expressing that information
KNow strucutral difference in DNA and RNA
slide 16
monomeric unit of DNA and RNA
nucleotides
Each nucleotide consists of a five-carbon sugar to which a
phosphate group and N-containing aromatic base are attached
Each base of a nucleotide is either a
purine and pyrimidine
Purines are
adenine (A) and guanine (G)
Pyrimidines are
thymine (T) and cytosine (C), and
in RNA, uracil (U)
The sugar-base portion without the phosphate
group is called
nucleoside
nucleoside
The sugar-base portion without the phosphate
group
know how they are names table 3.4
Nomenclature slide
page 17
the polymers of genetic information
Nucleic acids are linear polymers of
nucleotides linked by a 3ʹ,5ʹ
phosphodiester bridge, a
phosphate group linked to two
adjacent nucleotides via two
phosphodiester bonds
The polynucleotide formed by this
process has a directionality with a 5ʹ
phosphate group at one end and a
3ʹ hydroxyl group at the other
Phosphodiester bonds are ester bonds that form between sugar and phosphate to form the backbone of nucleic acids
why is it called 3’
third carbon of that sugar
The numbers 3′ and 5′ refer to the number of carbon atoms in a deoxyribose sugar molecule that a phosphate group binds to
why is it called 5’
5 carbons attached
Nucleotide sequences are
conventionally written in
the 5’ to 3’ direction
A preexisting molecule is used to ensure that new
nucleotides are
added in the correct order
what are they?
(NTPs for RNA, dNTPs for DNA) ??
templates
(N refers to AGCT or AUGC)
what is a template
This molecule is called a template, and correct
base pairing between the template and the
incoming nucleotide is required to specify correct
order
what type of relationship exists between purines and pyrimidines
complementary
complementary base pairing and how many bonds hold the pair
Complementary base
pairing allows A to
form two hydrogen
bonds with T and G
to form three
hydrogen bonds with
C
base pairing is a
fundamental property of nucleic acids
double helix model
Two antiparallel and complementary
strands of DNA twist around a common
axis to form a right-handed spiral
structure
RNA is normally ( in terms of strandedness)
single stranded but also depends on base pairing
RNA base pairing
the pairing is usually between bases in
different areas of the same molecule and is less
extensive than that of DNA
( tRNA does have areas of double strandedness)
Watson and crick
postulated Double helix structure in 1953
The structure accounted for the known
physical and chemical properties of
DNA
It also suggested a mechanism for DNA
replication
Polysaccharides are
are long chain polymers of
sugars and sugar derivatives
They usually consist of a single kind of repeating
unit or sometimes an alternating pattern of two
kinds
polysacc. funciton
They serve primarily in structure and storage
oligosaccharides
Short polymers, oligosaccharides, are sometimes
attached to cell surface proteins
monomers of polysacc.
monosaccharides
A sugar may be
an aldehyde, aldosugars with a terminal
carbonyl group; or ketone, ketosugars with an internal carbonyl
group
Sugars within these groups are named generically based on
how many carbon atoms they contain
sugars with three carbons are called
Trioses
sugars with 4 carbons
Tetroses
5 carbon sugar
pentoses
6 carbon sugar
hexoses
7 carbon sugars
heptoses
most common monosaccharide is
the
aldohexose D-glucose (C6 H12 O6)
Common sugars are called commonly called carbohydrates because
the formula CnH 2nO
hydrated carbon
For every molecule of CO 2 incorporated into a
sugar
One water molecule is consumed
naming the carbons of glucose
and other organic
molecules) are numbered from the more oxidized,
carbonyl end
the structure of glucose
come bakc to slide
how many rings for D-glucose
2 rings
know difference between alpha d - glucose and beta d-glucose
OH on carbon 1 is oriented down for alpha
Oh is oriented up for beta
two rings forms of D-glucose
The formation of a ring by D-
glucose can result in two
alternative forms
These depend on the spatial
orientation of the hydroxyl
group on carbon number 1
These forms are designated
α(hydroxyl group downward)
and β (hydroxyl group upward)
disaccharides are
covalently linked monosaccharides
maltose is a disacc made up of
two glucose units
lactose is a disacc. made up of
one glucose linked to one galactose
sucrose is a disacc. made up of
one glucose linked to one fructose
glycosidic bond
The linkage of disaccharides is
a glycosidic bond, formed
between two monosaccharides
by the elimination of water
Glycosidic bonds involving the α
form of glucose are called α
glycosidic bonds (e.g.,
maltose); those involving the β
form are called β glycosidic
bonds (e.g., lactose)
Most familiar stoarge polysacc. in plants and animal cells/ a bacterial
starch in plant cells
glycogen in animal cells and bacteria
starch and glycogen consist of
α- D-glucose units linked by α
glycosidic bonds, involving carbons 1 and 4 (1→4)
Occasionally α(1→6) bonds may form, allowing for
the formation of side chains (branching)
where is starch also stored in plants
roots and ..?
