chapter 3- carbohydrates Flashcards by Jodie Hancock

in a glucose molecule which carbon atom is carbon 1?

the carbon on the right to the oxygen

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what is a glycosidic bond

a covalent bond between a carbohydrate and a hydroxyl group on another molecule resulting from a condensation reaction

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how is sucrose formed and what bond

condensation of glucose and fructose forming a 1, 4 glycosidic bond (alpha)

there is oxygen in the middle

A condensation reaction is taking place between the molecules glucose and fructose. Water is eliminated to form a disaccharide called sucrose

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how is lactose formed and what bond

condensation of glucose and galactose forming a 1,4 glycosidic bond (beta)

lactose is a disaccharide

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how is maltose formed and what bond

between the condensation of 2 (alpha)glucose molecules forming a 1,4 glycosidic bond (alpha)

the oh on one glucose and the h adjacent h on the other form a water molecule allowing the maltose to form

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what are the chemical elements that make up carbohydrates

carbon, hydrogen and oxygen

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what is the chemical compostion of carbohydrates (2 elements and a ratio)

hydrogen and oxygen in a ratio of 2:1

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The disaccharide sucrose is broken down through the addition of water. The products from this reaction are…

This process is called a

glucose + fructose
hydrolysis reaction.
gluey fruit sucks

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Glucose and galactose bond and eliminate a water molecule.

What is the resulting disaccharide? and what is the process called

lactose
condensation reaction

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describe the structure of starch

a polysaccharide made up of many alpha glucose molecules joined by glycosidic bonds

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what are the 2 polysaccharide molecules known collectively as starch

amylose and amylopectin

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describe the structure of amylose

alpha glucose molecules linked by only 1,4 glycosidic bonds the angle of which allows the long chain to twist forming a helix stablised by H bonds from within = more compact and less soluble than just glucose

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describe the strucutre of amylopectin

alpha glucose molecules with long chains linked by 1,4 glycosidic bonds and branches linked by 1,6 glycosidic bonds that occur every 25 glucose subunits

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what is the general formula for carbohydrates

Cx(H2O)y

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examples of disaccharides

lactose
sucrose

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examples of polysaccharides

glycogen, cellulose and starch

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glucose contains …. carbon atoms making it ….. sugar

6 carbon atoms
hexose sugar

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general formula of glucose

C6H12O6

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is glucose soluble or insoluble

soluble

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what is the main form carbohydrates are transported around the body of animals

glucose

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what are 2 structural isomers of glucose

alpha glucose and beta glucose w

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what is the difference between alpha and beta glucose

the OH group on carbon 1 is below on alpha and above on beta

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what enzyme will digest maltose and what into

maltase into 2 glucose molecules

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what are the 2 pentose sugars you need to know

ribose and deoxyribose
(will not be asked to draw them)

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what is the difference between ribose and deoxyribose

on carbon 2 ribose has 1 H atom and 1-OH group whereas deoxyribose and 2H and no OH group

what is the difference between an alpha and beta glycosidic bond

alpha the bonds point down to O beta the bond goes up O then down vv

in polymers, monomers are joined up by

glycosidic bonds

polysaccharides are mainly used for (2)`

energy store structural components of cells (cellulose plant cell wall)

how is starch usually stored

stored as intracellular starch grains in plastids

what are plastids

organelles including chloroplasts and amyloplasts eg in potatoes

describe the structure of glycogen

a branched polysaccharide made up of many glucose molecules with long chains linked by 1,4 glycosidic bonds and branches formed by 1,6 glycosidic bonds

what is the benefit of glycogen having a branched structure

more efficient storage and release of glucose for respiration than amylopectin etc as it increases the amount of free ends so that glucose can be stored (added) or released quicker

glycogen is less..... and more..... than starch and what is the benefit of this

less dense more soluble it can be broken down more rapidly/quicker to digest as animals need to mobolise reserves quicker

