Topic 1: Monomers & Polymers, Carbohydrates And Lipids Flashcards
What is a monomer?
A smaller unit from which larger molecules are made
Name 5 examples of monomers
-amino acids
-nucleotides
-glucose
-fructose
-galactose
What is a polymer?
Molecules made from a large number of monomers joined together
Name 3 examples of polymers
-polynucleotides
-polysaccharides
-polypeptides
Name 2 polynucleotides
-DNA
-RNA
Name 3 polysaccharides
-starch
-glycogen
-cellulose
What is a condensation reaction?
Where 2 molecules are joined together with the formation of a chemical bond and a molecule of water is removed
What is the name of the chemical reaction where molecules are joined and water is removed?
Condensation reaction
Do molecules join together or split in a condensation reaction?
They join together
Do molecules gain or lose a water molecule in a condensation reaction?
A molecule of water is removed
What is a hydrolysis reaction?
It breaks a chemical bond between 2 molecules and involves the addition of a water molecule
What is the name of the chemical reaction where a chemical bond is broken because a water molecule is added?
A hydrolysis reaction
Is a chemical bond made or broken in a hydrolysis reaction?
Broken
Is water added or removed in a hydrolysis reaction?
Added
Give 3 organic molecule examples
Carbohydrates
Proteins
Lipids
What does it mean if a molecule is an organic molecule?
It means they contain the chemical elements: carbon,hydrogen and oxygen
What type of monomers are larger carbohydrates made of?
Monosaccharides
What is the bond created between 2 monosaccharides after a condensation reaction?
Glycosidic
What is a disaccharide?
When 2 monosaccharides are joined together by a glycosidic bond following a condensation reaction
Name 3 disaccharides
Maltose
Sucrose
Lactose
How is the disaccharide, Maltose formed?
The condensation of 2 glucose molecules
How is the disaccharide, sucrose formed?
By the condensation of a glucose and a fructose molecule
How is the disaccharide, lactose formed?
By the condensation of a glucose and a galactose molecule
How are polysaccharides formed?
By the condensation of many glucose units
What s glucose also known as and why?
A hexose sugar because it is a 6 carbon molecule
Glucose has 2 what?
Isomers
What are the 2 isomers of glucose?
Alpha-glucose
Beta-glucose
What is an isomer?
Molecules with the same molecular formula as each other other but with atoms connected a different way
What is the difference between the isomers of glucose?
The hydroxyl group and the hydrogen are reversed
Glucose, Galactose and Fructose are all monosaccharides. Why are they similar?
- they all have a C6H12O6 formula
- they are all isomers of alpha-glucose
Define hydrolysis
A hydrolysis reaction breaks down a chemical bond between 2 molecules and involves the addition of water
How is hydrolysis involved in digestion?
Larger molecules are broken into smaller molecules by hydrolysis
The smaller molecules are then absorbed
How do plants store extra glucose?
As the polysaccharide- Starch
How/ where is starch found in a plant?
-in many parts of the plants as small grains
-there is large amounts in seeds and storage organs e.g potato tubers
What is starch made up of?
Chains of alpha-glucose
Is starch made up of alpha-glucose or beta-glucose?
Alpha-glucose
How are the monosaccharides of starch linked?
By glycosidic bonds that are formed by condensation reactions
How is the structure of starch linked to the function?
- the chain is wound into a tight coil that makes molecules very compact
-starch is branched (but not as much as glycogen) so it can be easily hydrolysed so alpha-glucose can be released quickly for use in respiration - starch is insoluble in water so it doesn’t affect water potential and water doesn’t enter the cell causing it to swell- this makes it good for storage, also means it can’t easily diffuse or cross cell membranes
- it is a large molecule- so it is insoluble and osmotically inactive
The chains of alpha-glucose in starch are coiled. How is the helix held together ?
By hydrogen bonds
What 2 polysaccharides of alpha-glucose is starch a mixture of?
Amylose and Amylopectin
Describe the structure of amylose and how this is useful for the function of starch
- it has long unbranded chains of alpha-glucose
-the angles of the glycosidic bonds result in the coiled structure
-coiled structure means it is compact and good for storage because it can fit in small spaces
Describe the structure of amylopectin and how it is useful for the function of starch
- it has long, branched chains of alpha-glucose
- the side chains make the glycosidic bonds easily accessible for enzymes to break them down
-this means glucose can be released quickly for use in respiration
Where is the polysaccharide glycogen found?
-it is the major carbohydrate storage product in animals and it is mainly stored as small granules in the liver and muscles
Why is glycogen sometimes known as ‘animal starch’?
-Plants store excess energy as starch, animal cells also get energy form glucose but store it as glycogen instead
-they are both alpha-glucose molecules
-they have similar structure which allow them both to act as storage molecules
How is glycogen different to starch?