where does branching chains occur in polymers
α(1→6)
glycogen structure
where is it stored ?
Glycogen is highly branched, the branches
occurring every 8–10 glucose units along the
backbone
Glycogen is stored mainly in the liver (as a source
of glucose) and muscle tissues (as a fuel source for
muscle contraction) of animals
Bacteria also store glycogen as a glucose reserve
starch structure
Starch is the glucose reserve commonly found in plant tissue
It occurs both as unbranched amylose (10–30%) and
branched amylopectin (70–90%)
Amylopectin has α(1→6) branches once every
12–25 glucose units and has longer side chains than glycogen
Starch is stored as ____________ within the plastids
starch grains
Chloroplasts,
the sites of carbon fixation and sugar
synthesis in photosynthesis
Amyloplasts
plastid which are specialized for starch storage
glycogen vs strach branching and spacing
glycogen = highly branched and more compact and longer branches
starch can be either way and more gaps between branches
cellulose is …
The best-known structural
polysaccharide is the cellulose
found in plant cell walls
cellulose composition
Cellulose, composed of repeating
monomers of
β- D-glucose, is very abundant in
plants
mammal relationship to cellulose
Mammals cannot digest cellulose
(though some have
microorganisms in their digestive
systems that can)
how does cellulose of fungal cell walls differ from that of plants
The cellulose of fungal cell walls differs from that of
plants and may contain either β(1→4) or β(1→3)
linkages
Bacterial cell walls contain
Bacterial cell walls contain two kinds of sugars:
GlcNAc (N-acetylglucosamine) and MurNAc
(N-acetylmuramic acid)
Both are derivatives of β-glucosamine and are
linked alternately in cell walls
what is chitin
polysaccharide
Chitin is found in insect exoskeletons, crustacean
shells, and fungal cell walls
chitin composition
consists of GlcNAc (N-
Acetylglucosamine) units only, joined by β(1→4)
bonds
what does polysacc. structure depend on
Polysaccharide Structure Depends on the
Type of Glycosidic Bonds Involved
α and β glycosidic bonds are associated with
marked
structural differences
Starch and glycogen have what type of bond
The most familiar storage polysaccharides are
starch in plant cells and glycogen in animal cells
and bacteria
Both consist of α- D-glucose units linked by α
glycosidic bonds, involving carbons 1 and 4 (1→4)
Occasionally α(1→6) bonds may form, allowing for
the formation of side chains (branching)
Starch and glycogen (α polysaccharides) form loose helices
that are not highly ordered because of the side chains
cellulose forms what linkages
Cellulose (that forms β linkages) exists as rigid linear rods
that aggregate into microfibrils, about 5–20 nm in diameter
Plant and fungal cells walls contain
these rigid microfibrils in
a noncellulose matrix containing other polymers
(hemicellulose, pectin) and a protein called extensin
Lipids are not formed by
polymerization
why are lipids regarded as macromolecules
because of their high molecular weight and their
importance in cellular structures, particularly
membranes
features of lipids
Although heterogeneous, all have a hydrophobic
nature and thus little affinity for water; they are
readily soluble in nonpolar solvents such as
chloroform or ether
They have relatively few polar groups, but some
are amphipathic, having polar and nonpolar
regions
lipid function
Functions include energy storage, membrane
structure, or specific biological functions such as
signal transmission
how many classes of lipids exist and what are the types
6 classes based on structure
- Fatty acids
- Triacylglycerols
- Phospholipids
- Glycolipids
- Steroids
- Terpines
Describe Fatty Acids
Fatty acids are components of / building blocks several other kinds
of lipids
A fatty acid is a long amphipathic, unbranched
hydrocarbon chain with a carboxyl group at one
end
The polar carboxyl group is the “head,” and the
nonpolar hydrocarbon chain is the “tail”
fatty acid structure
The hydrocarbon tails are variable in length but
usually 12 to 20 carbons long
