3.1, 3.2, 3.3: Biological Elements, Water, Carbohydrates Flashcards
What are the 4 key elements that all living things are primarily made from?
Carbon, Hydrogen, Oxygen and Nitrogen
Why is life on Earth often referred to as being “carbon-based”?
Because carbon forms the backbone of most biological molecules
What is an atom called if it has lost electrons?
Cation
What is an atom called if it has gained electrons?
Anion
What elements are in Carbohydrates?
Carbon Hydrogen and Oxygen
What elements are in lipids?
Carbon, Hydrogen and Oxygen
What elements are in Proteins?
Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur
What elements are in Nucleic Acids?
Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus.
What are polymers?
Long-chain molecules made by the linking of multiple individual molecules in a repeating pattern.
What are organic molecules?
Molecules that contain hydrogen and carbon
What is the definition of hydrophobic?
Repels water
What does hydrophilic mean?
Attracted to water
What does intermolecular mean?
Between molecules
What does intramolecular mean?
Within molecules
What does polar mean?
Having regions of both negativity and positivity, but with an overall neutral charge
What is the definition of a property?
The way something behaves.
What is the definition of cohesion?
Attraction between molecules
What is the definition of adhesion?
Attraction to other molecules
What is the definition of electronegative?
Tending to acquire electrons.
Why is water polar?
-The electrons are shared unevenly. The oxygen has a greater share of negative electrons, so it is slightly negative, and the hydrogen is slightly positive
What gives water its unique characteristics?
The hydrogen bonds formed between molecules
Is water adhesive or cohesive?
Both
What makes water a solvent?
The fact that it is polar.
Describe the solvent property of water
-Allows hydrophilic substances to be dissolved
-Acts as a medium for chemical reactions
-Also helps transport dissolved substances into and out o cells.
State the properties of water.
Cohesive, adhesive, univesal solvent, high head capacity, high latent heat of vaporisation, lower density as a solid than as a liquid, polar
Describe the density of water.
-The density of water is similar to the density of most organisms, which enables organisms to live in water without sinking
-Water in solid form (ice) is less dense than water so it floats on the surface, insulating the water below.
What property gives water a high heat capacity?
-Because of its hydrogen bonds.
-Lots of weak hydrogen bonds add up to make a strong intermolecular force of attraction.
-These bonds require a lot of energy to break for the temperature to increase.
How does water buffer temperature change?
Water has to absorb/lose a large amount of energy before its temperature can change, which takes a large amount of time.
What does it mean that water is a metabolite?
Water can be used as a reactant in many chemical reactions in cells.
What is a condensation reaction?
A type of chemical reaction in which water is produced when smaller molecules are joined together to make bigger ones.
What is a hydrolysis reaction?
A type of chemical reaction in which large cells are broken down into smaller ones using water.
Why does water have a “skin” of surface tension?
Water molecules are more strongly cohesive to eachother than they are to air.
What is capillary action?
The process by which water can travel up a narrow tube against the force of gravity.
What is a functional group?
A group that is added to a molecule and changes its properties.
What is the Hydroxyl group?
“-OH”
How does the hydroxyl group help a molecule to dissolve when it is added to it?
Because the hydroxyl group is polar.
What is the carboxylic acid group?
-COOH
What is the molecular formula of Alpha Glucose?
C6H1206
What makes glucose polar?
The presence of the hydroxyl group
What are the two structural variations of glucose?
Alpha and Beta Glucose
What is the definition of an isomer?
Compounds with the same formula but a different arrangement of atoms in the molecule and different properties.
Is glucose soluble or insoluble?
Soluble
What makes Beta glucose different to Alpha?
The hydroxyl group has been flipped upside down on one side
What are the functions of carbohydrates?
-Energy sources (sugars, eg glucose)
-Long term energy stores (eg starch for plants, glycogen for animals)
-Act as structures (eg cellulose in plant cell walls)
Give 4 examples of monosaccharides
Glucose, fructose, galactose, ribose
What does hexose mean?
Containing 6 carbon atoms
Which monosaccharides are hexose?
Glucose, fructose and galactose
Which monosaccharides are pentose?
Ribose
What do two or more monosaccharides linked together form?
Polysaccharides
Give some examples of polysaccharides
Glycogen, cellulose and starch
What are the products of two alpha glucoses reacting with eachother?
Maltose and water
What is the name of the bond between two glucose molecules?
A 1-4 glycosidic bond
What is maltose made of?
Two alpha glucoses
What is sucrose made of?
Alpha glucose and fructose
What is lactose made of?
Glucose and galactose
What is ribose?
A pentose monosaccharide. The sugar present in RNA nucleotides
What is deoxyribose?
A pentose monosaccharide. The sugar present in DNA nucleotides.
What is glucose stored as?
Starch by plants or as glycogen by animals and fungi
How do you release glucose for respiration?
