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162 Cards in this Set

  • Front
  • Back
What is cell biology a combination of?
3 life sciences:
Who is Robert Hooke?
1665- coined the them cell when he examined slices of cork(dead phlom)and observed honeycomb like compartments calling them cells
Who is Van Leeuwenhoek?
First to observe living cells in the 1670's
-observed blood cells and single cell organisms in pond water
Which 3 scientits developed the cell theory
Matthias Schleiden (botanist)
Thodore Schwann (zoologist)
Rudolf Virchow (pathologist)bacteria
What does the cell theory state?
1. All Living things are made of cells
2.The Cell is the basic unit of Life
3.All cells come from pre-existing cells
What are the Fundamental Properties of Cells?
1.cells are Microscopic, aqueous compartments

2. All cells have a Plasma membrane

3.Obey the laws of chem and physics

4. use enzymes as catalysts

5. engage in energy transduction (sun-organic-energy)

6. are irritable: respond to their enviornment

7. Can reprduce themselves

8. use DNA as gentic material

9.Follow central dogma for gene expression (DNA-RNA-Protien)
What are the 2 major cell types?
Prokaryotic and Eukaryotic
What are the basic charateristics of Prokaryotic cells
Lack a true nucleus
Relatively small (1-5 microns)
Relatively Old (3.5 billion)
simple construction
What is Prokaryotic cell construction like?
One compartment
bounded by plasma membrane
bounded by a cell wall (peptidoglychan)
May have a capsule
What does the Prokaryotic cell's cytoplasm consist of?
NO organelles or cytoskeleton
-is one circular chromosome
- confined to an area "nucleoid"
Has many ribosomes around nucleoid
What is an example of a Prokaryotic Cell?
Bacteria --- E.COlI
What are the basic charateristics of a Euckaryotic cell?
True Nucleus
Relatively Large 10-50 micron
Relatively young-evloved from prokaryotic cells,1.5 billion

Complex construction
What is the COnstruction of a
Eukaryotic cell?
Subcellular compartments
each bounded by either a nuclear envelope or a cell membrane resepectively

Has organelles
Has Cytoskeleton
Rich in Ribosomes
WHat is found in the Eukaryotic Nucleus?
DNA - more than one linear chormosome
what is found in the Eukaryotic cytoplasm?
Has a cytoskeleton
Rich in Ribosomes
Name the Euckaryotic Organelles (Family of cell organelles)
Endoplasmic Reticulum
-rough and smooth
Golgi Appartus
Plastids - Chloroplast (plants only)
Vacuoles (small-animal, Large-Plant)
What are the Non-membranous structures found in Eukaryotic Cell Cytoplam?
What are Ribosomes?
Scaffolds on which protien synthesis takes place
Found in cytosol
WHat is the Cytoskeleton?
Fibrous protien filaments that provide mechanical support and produce mechanica force in the cell
What is the plant cell composed of?
All Subcellular compartments
-nucleus, cytoplasm
All Organelles
All Non-membranous sturctues
-including cell wall
What does the Animal Cell Consist of?
ALl Subcellular compartments
ALL Organelles except... plastids and large vacuole
All Non membranous sturctures except: Cell walls
How many Eukaryotic cell groups are there? What are they?
How many Prokarotic Cell groups are there? what are they?
Why do cells require a High surface area to volume ratio?
B/C a cells volume represents the cells capacity to consume nutrients and produce wastes

while the cells surface area is the cells capacity to deliver nutrients to and remove wastes from its volume

Thus the surface area must be high enough to meet needs of a cells volume
How do surface area and volume change as a cell gets larger?
As a cell gets larger volume increases faster than surface area

surface area to volume ratio decreases thus smaller is better
How do you increase surface area without increasing volume?
Through the use of microvilli and surface folds
What is Eubacteria
present day bacteria including cynobacteria (blue-green algae)
What is Archea?
ancient/original form of bacteria divided into 3 maingroups:
rate varies inversly with size though can use cytoplasmic streaming (active transport)
why do living systems engage in energy transduction?
Living systems are highly ordered
reactions within system require energy
get energy from reactions that release energy