Even numbers of carbons are favored because
fatty acid synthesis occurs via the stepwise addition
of two-carbon units to the growing chain
Fatty acids are highly reduced and so yield a large
amount of energy upon oxidation
saturated fatty acid structure
( saturated - max number of hydrogens no double bonds)
linear structure
allows it to stack and creates blockages
In saturated fatty acids, each carbon atom in the chain is
bonded to the maximum number of hydrogens
These have long straight chains that pack together well
Triacylglycerol
3 fatty acids
phospholipid contains
phosphate group
ask what to know abt chart with lipids
on slide of main classes of lipids ( or j to go through them)
2 groups
fatty acoids with zero double bonds and some with at least one double bond
zero vs 1+ double bond
zero double bonds = saturated with hydrogen
other = unsaturated
number of carbons are normally in pairs and even
be somewhat familiar with the name but wont be asked ( j good to know0
what is the structure of unsaturated fatty acids
Unsaturated fatty acids have one or more double bonds, so
they have bends in the chains and are less tightly packed
what are trans fats?
Trans fats are a type of unsaturated fatty acid with a particular
type of double bond that causes less of a bend in the chain
They are relatively rare in nature and are produced artificially in
shortening and margarine
They have been linked to increased risk of heart disease and
elevated cholesterol levels
describe how to ID a trans fat molecule
what is the function of triacylglycerol?
storage
what are triaclyglycerols?
Triacylglycerols, also known as triglycerides,
consist of a glycerol molecule with three fatty acids
attached to it
( know what glycerol is)
what is glycerol?
Glycerol is a three-carbon alcohol with a hydroxyl
group on each carbon
Fatty acids are linked to glycerol, one at a time, by
ester bonds formed by the removal of water
what type of. bond links fatty acids to glycerol?
ester bonds- formed by the removal of water
describe the structure of Triacylglycerol
Monoacylglycerols contain a single fatty acid
Diacylglycerols have two fatty acids
The three fatty acids on a triacylglycerol may vary
in length and degree of saturation
what is the main function of triacylglycerols?
energy storage
whay are some triacylglycerols called fats? ( which ones?)
Triacylglycerols containing mostly saturated fats are usually
solid or semisolid at room temperature and are called fats
what is unique about Triacylglycerols in plants
Triacylglycerols in plants are liquid at room temperature (e.g.,
vegetable oil) and are predominantly unsaturated
why are phospholipids important to membrane structure?
Phospholipids are important to membrane structure because of their amphipathic nature
( hydrophilic and hydrophobic )
what are the two categories of phospholipids
phosphoglycerides or
sphingolipids, depending
on their chemistry
what are Phosphoglycerides?
what are their basic components/ structure?
Phosphoglycerides are the
predominant phospholipids in
most membranes
The basic components of
phosphoglycerides is
phosphatidic acid, which has
two fatty acids and a phosphate
group attached to a glycerol
Typical phosphoglycerides often have one
saturated and one unsaturated fatty acid
The length and degree of saturation of the fatty
acids have profound effects on membrane fluidity
Membrane phosphoglycerides
invariably have a small
hydrophilic alcohol linked to the
phosphate by an ester bond
What are common alcohol groups of a Phosphoglycerid?
The alcohol is usually serine, ethanolamine,
choline, or inositol, which contributes to the polar
nature of the phospholipid head group
What are Sphingolipids?
Sphingolipids are based on the amine
sphingosine, which has a long hydrocarbon chain
with a single site of unsaturation near the polar end
Sphingosine can form an amide bond to a long-
chain fatty acid, resulting in a molecule called a
ceramide
A whole family of sphingolipids exists, with different
polar groups attached to the hydroxyl group of the
ceramide
where are Sphingolipids normally found?
