2.3 carbohydrates and lipids Flashcards
what are carbohydrates?
have three elements in ratio
2 : 1 : 1
H : C : O
glycolipids, glycoproteins, nucleic acids all have carbohydrate components
the name of units of monomers are monosaccharides etc
what are monosaccharides , disaccharides and polysaccharides?
monosaccharide is a monomer which can link together to form di/polysaccharides
e.g. single sugar units, glucose, fructose and ribose
Disaccharides are two monosaccharides linked together by a glycosidic bond in a condensation reaction
e.g. maltose - 2 glucose
sucrose - glucose and fructose
lactose - galactose and glucose
(all use glycosidic bonds and release H2O in reaction)
polysaccharides are many monosaccharides linked
e.g. starch, glycogen and cellulose
draw a glycodisic bond
how do monosaccharides bond?
when they combine they do this by condensation. involves loss of H2O (OH from one H from the other)
condensation is the reaction between two molecues resulting in the formation of a larger molecule and the release of a water molecule using enzyme action
the linking is anabolic and you need energy ATP
hydrolysis is teh breakdown of a molecule into two smaller molecules requirinf the addition of a water molecules using enzyme action
how is the structure of glucose important in making polysaccharides?
glucose bonds on C 1&4 and sometimes forms side chains or branches using 6
there are two types of glucose alpha (a) and beta (b) if not otherwise specified assume it is a
in b the OH group on carbon 1 points up not down which greatly affects the polysaccharide
how is cellulose structured?
- uses B glucose so in order for them to condense they have a position of 180 to the previous one i.e. upside down
- so straight chain and not curved
- unbranched so can form bundles with hydrogen bonds by linking the cellulose molecules
- these bundles are called microfibrils and have high tensile strength so are used in plant cell wall basis to as they do no burst even when you have high pressure inside the cell due to osmosis
how is starch structured?
- a glucose molecules
- carbon 1 and 4
- curved not straight, spiral shape
two forms of starch
1 - amylose
- chain of a glucose
- unbranched
- helix
in the hydrolysis of starch breaking it down into glucose amylase and glucosidase are used
easy to add or remove extra glucose molecules to either end or at the end of a branch (more places so less time and more efficient repiration) so no fixed size
2- amylopectin
- branched
- globular shape
starch is only made by plants and molecules of starch are hydrophilic by too large to be soluble. They are thus useful when you want to store large amounts of glucose without changing conc of glucose of solution causing ater to enter by osmosis and the cell to burst.
therefore it is a good temporary store of glucose in leaf cells and a good energy store in seeds and storage organs such as potato cells.
how is glycogen structured?
- similar to starch but more branching so more compact
- a glucose
- does not coil
- used in animals and some fungi to store energy in the liver and some muscles in humans
- easy to add or remove extra glucose molecules to either end or at the end of a branch so no fixed size
what are reducing and non-reducing sugars?
all monosaccharides as well as maltose and lactose are capable of reducing copper 2 sulphate in benedicts solution. They can donate electrons to oxidise the copper
Cu2+ –> CU+
blue –> brick red
sucrose is however non reducing but can be broken down into glucose and thus becomes reducing
ways to do this
- add sucrase and leave at RTP
- boiling in acid (acid hydrolysis) and then neutralise resultants
how to test for glucose
add benedicts solution
non reducing sugar
blue
green
yellow
brown
brick red
reducing sugar
then compare colours or…
leave to settle and place in curvette and test intesity of colour in colorimeter. The more CUSO4 is used up (i.e. the more conc of sugar) the less light will be blocked out and the more light will be transmitted.
Then draw calibration curve to estimate readings of unknow conc.
could also measure mass of precipitate
could use a glucos strip where the colour is compared to a colour chart
draw the structure of a triglyceride
made of glycerol and 3 fatty acids
releases 3 water molecules and is therefore a condensation reaction
is used for
- energy store
- insulation as do not conduct heat well - e.g. blubber in arctic marine mammals
- buoyancy
- protection
example - the fat in adipose tissue
what are lipids?