-Starch or glycogen has to undergo hydrolysis, requiring the addition of water molecules.
-The reaction is catalysed by enzymes.
What are the two key properties of glucose?
It is small and soluble
Why is it important that glucose is small?
So it can easily pass into cells through the cell membrane
What is the difference between ribose and deoxyribose?
On the second carbon, ribose has a hydroxide but deoxyribose only has a hydrogen
What two forms does starch come in?
An unbranched form (amylose), and a branched form (amylopectin)
Describe the structure of amylose.
-A polysaccharide made of chains of alpha-glucose molecules linked by 1-4 glycosidic bonds
-The glucose molecules are linked together by a condensation polymerisation reaction
-The chains are unbranched
-Chain is coiled into a helix that is maintained by hydrogen bonds holding the sugars together, making it compact and less soluble
Describe the features of amylose
-Large molecule
-Compact
-Can be hydrolysed
-Soluble
-Large polymer
Describe the structure of amylopectin
-Polysaccharide made of chains of alpha glucose molecules, linked together by 1-4 glycosidic bonds
-Once in every 25 glucose subunits, a 1-6 glycosidic bond is formed, allowing the glucose to branch out
Describe the features of amylopectin
-Compact
-Insoluble, (no effect on water potential)
-Can be hydrolysed faster than amylose
-Branched
-Large polymer
Why can amylopectin be broken down/hydrolysed faster than amylose?
Because it is branched, so there are more exposed ends for the enzyme to work, so more available sites to work and remove glucose.
What are the uses of starch?
-Stores energy in plant cells
-Can be broken down into smaller molecules of maltose through hydrolysation
If a chemical is insoluble, how does it effect the water potential of a cell?
It has no effect on the water potential as it has no osmotic effect.
Why is it important that energy stores are compact?
So that it can be an efffective store of energy (more can be stored in a small space)
What cells is glycogen found in?
Animal cells (especially liver and muscle), and bacteria
What is glycogen made of?
Alpha glucose molecules
What bonds does glycogen contain?
1-4 glycosidic bonds and 1-6 glycosidic bonds
What is the difference between a 1-4 glycosidic bond and a 1-6 glycosidic bond?
1-6 glycosidic bond is used to connect branches, 1-4 glycosidic bond is used to connect molecules.
How branched is glycogen?
More branched than amylopectin, with a new branch roughly every 10 sugars.
What is the shape of glycogen?
Helical
What holds the coil shape of glycogen?
Hydrogen bonds between glucose molecules
Is glycogen soluble or insoluble?
Insoluble
What is the use of glycogen?
Store of energy in cells.
Why do animals use glycogen as an energy store but not plants?
-Animals are metabolically active, meaning they require energy for respiration faster than plants.
-So more glucose has to be converted to energy at any given time in animals than in plants
-Because glycogen is so highly branched, it is very compact and has more terminal glucose molecules that can be extracted at any given time.
What is the name for the ends of branches in polysaccharides?
Terminal glucose molecules
If a polysaccharide is more branched, can it be hydrolysed faster or slower?
Faster
What is cellulose a polymer of?
Beta glucose molecules
What are the monomers in cellulose joined by?
1-4 glycosidic bonds
Describe the layout of the monomers in cellulose.
Because the ends of the hydroxyl groups are too far apart, they cannot link up. So, every alternative beta glucose monomer is flipped upside down, and then bonded to the next monomer.
Describe the structure of cellulose
Uncoiled, made of straight, unbranched chains that run parallel to eachother, with hydrogen bonds forming cross-linkages between adjacent chains
Where are the hydrogen bonds in cellulose?
Between the hydroxyl groups of Beta Glucose
What gives cellulose its tensile strength and rigidity?
Hydrogen bonds between monomers
What are the properties of cellulose?
-High tensile strength
-Insoluble
-Rigid on a large scale, flexible on a small scale
-Unreactive
What makes cellulose insoluble?
Strong hydrogen bonds.
What do chains of cellulose molecules form?
Microfibrils
What do bundles of microfibrils grouped together make?
Macrofibrils
What are macrofibrils?
Bundles of microfibrils grouped together
What are microfibrils?
Chains of cellulose molecules
What makes up cellulose fibres?
Macrofibrils
What do macrofibrils make up?
Cellulose fibres
What are cellulose fibres?
A major component in cell walls of plant cells that provide tensile strength and rigidity.
How do cellulose fibres provide rigidity to cell walls?
They provide an inward force to the cell, which prevents it from bursting and maintains turgor inside the cells, which helps support the tissues.
Why are cellulose fibres an important part of our diet?
Because it is hard to break down into its Beta-Glucose monomers, it provides roughage needed in a healthy digestive system.
What can cellulose be hydrolysed by?
The enzyme cellulase, which is present in the digestive system of herbivores (ie not in humans).
What molecule can Lysozyme break down?
Peptidoglycan