Sphingolipids are predominantly found in the outer
leaflet of the plasma membrane bilayer, often in
lipid rafts, localized domains within a membrane
Lipid rafts are important in communication between
a cell and its external environment
what are glycolipids?
Glycolipids are lipids containing a carbohydrate instead of a
phospholipid and are often derivatives of sphingosine and
glycerol (glycosphingolipids)
Carbohydrate groups attached to a glycolipid may be one to six
sugar units (D-glucose, D-galactose, or N-acetyl- D-
galactosamine)
Glycolipids occur largely on the outer monolayer of the plasma
membrane
I facilitates cell-cell communication)
glycolipids are often derivatives of what kind of phospholipid?
sphingosine and
glycerol (glycosphingolipids)
where are glycolipids located?
Glycolipids occur largely on the outer monolayer of the plasma
membrane
what are steroids?
Steroids are derivatives of a four-
ringed hydrocarbon skeleton,
which distinguishes them from
other lipids
They are relatively nonpolar and
therefore hydrophobic
Steroids differ from one another in
the positions of double bonds and
functional groups
The most common steroid in
animal cells is cholestero
what makes steroids unique from other lipids
they are derivatives of a four-
ringed hydrocarbon skeleton,
which distinguishes them from
other lipids
are steroids polar or nonpolar?
Hydrophobic or hydrophilic?
They are relatively nonpolar and
therefore hydrophobic
How do steroids differ from one another?
Steroids differ from one another in
the positions of double bonds and
functional groups
what is the most common steroid in animal cells?
CHOLESTEROL
what is cholesterol?
Cholesterol is insoluble and found primarily in
plasma membranes of animal cells and most
membranes of organelles
Similar molecules are found in plant cells
(stigmasterol and sitosterol) and fungal cells
(ergosterol)
Cholesterol is the starting material for synthesis of
steroid hormones
- including male and female sex
hormones, the glucocorticoids, and the
mineralocorticoid
sex hormones include
estrogens produced by the
ovaries of females (e.g., estradiol) and androgens
produced by male testes (e.g., testosterone)
what are glucocorticoids?
provide an example
The glucocorticoids (e.g., cortisol) are a family of
hormones that promote synthesis of glucose and
suppress inflammation
what are Mineralocorticoids? provide an example
Mineralocorticoids (e.g., aldosterone) regulate ion
balance by promoting reabsorption of sodium,
chloride, and bicarbonate ions by the kidney
Carboxyl group
COOH
Fatty acids are usually how long?
12 - 20 carbons
( EVEN numbers are favored in the tail)
Y? bc synthesis is normally in pairs - addition of 2 carbons at a time
1-4 double bonds are possible
for table 3-5 of fatty acids
be able to recognize the names are fatty acids
double bonds in fatty acids change the structure from linear to
Bent
(lower melting point
why is it called trans
the double bond is in a trans configuration
( are linear?)
cis unsaturated Fatty acid
H on same side
( not linear)
know different bonds in different macromolecules
ester in lipid linkage
glycosidic bond - polysaccaride
nucleic acids have a 3’5 phosphodiester bridge
ask her about structure of lipid review
know fatty acid has hydrocvarbon tail with cooh on the end
saturated v unsaturaed
know glycerol and that three fatty acods are attached
phosphate in phosopholipid
be able to id glycerol stucutre
more saturated would be more or less fluid
less fluid bc more packed
what Lipid rafts important
regions/ domains in the plasma membrane important for communication between a cell and its environment
Lipid rafts are dynamic assemblies of proteins and lipids that float freely within the liquid-disordered bilayer of cellular membranes but can also cluster to form larger, ordered platforms.
Rafts are small platforms, composed of sphingolipids and cholesterol in the outer exoplasmic leaflet, connected to phospholipids and cholesterol in the inner cytoplasmic leaflet of the lipid bilayer.
be able to ID a glucose or sugar molecule
so u can ID a lipid
dehyration vs condensation v hydrolysis vs oxidation
dehydration = condenstion ( h200?
oxidation = removal of 2 H
hydrolysis = additon of water
Reduction = addition of H+
d-alanine vs I-alanine
same chemcial formula and carboxyl + amnio group
