Lipids are organic compounds formed from fatty acids and alcohol. They include fats, oils, waxes and related compounds. Lipids provide energy, essential fatty acids, and aid in the absorption of fat-soluble vitamins. They are important components of cell membranes and play roles in insulation, cushioning of organs, and energy storage. Analysis of lipid properties such as iodine number and saponification number can provide information about degree of unsaturation and fatty acid content. Rancidity reduces lipid quality through hydrolysis or oxidation.
Lipids Chemistry Structure & Function (More Detailed)hafizayyub
This presentation is for Medical students. It is more detailed explanation of Lipids including types and medical importance. It is made by Drs Charles Stephen and Dr Ayyub Patel
Coenzyme - Introduction, Definition, Examples for coenzyme, reaction catalysed by coenzyme, Types of coenzymes - cosubstrate and prosthetic group coenzymes, second type of classification of coenzyme- hydrogen group transfer , other than hydrogen group transfer.
introduction of Lipids,Chemistry,Fuctions of lipids,Classification of lipids Structural elucidation of Essential Fatty acid,Prostaglandins, Vitamin A, Phospolipids,Cholesterol,Lanosterol
Lipids Chemistry Structure & Function (More Detailed)hafizayyub
This presentation is for Medical students. It is more detailed explanation of Lipids including types and medical importance. It is made by Drs Charles Stephen and Dr Ayyub Patel
Coenzyme - Introduction, Definition, Examples for coenzyme, reaction catalysed by coenzyme, Types of coenzymes - cosubstrate and prosthetic group coenzymes, second type of classification of coenzyme- hydrogen group transfer , other than hydrogen group transfer.
introduction of Lipids,Chemistry,Fuctions of lipids,Classification of lipids Structural elucidation of Essential Fatty acid,Prostaglandins, Vitamin A, Phospolipids,Cholesterol,Lanosterol
Lipids are a heterogenous group of
water –insoluble ( hydrophobic ) organic
molecules. Presentation on how they affect the body and what to do to prevent their effects.
Introduction of fats, Reaction of fatty acids, Reaction of fats or oil- Hydrolysis, Hydrogenation, Halogenation, saponification, Drying of oil, Rancidity, Determination of acid value, saponification value, iodine value, acetyl value,
Lipid Chemistry-Complete - Alex -Dr Ayman- 2015 - 2016 - More Detailed.pptAyman Abdo
This presentation shows the classification and occurrence of human lipids and their biological value. It also reveals the chemical formula of human lipids
Lipids are organic compounds formed mainly from alcohol and fatty acids combined together by ester
Lipids are insoluble in water, but soluble in fat or organic solvents (ether, chloroform, benzene, acetone).
Lipids include fats, oils, waxes and related compounds.
They are widely distributed in nature both in plants and in animals.
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
The increased availability of biomedical data, particularly in the public domain, offers the opportunity to better understand human health and to develop effective therapeutics for a wide range of unmet medical needs. However, data scientists remain stymied by the fact that data remain hard to find and to productively reuse because data and their metadata i) are wholly inaccessible, ii) are in non-standard or incompatible representations, iii) do not conform to community standards, and iv) have unclear or highly restricted terms and conditions that preclude legitimate reuse. These limitations require a rethink on data can be made machine and AI-ready - the key motivation behind the FAIR Guiding Principles. Concurrently, while recent efforts have explored the use of deep learning to fuse disparate data into predictive models for a wide range of biomedical applications, these models often fail even when the correct answer is already known, and fail to explain individual predictions in terms that data scientists can appreciate. These limitations suggest that new methods to produce practical artificial intelligence are still needed.
In this talk, I will discuss our work in (1) building an integrative knowledge infrastructure to prepare FAIR and "AI-ready" data and services along with (2) neurosymbolic AI methods to improve the quality of predictions and to generate plausible explanations. Attention is given to standards, platforms, and methods to wrangle knowledge into simple, but effective semantic and latent representations, and to make these available into standards-compliant and discoverable interfaces that can be used in model building, validation, and explanation. Our work, and those of others in the field, creates a baseline for building trustworthy and easy to deploy AI models in biomedicine.
