Flashcards in Biological Molecules Deck (122):
What is evidence for evolution?
Information that supports the theory of evolution
What is the theory of evolution?
That all organisms on earth are descended from one or a few common ancestors and that they have changed and diversified over time
What are polymers?
Large, complex molecules composed of long chains of monomers joined together
What are monomers?
Small, simple molecular units that can form a polymer
Name some examples of monomers
What reaction occurs when polymers are formed from their monomers?
What happens during a condensation reaction between two monomers to make a polymer?
A condensation reaction forms a chemical bond between monomers, releasing a water (H2O) molecule
What reaction can break down polymers into monomers?
What happens during a hydrolysis reaction when a polymer is broken down into monomers?
The hydrolysis reaction breaks the chemical bond between the monomers, using a water molecule
What is sugar a general term for?
Monosaccharides and disaccharides
What elements do all carbohydrates contain?
Carbon, hydrogen and oxygen
What are the monomers that carbohydrates are made from called?
Give some examples of monosaccharides
What is meant by glucose being a hexose sugar?
It is a monosaccharide with 6 carbon atoms in each molecule
Name the two types of glucose
Alpha and beta
What is a isomer?
Molecules that have the same molecular formula as each other but with the atoms connected a different way
When is a disaccharide formed?
When two monosaccharides join together
Monosaccharides are joined together by what kind of reaction?
A condensation reaction
What kind of bond is between two monosaccharides when it forms a disaccharide?
Glucose + glucose = what disaccharide?
Glucose + fructose = what disaccharide?
Glucose + galactose = what disaccharide?
When testing for a reducing sugar, if the sample stays blue once the benedict reagent is added, is it a positive or negative result?
What colour will the sample change when the benedict's reagent is added if the test for reducing sugar is positive?
A coloured precipitate (green, yellow, orange, brick red)
Name three examples of biological molecules
What type of biological molecule are polysaccharides
What are the monomers of polysaccharides
How many monosaccharides must join together to form a polysaccharide
More than two
What reaction joins monosaccharides together to form a polysaccharide
A condensation reaction
What type of glucose molecules are joined together to form amylose
What bonds join alpha glucose molecules together to form amylose
What type of reaction can break polysaccharides down into their constituent monosaccharides
A hydrolysis reaction
What is the name of the molecule that cells get energy from?
What do plants store excess glucose as?
When a plant needs more glucose for energy, what does it do?
Break down starch to release the glucose
Starch is a mixture of what two polysaccharides of alpha glucose?
Amylose and amylopectin
Describe the structure of amylose
It's a long, unbranched chain of alpha glucose
What do the angles of the glycosidic bonds in amylose do to its structure
Make it coiled, so it's compact
Describe the structure of amylopectin
It is a long, branched chain of alpha glucose
What do its branches allow enzymes to do?
To break the glycosidic bonds easily, meaning the glucose is released quickly
Is starch soluble or insoluble in water
Why does starch being insoluble make it good for storage?
Because it means it doesn't effect water potent ion and water doesn't move into the cells by osmosis, meaning that the cells don't swell
What do animals store excess glucose as?
What is glycogen a polysaccharide of?
Why does glycogen's structure make it good for storage?
It has a lot of branches coming off it meaning stored glucose can be released easily.
What is cellulose a polysaccharide of?
Describe the structure of cellulose
It is long and unbranched
What happens when beta glucose molecules bond?
They form straight cellulose chains
What are the cellulose chains linked together by?
Which polysaccharide is the major component of plant cell walls?
What is the main energy storage material in plants
What is the main energy storage material in animals
If you want to test for the presence of starch in a sample, what test do you use?
The iodine test
What are lipids commonly known as?
Fats or oils
How are lipids different from proteins and carbohydrates?
Because they're not polymers formed from long chains of monomers.
What do all lipids contain
What are hydrocarbons?
Molecules that contain only hydrogen and carbon atoms
What are the two types of lipids you must know?
Phospholipids and triglycerides
What are the components of triglycerides?
A molecule of glycerol and three fatty acids
What are the long tails made of on a fatty acid
Are the fatty acid tails hydrophilic or hydrophobic?
What effect does the fatty acid tails being hydrophobic have with water?
