Chapter 03 - Biological Molecules Flashcards
Food nutrients contain water, ____, ____ and ____
Food nutrients contain water, carbohydrates, fats and proteins
What are carbohydrates?
Carbohydrates are organic molecules made up of carbon, hydrogen and oxygen. The hydrogen to oxygen atoms are present in the ratio 2:1.
What are the 3 types of carbohydrates
1) Simple Sugars (monosaccharides)
2) Double Sugars (disaccharides)
3) Complex Carbohydrates (polysaccharides)
Name 3 examples of polysaccharides
Starch, Glycogen, Cellulose
Name 2 examples of disaccharides
Maltose, Sucrose
Name 3 examples of monosaccharides
Glucose, Fructose, Galactose
Polysaccharides are ____, ____ and ____
Polysaccharides are large, complex and insoluble
Disaccharides are ____, ____ and ____
Disaccharides are small, simple and soluble
Monosaccharides are ____ ____ ____
Monosaccharides are one basic unit
What are the 3 properties of sugars?
1) Soluble in water
2) Lowers water potential of solutions
3) Provides energy
All monosaccharides have the same formula: ____
C6H12O6
Even though monosaccharides have the same formula, they differ in ____ of various atoms, resulting in different ____ and ____ properties
Even though monosaccharides have the same formula, they differ in arrangement of various atoms, resulting in different chemical and biological properties
Can monosaccharides pass through a partially permeable membrane?
Yes, monosaccharides pass through partially permeable membranes for absorption
Where can glucose be found?
In plants and animals
Where can fructose be found?
Commonly in plants (fruit sugar), rarely in animals
How do double sugars form?
Double sugars are formed when 2 single sugars join together
Which 2 monosaccharides make up maltose?
2 glucose molecules
Where does maltose occur in?
Maltose occurs in germinating grains
Where does sucrose occur in?
Sucrose occurs in fruits
What can an enzyme do to a disaccharide?
An enzyme can split a disaccharide into 2 monosaccharides
e.g Maltase splits maltose into 2 glucose moleucles
All disaccharides have the same formula: ____
C12H22O11
Even though disaccharides have the same formula, they differ in ____ of various atoms, resulting in different ____ and ____ properties
Even though disaccharides have the same formula, they differ in arrangement of various atoms, resulting in different biological and chemical properties
How do complex carbohydrates form?
Many similar molecules of single sugars joined together
Starch, cellulose and glycogen are formed by many ____ molecules joined together in ____ ways resulting in different ____ and ____ properties
Starch, cellulose and glycogen are formed by many glucose molecules joined together in different ways resulting in different biological and chemical properties
What is starch made up of?
Several thousands of glucose molecules
What can starch do?
Starch is required for respiration, as it can be digested to provide energy when needed
Is starch formed or stored by animals?
No, starch is formed by plants (photosynthesis) and is a storage form of carbohydrates for plants for when they need energy
Is starch soluble?
Starch is insoluble, making it ideal for storage
Where can starch be found?
In storage organs of plants
e.g potato tubers
What is cellulose made up of?
Many glucose molecules linked together, bonds between glucose are different from those in starch
Cellulose is not easily broken down in the digestive system and also is a major component of ____ ____ for humans to avoid ____
Cellulose is not easily broken down in the digestive system and also is a major component of dietary fibre for humans to avoid constipation
Cellulose is a major component in ____ ____ to protect the plant cells from ____ or ____
Cellulose is a major component in cell walls to protect the plant cells from bursting or injury
What is glycogen made up of?
Many glucose molecules into a highly branched molecule
Like starch, glycogen is also a ____ ____ of carbohydrates but for ____
Like starch, glycogen is also a storage form of carbohydrates but for mammals
What can glycogen be converted to, to provide what when needed?
Glycogen can be digested into glucose to provide energy when needed
Where can glycogen be found?
In the liver and muscles
Why are glycogen and starch ideal for storage? (4 reasons)
1) Insoluble in water - doesn’t change water potentials in cell
2) Cannot pass through cell membrane - won’t be lost from cells
3) Can be broken down easily to glucose when needed
4) Highly compact - less space needed than individual glucose molecules
Which enzymes breaks down starch and into what?
Amylase breaks down starch molecules into maltose molecules
Which enzyme breaks down maltose and into what?
Maltase breaks down maltose molecules into glucose molecules
What are the 6 functions of carbohydrates?
1) Substrate for respiration, to provide energy for cell activities
2) Forms supporting structures (e.g cell wall)
3) Converted to other organic compounds (e.g amino acids + fats)
4) Forms nucleic acid (e.g DNA)
5) Synthesises lubricants (e.g mucus)
6) Synthesises nectar in flowers
Describe the test for starch
1) Add a few drops of iodine solution to the sample
+: If starch is present, brown iodine turns blue-back
-: If starch is absent, brown iodine remains brown
Describe the test for reducing sugars
1) Add 2cm3 of test sample into a test tube
2) Add 2cm3 of Benedict’s solution to the test tube. Shake
3) Place in a hot water bath for 5 minutes
If reducing sugars are present, blue solution turns green/orange/yellow/brick-red preicpitate
If absent, blue solution remains blue
What are fats?
Fats are organic molecules made up of carbon, hydrogen and oxygen. Does not contain as much oxygen as carbohydrates. Proportions of elements are not fixed , hence no general formula
Fats are only in humans. True or false?
False, fats can be animal or plant fats
Enzymes speed up the break down of fats into ____ and 3 ____ ____ ____
Enzymes speed up the break down of fats into glycerol and 3 fatty acid molecule
What are the 5 functions of fats?
1) Long term storage in the body, higher energy value than carbs
2) Natural insulating material to prevent excessive heat loss
3) Solvent for fat soluble vitamins and hormones
4) Main part of cell membrane
5) Oil substance secreted to form a thin layer over skin surface to reduce rate of evaporation of water and reduces heat loss
Describe the test for fats
1) To a dry test tube, add 2cm^3 of ethanol to a test sample. Shake.
2) Add 2cm^3 of distilled water
+: If fats are present, a white emulsion forms
-: If fats are absent, solution remains colourless
What are proteins?
Proteins are organic molecules made up of carbon, hydrogen, oxygen and nitrogen. Sulfur may be present
Proteins are present in all cells and is the ____ and most ____ of all the food substances
Proteins are present in all cells and is the largest and most complex of all the food substances
What are the building blocks of proteins?
Amino acids
What do different amino acids join together to form?
Different amino acids join together through peptide bonds in a linear sequence to form a polypeptide
What do different polypeptides join together to form?
Different polypeptides join together to form a longer chain of amino acids
What forms when one or more longer chains of amino acids interact and combine?
A protein molecule, folded into a more complex, 3D shape
What are the 3 functions of proteins?
1) Synthesis of new cytoplasm for growth and repair of worn out cells
2) Synthesis of enzymes and some hormones
3) Formation of antibodies to fight diseases
Describe the test for protein
1) Add equal amounts of 1% copper (II) sulfate to teh test sample
2) Add sodium hydroxide drop by drop and shake after each drop
+: If protein is present, a violet colouration forms
-: If protein is absent, solution remains blue
Name 2 foods with carbohydrates
Brown rice, Sweet potato, Bread, Oats, Lentils
Name 2 foods with fats
Oil, Nuts, Chia seeds, Butter, Egg
Name 2 foods with proteins
Chicken, Milk, Cottage cheese, Fish, Beans