Bio
Dr. Michel Dumontier is the Distinguished Professor of Data Science at Maastricht University, founder and executive director of the Institute of Data Science, and co-founder of the FAIR (Findable, Accessible, Interoperable and Reusable) data principles. His research explores socio-technological approaches for responsible discovery science, which includes collaborative multi-modal knowledge graphs, privacy-preserving distributed data mining, and AI methods for drug discovery and personalized medicine. His work is supported through the Dutch National Research Agenda, the Netherlands Organisation for Scientific Research, Horizon Europe, the European Open Science Cloud, the US National Institutes of Health, and a Marie-Curie Innovative Training Network. He is the editor-in-chief for the journal Data Science and is internationally recognized for his contributions in bioinformatics, biomedical informatics, and semantic technologies including ontologies and linked data.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Earliest Galaxies in the JADES Origins Field: Luminosity Function and Cosmic ...Sérgio Sacani
We characterize the earliest galaxy population in the JADES Origins Field (JOF), the deepest
imaging field observed with JWST. We make use of the ancillary Hubble optical images (5 filters
spanning 0.4−0.9µm) and novel JWST images with 14 filters spanning 0.8−5µm, including 7 mediumband filters, and reaching total exposure times of up to 46 hours per filter. We combine all our data
at > 2.3µm to construct an ultradeep image, reaching as deep as ≈ 31.4 AB mag in the stack and
30.3-31.0 AB mag (5σ, r = 0.1” circular aperture) in individual filters. We measure photometric
redshifts and use robust selection criteria to identify a sample of eight galaxy candidates at redshifts
z = 11.5 − 15. These objects show compact half-light radii of R1/2 ∼ 50 − 200pc, stellar masses of
M⋆ ∼ 107−108M⊙, and star-formation rates of SFR ∼ 0.1−1 M⊙ yr−1
. Our search finds no candidates
at 15 < z < 20, placing upper limits at these redshifts. We develop a forward modeling approach to
infer the properties of the evolving luminosity function without binning in redshift or luminosity that
marginalizes over the photometric redshift uncertainty of our candidate galaxies and incorporates the
impact of non-detections. We find a z = 12 luminosity function in good agreement with prior results,
and that the luminosity function normalization and UV luminosity density decline by a factor of ∼ 2.5
from z = 12 to z = 14. We discuss the possible implications of our results in the context of theoretical
models for evolution of the dark matter halo mass function.
(May 29th, 2024) Advancements in Intravital Microscopy- Insights for Preclini...Scintica Instrumentation
Intravital microscopy (IVM) is a powerful tool utilized to study cellular behavior over time and space in vivo. Much of our understanding of cell biology has been accomplished using various in vitro and ex vivo methods; however, these studies do not necessarily reflect the natural dynamics of biological processes. Unlike traditional cell culture or fixed tissue imaging, IVM allows for the ultra-fast high-resolution imaging of cellular processes over time and space and were studied in its natural environment. Real-time visualization of biological processes in the context of an intact organism helps maintain physiological relevance and provide insights into the progression of disease, response to treatments or developmental processes.
In this webinar we give an overview of advanced applications of the IVM system in preclinical research. IVIM technology is a provider of all-in-one intravital microscopy systems and solutions optimized for in vivo imaging of live animal models at sub-micron resolution. The system’s unique features and user-friendly software enables researchers to probe fast dynamic biological processes such as immune cell tracking, cell-cell interaction as well as vascularization and tumor metastasis with exceptional detail. This webinar will also give an overview of IVM being utilized in drug development, offering a view into the intricate interaction between drugs/nanoparticles and tissues in vivo and allows for the evaluation of therapeutic intervention in a variety of tissues and organs. This interdisciplinary collaboration continues to drive the advancements of novel therapeutic strategies.
Richard's aventures in two entangled wonderlandsRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Multi-source connectivity as the driver of solar wind variability in the heli...Sérgio Sacani
The ambient solar wind that flls the heliosphere originates from multiple
sources in the solar corona and is highly structured. It is often described
as high-speed, relatively homogeneous, plasma streams from coronal
holes and slow-speed, highly variable, streams whose source regions are
under debate. A key goal of ESA/NASA’s Solar Orbiter mission is to identify
solar wind sources and understand what drives the complexity seen in the
heliosphere. By combining magnetic feld modelling and spectroscopic
techniques with high-resolution observations and measurements, we show
that the solar wind variability detected in situ by Solar Orbiter in March
2022 is driven by spatio-temporal changes in the magnetic connectivity to
multiple sources in the solar atmosphere. The magnetic feld footpoints
connected to the spacecraft moved from the boundaries of a coronal hole
to one active region (12961) and then across to another region (12957). This
is refected in the in situ measurements, which show the transition from fast
to highly Alfvénic then to slow solar wind that is disrupted by the arrival of
a coronal mass ejection. Our results describe solar wind variability at 0.5 au
but are applicable to near-Earth observatories.
