Biology Chapter 3 biological molecules Flashcards
What are the top 10 genetically modified foods
Corn, soy, cotton, papaya, rice, canola, potatoes, tomatoes, dairy products and peas
Why do we need food?*
The nutrients in food are needed to:
- release energy
- supply raw materials to make new protoplasm
- help us stay healthy
What are nutrients?*
Nutrients are chemical substances in food that release energy and materials needed by the body
What are carbohydrates
(Major categories of carbo can be like starch, glucose)
Carbohydrates are organic molecules made up of carbon, hydrogen and oxygen
- The general formula for carbohydrates is CnH2mOm
The ratio of hydrogen atoms to the oxygen atoms in carbo is 2:1
What are the monosaccharides(single sugars) of carbs
- Glucose
- Fructose
- Galactose
Disaccharides (double sugars)
- Maltose
- Sucrose
- Lactose
Polysaccharides (complex carbs) just means a lot of sugars together
Starch- plant store
Glycogen- animal store
Cellulose
How many carbons are present glucose, galactose and fructose?
Glucose has 6 carbons, in the shape of a hexagon, same as galactose
Fructose(present in fruits) only has 5 carbons
How is maltose formed
glucose + glucose = maltose- two unit sugar
How is lactose formed
glucose + galactose = lactose (present in milk)*, it’s a milk sugar
how is sucrose formed and consequences of too much of it
glucose + fructose = sucrose (found in fruits) too much can lead to fatty liver, more health risks, not really a good sugar
How starch is formed, also an example of it breaking down
4 glucose are stringed up together to form starch
Example: If we bite bread for long enough, it will taste sweet as starch breaks it down into glucose
How cellulose (cell wall) if glucose
4 glucose again like starch but stringed up in another way
How glycogen is formed
6 glucose, highly branched glycogen
Which ones are reducing sugars
All monosaccharides which are glucose, galactose and fructose, and all disaccharides which are lactose and maltose, they do not include sucrose
How are disaccharides formed
- A condensation reaction is a chemical reaction in which two smaller, simple molecules are joined together to form a larger, complex molecule with the removal of one molecule of water
For example, when two glucose molecules join together via the condensation reaction, maltose is formed
Hydrolysis of disaccharides
- A chemical reaction in which a water molecule is needed to break down one larger, complex molecule into two smaller, simple molecules
- A double sugar can be split into two single sugar molecules by hydrolysis in teh presence of an enzyme
For example, maltose + water and maltase —> glucose + glucose
Starch description
- A storage form of carbohydrates in plants
- Found in storage organs in plants
Cellulose description
- Cellulose cell wall protects plant cells
- Serves as dietary fibres to prevent constipation
( the kind of bond cellulose has makes it indestructible, cannot be broken down)
Glycogen description
- A storage form of carbs in mammals in liver and muscles ( as the liver and muscles contain a lot of mitochondria to release energy for cellular functions, a lot of glucose is needed too)
- digested to form glucose when needed
Hydrolysis of starch example
Starch is digested into maltose molecules by amylase (enzyme)
Maltose molecules are digested into glucose by maltase (enzyme)
How carbohydrates can be bad if too much
Can cause diabetes, can be turned into too much fats, leading to obesity, and fats are much harder to lose than carbs
How we can test for starch
Iodine test- add 2cm^3 of food sample to a clean test tube. Add a 2-3 drops of iodine solution to the test tube
Positive: blue-black
negative: solution remains brown
How can we test for reducing sugar’s and how to see the results
Benedict’s test-
1. add 2cm^3 of Benedict’s solution to 2cm^3 of food sample in a test tube
2. Shake the mixture
3. Heat the contents in a boiling water bath for 2-3 minutes
Positive: Green precipitate- trace amount
- yellow/orange precipitate- moderate amount
orange red precipitate- large amount
negative: solution remains blue
What are fats? and what are their proportions when it comes to oxygen and hydrogen, as well as their elements?
Fats are organic compounds mad up of carbon, hydrogen and oxygen (the elementals of fats are C, H and O, which is why carbs can turn into fats)
- Fats contain much less oxygen in proportion to hydrogen
- The proportions of the elements in fats are not fixed
What is a fat molecule made up of?
A fat molecule is made up of:
1 glycerol molecule
3 fatty acid chains
Hydrolysis of fats, the process and what it is broken down into
Fats can be broken down into simpler compounds by hydrolysis
Hydrolysis of fats produces fatty acids and glycerol
Fat molecule + 3 of H2O —>lipase (enzyme) for glycerol + 3 fatty acid
About saturated fats’ molecule’s shape and what state of matter they are in at room temp
Mostly found in animal sources
Fatty acid chains are straight in saturated fats
- A saturated fat molecule tends to be a semi-solid at room temp
Most are solid at room temp (e.g. butter, cheese, biscuits )
About Unsaturated fats and what state of matter they are in at room temp as well as the shape of their molecule
Fatty acid chain has kinks
Liquid at room temperature (e.g. sunflower seed oil, peanut oil, olive oil)
- comes from plant sources
Consequences of eating too much saturated fats and how unsaturated fats are better for us
Since saturated fats tend to be solid or semi-solid at room temp, there would be a risk of the saturated fats depositing on the walls of the blood vessels and clogging the blood vessels, resulting in cardiovascular disease. Therefore, unsaturated fats are better for us as they are liquid at room temp, so unsaturated fats are healthier
Functions of fats
- A source and store if energy
- act as an insulating material to prevent excessive heat loss
- are a solvent for fat soluble vitamins and some hormones
- form the main part of cell ,membrane
- help reduce water loss from skin surface
- essential for growth, repair and synthesis of cells
What fats is an alternative source of
Fats is an alternative source of energy for carbohydrates when burning energy
Example of carbs
Banana, bread- both rich in sugars and starch, offers immediate source of energy
How can we test for fats?*
Ethanol emulsion test-
1.Add 2cm^3 of ethanol to 2cm^3 of food sample in a test tube
2. Shake the contents of the tube vigorously
3. Decant the ethanol into another test tube with 2cm^3 of water and shake the mixture
Positive: cloudy white emulsion is formed if fats are present
Negative: Solution remains clear and colourless if fats are absent
What are proteins and what they consist of, also what are they are made of
Proteins are organic compounds made up of carbon, hydrogen, oxygen, nitrogen and sulfur
- Each protein molecule is made up of smaller basic units, which are amino acids
The building blocks of proteins
Amino acids, the building blocks of proteins, are made up of:
- an amino group
- an acid group
- a side chain
Amino acids —> peptide bonds —> protein process
(There are 20 different types of amino acids)
Amino acids are the building block of proteins
Peptide bonds link up amino acids to form a polypeptide chain(a chain of amino acids)
Two or more polypeptide chains fold to form a three-dimensional molecule, that is protein ( only when in 3-D then it is considered a protein)
A break hehe, look at your notability notes for how the picture is like on how peptide bonds link up to form a polypeptide
Functions of proteins
Proteins are needed for:
- the synthesis of new protoplasm for growth and repair of worn-out cells
- the synthesis of enzymes and some hormones
- the synthesis of antibodies
How can we test for proteins
Biuret test-
1. Add 2cm^3 of sodium hydroxide solution to 2cm^3 of food sample into a test tube
2. Shake the mixture thoroughly
3. Add 1% copper (II) sulfate solution drop by drop, shaking mixture after each drop
OR
1. add 2cm^3 of Biuret solution to 2cm^3 of the food sample and shake the mixture thoroughly
Positive: A violet solution is formed if proteins are present
Negative: Solution remains blue if absent
How do protein molecules maintain their 3-D structure
Through hydrogen bonds
