Biological Molecules Flashcards
what are biological molecules?
all the molecules used to construct living organisms
state examples of biological molecules
Carbohydrates
proteins
lipids
nucleic acids
ATP
what do all biological molecules contain?
carbon
hydrogen
oxygen
what could biological molecules contain?
nitrogen
phosphorus
sulfur
what are the different types of carbohydrates?
Monosaccharides (single)
Disaccharides (double)
Polysaccharides (many)
what are the 3 types of monsaccharides?
Hexose sugars
Pentose sugars
Triose sugars
Properties of hexose sugars
energy source
sweet
soluble
examples of hexose sugars
glucose - plants + animals
fructose - plants
galactose - animals
Properties and examples of pentose sugars
Structural purposes
Used to make DNA
c5h10O5 - ribose sugar
c5h10o4 - deoxy ribose
properties and examples of triose sugars
part of respiration
c3h6o3
what are the two types of glucose?
alpha glucose
beta glucose
(known as isomers)
where is alpha glucose found?
animals and plants
what are the 3 types of disaccharides and what are they made of?
Sucrose - alpha glucose + fructose
Lactose - alpha glucose + galactose
Maltose - alpha glucose + alpha glucose
where is beta glucose found?
exclusively in plants
what is the OH group known as?
Hydroxil group
where is the hydroxyl group found on carbon 1 in alpha glucose?
below the ring
where is the hydroxyl group found on carbon 1 in beta glucose?
above the ring
Define details of Disacharrides
- Formed in condensation reactions
- Made up of 1-4 glycosidic bonds
- Chemical formula is C12H22O11
- Sweet
- Soluble
- Used in respiration
Where is Sucrose found?
Plants
Where is Lactose found?
Animals
Where is maltose found?
Plants and animals
How does the condensation reaction work?
- The hydroxil group from one glucose and the hydrogen from another join to form water
- Then Carbon 1 and Carbon 4 are bonded/linked by the remaining oxygen
- This is known as a 1-4 glycosidic bond
How would you separate a disacharride and what is it known as?
- You would add 1 water molecule
- This is known as hydrolysis
What are polysacharrides?
Polymers with many 1000s subunits of monosacharrides
How are polysacharrides made?
By repeated condensation reactions (many 1-4 glycosidic bonds)
Are polysacharrides sugars?
No - they are not sweet or soluble
List the polysacharrides
Starch - plants
Cellulose - plants
Glycogen - animals
Define details of cellulose
- most abundant organic molecule on the planet
- structural purposes (mechanically very strong)
- polymer of beta glucose
- Present in plant cell walls
- has a slow decomposition
Define details of starch
- polymer of glucose
- storage of alpha glucose
- it’s a plant storage polysacharride - if there’s no sun, it is used to create ATP for respiration
What 2 substances is starch made up of?
Amylose
Amylopectin
Define details of amylose
- made up of 1000s of condensation reactions between alpha glucose with 1-4 bonds
- coiled springs are formed
- alpha helix structure
- long alpha glucose polymer chain
How is amylose adapted to its function?
The alphahelix structure is a good storage of starch as it is compact so it stores a lot of glucose in a small space which is used for respiration to transfer energy/ATP
Why is it good that amylose is insoluble?
It means you can store a lot of starch (amylose) without it affecting water potential
Define details of amylopectin
- Made of condensation reactions between alpha glucose(1-4 bonds)
- Also has branches of 1-6 glycosidic bonds
- Coiled springs with a branched structure are formed
What is the benefit of the branched structure of amylopectin?
There is an increased surface area (due to branching) so there are more terminal ends so the rate of glycosidic bond hydrolysis is greater which means more alpha glucose is released per second
What are the other properties of amylopectin?
It has many of the same properties as amylose - compact and insoluble (and therefore is useful in the same ways)
What is glycogen?
The storage polysaccharride in animals
What is the structure of glycogen?