It makes lipids insoluble
What varies in the structure of different fatty acids
Name the two kinds of fatty acid
Saturated and unsaturated
Explain the difference between a saturated fatty acid and an unsaturated fatty acid
A saturated fatty acid doesn't have any double bonds between their carbons, unsaturated fatty acids do
What type of reaction forms triglycerides
What type of bond is found in a triglyceride
What are the lipids called in cell membranes
What's the difference in the structure between triglycerides and phospholipids
One of the fatty acid molecules that would be in a triglyceride is replaced by a phosphate group in phospholipids
Is the phosphate group in phospholipids hydrophilic or hydrophobic
Are the two fatty acid tails in phospholipids hydrophobic or hydrophilic
What is the main use of triglycerides
For storing energy
Why are triglycerides good for energy storage?
Because their long hydrocarbon tails of fatty acids contain lots of chemical energy
Because of their tails, how much more energy per gram do triglycerides contain than carbohydrates
Twice as much
Why does triglycerides being insoluble make them good as a energy storing molecule?
Because they don't affect theatre potential of the cell, meaning water doesn't enter the cell by osmosis
Because the fatty acid tails on triglycerides are insoluble what does this cause them to do together?
Bundle in a circle with the hydrophilic heads facing outwards and the hydrophobic tails facing inwards
What do phospholipids make up?
The bilayer of the cell membrane
What do cell membranes do
Control what does in and out a cell
The centre of the bilayer in a cell membrane is insoluble, what does this mean for water soluble substances passing through the membrane
That they can't easily pass through it
What test would you have to carry out in order to see if lipids in a sample were present
The ethanol/emulsion test
What does a positive result look like for the emulsion/ethanol test?
A milky white emulsion is present
Give two reasons why triglycerides are used as energy storage molecules
- they contain lots of chemical energy
- they're insoluble in water
What are the monomers of proteins?
What is formed when two amino acids join together
What is formed when more than two amino acids join together?
One or more polypeptide joins together to make up what?
What are the components in an amino acid structure?
A carboxyl group, an amino group, an R group, and a central C and H
How many amino acids are there?
What kind of reaction are amino acids joined up by to form dipeptides and polypeptides
What reaction breaks down dipeptides and polypeptides to into amino acids?
Name the four levels of a proteins structure
Describe the primary structure of proteins
The sequence of amino acids in a polypeptide chain
Describe the secondary structure of a protein
Hydrogen bonds form between the amino acids
This makes them coil into an alpha helix or fold into beta pleated sheets
Describe the tertiary structure of a protein
The coiled/folded chains of amino acids is often coiled/folded further
More bonds form: hydrogen bonds, ionic bonds and disulphide bridges
Describe the quaternary structure of a protein
The way polypeptide chains with several different polypeptides are assembled together
How does haemoglobin's shape determine its function?
It is a compact and soluble protein which makes it easy to transport
Makes it good for carrying oxygen around the body
Name the 3 bonds that may be for,ed between the amino acids in a polypeptide chain to form the tertiary structure of a protein
What test would you carry out if you needed to find out if a substance contained protein?
The biuret test
What are the two stages of the biuret test?
1. The test solution needs to be alkaline so you add a few drops of sodium hydroxide solution
2. Then you add some copper sulfate solution
What colour will the solution turn if the biuret test comes up positive for protein
What colour will the solution turn if the biuret test comes up negative for protein
What do enzymes work as
What is an example of an enzyme catalysing a reaction at a cellular level
What is an example of an enzyme catalysing a reaction for the organism as a whole
What term is used to describe an enzyme that acts outside of cells?
What term is used to describe an enzyme that acts within cells?
What binds to the active site of a enzyme
When a substrate fits into the enzyme's active site what does it form?
An enzyme-substrate complex
What does the enzyme-substrate complex do?
Lower the activation energy for the chemical reaction to start
What is activation energy?
The certain amount of energy that needs to be supplied to the chemical before the reactions will start
What do enzymes do to the activation energy
They lower the amount of activation energy that is needed, speeding up the reaction
What is the lock and key model?
The model which says a substrate fits into the active site of an enzyme like a key fits a lock
That the substrate has a complementary shape to the active site of the enzyme
What's the induced fit model
That the enzymes active site has to slightly change shape for the substrate to completely fit, therefore the substrate has to make the active site change shape
Enzymes are very specific therefore the usually only catalyse how many reactions?
Maltase only breaks down what?
Sucrase only breaks down what?
Why do most enzymes only catalyse one reaction?
Because only one complementary substrate will fit into the active site
What is the active site's shape determined by?
The enzymes tertiary structure
What is an enzymes tertiary structure determined by?
It's primary structure
If the tertiary structure of a protein is altered in any way, what will happen to the shape of the active site and what does this mean?
It will change meaning the substrate won't fit into the active site and the enzyme won't be able to carry out its function anymore
What may alter the tertiary structure of an enzyme?
Changes in pH or temperature