2. Chemistry of Lipids
Definition:
Lipids are organic compounds formed mainly from
alcohol and fatty acids combined together by ester
linkage.
CH2R
Fatty alcohol
OH C R
Fatty acid
HO
O
+
H2O
CH2R O C R
O
Esterase (lipase) ester (lipid)
3. Lipids are insoluble in water, but soluble in fat or organic
solvents (ether, chloroform, benzene, acetone).
Lipids include fats, oils, waxes and related compounds.
They are widely distributed in nature both in plants and
in animals.
4. Biological Importance of Lipids
They are more palatable and storable to unlimited
amount compared to carbohydrates.
They have a high-energy value (25% of body needs) and
they provide more energy per gram than carbohydrates
and proteins but carbohydrates are the preferable
source of energy.
Supply the essential fatty acids that cannot be
synthesized by the body.
5. Supply the body with fat-soluble vitamins (A, D, E and K).
They are important constituents of the nervous system.
Tissue fat is an essential constituent of cell membrane and
nervous system. It is mainly phospholipids in nature that
are not affected by starvation.
6. Stored lipids “depot fat” is stored in all human cells
acts as:
a) A store of energy
b) A pad for the internal organs to protect them from
outside shocks
c) A subcutaneous thermal insulator against loss of body
heat
7. Lipoproteins
a) complex of lipids and proteins, are
b) important cellular constituents
c) present both in the cellular and subcellular membranes.
Cholesterol enters in membrane structure and is used for
synthesis of adrenal cortical hormones, vitamin D3 and
bile acids.
Lipids provide bases for dealing with diseases such as
obesity, atherosclerosis, lipid-storage diseases, essential
fatty acid deficiency, respiratory distress syndrome,
9. Fatty alcohols
Glycerol:
It is a trihydric alcohol (i.e., containing three OH
groups) and has the popular name glycerin.
It is synthesized in the body from glucose.
It has the following properties:
10. Colorless viscous oily liquid with sweet taste.
On heating with sulfuric acid or KHSO4 (dehydration)
it gives acrolein that has a bad odor.
This reaction is used for detection of free glycerol or
any compound containing glycerol.
CH2 OH
CH
CH2 OH
HO
CHO
CH
CH2
2 H2O
Heating, KHSO4
Glycerol Acrolein
11. It combines with three molecules of nitric acid to form
trinitroglycerin (TNT) that is used as explosive and
vasodilator.
On esterification with fatty acids it gives:
a) Monoglyceride or monoacyl-glycerol: one fatty acid +
glycerol.
b) Diglyceride or diacyl-glycerol: two fatty acids +
glycerol.
c) Triglyceride or triacyl-glycerol: three fatty acids +
glycerol.
It has a nutritive value by conversion into glucose and
enters in structure of phospholipids.
12. Sphingosine:
It is the alcohol(monohydric) present in sphingolipids.
It is synthesized in the body from serine and palmitic
acid.
It is not positive with acrolein test.
CH CH NH2
CH2OH
CHCH(CH2)12CH3
OH
Sphingosine
13. Simple Lipids
01) Neutral Fats and oils (Triglycerides)
Definition:
They are called neutral because they are uncharged due to
absence of ionizable groups in it.
The neutral fats are the most abundant lipids in nature.
They constitute about 98% of the lipids of adipose tissue,
30% of plasma or liver lipids, less than 10% of erythrocyte
lipids.
14. They are esters of glycerol with various fatty acids.
Since the 3 hydroxyl groups of glycerol are esterified, the
neutral fats are also called “Triglycerides”.
Esterification of glycerol with one molecule of fatty acid
gives monoglyceride, and that with 2 molecules gives
diglyceride.
15. H2C O
C HO
H2C
C
C
O C
R1
R3
R2
O
O
O
+
3 H2O
CH2 OH
C HHO
CH2 OH
HO C R1
O
HO C R3
O
HO C R2
O
Fatty acids Glycerol Triglycerides
(Triacylglycerol)
16. Types of triglycerides
1-Simple triglycerides:
If the three fatty acids connected to glycerol are of the
same type the triglyceride is called simple triglyceride,
e.g., tripalmitin.