It’s structure has many branches and many more 1-6 glycosidic bonds so it has far more terminal ends so that the release of alpha glucose per second is greater as the energy requirements for humans is very large (rate of hydrolysis is greater)
How do beta glucose molecules form glycosidic bonds?
- Originally, they can’t as the hydroxyl groups are not next to each other
- So 1 of the beta glucose has to turn 180 degrees so that the hydroxyl groups are next to each other
What are hydrogen bonds?
- They are electrostatic forces of attraction between molecules
- Hydrogen bonds are individually weak but on mass, they provide strength and stability
What is the structure of cellulose?
- Made up of 1-4 glycosidic bonds
- Made up of beta glucose so alternate beta need to flip
- This is what makes cellulose so strong
- It has hydrogen bonds holding it together
Describe the chains of cellulose
- One chain of cellulose has long unbranched chains
- Another chain of cellulose will lie beneath it and they run parallel to each other
- The actual chain has 1-4 bonds but the 2 chains are linked together by hydrogen bonds - known as cross bridges
- Because of the many hydrogen bonds, it adds considerable strength
How are cell walls made?
- Several hundreds of cellulose chains form a microfibril
- Several microfibrils form a fibril
- Many fibrils knit together to form a cell wall
What is a monomer?
Atoms or small molecules that bond together to form more complex structures such as polymers
What are some examples of lipids?
Fats and oils, phospholipids, waxes, steroils
Where are oils found and what is their melting point?
In plants and the melting point is lower - it is a liquid at room temperature
Where are fats found and what is their melting point?
In animals, the melting point is higher and they are solid at r.t.
What are uses of lipids?
- Insulators (reduce thermal transfer - found under skin)
- Energy store (3-5 x more energy)
- Oils on skin/hair - makes it supple
- Acts as a lubricant for joints
- Hormones
- Cell Membrane
- Insulates nerve cells (neurones)
What is the solubility of lipids?
They are insoluble
What do lipids act as?
Structural and Nutrient substances
What are lipids made up of?
Glycerol and fatty acids
What is glycerol?
A 3 carbon alchohol
What 3 groups are in a fatty acid?
Carboxylic acid (COOH), Hydrocarbon chain ((CH2)n), Methyl (CH3)
Is the length of the hydrocarbon chain in a fatty acid always the same?
No, it can vary
Does the hydrocarbon chain in a fatty acid only have a carbon carbon single bond?
No, it can also have a carbon carbon double bond (fatty acids can also have more than one double bond)
What is a fatty acid with no double bonds known as?
A saturated fatty acid (and one with a double bond is known as an unsaturated fatty acid)
How does hydrogen bonding affect the melting point in a lipid?
The less hydrogens there are (such as in fatty acids with double carbon bonds), the less hydrogen bonding there is and so it is less stable and has a lower melting point
What is a fatty acid with 3 c-c double bonds known as?
A poly unsaturated fatty acid
What is a triglyceride made up of?
A glycerol bonded with 3 fatty acids (they don’t have to be the same type of fatty acids)
What kind of bond does the condensation reaction form in a lipid?
An ester bond
what do we need to form a triglyceride?
3 condensation reactions
3 ester bonds
3 water molecules
How do we hydrolyse a triglyceride?
Add 3 water molecules
How many monomers do we end up with if we fully hydrolyse a triglyceride?
4 monomers - 1 glycerol and 3 fatty acids
What kind of glycerides can we also make apart from triglycerides?
Monoglycerides and diglycerides
What do diglycerides consist of?
1 glycerol and 2 fatty acids - there is a free hydroxyl group to react with other monomers
What happens when lipids are hydrolysed naturally?
1 monoglyceride and 2 fatty acids are produced (and 2H2O). This is now sufficiently small to be absorbed into the digestive system
What is a phospholipid formed from?
- A diglyceride and a phosphate ion (PO4 2-)
- Phosphoric acid reacts with glycerol and the phosphate ion attaches to the hyrdroxyl group
What is glycerol in terms to water?