To obtain energy for reactions
How do you determine which reactions release energy and or require it?
Through the study of Thermodynamics
What is biogenetics
the application of thermodynamics to biological systems
what is chemical equilibruim?
estabilished when concentrations of each reactant and each product remains constant with time
thus the rate of the forward reaction is equal to the rate of the reverse reaction
What is K ?
equibrium constant
K=1 [p]=[r] At equilibrum
k>1 [p]>[r]far to right of center product side
k<1 [p]<[r] equilbrim is far to the left reactant side
What is Free Energy (G)?
-is the amount of energy available in a molecule that can be released to do work
-spontaneous chemical reactions release free energy to their enviornments as they proceed
What are spontaneous reactions?
reactions that proceed without out side intervention (w/o input of energy)
- loose free energy
- have a negative change G
- are exergonic
what are charateristics of Non-spontaneous reactions?
-move away from equilbrium
-are irreversable
-require energy input to start the reaction
-have a positve change G
-Are Endergonic
How much free energy is lost/required in a spontaneous/nonspontaneous reaction?
dependent on the Keq and concentrations of reactant and product

the furter away we get from equilibrium the greater the change G
what are the 3 ways to calculate ∆G?
Standard form
ambient form
generic form
What is the Formula for the Standard Form of the ∆G?
RT ln([p]/[r])- RT ln Keq
-where R= 1.98
-T=298 K
-P and r = 1.0M

comes to :-RTlnKeq
What is the Formula for the Ambient Form for the ∆G?
standard K and R
= 592cal/mol ln ([p]/[r])-592ln Keq
=RTln([p]/[r])+ (∆G standard)
How do you interpret the ∆G?
∆G<0 = neg, spontanous, reation quotient is < Keq'
The reaction is exergonic and releases energy, proceeds from Right to Left spontaneously

If ∆G > 0 = Positive
non spontanous, product favored (L-R),endergonic, REQUIRES ENERGY

If ∆G= 0 it is at equillibrium
what 2 conditons must reactions satisfy to be effective with in the cell?
High rate of the reaction
reaction rate must be capable of being regulated
What is the primary function of enzymes
increase the reate of chemical reactions
What are enzymes?
Biological catalysts- increase the rate of the reaction with out being consumed in it
what are the 8 fundamental charateristics of enzymes?
1. Enzymes accelerate the rate of chemical reactions
2. Enzymes do not alter the Keq or the ∆G of the reactions
3.Enzymes are not consumed in rxn
4. Enzymes are effective for a particular rxn or group of simal rxns (specific for substrate)
5. Are effective in small quantities
6.Most are protiens
7.affected by temp and PH
8.some require the used of coenzymes or proshtetic groups
What does the amino acid structre consist of ?
Center= Alpha carbon
Left= Amnio Group
Right= Hydorgen atom
Top= Carboxly group (o-C =o)
Bottome= Varriable R Group
What is Zwitterions?
When a free amno acid at neutral pH have a negative and positve charge, thus has an inoization at a neutral pH
What is the steroisometeric form that protiens exist in?
L form
-center carbon
left NH3+
Right; Hydrogen group
Bottom:Variable R group
What are the charateristics of the Nonpolar Amino Acids?
Most Hydrophobic, least hydrophillic
R groups are nonpolar hydrocarbons
Name the 9 Group A: Nonpolar Amnio Acids?
Glycine: H
Alanine: CH3
Valine: CH-CH3-CH3
Leucine: CH2-CH-CH3-CH3
Isoleucine: H3C-CH-CH2-Ch3
Methoinine: CH2-CH2-S-Ch3
Phenylanine: CH2- Carbon group
Proline: H2C-CH2-CH2
What are the Group B Amno Acids Charateristics?
Polar, uncharged amnio acids
Moderately hydrophobic, Moderately hydrophilic
What are the names of the Group B Charged amnio acids?
Serine: CH2-OH
Threonine: CH-OH-CH3
Cysteine: CH2-SH
Asparagine: CH2-C-NH2=O
What are the Group C charged Amino Acids charateristics?
Polar, charged
R groups are charged
poorly hydorphobic, very hydrophilic
Name the Acidic Group C Amnio Acids
Aspartate: CH2-C-O=O
Glutamate: CH2-CH2-C-O=O
What are the Basic Group C Amino Acids?
Lysine: Long chain of CH2 + NH3
Arginine long chain of CH2-NH-C=NH2
What is Hydorphobicity?
the realative degree to which a molecule is hydrophobic, Amino Acids are ranked according to the hydrophobicity scales
What do hydorphobicity scales show?
- the nonpolar amino acids= Most hydrophobic
- The Charged amino acids are the least hydophobic
- The polar, uncharged amino acids are moderately hydrophobic
What are the two sturtural types of Protiens?
Fibrous Proteins-very important,small fraction of cell
Globular Protiens- Most proteins in the cell are globular including enzymes
What is the structure of Globular proteins?
They have a hierarchical structure:
-Primary Structure
-Secondary Structure
-Tertiary Structure

