4. Biological Molecules Flashcards
What 3 categories do most molecules in living organisms fall into?
carbohydrates, proteins and lipids
What do all organic molecules contain?
Carbon
What chemical elements do carbohydrates include?
carbon
oxygen
hydrogen
What chemical elements do proteins include?
All contain C, O2, H2 and nitrogen
- some contain small amounts of other elements such as sulphur
What chemical elements do lipids include?
C, O2, H2
What is the structure of carbohydrates?
Long chains of simple sugars
What type of sugar is glucose?
a monosaccharide
What is formed when 2 glucose molecules join together?
maltose is formed (a disaccharide)
What happens when lots of glucose molecules join together? Examples?
When lots of glucose molecules join together starch, glycogen or cellulose can form (a polysaccharide)
What are most fats made up of?
Most fats (lipids) in the body are made up of triglycerides
What is 1 basic unit of triglycerides made up of?
1 glycerol molecule chemically bonded to 3 fatty acid chains
What are lipids divided into?
Lipids are divided into fats (solids at room temperature) and oils (liquids at room temperature)
What are proteins?
Long chains of amino acids
How are enzymes’ shapes different?
Enzymes have an area in them known as the active site – this is important as this is the place where another molecule fits into the enzyme in order for a reaction to take place
What happens if the shape of the active site does not match the shape of the molecule?
If the shape of the active site does not match the shape of the molecule that fits into it, the reaction will not take place
Do active sites in enzymes differ?
Every enzyme has a different shaped active site
What are antibodies?
Antibodies are proteins produced by certain types of white blood cell to attach to antigens on the surface of pathogens
What must the shape of the antibody match?
The shape of the antibody must match the shape of the antigen so that it can attach to it and signal it for destruction
What gives rise to different shapes of protein and what does this give proteins?
The different sequences of amino acids cause the polypeptide chains to fold in different ways and this gives rise to the different shapes of proteins
In this way every protein has a unique 3-D shape that enables it to carry out its function
What test is used for testing for reducing sugars?
Benedicts test
Describe the procedure for a test for reducing sugars/glucose
Add Benedict’s solution into sample solution in test tube
Heat at 60 – 70 °c in water bath for 5 minutes
Take test tube out of water bath and observe the colour
A positive test will show a colour change from blue to orange or brick red
What safety precautions are necessary with the Benedict’s test?
handle test tube with tongs
- wear safety googles and heatproof gloves
What test can be used to test for starch?
Iodine test
Describe procedure for a test for presence of starch
Add drops of iodine solution to the food sample
- A positive test will show a colour change from orange-brown to blue-black
What test is used to test for protein?
Biuret test
Describe procedure for a test for presence of protein
Add drops of Biuret solution to the food sample
- A positive test will show a colour change from blue to violet / purple
What test is used to test for lipids?
emulsion test
Describe procedure for a test for presence of lipids
Food sample is mixed with 2cm3 of ethanol and shaken
The ethanol is added to an equal volume of cold distilled water
A positive test will show a cloudy emulsion forming
Describe procedure for a test for presence of vitamin C
Add 1cm3 of DCPIP solution to a test tube
Add a small amount of food sample (as a solution)
A positive test will show the blue colour of the dye disappearing
(DCPIP goes from blue to colourless if positive)
What does DNA stand for?
deoxyribonucleic acid
Definition of DNA
molecule that contains the instructions for growth and development of all organisms
What is the structure of DNA?
It consists of two strands of DNA wound around each other in what is called a DOUBLE HELIX
What are the individual units of DNA called?
NUCLEOTIDES
What similarities do nucleotides have and what one difference?
All nucleotides contain the same phosphate and deoxyribose sugar, but differ from each other in the base attached
What are the 4 different bases?
Adenine (A), Cytosine (C), Thymine (T) and Guanine (G)
How are the bases joined?
The bases on each strand pair up with each other, holding the two strands of DNA in the double helix
In what way do the bases pair up?
Adenine always pairs with Thymine (A-T)
- Cytosine always pairs with Guanine (C-G)
What forms the backbone of the DNA?