2-Mixed triglycerides:
if they are of different types, it is called mixed
triglycerides, e.g., stearo-diolein and palmito-oleo-
stearin.
Natural fats are mixtures of mixed triglycerides with a
small amount of simple triglycerides.
17. CH2 O
C HO
CH2
C
C
O C
(CH2)14
O
O
O
Tripalmitin
(simple triacylglycerol)
CH3
(CH2)14CH3
(CH2)14 CH3
CH2 O
C HO
CH2
C
C
O C
(CH2)16
O
O
O
1-Stearo-2,3-diolein
(mixed triacylglycerol)
CH3
(CH2)7CHCH(CH2)7CH3
(CH2)7 CH CH (CH2)7 CH3
CH2 O
C HO
CH2
C
C
O C
(CH2)14
O
O
O
1-palmito-2-oleo-3-stearin
(mixed triacylglycerol)
CH3
(CH2)16 CH3
(CH2)7CHCH(CH2)7CH3
18. Physical properties of fat and oils:
1. Freshly prepared fats and oils are colorless, odorless and
tasteless. Any color, or taste is due to association with
other foreign substances, e.g., the yellow color of body fat
or milk fat is due to carotene pigments(cow milk).
2. Fats have specific gravity less than 1 and, therefore, they
float on water.
3. Fats are insoluble in water, but soluble in organic solvents
as ether and benzene.
4. Melting points of fats are usually low, but higher than the
solidification point,
19. Chemical Properties of fats and oils:
1-Hydrolysis:
They are hydrolyzed into their constituents (fatty acids and
glycerol) by the action of super heated steam, acid, alkali or
enzyme (e.g., lipase of pancreas).
During their enzymatic and acid hydrolysis glycerol and
free fatty acids are produced.
CH2 O
C HO
CH2
C
C
O C
R1
R3
R2
O
O
O
3 H2O
H2C OH
C HHO
H2C OH
OHCR1
O
OHCR3
O
+ OHCR2
OLipase or Acid
Triacylglycerol Glycerol Free fatty acids
20. 2-Saponification
Alkaline hydrolysis produces glycerol and salts of fatty
acids (soaps).
Soaps cause emulsification of oily material this help easy
washing of the fatty materials
CH2 O
C HO
CH2
C
C
O C
R1
R3
R2
O
O
O
H2C OH
C HHO
H2C OH
ONaCR1
O
ONaCR3
O
+ ONaCR2
O
Triacylglycerol Glycerol Sodium salts of
fatty acids (soap)
3 NaOH
21. 3-Halogenation
Neutral fats containing unsaturated fatty acids have the
ability of adding halogens (e.g., hydrogen or hydrogenation
and iodine or iodination) at the double bonds.
It is a very important property to determine the degree of
unsaturation of the fat or oil that determines its biological
value
CH (CH2)7 COOHCHCH2CH
Linoleic acid
CH(CH2)4CH3
2 I2
CH (CH2)7 COOHCHCH2CH
Stearate-tetra-iodinate
CH(CH2)4CH3
II I I
22. 4-Hydrogenation or hardening of oils:
It is a type of addition reactions accepting hydrogen at the
double bonds of unsaturated fatty acids.
The hydrogenation is done under high pressure of hydrogen
and is catalyzed by finely divided nickel or copper and heat.
It is the base of hardening of oils (margarine
manufacturing), e.g., change of oleic acid of fats (liquid) into
stearic acid (solid).
It is advisable not to saturate all double bonds; otherwise
margarine produced will be very hard, of very low biological
value and difficult to digest.
23. 5-Oxidation(Rancidty)
This toxic reaction of triglycerides leads to unpleasant
odour or taste of oils and fats developing after oxidation
by oxygen of air, bacteria, or moisture.
Also this is the base of the drying oils after exposure to
atmospheric oxygen.
Example is linseed oil, which is used in paints and
varnishes manufacturing
24. Rancidity
Definition:
It is a physico-chemical change in the natural properties of
the fat,
leading to the development of unpleasant odor or taste or
abnormal color,
particularly on aging after exposure to atmospheric
oxygen, light, moisture, bacterial or fungal contamination
and/or heat.
Saturated fats resist rancidity more than unsaturated fats
that have unsaturated double bonds.