It has a specific 3D shape called conformation which is achieved through a complex process of folding that takes place after synthesis

shape is held together by mostly non-covalent bonds and a few covalent
what does the primary structure of a globular protein consit of?
is the specific sequence of amino acids in that protein

This primary sturcture is very specific for a protein(determined by the sequence of nucleotide in the gene that codes for the protein
Adhacent amino acids are held together by a covalent bond called a peptide bond
What is a peptide bond?
is a condensation reaction (dehydration) reaction between the alpha carboxyl group of one amino acid and the alpha amnio groups loose their charge
What is the size of an average protien?
50-25,000 AA
What does folding have to do with proteins?
after the primary structure is synthesized, it carefully folds into a specific 3-d shape maintianed by molecular interactions among amnio acids, and polar and nonpolar R groups
How is folding of proteins maintained?
By molecular interaction among amnino acids which are located btwn N-H and C=O and
Non polar R groups interact with each other, Polar R groups interact with each other
How many levels of folding exist in the primary sturcture?
2- secondary struture and teritiar structure
What are the 2 major secondary structures?
alpha helix
beta sheet
what is the alpah helix?
multipule hydrogen bonds btwn the alpah N-H and alpha C=O groups of every peptide bond within the struture
-whether parts of the secondary struture become this depends on the sequence of amino acids
Is there a limit o the alpha helix length?
No practical limt
What is the beta sheet?
created through interactions of adjacent beta strands which is about 5-10 residues long and the sheets are pleated with alternating r groups in opp directions
What is the tertiary structure of globular protiens?
it is the final 3-D shape (conformation) of the protien
that comes about through the global folding of amino acid chains along with it seconday structures
What does the tertiary structure consist of ?
regions of high hydrophbicity = interior of the protein
Stabailized through several different types of molecular interactions between R groups
what is the single most important driving force that determines the final specific 3D shape of a protien
requirement that the interior
core of the globular protein be densely packed and very
hydrophobic.Regions of high hydrophobicity usually fold into the interior of the
what forces stablize the teritiar structure?
Intermolecular forces:
Noncovalent bonds among
R groups
• Hydrophobic interactions
• Ionic bonds
• Hydrogen bonds
– Covalent bonds among R
• Disulfide bonds
What about the quaternary structure?
found only in complex protiens composed of more than one smaller protien subunit called multimeric subunits and each subunit has a complete sturctrue

