biological molecules

what is a carbohydrate?
Carbohydrates (also called saccharides) are molecular compounds made from just three elements: carbon, hydrogen and oxygen.
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what is a Monosaccharide?
A single sugar molecule such as glucose or fructose, the simplest type of sugar.
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what is a disaccharide?
A molecule composed of two monosaccharides linked by glycosidic bonds. Formed in condensation reactions.
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what is a polysaccharise?
Polymers containing many monosaccharides linked by glycosidic bonds. Formed by condensation reactions.
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what is a monomer?
small, basic molecular units that can form a polymer.
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Examples of monomers
monosaccharides, amino acids and nucleotides
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what is a polymer?
Large, complex molecules composed of long chains of monomers joined together.
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How are polymers formed?
Monomers joined by condensation reactions.
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How are polymers broken down?
broken down into monomers by hydrolisis reactions.
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what is a condensation reaction?
A chemical reaction in which two molecules become covalently bonded to each other through the loss of a water molecule.
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what is a hydolysis reaction?
A chemical reaction in which water breaks covalent bond
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what is a glycosidic bond?
The bond between a hydroxyl (OH) group on one monosaccharide and a a hydroxyl group on another monosaccharide
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what is an isomer?
Compounds with the same formula but different structures.
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Name 3 important disaccharides
Maltose, Sucrose & Lactose
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what monosaccharides form Maltose
2 glucose molecules.
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what monosaccharides form Sucrose
glucose and a fructose.
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what monosaccharides form Lactose
glucose and galactose.
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3 uses of glucose and explanation
1) Small molecule: which means it can be transported across a cell membrane. 2) Its easily and quickly broken down: to release energy fast. 3) Soluable: can be trasported by the blood.
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2 main uses for polysaccharides
An energy store and as structural components of cells.
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what is starch?
A polysaccharide storage molecule made by plants from glucose.
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Structure of starch
Chains of alpha glucose molecules joined by glycosidic bonds, formed by condensation reactions.
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what is amylose?
1 form of starch structure. All glucose molecules are joined by alpha 1-4 glycosidic bonds. Resulting in unbranched chains which form a compact helical structure.
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what is amylopectin?
1 form of starch structure. Glucose molecules are joined by 1-4 glycosidic bonds and many more alpha 1-6 glycosidic bonds. Resulting in highly branched structure.
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Where is starch found in a plant?
Seeds & Storage organs
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How is starch produced?
From glucose made during photosynthesis, it is broken down during respiration to release energy.
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Why is starch a good molecule for storage in plants? 1
It is insoluble, so doesn’t draw water into cells by osmosis
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Why is starch a good molecule for storage in plants? 2
Won’t easily diffuse out of cells because it is insoluble
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Why is starch a good molecule for storage in plants? 3
It can be stored in a small space because the tight coils make it compact
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what is glycogen?
The animal equivalent of starch.
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Describe the structure of glycogen
An extensively branched glucose storage polysaccharide.
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How is glycogen stored and where is it found?
As small granuels in the liver and muscle cells of animals.
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How is glycogen simular to amylopectin?
They have a simular structure (contains many alpha 1-6 glycosidic bonds) but is even more highly branched.
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How is glycogen different to starch?
Glycogen is less dense and more soluable than starch, and is brocken down more rapidly.
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where is cellulose found?
Main part of plant cell walls.
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What is the role of cellulose?
Very strong, prevents cell bursting. Provides structural support.
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Describe the structure of cellulose
Long straight chains of glucose molecules joined by beta 1-4 glycosidic bonds. Every other glucose molecule rotates 180 degrees so that the hydroxyl groups on each molecule are adjacent to each other.
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....
These chains hydrogen-bond together into fibres (microfibrils) which gives cellulose great tensile strength.
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what is a hexose sugar?
Monosaccharide with 6 carbons e.g glucose
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what is a pentose sugar?
Monosaccharide with 5 carbons
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Name 2 important pentose molecules
ribose and deoxyribose
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what is a lipid?
Lipids are a diverse group of compounds that are insoluble in water but soluble in organic solvants such as ethanol.
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what are the most common type of lipids?
Triglycerides.
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Name some other important lipids
Waxes, steroids & cholesterol
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What are simularities between carbohydrates and lipids?
They contain carbon hydrogen and oxygen.
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What makes lipids different to carbohydrates?
Lipids have a higher proportion of hydrogen and a lower proportion of oxygen.
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Describe the structure and formation of triglycerides
Triglycerides are made from a glycerol backbone joined to 3 fatty acid chains
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How are the 3 fatty acids joined to the glycerol backbone?
Ester bonds
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What is the formula for glycerol?
C3 H8 O3
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How many hydroxyl (OH) groups does glycerol contain?
3
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What is a fatty acid?
Long chains of hydrocarbons containing a carboxyl (COOH) group on one end.