The phosphate and sugar section of the nucleotides form the ‘backbone’ of the DNA strand (
Overall summary of the structure of the DNA helix
The DNA helix is made from two strands of DNA held together by hydrogen bonds
What holds the code for the formation of proteins?
It is this sequence of bases that holds the code for the formation of proteins
Why is water important (generally)?
Water is important for all living organisms as many substances are able to dissolve in it (it is a solvent)
This makes it incredibly useful and essential for all life on Earth
What is water’s role with dissolved substances?
Dissolved substances can be easily transported around organisms – eg xylem and phloem of plants and dissolved food molecules in the blood
What is water’s role with digested food molecules?
Digested food molecules are in the alimentary canal but need to be moved to cells all over the body – without water as a solvent this would not be able to happen
What is water’s role with toxic substances?
Toxic substances such as urea and substances in excess of requirements such as salts can dissolve in water which makes them easy to remove from the body in urine
What is water’s role with cytoplasm?
Water is also an important part of the cytoplasm and plays a role in ensuring metabolic reactions can happen as necessary in cells
What two types of molecules do living organisms contain and give examples of both?
Living organisms contains inorganic molecules (water, iron and calcium) and organic molecules obtained by nutrition (carbohydrates, lipids, proteins and DNA).
What do all organic molecules contain?
Organic molecules all contain carbon.
Why do organisms need organic molecules?
Organisms need organic molecules (food) for all the chemical reactions that take place in the cells of the body (metabolism).
Give five examples that go with the statement organisms need organic molecules for metabolism.
Release energy in respiration for muscle contraction.
Provide raw materials for the growth and repair of cells and tissues.
Protein synthesis.
Maintaining good health (efficient metabolism).
Maintaining body temperature (37°C).
What are the chemical elements that make up carbohydrates?
Carbohydrates are made of the chemical elements carbon (C), hydrogen (H) and oxygen (O).
What large molecules are formed when many small glucose molecules join together?
When lots of glucose molecules join together starch, glycogen or cellulose can form (a polysaccharide).
What happens when 2 glucose molecules join together?
When 2 glucose molecules join together maltose is formed (a disaccharide).
There are two main classes of carbohydrates. Name them.
Simple sugars (glucose C₆H₁₂O₆ (( a monosaccharide) (soluble)) and complex sugars (are built up from small simple sugars such as glucose).
What are the 1 steps of using the iodine test for starch and the colour change for a positive test?
Add drops of iodine solution to the food sample on a white tile.
A positive test will show a colour change from orange-brown → blue-black.
What are the 3 steps for using Benedict’s solution test for reducing sugars/glucose and the colour change for a positive test?
Grind the food and add water to make a food solution.
Add an equal amount of Benedict’s reagent to the unknown solution.
Heat the mixture in a water bath for 2 to 3 minutes.
A positive test for glucose will show a color change from blue → green → orange → red-brown.
What are the chemical elements that makeup fats or lipids?
Lipids are made of the chemical elements carbon (C), hydrogen (H), and oxygen (O).
What small molecules make up the large molecules called fats and oils (insoluble)?
Fats and oils from fatty acids and glycerol.
What are the 3 steps for using the ethanol emulsion test for fats and oils and the colour change for a positive test?
Add 2cm³ ethanol to 2cm³ of the unknown food solution.
Shake the mixture gently.
Add the mixture to distilled water.
A positive test for fats and oils will show a color change from colourless → milky white emulsion.
What are the building blocks of lipids?
Glycerol + 3 fatty acids.
What small molecules make up the large molecule called protein?
Proteins (enzymes and antibodies) from amino acids.
What are the chemical elements that make up proteins?
Proteins are made of the chemical elements carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulphur (S).
What are the 2 steps for using the Biuret test for proteins and the colour change for a positive test?
Add a few drops of Biuret solution to 2cm³ of the unknown solution.
Shake the mixture gently.
A positive test for protein will show a color change from blue → purple.
What are the elements that makeup DNA?
Carbon, hydrogen, oxygen, nitrogen, phosphorus.