4th is stablized by same bonds teritary sturture
What is an active site?
locus on the protein wehre the substrate binds

it is a crevice or pocket extending from the surface of the protein to the interior consiting of 15-30 amino acids R groups exposed on the surface of the crevice
What are coenzymes and prosthetic groups?
molecules that possess properties required by the enzyme to catalyze a partiular reaction but not possessed by the enzyme
What do coenxymes and prosthetic groups consist of?
they are always non-protein molecules, realatively small moleular weight, may be inorganic or organic
what is the difference between coenzymes and protosthic groups?
Prosthetic groups are tightly bound, functionally permanent parts of the enzyme

while conezymes are loosely bound and reverisbly bind to the enxyme during the reation and take part in some critical aspect of the enzymes function
what is an example of a coenzyme?
NAD, used in some biological oxidation reduction reactions
what is an example of a prosthetic group?
Why do reactions proceed so slowly?
Reaction rate is dependant upon activaton energy, thus if the EA is High the reaction rate will be slow and if the EA is low then the reaction rate will be fast
thus the activation of cellular processes are suffently high so that the reaction proceeds slowly
what is Activation Energy?
is the minumum amount of energy needed to activate the reactants
What is a Transistion State?
an intermediate state between reatants and products
HOw do you lower activation energy and why?
To speed up reactions cells must lower the activation energy

to do so you can increase the temperature, and use catalysts (enzymes)
How do enzymes lower activation energy?
they lower activation energy by decreasing free energy of the transistion state and activation energy
What is kinetics?
is the study of the mechanism of a chemical reaction through the study of the rate law that governs the reaction
What do rate laws do?
Define the mechanism of the reaction
What is the mechanism of a basic enzyme catalized reaction?
It is a 2 step reaction:

E= free unbound enzyme
S= is unbound substrate
p= unbound prouduct
ES= is enzyme-substrate complex

reaction 1: substrate binding step
reaction 2: catalytic step

Thus the enzyme has an active site
what were the 3 scientist asked to find the basic mechanism of an enzyme reation?
M.L. Menten
V. Henri
what happens at a realitivly low substrate level?
there are more enzymes than substrate therefore there are more sites to bind if more substrate is added = as the substrate concentrtion increase the velocity increases
thus the hyperbolic curve continues upward
what happens when the substrate concentration is equal to the enzyme concentration?
the enzyme is completely saturated so velocity is saturated, there is no free active sites to bond to and increase the velocity thus it stays the same/constant
what are the two models of substrate bonding?
Lock and Key model
infuced fit model
What does the lock and key model consist of?
-Enzyme and Active Site have a rigid shape
-Enzyme and active site have one conformation
- substrate has a perfectly complementary/shape
-upon substrate binding there is no complementary change in the active site
What does the induced fit model consist of?
More accepted model
-enzyme and active sites are Not rigid structures
- Enzyme and active site have 2 basic conformations
1.when it is bound
2.when substrate is not bound
- Substrate has a near-complementary size/shape
- at binding the substrate interacts with a few critical R groups thus inducing a shape change that results in a perfect fit for the enzymes active site
What are the two basic phases of catalysis?
Substrate activation
product formation
what does substrate activation consist of?
period when the substrate reaches the transition state
what are the 3 most common mechanisms of substrate acivation used in catalysis?
-Substrate bond distortion: makes the bonds vunerable to catalytic attack
-change in the active site pH through proton exchange
-electron rearrangement and formation of temporary covalent bonds
what is teh Vmax?
it is a qualitative charaterization of Enzyme Function that measures the velocity of catalysis

It is directly dependant on the [E]
what is the Km?
It is the michaelis -Menton constant for the measure of the enzymes affinity for a substrate

what is substrare binding affinity
how strongly a substrate binds to an acive site

a substrate meant for the active site is going to bind strongly to the active site

one that is not will form a weak bond

can be measured using Km
What is the significance of Km in reguards to binding affinity?
the lower the Km the higher the substrate binding affinity for that enzyme is thus a high specificty
and the less substrate is needed to create product

