2.2 :Biological Molecules Flashcards
State 3 functions of water
- It’s a habitat. Less dense when it freezes means animals can live in it
- Water is a solvent, meaning some substances can dissolve in it.
- Helps with temperature control, because of the high specific heat capacity, and latent heat of evaporation
- Water is a reactant in important chemical reactions, including hydrolysis
What are the bonds between two water molecules?
Hydrogen bonds
why is water polar molecule?
Because oxygen has a slightly negative charge and hydrogen has a slightly positive charge
State the properties of water (5)
- high specific heat capacity
- High latent heat of evaporation
- Very cohesive
- Lower density when solid
- Good solvent
why is water good for cooling things?
Because it takes a lot of energy (heat) to break the hydrogen bonds between the molecules so water has a high latent heat of operation, and a lot of energy is used up when water evaporates
What is a macromolecule?
A complex molecule with a relatively large molecular mass includes proteins, carbs, and lipids, as well as polymers
what happens in condensation and hydrolysis reactions?
in condensation reactions: a bonds between two molecules is made producing a H2O molecule.
in hydrolysis, a water molecule is used to break a bond between two molecules.
what elements are found in carbs, lipids, proteins + nucleic acids
Carbs: C H O
Lipids: C H O N S
Nucleic acid: C H O N P
Proteins: C H N O S
What is the monomers for carbohydrates? Also state two examples.
carbohydrates are polymers made of lots of monomers called monosaccharides, which combine to make a disaccharide or polysaccharide
Examples are glucose and ribose.
what is the structure of glucose?
glucose is a six carbon ringed structure, monosaccharide (hexose)
what is the difference between alpha and beta glucose?
Alpha glucose has the OH on carbon one pointing down towards the ankles
whereas beta glucose has the OH on carbon one pointing towards the brain?.
describe the structure of ribose
Ribose is a five carbon ring structure (pentose) It is also a monosaccharide
what is the difference between ribose and deoxyribose?
ribose is found in RNA and has an oxygen atom on the second carbon, whereas deoxy ribose is found in DNA and has no oxygen on the second carbon therefore is ddee oxy ribose
what bond forms when monosaccharides react to form polysaccharides?
Glycosidic bond
Name three disaccharides and describe how they form
form when condensation reactions occur to form glycosidic bonds between two monosaccharides
- Maltose (glucose + glucose)
- Sucrose ( glucose + fructose)
- Lactose (glucose + galactose
Describe the structure and functions of starch
Energy storage of alpha glucose in plant cells. It’s also large so can’t diffuse out of cells and insoluble.
Starch is made of amylose and amylopectin.
Amylose: is a long and branched chain of glucose. It’s got a coiled structure which makes it compact and good for storage.
Amylopectin: is a Long branched chain of glucose, its branches allow for glucose to be released quickly
Describe the structure and functions of glycogen
glycogen is the main energy storage of alpha glucose in animal cells
Its structure is similar to amylopectin however, it has lots more branches. It’s also insoluble and compact.
describe the structure + functions of cellulose
cellulose is a polymer of beta glucose and is found in the cell walls of plants. It helps give rigidity to plant walls.
Its structure is made of long unbranched chains of beta glucose linked by hydrogen bonds to form strong fibres called microfibrils. These help provide structural support.
describe the structure of triglycerides
Triglycerides are made of one molecule of glycerol with three fatty acids attached to it by condensation using ester bonds.
How many ester bonds does one triglyceride molecule have?
Three
what is the process called in which triglycerides are synthesised
Esterification
what is the difference between saturated and unsaturated fatty acids?
Saturated
- Contain only single bonds
- Found in animal fats
- Higher melting point (solid at room temp)
- Straight chain molecules
Unsaturated
- Contain at least one double bond between the carbon atoms
- Kinked molecules
- Found in plant oils
- Lower melting point (liquid at room, temp)
describe the structure and function of phospholipids
Phospholipids are similar to triglycerides but only have two fatty acids and have a phosphate group added. The phosphate group (head) is hydrophilic, and the fatty acid tails are hydrophobic.
The function of phospholipids is that they form a phospholipid bilayer .
Describe the structure and function of cholesterol
cholesterol has a hydrocarbon ring structure with an attached hydrocarbon tail and a hydroxyl (HO) group attached.
It adds stability to cell surface phospholipid bilayers by reducing the fluidity
What is the food test for proteins and describe it
Biurets test.
1. Add sodium hydroxide to sample and then add copper sulfate solution
blue=negative lilac=positive
What is the food test for starch
Iodine test.
1. add iodine.
brown=negative blue\black=positive
What is the food test for lipids?
Ethanol emulsion.
1. Shake sample with ethanol then pour into water.
clear=negative milky=positive
What is the test for reducing sugars
Benedict’s test.
1.Add benedict’s reagent (blue) to sample and heat in water bath
blue=negative
green/yellow/orange/brick red = positive (traffic light to show how strong red is strongest)
What is the test for non reducing sugars?
Benedict’s test.
1. If not reducing sugar might be non reducing so get new sample
2. Add dilute hydrochloric acid (HCL) and heat in water bath
3. Neutralise it with sodium hydro carbonate then carry out normal benedict’s test
results is same as reducing! higher conc = further change in traffic lights
What is the monomers for proteins?
Amino acids
What bond is formed between two amino acids to form a dipeptide?
peptide bond.
Draw out the amino acid structure and label the carboxyl group and amine group.
check book.
What elements do proteins contain?
C, O, H, N, S
What is the polymer for protein?
Polypeptide.
What are the different stages of protein structure?
Primary
Secondary
Tertiary
Quaternary
What is the primary structure of a protein?
The number and sequence of amino acids in a polypeptide chain.
What is the secondary structure of an amino acid?
Where hydrogen bonds form and it forms alpha helix or beta pleated sheets.
What is the tertiary structure of proteins? Also where do these occur?
More bonds form between different parts of the polypeptide chain.
Ionic bonds between R groups.
Disulphide bridges/ bonds.
Hydrophobic/ hydrophilic interactions.
Hydrogen bonds.
What is the quaternary structure?
Give an example of a molecule too!
When several polypeptide chains are held together by bonds. eg haemoglobin has 4 polypeptide chains held together. It determines the 3D structure.
What is a globular protein? give an example.
Round and compact protein.
Eg haemoglobin.
What are fibrous proteins ? give an example
Tough and rope shaped proteins.
eg Collagen
