IB Biology - 2.3

condensation

occurs when two or more sub units of carbohydrates, lipids or proteins join and yield water

Evidence supporting health claims

A positive correlation has been found between the intake of saturated fats and the incidence of CHD in human populations Counter: Certain populations do not fit this trend (e.g. the Maasai tribe in Africa have a fat-rich diet but very low rates of CHD) Intervention studies have shown that lowering dietary intakes of saturated fats reduces factors associated with the development of CHD (e.g. blood cholesterol levels, blood pressure, etc.) Counter: Validity of intervention studies is dependent on size and composition of cohort, as well as the duration of the study In patients who died from CHD, fatty deposits in diseased arteries were found to contain high concentrations of trans fats Counter: Genetic factors may play a role (e.g. blood cholesterol levels only show a weak association to dietary levels)

INORGANIC COMPUNDS

ALL THE others eg water

glycosidic bonds

C1 AND C4 the OH is reacting Glucose has 5 OH groups of any of which can form a bond through hydrolysis- but three of them are used to make polyschharides. The most common is a 1,4 linkage. This allows the C6 to be used to make side branches in some polysaccharides. Glucose can have the OH group on C2 either pointing up or down- ie beta or alpha glucose. This small difference has major consequences to the polsaccharides formed. Cellulose for example is made up of all Beta glucose molecules linked together.. ______________________-

Carbohydrates and Lipids

Carbohydrates are made of C, H and O ('carbo' - contains carbon ; 'hydrate' - contains H and O) Carbohydrates are composed of recurring monomers called monosaccharides (which typically form ring structures) These monosaccharides may be linked together via condensation reactions (water is formed as a by-product)

Cellulose

Cellulose is a structural polysaccharide that is found in the cell wall of plants It is a linear molecule composed of β-glucose subunits (bound in a 1-4 arrangement) Because it is composed of β-glucose, it is indigestible for most animals (lack the enzyme required to break it down) Ruminants (e.g. cows) may digest cellulose due to the presence of helpful bacteria in a specialised stomach Caecotrophs (e.g. rabbits) will re-ingest specialised faeces that contain digested cellulose (broken down in the caecum)

CIS and Trans fats- ONLY UNSATURATED

Cis fatty acids have the hydrogen atoms on the same side of the C=C double bond making them bent and generally liquids eg olive oil Whereas TRANS isomers have the hydrogen atoms on opposite sides making them straight on at least one of the double bonds. Most trans- fats are solids are are created MOSTLY, eg. margarine.

Types of fatty acids- Unsaturated

DOUBLE carbon bonds= Unsaturated only single double carbon bond= mono-unsaturated multiple double carbon bond= poly-unsaturated - Usually oils at room temp - Usually plant sources, e.g olive oil - LOWER contribution to coronary hear disease

Regulating Blood Cholesterol Levels

Fats and cholesterol cannot dissolve in blood and are consequently packaged with proteins (to form lipoproteins) for transport Low density lipoproteins (LDL) carry cholesterol from the liver to the rest of the body High density lipoproteins (HDL) scavenge excess cholesterol and carry it back to the liver for disposal Hence LDLs raise blood cholesterol levels ('bad') while HDLs lower blood cholesterol levels ('good') High intakes of certain types of fats will differentially affect cholesterol levels in the blood Saturated fats increase LDL levels within the body, raising blood cholesterol levels Trans fats increase LDL levels and decrease HDL levels within the body, significantly raising blood cholesterol levels Unsaturated (cis) fats increase HDL levels within the body, lowering blood cholesterol levels

Glycogen

Glycogen is an energy storage polysaccharide formed in the liver in animals It is composed of α-glucose subunits linked together by both 1-4 linkages and 1-6 linkages (branching) It is akin to amylopectin in plants, but is more highly branched (1-6 linkages occur every ~10 subunits as opposed to ~20) is similar to startch but there is much more branching making it a more compact molecule. make by animals and some fungy. used as energy store in animals dont have a fixed size

Health Risks of High Cholesterol

High cholesterol levels in the bloodstream lead to the hardening and narrowing of arteries (atherosclerosis) When there are high levels of LDL in the bloodstream, the LDL particles will form deposits in the walls of the arteries The accumulation of fat within the arterial walls lead to the development of plaques which restrict blood flow If coronary arteries become blocked, coronary heart disease (CHD) will result - this includes heart attacks and strokes

Fatty Acids

Lipids are composed of a molecule of glyerold bonded to 3 fatty acids Fatty acids are a carboxylic acids (have COOH) Rest of the molecule is a chain (or ring) of carbon atoms with hydrogen atoms.

polysaccharides

Many monosaccharide monomers may be joined via glycosidic linkages to form polysaccharides Polysaccharides (many sugar units) may be used for energy storage or cell structure, and also play a role in cell recognition Examples of polysaccharides include cellulose, glycogen and starch

Monosaccharides

Monosaccharides (one sugar unit) are typically sweet-tasting and function as an immediate energy source for cells Carbohydrates are composed of recurring monomers called monosaccharides (which typically form ring structures) SINGLE RING Examples of monosaccharides include glucose, galactose and fructose