A High Km =
Lower binding affinity and a lower specificity
what is the usefullness of Km?
helps determine the specificity of the enzyme
helps identify the natural substrates
helps determine the approximate intercellular concentrations of the natural substrate which is approx to Km
how can Km regulate rate the reaction?
if intracellular concentration of substrate is = KM then the cell can regulare the Velocity of the reaction by simply regulating the concentration of the substrate
what is the equation of the hyperbolic curve velocity vs. substrate concentration?
Vi = (Vmax [S]) / (KM + [S])
what are the 3 ways Cells can regulate the rate of an enzyme-catalyzed reaction?
1. Regulating the [E]–because Velocity of the reaction is directly dependent on [E]
2. Regulating the [S] of the substrate – Assuming it is approx equal to KM.
3. Regulating the activity of the enzyme. The activity of many enzymes can be increased or decreased. increasing enzyme activity is known as “enzyme activation” or positive regulation
• Decreasing enzyme activity is known as “enzyme
inhibition or negative regulation
what are the two major mechanisms for controlling enzyme activity?
Allosteric regulation
covalent modification
What is allosteric regulation?
Allosteric regulation is the single most
important mechanism used by the cell to
control enzyme activity.
– Used to regulate a special class of enzymes called allosteric enzymes. done by binding to the allosteric site increasing or decreasing activity of the enzyme.
What is the structure of an allosteric enzyme?
It is a multimeric protien that have two basic subunits
- catolic subunit (C)
contains an active site
- regulatory subunits (R)
contains an allosteric site
what are the 2 conformations of allosteric regulation?
Allosteric enzymes have two
possible conformations:
- Active conformation with high substrate affinity
- Inactive conformation with low substrate affinity
what is postive cooperativity?
allosteric enzymes kinetics:
at a vey low substrate concentration an enzyme exhibits low affinity and thus low velocity

with addition of more substrate , the substate induces a greater binding affinity and thus greater velocity

At high substrate concentration there is saturation
what is the effect of allosteric regulators on kinetics?
– No change in Vmax/ do not effect the Vmax

1. Allosteric activators shift
the curve to the left decreaseing Km thus increasing substrate binding affinity as well as the velocity of the reaction

2. Inhibitors shift the curve to the right (increase the KM)decreasing substrate binding affinity and decreasing velocity
what is allosteric inhibition?
the most common form of allosteric regulation applied in the cell through feedback inhibition along the metabolic pathway
what is feedback inhibition?
the downstream product of a partiular reaction serves as an allosteric inhibitor of an upstream enzyme
How does feedback inhibition work?
The greater the activity of the pathway leads
to . . .
– the greater production of the final downstream product, which leads to . . .
– the increased inhibition of the upstream enzyme, which results in . . .
– a decrease in the activity of the pathway and a reduction in the synthesis of the downstream product.
• Purpose: control the concentration of the
product (prevent the toxic accumulation of
the product)
• Analogy: operation of a thermostat
what is an example of feedback inhibition?
Biosynthesis of Isoleucine through 5 reactions
Isoleucine is the downstream
product – it is an allosteric
inhibitor of threonine deaminase(an allosteric enzyme)
• As isoleucine is produced and accumulates, it allosterically inhibits threonine deaminase.

1. allosteric inhibitor binds to the allosteric site of the enzyme
2. that causes the active site to go through conformation change
3 change in the substrate binding affinity-- stabilizes the enzyme in its low affinity form resulting in no or little activuty
what is covalent modification?
A mechanism in which enzyme activity is regulated through the covaletn addition or removal of a functional group to or from a particular amino acid R group on the enzyme
How is covalent modification different from feedback inhibition?
– regulator molecule is a simple functional group
– site of binding is NOT a crevice or pocket (with
specificity), but rather a simple amino acid R group
exposed on the enzyme surface
– binding of the regulator to the enzyme is COVALENT
– binding reaction is enzyme-catalyzed
– Removal of the regulator requires breaking the covalent
• Requires a different enzyme
what are the three basic types of covalent modification?
Protein Mehylation
Protien Acetylation
Protien Phosphoralation
what are the basic features of protien phosporalation?
the additon of a phospate group to an enzyme
- it is covalently linked/bonded to amnio acid groups
- The reaction is protien mediated
-the dephosphoralation reaction is enzyme mediated
- can result in the activation or inhibiton of and enzyme depending on the particular enzyme
To which amino acid residues does the phosphate group attach during phosporalation?
which protein mediates the phosphoralation reaction? The dephosphoralation reaction?
Protien Kinase