Describe the structure of a DNA molecule (4 characteristics).
Two strands coiled together to form a double helix.
Each strand contains chemicals called bases.
Bonds between pairs of bases hold the strand together.
The bases always pair up in the same way: A with T and C with G.
What are the characteristics of organisms which share a more recent ancestor?
Organisms that share a more recent ancestor are more closely related and have base sequences in DNA that are more similar to those that share only a distant ancestor.
Scientists can now sequence the DNA of particular genes in nuclei to help identify and classify different species of many animals. The sequence they find are called “barcodes”. What do these help to do?
These help to identify an animal accurately and are useful if distinguishing characteristics is difficult and it can help identify unknown or endangered species.
What is glycogen’s use in animals (insoluble)?
The energy stored in animal cells can be easily broken down by enzymes to glucose to release energy (glycogen is usually stored in liver and muscle cells).
What is starch’s use in plants (insoluble)?
A very important energy store in plant cells (found in rice, potatoes and bread).
What is the use of cellulose in plants (insoluble)?
Forms plant cell walls.
What are the 2 steps for using the DCPIP test for Vitamin C and the colour change for a positive test?
Add 1cm³ of DCPIP solution to a test tube.
Add a small amount of food sample (as a solution).
A positive test for vitamin c will show a color change from blue → colorless.
What are the chemical elements that makeup DNA?
DNA is made of the chemical elements carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and phosphate (P).
Food test for carbohydrates (Starch)
Iodine Test
Add a few drops of iodine solution to the food sample
If starch is present (positive), solution will turn blue-black
If starch is absent (negative), the solution will remain yellowish-brown
Food test for Carbohydrates (sugars)
Benedict’s Test
Add the sample into a test tube
Add an equal volume of Benedict’s solution to the test tube
Shake the test tube to mix the contents
Place test tube in a boiling water bath for 2 to 5 minutes
If sugars are present (positive), the solution will turn red, orange, or green
If sugars are absent (negative), the solution will remain blue
Food test for proteins
Biuret test
Add the sample into a test tube
Add an equal volume of sodium hydroxide solution
Shake the test tube to mix the contents
Add copper II sulfate solution drop by drop shaking after each drop
If protein is present (positive), the solution will turn pinky purple
If protein is absent (negative), the solution will remain blue
Food test for fats (lipids)
Ethanol emulsion test
Add the sample into a test tube
Add an equal volume of ethanol
Shake the test tube to mix the contents
Add water
If fat is present (positive), a white emulsion will form and it will be cloudy
If fat is absent (negative), the solution will remain clear
Macromolecules of carbohydrates
Polymer: Polysaccharide (e.g. starch)
Monomer: monosaccharide (e.g. glucose/fructose)
Element: CHO (Carbon, Hydrogen, Oxygen)
Macromolecules of lipids
Polymer: Triglyceride (e.g. animal fat)
Monomer: fatty acids
Element: CHO (Carbon, Hydrogen, Oxygen)
Macromolecules of Proteins
Polymer: Polypeptide (e.g. enzymes)
Monomer: amino acids
Element: CHON (Carbon, Hydrogen, Oxygen, Nitrogen)
Polymer
chain of monomers
Monomer
most basic subunit of a larger substance/single unit of a larger molecule
Elements in a macromolecule
the molecules that make up a macromolecule
macromolecules
protein
carbohydrates
lipids
Water
Needed for cells and body fluids
Transports dissolved substances around the body
Provides a medium for chemical reactions
Found in fruit juice, milk, and water
Important as a solvent
What are organic molecules
Organic molecules are biological molecules
Which elements does carbohydrates have
C
H
O
What elements do lipids have?
C
H
O
What elements do proteins have?
C
H
O
N
S
P
What elements do nucleus acid have?
C
H
O
N
P
What are monomers?
Monomers are subunits that make up a large organic molecule
What is a polymer?
Polymers is a large molecule made up of a long chain of repeating monomers
What is condensation
Condensation is the process of turning monomers into polymers by removing water
What is hydrolysis?