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What is the general formula for a fatty acid?
CH3(CH2)nCOOH - where n is usually an even number.
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How is an ester bond formed?
In a condensation reaction between one of the hydroxyl groups of the glycerol and the carboxyl group of the fatty acid.
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What happens to the other two fatty acids?
they join to the remaining hydroxyl groups on the glycerol. forming 3 ester bonds all together.
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What determines the melting point?
The 3 fatty acids in a triglyceride can be the same or different. The type of fatty acids in a triglyceride affects its propertires, such as its melting point.
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what does saturated mean?
Saturated fatty acids only contain single bonds between carbon atoms. This makes molecules straight.
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What does unsaturated mean?
Unsaturated fatty acids contain double bonds between carbon atoms, creating a 'kink' to the chain.
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Whats the difference between monounsaturated fatty acids and polyunsaturated fatty acids?
Monosaturated fatty acids contain one double bond; polyunsaturated fatty acids contain two or more double bonds.
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What are cis and trans unsaturated fatty acids?
The arrangment of atoms/groups around a double bond in an unsaturated fatty acid can either be cis or trans.
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Which configuration produces the greatest 'kink' in fatty acids?
cis
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what does this mean for cis unsaturated fatty acids?
They are unable to pack closely together. This results in weak attractive forces between chains, leading to a lipid that is liquid (an oil) rather than a solid (a fat).
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What do plants and animals use triglycerides for?
To store energy
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What do some bacteria use triglycerides for?
To store energy and carbon
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Why are triglycerides good energy stores?
The long hydrocarbon (tails) of the fatty acids contains lots of chemical energy. Lots of energy is released when they are broken down.
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what contains more energy, lipids or carbohydrates? Why?
Due to the tails, lipids contain twise as much energy per gram.
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what is a phospholipid?
A lipid containing a phosphate group in its molecule.
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How are triglycerides and phospholipids simular?
They both contain glycerol and fatty acids.
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How are triglycerides and phospholipids different?
Phospholipids contain only 2 not 3 fatty acid chains. A polar phosphate group is joined to the third hydroxyl group of the glycerol molecule.
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What affects the properties of the phospholipid?
The alcohol group bound to the phosphate group.
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What does the polar nature of the phosphate group mean?
The 'head' end of the phospholipidis hydrophilic
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What does the non-polar nature of the fatty acid mean?
The 'tail' end of the phospholipid is hydrophobic
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What does hydrophilic mean?
Attracted to water
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What does hydrophobic mean?
Repelled by water
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What is a phospholipid bilayer?
The two layers of phospholipids arranged in such a way that their hydrophobic tails are projecting inwards while their hydrophilic head groups are projecting on the outside surfaces
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Describe a function of cholesterol
strengthens the plasma membrane by interacting with the phospholipids bilayer
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Describe a function of cholesterol
page 4
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Describe a function of cholesterol
page 4
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what is a protein?
proteins are a diverse group of large complex polymer molecules, made up of long chains of amino acids.
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Name the 4 roles of proteins
Structural, catalytic, signaling and immunological
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Describe proteins structural role
proteins are the main component of body tissues, such as muscle, skin, ligaments and hair.
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Describe proteins catalytic role
All enzymes are proteins, catalyzing many biochemical reactions.
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Describe proteins signaling role
many hormones and receptors are proteins.
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Describe proteins immunological role
all antibodies are proteins.
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what is the R group of an amino acid?
All amino acids have the same general structure, the only difference between each one is the nature of the R group. The R group therefore defines an amino acid.
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what type of bond joins amino acids together?
peptide bonds
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How are peptide bonds formed?
In condensation reactions
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Where does the peptide bond form?
between the carboxyl group on one amino acid and the amine group on the other amino acid.
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Describe the primary structure of a protein
simple long chains with no intermolecular bonds or interactions.
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Describe the secondary structure of a protein
Hydrogen bonds form between the -NH and -CO groups on the amino acids. This causes the chain to either coil into an alpha helix or fold into a beta pleated sheet.
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What are the 4 types of bonds in a tertiary structure of a protein?
Ionic bonds, disulphide bonds, hydrophobic and hydrophilic interactions & hydrogen bonds
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Describe an ionic bond
attractions between negetively charged Rgroups and possitvely charged R groups on different parts of the molecule.
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Describe a disulphide bond
2 molecules of the amino acid cystein come close together, and the sulfur atom in one cystein bonds to the sulfur atom in the other cystein.
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Other cards in this set

Card 2

Front

A single sugar molecule such as glucose or fructose, the simplest type of sugar.

Back

what is a Monosaccharide?

Card 3

Front

A molecule composed of two monosaccharides linked by glycosidic bonds. Formed in condensation reactions.

Back

Preview of the back of card 3

Card 4

Front

Polymers containing many monosaccharides linked by glycosidic bonds. Formed by condensation reactions.

Back

Preview of the back of card 4

Card 5

Front

small, basic molecular units that can form a polymer.

Back

Preview of the back of card 5
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