Flashcards in Biological Molecules Deck (65):
What do amino acids contain?
Carbon, hydrogen, oxygen and nitrogen, some contain sulfur
How many different amino acids are used in proteins?
What are proteins held together by?
What is the primary structure in proteins?
The order in which the amino acids are arranged in a protein chain
What is the secondary structure in proteins?
Some chains fold into pleats that are held together by weak forces of chemical attraction called hydrogen bonds, the pleats are the secondary structure
What is the tertiary structure in proteins?
Some proteins have a tertiary structure, the chain of amino acids is folded into a ball that's held together by a mixture of weak chemical bonds and stronger bonds.
What a globular protein?
If the protein has a spherical shape
What type of bond holds together the secondary structure of a protein?
What three elements do carbohydrates contain?
Give three examples of carbohydrates
What are monosaccharides?
Single units from which all the other carbohydrates are built
What two forms does glucose have?
Alpha and beta
What are disaccharides?
Formed when two monosaccharides are joined together by a chemical reaction, a molecule of water is also formed
What is a polysaccharide
It's formed when more than two monosaccharides are joined together by condensation reactions
What two polysaccharides are starch molecules made up of?
Amylose and amylopectin
Name two monosaccharides
Glucose and fructose
Name two polysaccharides
Starch and cellulose
What do lipids contain
Plant oils and animal fats are mostly made up of a group of lipids called...
What does a triglyceride consist of?
A molecule of glycerol with three fatty acids attached to it
What is a fatty acid molecule?
A long chain of carbon atoms with an acid group at one end
What are attached to the carbon atoms in a fatty acid molecule?
What does is mean by a fatty acid is saturated?
If every carbon atom in the chain is joined by a single bond
What does it mean when a fatty acid is unsaturated
If one or more of the bonds is a double bond
A fatty acid with many double bonds is...
What are phospholipids
A type of lipid
What are cell membranes made from?
A double layer of phospholipids
What do enzymes do?
Speed up biochemical reactions
What are enzymes?
What is activation energy?
The input energy in a reaction
What do enzymes do to the activation energy?
Why are all enzymes globular proteins?
Because they're roughly spherical
What determines an enzymes structure?
The order of amino acids
Enzymes can be involved in...
Breaking down molecules or building molecules
What do digestive enzymes do?
Break down food into smaller molecules
A substance that's acted upon by an enzyme is called
What is the active site?
A region on the surface of the enzyme molecule where a substrate can attach itself, this is where the catalysed reaction takes place
Why are enzymes described as specific?
Is can only catalyse one reaction, the substrate must be the correct shape to fit the active site and only one substrate will fit. Anything that changes the shape will affect how the enzyme works.
How does an enzyme denature?
At high temperatures the atoms of the enzyme molecule vibrate more rapidly and break the weak bonds that hold the tertiary structure together. The shape of the active site changes so the substrate will no longer fit.
What two things disrupt the weak bonds and change the shape of the active sites in enzymes?
Hydrogen ions in acids and hydroxyl ions in alkalis.
What are proteins made up of?
What are polymers?
Large complex molecules composed of long chains of monomers joined together
What's a monomer?
Small basic molecular units that can form a polymer
What is a condensation reaction?
Forms a chemical bond between molecules, releasing a molecule of water
How can polymers be broken down?
What is a hydrolysis reaction?
Breaks the chemical bond between monomers using a water molecule
What is the evidence for evolution in different organisms?
They share the same groups of carbon based compounds that interact in similar ways
What are the monomers that carbohydrates are made from?
How do disaccharides form?
When two monosaccharides join together
What is the test for sugars called?
Benedict's test for sugars
What do reducing sugars include?
All monosaccharides and some disaccharides
How do you test for sugar?
You add Benedict's reagent (blue) to a sample and heat with boiling water.
What will happen if the Benedict's test for sugars is positive?
It will form a coloured precipitate.
The higher the concentration of sugar...
The further the colour change goes
If Benedict's sample stays blue, what does it mean?
No reducing sugar present
If reducing sugar is present, what colour will the sample form?
Brick red precipitate
What is made from alpha glucose?
Amylose and amylopectin
What is amylose
Long chain of alpha glucose, it has a coiled structure like a cylinder, which makes it compact so it's good for storage
What is amylopectin
Long chain of alpha glucose, the side branches allow the enzymes that break down the molecule, so the glucose is released quickly
Is starch soluble in water? Why is this good?
No, so it doesn't swell - good for storage
What is cellulose made from
Long chains of beta glucose, the chains are linked by hydrogen bonds to form strong fibres which help support the cell
Explain the iodine test for starch
Add iodine dissolved in potassium iodide solution, if starch is present the sample changes from browny-orange to a dark blue-black colour
Why are lipids insoluble in water?
The triglycerides have fatty acid molecules that have 'tails' made from hydrocarbons, these tails are hydrophobic so they repel water molecules.
Which type of fatty acids have double bonds?
Unsaturated fatty acids