Hydrolysis is the use of water to break down polymers into monomer
What percentage of our body is water?
70%
Why is water important to living organisms?
Chemical reactions
Transport glucose around the body
Dissolves enzymes
Kidneys will remove waste products
carbohydrates
Monomers?
Glucose
Carbohydrates
Polymers
Disaccharide-sucrose
Polysaccharide - starch
Carbohydrates
Function
Primary fuel
Form cell walls
Storage of available energy
Proteins
Monomers
Amino acid
Proteins
Polymer
Polypeptide
Proteins
Functions
Digest food
Transport oxygen
Provides immunity
Form structures
Energy stored for developing embryo
Lipids
Monomers
Glycérol and fatty acids
Lipids
Polymer
Triglyceride
Lipids
Function
Fat stores long term energy
Cushion vital organs from damage
Nucleic acid
Monomers
Nucleotide
Nucleic acid
Monomers
Nucleotide
Nucleic acid
Polymer
Double stranded helix
Nucleic acid
Functions
Carries genetic info
Determines proteins made in cells and what they develop into
Why can’t lipids be polymers
They do not form large molecules bc they are not made of monomers
What is the food test for starch?
Add 1ml of iodine solution
Mix well
Colour change
Brown to blue black
What is the food test for Protein?
Add 1ml of biuret solution into an Aqueous solution of the food
Mix well
Colour change
Pale blue to purple
What is the food test for reducing sugar?
Add 1ml of Bénédicte solution
Place in water bath for 2min
Colour change
Blue to brick red
What is the test for lipids?
Add 1ml of ethanol
Mix well
Colour change
It turns milky white
What is flaccid
Floppy
What is turgid?
Firm
What is phagocytosis?
Phagocytosis is when particles are engulfed by the cel surface membrane flowing around them
What is plasmolysed?
Plasmolysed is when the cell membrane peels away from the cell wall.
What is cellular metabolism?
The total number of chemical reactions that occur constantly in each living cell
What are biochemical pathways?
Chemical reactions in cells occur in a series of controlled steps and each step in the pathway is controlled by an enzyme
What is a lipid
Fats and oils
What’s the structure of a lipid
3 fatty acids, 1 glycerol
Sources of lipids
Meat, cheese, eggs, seeds, peanut
Functions of lipids
Source of energy (and energy store)
insulation (electrical for nerve cells and thermal beneath skin)
form part of cell membrane
cholesterol used to make steroid hormones
What elements are found in lipids
Carbon, hydrogen, oxygen
What elements are found in proteins
Carbon, hydrogen, oxygen, nitrogen, sulphur
What is the test for glucose
The bennidicts test (solution is a test for all reducing sugars)
Positive benedict’s test
Solution turns from blue to a brick-red colour and precipitate is formed
Test for starch
Iodine
Positive test for starch (iodine)
Iodine solution goes from yellow to a blue/black colour
Energy released per gram (joules) =
Energy per gram = (mass of H2O) X (temperature rise *C) X 4.18
How to find energy content in food sample
Measure 1g of foodstuff. Measure out a volume of water and take the temperature. Burn the foodstuff under the test tube until all that’s left is ash, measure the temperature rise.
Energy (J) = water mass X temp rise X 4.18
How many joules in 1 calorie
1 calorie = 4200 j or 4.2Kj
What is the function of carbohydrates
They are a good source of energy and are the main fuel of the body as glucose (respiration). It is also used to store starch, glycogen, and cellulose which provide structural support
Sources of carbohydrates
Rice, wheat, barley
What elements do proteins contain
Carbon, hydrogen, oxygen, nitrogen
What is the test for Vitamin C?