- haev c /H / O and few Os and lots of Hs
- fats - solids at rtp but liquid at body temp and oil - liquid lipids
- nonpolar so not soluble
- are macromolecules so have monomers
saturated
- have no double bonds
- are bad for you as they are transported in a different way and can build up in the blood leading to high cholestera
unsaturated
- double bond in hydro-carbon chain
- not stored in the blood so not as bad for you
- double bond makes it have a bend which makes it be a liquid
draw the structure of a phospholipid
used in cell membranes and organelles and lipoprotein complexes
–> are polar
made of 2 fatty acids, glycerol and phosphate
uses of lipids
long term energy storage - adipose tissue located immediately beneath skin and around some organs e.g. kidneys
why
- the amount of energy released in 2x the amount of energy released from carbohydrates so adds half the body mass
- because lipids form pure droplets in cells with no water assosciation (each gram of glycogen as 2 grams of water) makes them 6x more efficient energy wise
Heat insulators
why
- poor conductors of heat
- therefore stores in sub cutaneous adipose tissue next to skin
shock absorbed
why
- lipid is a liquid at body temp
- put around organs
Why glycogen at all?
it is used for short term energy because it can be broken down more rapidly, and fats and fatty acids can only be used as an aerobic substrate
–> liver has 150 g of glycogen
–> 2% of body by mass of glycogen
what is BMI?
if a persons mass is at a healthy level
if below 18.5- underweight
18.5-24.9 - normal weight
25 - 29.9 - overweight
over 30 - obese
Problems - athletes? pregnant ladies? preventative medicine?
test for protein
buiret reageant
positive - purple
negative - blue
tests for lipids
substance + ethanol + water - layer of white emulsion being distince
or filter paper will go translucent
test for non-reducing sugars
add enzymes to undergo hydrolysis
add benedicts solution
positive - brick red
negative - blue
can also do it by mass of precipitate or calibration curve - more Cu2+ reduced so less light blocked
test for starch
iodine solution
postive - blue black
negative - red brown
types fatty acids
fatty acids in living organisms have between 14 and 20 carbon atoms, the bonding between these carbons is also variable
for some all are singel covalent some have one or more double bond
saturated - only single bonds
unsaturated- double bonds too
monounsaturated - one double bond
polyunsaturated - more than one double bond
cis - hydrogen all on one side
trans - hydrogen on both sides
How does this affect the fatty acid
- cis fatty acids cause a bend in the hydrocarbon chain so the fatty acids are less good at packing together in regular arrangement. This means that the melting point is lower, so oils at rtp
- transfatty acids do not have this bend so they have a higher melting point and are solid at rtp. they are produced artificially by partial hydrogenation of vegetable or fish oil e.g. margarine
what are the health risks of fats
main concern is coronary heart disease where artieries become partiallly blocked by fatty acids and blood clots can form leading to heart attacks
postive correlation between saturated fatty acids and rate of CHD – does not prove causation , could be another factor correlated to saturated fat intake such as low amounts of dietary fiber
PROBLEMS
population that do not fit the correlation, the maasai in Kenya have a diet rich in meat, fat and blood so loads of saturated fats. But not CHD
diets rich in olive oil - cis -monounsaturated fatty acids, are eaten in the mediterranean where there is low CHD – claims that this is due to intake of cis-monounsaturated fatty acis
PROBLEM - could be due to genetic factors or use of tomatoes or other foods in dishes
positive correlation between amound of transfats consumes and rates of CHD. other factors tested to see if tehy casue the correlation but they do not . Trans-fats probably cuase CHD. patients who died from CHD found to have high conc of transfats in their fatty deposits in diseased arteries - causal link
analyses of data for health risks of lipids
- implications - does the data support the claim
- limitations - were the research methods good enough
- is there a correlation
- how large is difference in rates of disease with or without the lipid?
- is the data widely spread –> less likely that the mean differences are significant
- do statistical tests done on the data show significant differences?
- how lanreg was the sample size
- how even was the same e.g. same ege, gender, health, lifestyle
- was it reliable, people accurately report their health, no misdiagnosis