Examples of Carbohydrates

Monosaccharides (one sugar unit) are typically sweet-tasting and function as an immediate energy source for cells Examples of monosaccharides include glucose, galactose and fructose Disaccharides (two sugar units) are small enough to be soluble in water and commonly function as a transport form Examples of disaccharides include lactose, maltose and sucrose Polysaccharides (many sugar units) may be used for energy storage or cell structure, and also play a role in cell recognition Examples of polysaccharides include cellulose, glycogen and starch

alpha vs beta saccharides

OH is different } alpha on bottom, beta on top

Evidence against health claims

Proportion of saturated and trans fats in Western diets has decreased over the last 50 years, but incidence of CHD has risen Counter: Increased carbohydrate intake may cause detrimental health effects associated with CHD (e.g. diabetes, obesity) Counter: Incidence of CHD dependent on a myriad of factors besides dietary intake (e.g. exercise, access to health care, etc.)

Types of Fatty acids- Saturated CH3(CH2)nCOOH

SINGLE CARBON BONDS = SSSaturated - high density energy storage - usually solid at room temp - animal products, palm and coconut oil - high contribution to coronary heart disease

Starch

Starch is an energy storage polysaccharide found in plants It is composed of α-glucose subunits (bound in a 1-4 arrangement) and exists in one of two forms - amylose or amylopectin Amylose is a linear (helical) molecule while amylopectin is branched (contains additional 1-6 linkages) Amylose is harder to digest and less soluble, however, as it takes up less space, is the preferred storage form in plants made of many alpha glucose molecules. as celluclose the bonds are made from the 1,4 OH parts of the glucose molecule. both of these pointing downwards making the startch molecule bend downwards making it curved. startch can only be made in plants. its hydrophilic making it a good store of energy.

Lipid health claims

There are two main health claims made about lipids in the diet: Diets rich in saturated fats and trans fats increase the risk of CHD Diets rich in monounsaturated and polyunsaturated (cis) fats decrease the risk of CHD These health claims are made based on evidence collected in a number of ways: Epidemiological studies comparing different population groups Intervention studies that monitor cohorts following dietary modifications Experimental designs utilising animal models or data based on autopsies

Lipids

Triglycerides are the building blocks for lipds Lipids are a diverse group of carbon compounds that share the property of being insoluble in water Examples of biological lipids include fat in adipose tissues in humans and the oil in a sunflower seed triglyceride made by combining three fatty acids with only glycerol used as an energy stores. The energy from them can be released in aerobic respiration. They are also good heat insulators and are found in the blubber of arctic animals. LIPIDS BETTER LONG TERM ENERGY STORE. Triglycerides are the largest class of lipids and function primarily as long-term energy storage molecules Animals tend to store triglycerides as fats (solid), while plants tend to store triglycerides as oils (liquid) Triglycerides are formed when condensation reactions occur between one glycerol and three fatty acids The hydroxyl groups of glycerol combine with the carboxyl groups of the fatty acids to form an ester linkage This condensation reaction results in the formation of three molecules of water Triglycerides can be either saturated or unsaturated, depending on the composition of the fatty acid chains any bonding reactions generally condensation, need water to break bonds- hydrolisis

Disaccharide

Two monosaccharide monomers may be joined via a glycosidic linkage to form a disaccharide Disaccharides (two sugar units) are small enough to be soluble in water and commonly function as a transport form Examples of disaccharides include lactose, maltose and sucrose lactose (glucose + glactose) sucrose (glucose + fructose) maltose (glucose + glucose)

Types of Fats

Whilst all types of fats consumed as part of dietary intake will cause adverse health effects if taken in excessive amounts, some types of fats are associated with increased health risks The mix of fats in the diet influences the level of cholesterol in the bloodstream Saturated fats and trans fats raise blood cholesterol levels, while (cis) unsaturated fats lower blood cholesterol levels

organic compounds

compounds found in living things containing carbon Organic compounds are produced by living things and include all compounds containing carbon that are found in living organisms. The exceptions are hydrogen carbonates (HCO3-) Carbonates (C032-) and oxides of carbon (C0 and C02)

BMI

body mass (kg)/ height (m)^2 The body mass index (BMI) provides a measure of relative mass based on the weight and height of the individual It is commonly used as a screening tool to identify potential weight problems in sedentary adults Body mass index can be calculated according to the following formula: Screen Shot 2015-01-05 at 12.18.12 pm BMI ranges from underweight to obese, according to predetermined values based on an average adult population BMI values are not a valid indicator for pregnant women or professional athletes with atypical muscle / fat ratios BMI calculations should not be used as a diagnostic tool and should be used in conjunction with other measuremen nongrams

carbohydrates in plants

fructose is a monosccharide that is used to make fruits sucrose =dissacharide celuclose = polysaccharide

carbohydrates in animals

glucose = monosaccharide is the major source of energy for all animals. it is transported in the blood to cells in the body. lactose = dissacharide that is a sugar found in milk in animals. it provides energy for young animals until they are weaned (animal that no longer needs to rely on mother for its energy source). glycogen = polysaccharide that is used as a short term energy store in the liver and muscles

hyrdrolisis

when the larger molecules formed by condensation react with water to produce man smaller molecules