Protien Phosphotase
what are the 5 major protien kinase families?
Receptor Tyrosine Kinases
Protein Kinase A
Protein Kinase C
CaM Kinases
Protein Kinase III
what is an example of protien kinase A in action?
what is glycogenolosis?
the chemical breakdown of glycogen to glucose by the enzyme glycogen phosphorolase
How does protien Kinase activate glycogenolosis?
1.cyclic AMP acivates the allosteric enzyme protien kinase A
2.1st reaction: Activation of glycogen phosphorylase kinase
3 second reaction:Activation of glycogen phosphorylase
How does the Activation of glycogen phosphorylase kinase occur?
this is the first reaction in glycolosis...

Glycogen phosphoylase kinase is activated by Protien Kinase A with the additon of a phosphate group to the
hydroxl group of the protien
How does the activation of glycogen phosphoralase occur?
This is the second reaction in glycolosis...
Glycogen phosphoralayse kinase
activates glycogen phosphoralase b (inactive) with the addtion of a phospate group from ATP to the hydroxl group of the protien creating glyogen phosphoralse a which
catalyzes the break down of glycogen
How does the Regulation of
Protein Kinase A by cAMP occur?
1.cAMP activates protien kinase A by binding to the regulatory subunits
2.the binding of cAMP to the regulatory subunits causes the regulatory subunits to change conforamtion and detach
from the catolic subunits
3. once the catolic subunits are free they are activated and capable of phosphorylating target protiens in the cell
How is glycogen broken down in the liver?
1. Decrease in blood [glucose]
stimulates glucagon (hormone)
2. Glucagon binds to surface receptors on liver & sksletal muscle
3. Causes a rise in cAMP in the cell
4. Activates Protein Kinase A
5. Stimulates glycogen phosphorylase kinase
6. Stimulates glycogen phosphorylase
7. Accelerates glycogenolysis
8. Increase in blood [glucose]
why are cells compartmentalized?
activity can be controlled with in the compartments different opperations can be carried out and run at differnt levels of concentration
what are the two catagories of biological membrane?
– Plasma membrane
– Internal membrane
what are the two common charateristics that all biological membranes share?
- Same basic structure
– All are selectively
- lipids are amphathic : hydrophillic head, hydrophobic tail
what is the fluid mosaic model?
The model states that
biological membrane is composed of proteins embedded to various extents in a fluid lipid-bilayer.

found by First proposed by
Singer & Nicholson in 1972
what is the average chemical composition of biological membrane?
Average membrane 47protien and lipid 6carbon protien lipid ratio 1:00
what is the sturture of a liposome and why are they formed?
• Structure of the lipid
membrane in a liposome:
a bilayer:
– hydrophobic tails come
together away from water
– Hydrophilic heads face

formed in the presence of water
What types of lipids are there?
what are phospholipids?
Lipids that contain phosphate groups
– 50 – 90% of the lipids in a membrane
What are sterols?
Lipids containing a 4-ring hydrocarbon
- 5 – 45% of the lipids in a membrane
What are glycolipds?
Lipids with carbohydrate covalently
– Less than 5% of lipids in a membrane
What are the two types of membrane phospholipids?
(Head) Chlorine-Phoshpate- (Tail)Glycerol- 2 fatty acids
chlorine-phospate-sphingosine- 1 fatty acid
What are the 4 R grops?
what does the sturctue of a sterol consist of?
Hydrophobic tail
• 4-ring structure
– Hydrophilic head
• Single OH group
– The main sterol in
animal cell membranes
is cholesterol
– The main sterols in
plant cell membranes
are the phytosterols
What doe the structure of a glycolipid consit of?
– Most are derivatives of
– Hydrophobic tail
• Sphingosine
• One fatty acid
– Hydrophilic head
• Six-carbon sugar
What is bilayer fluidity and why is it important?
bilayer fluidity: the ease with which the lipid molecules of a membrane move within the plane of the bilayer
what are the 3 types of possilbe membrane lipid movements?
Lateral diffusion: 1 particular lipid molecule can move laterally with in leaflet
– Rotational diffusion: roate along its access
– Transverse diffusion: moves out of it leaflet
• Aka “flip-flop”
• Extremely rare
How can you measure lipid fluidity?
Through the method of Fluorescence Recovery after Photobleaching.