It has shorter chains and is more highly branched
It is found in animal cells but never in plant cells
How is the structure of glycogen related to its function?
Because it is made of smaller chains it is readily hydrolysed to alpha-glucose
Lots of side branches means a quick energy release
Is glycogen made up of alpha-glucose or beta-glucose?
Alpha-glucose
Is the polysaccharide cellulose made up of alpha-glucose or beta-glucose?
Beta-glucose
What is the key difference between cellulose and glycogen and starch?
Cellulose is made of monomers of beta-glucose whereas glycogen and starch are made up of alpha-glucose
What must happen for beta-glucose molecules to form glycosidic bonds?
They must rotate 180 degrees
How is the cellulose structured?
-it has long,straight,unbranched chains of beta-glucose monomers
-the chains run parallel to each other
Hydrogen bonds form cross linkages between the cellulose molecules
-the cellulose molecules group together to form microfibrils which are arranged in parallel groups called fibres
How is the structure of cellulose related to its function?
-strength and rigidity is provided to the cell wall by the arrangement and bonds of beta-glucose molecules
-individual hydrogen bonds provide little strength, but many together provides overall strength as microfibrils are formed
The cellulose cell wall prevents cells from bursting as water enters by osmosis. How does it do this and why is it important to do so?
- does it by exerting inward pressure that stops further influx of water
-this results in living plant cells being turgid and pushing against each other - this makes the plant semi-rigid
-this is important in maintaining leaves and stems in a turgid state so they can provide the maximum surface area for photosynthesis
Why are lipids different to proteins and carbohydrates?
They aren’t polymers made of long chains of monomers, they are made of a variety of different compounds but they all contain hydrocarbons
They contain carbon,hydrogen and oxygen like proteins and carbohydrates but they also contain small amounts of other elements like phosphorous
What are the 2 main types of lipids?
Phospholipids
Triglycerides
Fats and oils are not what?
Polymers
What are the 2 parts that make up triglycerides?
Glycerol
Fatty acid chain
What do fatty acids have and what is it made of?
A carboxyl group and a side chain/R-group
The R group is made up of a hydrocarbon chain
What in the R group determines whether a fat is saturated or unsaturated?
Whether the bonds between carbons are single or double
How is a fatty acid ‘saturated’?
If all the bonds between the carbons on the R groups are single bonds
How would a fatty acid be ‘unsaturated’?
If there are one or more double bonds between carbons
What state are saturated fats at room temp?
Solids
E.g butter
What state are unsaturated fats in at room temp?
Liquid
E.g. oil
What are the bonds between triglycerides called?
Ester bonds
Why are phospholipids important?
They are an important component of plasma membranes
Name the 3 components of phospholipids
Glycerol
2 fatty acids
A phosphate group
How are triglycerides and phospholipids different ?
Triglycerides have 3 fatty acids and no phosphate group, phospholipids have 2 fatty acids and a phosphate group
How are fatty acids and glycerol joined?
By an ester bond by a condensation reaction
What part of the phospholipids is hydrophobic?
The tails
What part of the phospholipids is hydrophilic?
The head
What does hydrophobic mean?
‘Water-hating’
Repels water
What does hydrophilic mean?
‘Water-loving’
Attracted to water
How are phospholipids arranged in plasma membranes because of their hydrophilic and hydrophobic elements?
The hydrophilic heads point towards the extra cellular fluid which is a watery environment in one layer, and inside a cell towards the cytoplasm which is also watery with the other layer
The hydrophobic tails are in the middle of the bilayer and make it selective of what moves in and out of a cell
Why are the fatty acid tails in phospholipids said to be hydrophobic?
They aren’t charged and are non-polar and insoluble in water
Why are phosphate groups in the phospholipids head said to be hydrophilic?
Because it has a charge so it is polar and soluble in water
How are triglycerides and phospholipids structurally similar?
-both contain glycerol
-both have ester bonds
-both have saturated and unsaturated fatty acids
-both are insoluble in water
-both contain carbon,hydrogen and oxygen
How are triglycerides and phospholipids structurally different?
-phospholipids have a hydrophilic head and hydrophobic tail, triglycerides only hydrophobic (the heads of phospholipids are hydrophilic because of the phosphate group triglycerides dont have)
-phospholipids have phosphate and triglycerides dont
-triglycerides have 3 fatty acids, phospholipids have 2
How is the structure of triglycerides related to their function?
- used as energy storage molecules because the long hydrocarbon fatty acid tail contain a lot of chemical energy so a lot is released when they are broken down (twice the amount of energy per gram as carbs)
- they are insoluble in water- dont affect WP or cause swelling
- they also function as insulation to retain body heat
-waterproofing
-protection of some delicate organs like kidneys