25. Types and causes of Rancidity
1. Hydrolytic rancidity
2. Oxidative rancidity
3. Ketonic rancidity
26. 1-Hydrolytic rancidity:
It results from slight hydrolysis of the fat by lipase from
bacterial contamination leading to the liberation of free
fatty acids and glycerol at high temperature and
moisture.
Volatile short-chain fatty acids have unpleasant odor.
27. CH2 O
C HO
CH2
C
C
O C
R1
R3
R2
O
O
O
3 H2O
H2C OH
C HHO
H2C OH
OHCR1
O
OHCR3
O
+ OHCR2
OLipase
Triacylglycerol Glycerol Free fatty acids
(volatile, bad odor)
28. 2-Oxidative Rancidity:
It is oxidation of fat or oil,
catalyzed by exposure to oxygen, light and/or heat,
producing peroxide derivatives which on decomposition
give substances, e.g., peroxides, aldehydes, ketones and
dicarboxylic acids that are toxic and have bad odor.
This occurs due to oxidative addition of oxygen at the
unsaturated double bond of unsaturated fatty acid of oils.
30. 3-Ketonic Rancidity:
It is due to the contamination with certain fungi such as
Asperigillus Niger on fats such as coconut oil.
Ketones, fatty aldehydes, short chain fatty acids and fatty
alcohols are formed.
Moisture accelerates ketonic rancidity.
31. Prevention of rancidity
1. Avoidance of the causes (exposure to light, oxygen,
moisture, high temperature and bacteria or fungal
contamination).
2. By keeping fats or oils in well-closed containers in cold,
dark and dry place (i.e., good storage conditions).
3. Removal of catalysts such as Pb and copper that catalyze
rancidity.
4. Addition of anti-oxidants to prevent peroxidation in fat (i.e.,
rancidity).
5. They include phenols, naphthols, tannins and
hydroquinones. The most common natural antioxidant is
vitamin E that is important in vitro and in vivo.
32. Hazards of Rancid Fats:
1. The products of rancidity are toxic, i.e., causes food
poisoning and cancer.
2. Rancidity destroys the fat-soluble vitamins (vitamins
A, D, K and E).
3. Rancidity destroys the polyunsaturated essential fatty
acids.
4. Rancidity causes economical loss because rancid fat is
inedible.
33. Analysis and Identification of fats and oils
(Fat Constants)
Fat constants or numbers are tests used for:
1. Checking the purity of fat for detection of adulteration.
2. To quantitatively estimate certain properties of fat.
3. To identify the biological value and natural
characteristics of fat.
4. Detection of fat rancidity and presence of toxic hydroxy
fatty acids.
34. 1-Iodine number (or value):
Definition: It is the number of grams of iodine absorbed by
100 grams of fat or oil.
Uses: It is a measure for the degree unsaturation of the fat,
as a natural property for it.
Unsaturated fatty acids absorb iodine at their double bonds,
therefore, as the degree of unsaturation increases iodine
number and hence biological value of the fat increase.
It is used for identification of the type of fat, detection of
adulteration and determining the biological value of fat.
35. 2-Saponification number (or value):
Definition: It is the number of milligrams of KOH required
to completely saponify one gram of fat.
Uses:
Since each carboxyl group of a fatty acid reacts with one
mole of KOH during saponification
therefore, the amount of alkali needed to saponify certain
weight of fat depends upon the number of fatty acids
present per weight.
Thus, fats containing short-chain acids will have more
carboxyl groups per gram than long chain fatty acids and
consume more alkali,
i.e., will have higher saponification number.
36. 3-Acids Number (or value):
Definition:
It is the number of milligrams of KOH required to
neutralize the free fatty acids present in one gram of fat.
Uses:
It is used for detection of hydrolytic rancidity because it
measures the amount of free fatty acids present.
37. Waxes
Definition: Waxes are solid simple lipids containing a
monohydric alcohol (with a higher molecular weight than
glycerol) esterified to long-chain fatty acids.
Examples of these alcohols are palmitoyl alcohol, cholesterol,
vitamin A or D.
Properties of waxes: Waxes are insoluble in water, but
soluble in fat solvents and are negative for acrolein test.
38. Waxes are not easily hydrolyzed as the fats and are
indigestible by lipases and are very resistant to rancidity.
Thus they are of no nutritional value.