label with florecent dye, hit with laser in one area to bleach it, watch for rate of diffusion of dye back into the spot

find that a Typical phospholipid molecule can travel a few microns in a
second or less.
what are the factors that determine lipid fluidity in a bilayer?
Molecular characteristics of
the phosphoglycerides
– Fatty acid chain length
– # C=C double bonds in the fatty acid chain
• Concentration of sterols in the bilayer
What is the effect of temperature on bilayer fluidity?
generally as temperature increases bilayer fluidity increases because as you increase temp you are getting closer to the melting point of the bilayer
what is the melting point of a bilayer also known as?
The transition state (Tm)
when the bilayer undergoes a gel to liquid phase change
What does Tm Measure?
Tm Measures the bilayer fluidity
Rule:The lower the Tm , the
greater the bilayer fluidity.
What is the Effect of F.A.Chain Length on the Tm and Bilayer Fluidity?
Fatty acids are acids with a
hydrocarbon chain.
• In nature, fatty acid chain
lengths range from 10 – 20
carbons approx.
• Adding 2 carbons increases
Tm by 5 – 10 degrees C
• Membranes containing longer
chain fatty acids have higher
melting point
Why do chain lengths decrease fluidity?
The longer the hydrocarbon chain, the more hydrophobic
bonds. thus the more bonds that need to be broken = takes more energy (heat)increasing the temp and Tm

The longer the chain the more energy needed to break the hydrophobic bonds
What does the effect of a carbon to carbon double bond have on Tm and bilayer fluidity?
Each C=C creates a kink in the fatty acid chain, As the # of C=C double bonds increases, the melting
point of the fat (Tm)
decreases, and the fluidity
-One C=C drops MP by 55 degrees C.
what are fatty acids with no carbon to carbon bonds?
Saturated fatty acids
Why does the inclusion of C=C decrease Tm (increase fluidity)?
because the kink separtates the chain decreasing bond strength because they are not so densly packed
What effect does cholesteral have on membrane fluidity?
Cholesterol moderates the
effect temperature has on the membrane.
– Cholesterol reduces membrane
fluidity at higher temps
•Due to rigidity of the cholesterol molecule.
– Cholesterol increases membrane fluidity at lower temperatures
• Cholesterol prevents close
packing of phospholipids as temp is decreased
what is found in the extracellular leaflet?
1. Phosphatidylcholine and sphingomyelin are more
concentrated in extracellular leaflet.
2. Glycolipids are absolutely restricted to the extracellular leaflet (never found in the cytosolic leaflet)
What is found in the cytosolic leaflet?
1. Phosphatidylserine and phosphatidylethanolamine are more concentrated in cytosolic leaflet.
2. Phosphatidylinositol is absolutely restricted to the cytosolic leaflet. (never found in the extracellular leaflet)
What effect does cholesteral have on membrane fluidity?
Cholesterol moderates the
effect temperature has on the membrane.
– Cholesterol reduces membrane
fluidity at higher temps
•Due to rigidity of the cholesterol molecule.
– Cholesterol increases membrane fluidity at lower temperatures
• Cholesterol prevents close
packing of phospholipids as temp is decreased
what is found in the extracellular leaflet?
1. Phosphatidylcholine and sphingomyelin are more
concentrated in extracellular leaflet.
2. Glycolipids are absolutely restricted to the extracellular leaflet (never found in the cytosolic leaflet)
What is found in the cytosolic leaflet?
1. Phosphatidylserine and phosphatidylethanolamine are more concentrated in cytosolic leaflet.
2. Phosphatidylinositol is absolutely restricted to the cytosolic leaflet. (never found in the extracellular leaflet)