Add DCPIP until the colour changes permanently
from Blue to colourless
carbohydrates
These are compounds of (C, H, O)
- these are either starches or sugars
- there are six main types of sugars divided into 2 types monosaccharides and disaccharides
monosaccharides
❖ GLUCOSE
❖ GALACTOSE
❖ FRUCTOSE
The Disaccharides (2 sugar units)
❖ MALTOSE (GLUCOSE + GLUCOSE)
❖ LACTOSE (GLUCOSE + GALACTOSE)
❖ SUCROSE(GLUCOSE + FRUCTOSE)
Plants store energy as
starch
glycogen stored in
liver and muscles of animals
molecules are linked by
fibers -
thus very strong and rigid
polysaccharides
Starch which is made of many units of sugars
- starch
- glycogen
- cellulose
proteins
Proteins are complex molecules made up of (C, H, O,
N,(S)) Proteins are made of long strands of amino
acids . Different proteins end up in different shapes
because of their amino acid sequence. The shape
and structure of proteins determine their function
amino acids -> peptide -> protein
Lipids
Lipids are fats and oils . Lipids are large molecules made from
small fatty acids and glycerol.
Each fat molecule is made of one glycerol molecule attached to
three fatty acids. Made with Carbon, Hydrogen, Oxygen, and
Phosphorus (C, H, O,(P))
oxygen in the body only uses
4% since diffusion is a slow process
no nitrogen is used up since
its an inert gas
Fat test (lipids)
take sample in a test tube, add ethanol until you get a clear solution. add few drops of distilled water. if the solution turns cloudy or milky confirms the presence of starch
reducing sugars ( glucose ) test
take a known volume of sample, add equal volume of benedicts solution, heat using a thermostatically controlled digital water bath at 80°C. observe the color change
a) blue to green ( traces )
b) blue to yellow ( low concentration)
c) blue to orange ( mild concentration)
d) blue to brick red ( high concentration)
safety precautions
handle test tube with tongs, wear safety goggles and heatproof gloves
starch test
take few drops of sample on a white tile, add a drop of iodine solution. observe the color change from orange- brown to blue black confirming the presence of starch
protein test
take a knwon volume of sample, add few drops of buirette solution. observe the color change
a) blue to lilac ( traces )
b) blue to purple ( low concentration )
c) blue to violet ( high concentration)
vitamin C test
add 1cm³ of DCPIP solution in a test tube, add small amount of sample. observe the color of blue color disappearing
DNA
Chromosomes in nuclei are made of one long thread of a chemical called DNA DNA is made up of (C, H,
O, P,(N)). DNA is made up of units called nucleotides. A nucleotide is made up of :
● A phosphate
● A sugar
● A base
The molecule is twisted into a double helix
base pairing
-THYMINE(T) PAIRS WITH ADENINE(A) (2 H Bonds)
- CYTOSINE(C) PAIRS WITH GUANINE(G) (3 H Bonds)
Water
Water is an important solvent. It is very necessary in digestion, excretion, and transport
Carbohydrates and fats are made up of
carbon, hydrogen and oxygen.
Proteins are made up of
carbon, hydrogen, oxygen and nitrogen
Starch, glycogen, and cellulose are made from
glucose
Proteins are made from
amino acids
Fats and oils are made from
3 fatty acids and 1 glycerol.
starch test
A
take few drops of sample on a white tile, add a drop of iodine solution. observe the color change from orange- brown to blue black confirming the presence of starch
protein test
take a knwon volume of sample, add few drops of buirette solution. observe the color change
a) blue to lilac ( traces )
b) blue to purple ( low concentration )
c) blue to violet ( high concentration)
vitamin C test
add 1cm³ of DCPIP solution in a test tube, add small amount of sample. observe the color of blue color disappearing
Fat test (lipids)
take sample in a test tube, add ethanol until you get a clear solution. add few drops of distilled water. if the solution turns cloudy or milky confirms the presence of fats
reducing sugars ( glucose ) test
take a known volume of sample, add equal volume of benedicts solution, heat using a thermostatically controlled digital water bath at 80°C. observe the color change
a) blue to green ( traces )
b) blue to yellow ( low concentration)
c) blue to orange ( mild concentration)
d) blue to brick red ( high concentration)
Structure of DNA:
Two strands coiled together to form a double helix
Each strand contains chemicals called bases
Bonds between pairs of bases hold the strands together
The bases always pair up in the same way: A with T, and C with G