39. Type of Waxes:
Waxes are widely distributed in nature such as,
the secretion of certain insects as bees-wax,
protective coatings of the skins and furs of animals and
leaves and fruits of plants.
They are classified into true-waxes and wax-like
compounds as follows:
40. True waxes:
include:
Bees-wax is secreted by the honeybees that use it to form
the combs.
It is a mixture of waxes with the chief constituent is mericyl
palmitate.
41. Wax-like compounds:
Cholesterol esters: Lanolin (or wool fat) is prepared from
the wool-associated skin glands and is secreted by
sebaceous glands of the skin.
It is very complex mixture , contains both free and
esterified cholesterol, e.g., cholesterol-palmitate and other
sterols.
42. Differences between neutral lipids and waxes:
Waxes Neutral lipids
1.Digestibility: Indigestible (not
hydrolyzed by lipase).
Digestible (hydrolyzed by lipase).
2-Type of
alcohol:
Long-chain monohydric
alcohol + one fatty acid.
Glycerol (trihydric) + 3 fatty acids
3-Type of fatty
acids:
Fatty acid mainly palmitic
or stearic acid.
Long and short chain fatty acids.
4-Acrolein test: Negative. Positive.
5-Rancidability: Never get rancid. Rancidible.
6-Nature at
room
temperature.
Hard solid. Soft solid or liquid.
7-Saponification Nonsaponifiable. Saponifiable.
8-Nutritive
value:
No nutritive value. Nutritive.
9-Example: Bee & carnuba waxes. Butter and vegetable oils.
43. Compound Lipids
Definition:
They are lipids that contain additional substances, e.g., sulfur,
phosphorus, amino group, carbohydrate, or proteins beside fatty
acid and alcohol.
Compound or conjugated lipids are classified into the following
types according to the nature of the additional group:
1. Phospholipids
2. Glycolipids.
3. Lipoproteins
4. Sulfolipids and amino lipids.
45. Importance1. They are present in large amounts in the liver and brain as
blood.
2. Every animal and plant cell contains phospholipids.
3. The membranes bounding cells and sub cellular organell
composed mainly of phospholipids.
4. Thus, the transfer of substances through these membrane is con
by properties of phospholipids.
5. They are important components of the lipoprotein coat essen
secretion and transport of plasma lipoprotein complexes.
6. Myelin sheath of nerves is rich with phospholipids.
46. Sources:
They are found in all cells (plant and animal), milk and egg-
yolk in the form of lecithins.
Structure:
phospholipids are composed of:
1. Fatty acids (a saturated and an unsaturated fatty acid).
2. Nitrogenous base (choline, serine, threonine, or
ethanolamine).
3. Phosphoric acid.
4. Fatty alcohols (glycerol, inositol or sphingosine).
47. Glycolipids
Definition:
They are lipids that contain carbohydrate residues with
sphingosine as the alcohol and a very long-chain fatty
acid (24 carbon series).
They are present in cerebral tissue, therefore are called
cerebrosides.
48. Classification:
According to the number and nature of the carbohydrate
residue(s) present in the glycolipids
1. Cerebrosides -They have one galactose molecule
(galactosides).
2. Sulfatides -They are cerebrosides with sulfate on the
sugar (sulfated cerebrosides).
3. Gangliosides -They have several sugar and sugar amine
residues.
49. 1-Cerebrosides:
Occurrence: They occur in myelin sheath of nerves and
white matter of the brain tissues and cellular membranes.
They are important for nerve conductance.
Structure: They contain sugar, usually -galactose and may
be glucose or lactose, sphingosine and fatty acid, but no
phosphoric acid.
CH CH NH
CH2
CHCH(CH2)12CH3
OH
Sphingosine
C R1
O
O
Psychosin
Fatty acid
Ceramide
Cerebroside
OOH
H H
H
OHH
OH
CH2OH
H
Galactose
50. 2-Sulfatides:
They are sulfate esters of kerasin or phrenosin in which
the sulfate group is usually attached to the –OH group of
C3 or C6 of galactose.
Sulfatides are usually present in the brain, liver, muscles
and testes.
CH CH NH
CH2
CHCH2(CH2)12CH3
OH
C R1
O
O
Sulfatides (sulfated cerebroside)
OOH
H H
H
OHH
OSO3H
CH2OH
H
51. 3-Gangliosides:
They are more complex glycolipids that occur in the gray
matter of the brain, ganglion cells, and RBCs.