what is the most abundant organic polymer

cellulose

cellulose prevents cells from

bursting when they take in excess water

describe the structure of cellulose

long chains of beta glucose molecules joined by [beta]1,4 gbonds, the glucose chains form rope like microfibrils which are layered to form a network

is cellulose a branched or straight chain molecule and why

straight because beta 1-4 gbonds cant form branches as one glucose has to flip so that the OH groups are close enough to react but that means that it cannot coil or form branches and so it is straight

is cellulose easy or hard to digest

hard because we lack the neccessary enzymes to breakdown the beta gbonds

cellulose molecules form ... bonds with each other meaning

H bonds forming microfibrils which join together to form macrofibrils which combine to produce fibres that provide tensile strength for the plant cell wall they are also insoluble and tough

in starch the polysaccharide that makes up the coiled shape is

amylose

what is the starch that is found in animals and fungi

glycogen

in starch the polysaccharide that makes up the branched part is

amylopectin

is cellulose branched or unbranched

unbranched

is amylose branched or unbranched

unbranched

is amylopectin branched or unbranched

branched

is glycogen branched or unbranched

branched

starch and glycogen are ...... in water, why does this make them good storage molecules

insoluble , it means they dont affect the water potential of the cell

why is glycogen insoluble

because it doesn't have enough free polar groups to participate in hydrogen bonding with water. This is because most of the polar OH groups in glycogen hydrogen bond with other groups within the molecule leaving few groups available to participate in bonding with water.

starch and glycogen are ...... why does this make them good storage molecules (think space)

coiled, it means they are compact

starch and glycogen are...... why does this make them good storage molecules (think structure)

branched, it means there are more ends for fast breakdown.

starch and glycogen are polymers of ....., why does this make them good storage molecules

glucose, it means they can provide glucose for respiration

starch and glucose are .... molecules, why does this make them good storage molecules (think size)

large, it means they cant cross the cell surface membrane

amylopectin is a ...... molecule (length) so

it is a long molecule so it cannot leave the cell as it cannot cross the plasma membrane

What are isomers?

Isomers are molecules which have the same molecular formula but a different arrangement of atoms.

What chemical test is used to detect the presence of reducing and non-reducing sugars and what colour change would be seen with a positive result?

is detected using the Benedict's test + result: change from blue to green, yellow, orange or brick red depending on the conc of the sugar

is glycogen quicker or slower to digest than starch and why is this beneficial

it is quicker to digest which is necessary because animals are mobile and plants arent

compare the density and the solubility of glycogen and starch

glycogen is less dense and more soluble than starch

how is glycogen stored

as small granules in the muscles and liver

animals do not store starch but

as glycogen

what are polysaccharides mainly used fo

as an energy store and as structural components of cells

what effect does the structural differences of alpha and beta glucose have

major effect on the biological role

glucose is the main form in which.....

carbohydrates are transported around the body

what are examples of disaccharides

glycogen, cellulose and starch

what are polysaccharides

long chain carbohydrates formed from many monosaccharides joined by glycosidic bonds . they are formed by condensation reactions

what are disaccharides

large sugars, double sugars formed from 2 monosaccharides

what are examples of monosaccharides

glucose, fructose, ribose

what is a monosaccharide

a small simple sugar

what is the general formula of monosaccharides

(CH20)n where n can be 3-7

how is a glycosidic bond formed

via a condensation reaction

which is correct about the structure of cellulose: a) alternate alpha glucose monomers rotate 180deg b) straight chains contain 1,4 glycosidic bonds

outline how the different properties of glucose, starch and glycogen relate to their function in cells (4)

glucose is soluble and polar, has chemical energy in its bonds, or respiratory substrate/source of energy starch/glycogen are insoluble and compact and larger/bigger sa used for energy/glucose storage and allows quick release of..... glycogen is broken down faster than starch due to higher sa/many branch ends

what is a polysaccharide

a polymer molecule formed of one or more monosaccharides joined by glycosidic bonds

break poly/disaccharides into monosaccharides

starch and cellulose in plants and glycogen in animals

break poly/disaccharides into monosaccharides

starch and cellulose in plants and glycogen in animals