Hydrohphilic
- Water loving
- Water soluble
- Polar
What are fatty acids in term to water?
Hydrophobic
- Non-polar
- Water hating
Why is a cell membrane formed from fatty acids and phosphate ions?
In a cell membrane, we need lipids, so the cell doesn’t dissolve but it needs water soluble parts as well so that the cells do not separate out
Define details of cholesterol
- Part of the steroid family
- Used for structure and strength in cell membranes
- Used to make hormones (tesosterone and progesterone)
What are proteins made up of?
Amino acids (all made up of C, H, O, N and sometimes sulphur)
How many naturally occurring amino acids are there?
20
What are some functions of proteins?
enzymes - amylase
transport - haemoglobin
movement - actin and myosin
cell recognition - antigens
channels - membrane proteins
structure - collagen and keratin
hormones - insulin
protection - antibodies
What is an amino acid made up of?
An amine group, a carboxylic acid group, a central carbon and a variable group (named R - it differs with different amino acids)
Give a detail of an amino acid
Some are polar - hydrophilic, water soluble because of the R variable
Give a detail of an amino acid
Some are non-polar - hydrophobic, not water soluble because of the R variable
Give a detail of an amino acid
Some are ionic so they can form ionic bonds
Give a detail of an amino acid
Some contain lots of hydrogens which means they can form hydrogen bonds with other molecules
What kind of condensation reaction happens between 2 different amino acids?
A peptide bond between the carbon and the nitrogen (+ 1 h20 molecule)
What happens when you have 2 amino acids?
A dipeptide is formed
When are polypeptides formed?
When 1000’s of amino acids link up (ribosomes convert amino acids to polypeptides)
What is the primary structure of a protein?
It is the specific order of amino acids in the polypeptide chain
What is the secondary structure of the protein?
It is the folding of the polypeptide chain
What are the two ways a protein can fold?
- As an alpha helix
- As a beta pleated sheet
(one polypeptide chain could contain both types of folds in different places)
How is the structure of amino acid chains held?
- Hydrogen bonds form between the oxygen remaining on the carboxylic acid and the hydrogen remaining on the amine end of different amino acids
- This holds alpha helix and beta pleated sheet in its formation
- hydrogen bonds are individually weak but provide strength on mass so it holds the structure in its shape
What will happen to the amino acid chain at high temperatures?
The hydrogen bonds will break as they are individually weak, which means the structure will unravel and the protein will change shape (denatured)
What will happen to the amino acid chain in acidic environments?
There are lots of H+ ions, so the oxygens on the amino acids might start forming bonds with the hydrogens and this can alter the structure (same in alkaline environments as the H’s might form bonds with the OH- ions)
What is the tertiary structure of proteins?
- The folding of the folds
- Forms a specific 3D structure (e.g. enzyme)
What determines how the folding will fold again in tertiary structures?
The R group - these form tertiary structure bonds
What are the 5 types of bonding between different R groups?
- Hydrogen bonding
- Polar-polar bonds (if both R groups are water soluble)
- Non-polar/non-polar bonds (hydrophobic interactions)
- Ionic bonding
- Disulphide bonds (between S and S)
What is the quaternary protein structure?
2 or more polypeptide chains bonded together and this can also include an inorganic prosthetic group (e.g. copper ion)
What are the 2 types of quaternary protein structures we can have?
- Globular (round shaped)
- Fibrous proteins (collagen) - used for more structural proteins
What is a Haemoglobin made of?
- 4 polypeptide chains
- 2 alpha
- 2 beta
- Each chain contains a prosthetic group with one Fe3+ (iron ion)
- Each Haemoglobin can hold 8 oxygens
How is the structure of the haemoglobin useful?
- The inside amino acids have hydrophobic tendencies
- The outer amino acids have hydrophilic tendencies
- The inside amino acids don’t like water so they stay bonded together but the outer amino acids like water so they are soluble and the oxygen can be accessed