They transfer biogenic amines across the cell membrane
and act as a cell membrane receptor.
Ceramide-Glucose-Galactose-N-acetylgalactosamine-Galactose
Monosialoganglioside
Sialic acid
53. Structural lipoproteins:
These are widely distributed in tissues being present in
cellular and sub cellular membranes.
In lung tissues acting as a surfactant in a complex of a
protein and lecithin.
In the eye, rhodopsin of rods is a lipoprotein complex.
54. Transport lipoproteins:
These are the forms present in blood plasma.
They are composed of a protein called apo lipo protein and
different types of lipids. (Cholesterol, cholesterol esters,
phospholipids and triglycerides).
As the lipid content increases, the density of plasma
lipoproteins decreases
55. a) Chylomicrons:
They have the largest diameter and the least density.
They contain 1-2% protein only and 98-99% fat.
The main lipid fraction is triglycerides absorbed from the
intestine and they contain small amounts of the absorbed
cholesterol and phospholipids.
56. b) Very low-density lipoproteins (VLDL) or pre--
lipoproteins:
Their diameter is smaller than chylomicrons.
They contain about 7-10% protein and 90-93% lipid.
The lipid content is mainly triglycerides formed in the liver.
They contain phospholipid and cholesterol more than
chylomicrons.
57. c) Low-density lipoproteins (LDL) or -lipoproteins:
They contain 10-20% proteins in the form of apo
lipoprotein B.
Their lipid content varies from 80-90%.
They contain about 60% of total blood cholesterol and 40%
of total blood phospholipids.
As their percentage increases, the liability to atherosclerosis
increases.
58. d) High-density lipoproteins (HDL) or -
Lipoproteins:
They contain 35-55% proteins in the form of
apolipoprotein A.
They contain 45-65% lipids formed of cholesterol (40% of
total blood content) and phospholipids (60% of total
blood content).
They act as cholesterol scavengers, as their percentage
increases, the liability to atherosclerosis decreases.
They are higher in females than in males.
Due to their high protein content they possess the highest
density.
59. Cholesterol:
Importance: -
It is the most important sterol in animal tissues as free
alcohol or in an esterified form (with linoleic, oleic,
palmitic acids or other fatty acids).
Steroid hormones , bile salts and vitamin D are
derivatives from it.
Tissues contain different amounts of it that serve a
structural and metabolic role, e.g., adrenal cortex content
is 10%, whereas, brain is 2%, others 0.2-0.3%.
60. Source: -
It is synthesized in the body from acetyl-CoA (1gm/day,
cholesterol does not exist in plants) and is also taken in the
diet (0.3 gm/day as in, butter, milk, egg yolk, brain, meat
and animal fat).
61. Steroids
Steroids constitute an important class of biological compounds.
Steroids are usually found in association with fat.
They can be separated from fats after saponification since they
occur in the unsaponifiable residue.
They are derivatives of cholesterol that is formed of steroid
ring or nucleus.
62. Biologically important groups of substances, which contain this
ring, are:
1. Sterols.
2. Adrenal cortical hormones.
3. Male and female sex hormones.
4. Vitamin D group.
5. Bile acids.
6. Cardiac glycosides.
63. General consideration about naturally occurring steroids:
A typical member of this group is cholesterol.
1) There is always oxygen in the form of hydroxyl or ketone on
C3.
2) Rings C and D are saturated (stable).
3) Methyl groups at C18 C19.
In case of vitamin D, the CH3 group at C19 becomes a methylene
group (=CH2) and the ring B is opened, whereas, this methyl
group is absent in female sex hormones (estrogens).
4) In estrogens (female sex hormones) ring A is aromatic and
there is no methyl group on C10.
65. Bile acids
They are produced from oxidation of cholesterol in the
liver,
producing cholic and chenodeoxycholic acids that are
conjugated with glycine or taurine to produce glycocholic,
glycochenodeoxycholic, taurocholic and
taurochenodeoxycholic acids.
They react with sodium or potassium to produce sodium
or potassium bile salts.
66. Their functions
1. Emulsification of lipids during digestion.
2. Help in digestion of the other foodstuffs.
3. Activation of pancreatic lipase.
4. Help digestion and absorption of fat-soluble vitamins.
5. Solubilizing cholesterol in bile and prevent gall stone
formation.
6. Choleretic action (stimulate their own secretion).
7. Intestinal antiseptic that prevent putrefaction