Biological molecules Flashcards
What’s the general formula for monosaccharides?
(CH2O)n n=3-7
What are monosaccharides?
Sweet-tasting soluble substances
Why are they called reducing sugars?
A sugar that can donate electrons to another chemical
What do alpha and beta glucose look like?
Alpha hydroxyl group is on the bottom of the right and beta is in the top right
What is Benedict’s reagent?
An alkaline solution of copper (II) sulfate
What happens when a reducing sugar is heated with Benedict’s reagent?
Forms an insoluble red precipitate of copper (I) oxide
What colours do the Benedict’s reagent test move through?
Blue, green, yellow, orange then red depending on the concentration of sugar molecules
What happens when monosaccharides are joined together?
Condensation reaction forms glycosidic bond
What disaccharides are reducing sugars?
Maltose is and sucrose isn’t
How do we test for non-reducing sugars?
Add dilute hydrochloric acid in a test tube and boil for 5 minutes, the HCl will hydrolyse the disaccharide present int its constituent monosaccharides, add sodium hydrogen carbonate to neutralise and then perform Benedict’s reagent
Are polysaccharide soluble?
No, they are large, this makes them suitable for storage
How many alpha glucose molecules are in starch?
200-100,000
What’s the main role of starch?
Energy storage
Why does starch not affect water potential?
It’s insoluble, no osmosis
Why does starch being large and insoluble benefit it?
It does not diffuse out of cells
Why is starch being compact beneficial?
Stored in a small place
Why is starch being made of alpha glucose beneficial?
Hydrolysis allows transport and readily used in respiration
Why is starch having branched ends beneficial?
Each can be acted on simultaneously meaning that glucose monomers are released very rapidly
How is glycogen stored?
Mainly as granules in the muscles and liver
What are the structures of glycogen?
Insoluble-no osmosis and doesn’t diffuse out
Compact- increase storage efficiency
Highly branched- ends can be acted on simultaneously by enzymes
What’s the shape of cellulose?
Straight, unbranched chains which run parallel to one another, allowing hydrogen bonds to form cross-linkages between adjacent chains
What do cellulose molecules group together to form?
Microfibrils, which are in turn arranged into parallel groups called fibres
How does cellulose prevent the cell wall bursting by osmosis?
Exerting an inward pressure that stops any further influx of water, as a result living plant cells are turgid and pushed against one another, making non-woody parts of the plant semi-rigid
How does carbon-based life lead to a variety of life on Earth?
Readily forms bonds with other carbon atoms, which allows various lengths to form a backbone (versatility of the atom)
What are the roles of lipids?
Waterproofing, source of energy, insulation and protection
How does the structure of triglycerides relate to their properties?
Low mass: energy, good storage
Insoluble: no osmotic effect
High hydrogen oxygen ratio: releasing water when oxidised
What type of bonds form the secondary structure of proteins?
Hydrogen bonds
What is the role of DNA?
Base sequence of genes codes for functional RNA and amino acid sequence of polypeptides
Genetic information determines inherited characteristics
What is the theory of evolution?
The idea that all organisms evolved from one or a few ancestors as we all have the same biochemistry
What’s the difference between saturated and unsaturated fatty acids?
Saturated don’t have any double bonds whereas unsaturated do between carbon atoms, causing the chain to kink
Why are lipids insoluble?
Long fatty acid hydrocarbon tails are hydrophobic
What do lipids do in the body?
Insulate, hormone coordination, energy yield and energy storage
Why are lipids different from carbs and proteins?
They all contain hydrocarbons and a variety of different components relating to their lipids function
What type of proteins are enzymes?
Globular
What are prosthetic groups?
Non-protein groups associated with quaternary structures of protein, such as iron containing haem group in haemoglobin
What are the key words for enzymes?
Activation energy, substrates and enzyme-substrate complexes
What does the induced fit model propose?
Active site forms as the enzyme and substrate interact, the enzyme is flexible and moulds around the substrate
How do pH changes affect an enzyme?
Alters amino acid charges so no ES complexes form and may break the bonds in tertiary structure
What’s the name of the bond between two mono nucleotides?
Phosphodiester bond
What are the four types of RNA nucleotides and how do they bond?
Adenine- Uracil
Cytosine- Guanine
How are the two polynucleotide chains bonded together?
Hydrogen bonds
How many complimentary base pairs form the H bonds?
C-G form 3
A-T form 2
What’s DNA responsible for?
Passing genetic information from cell to cell and generation to generation
How many base pairs of DNA are there in a typical mammalian cell?
3.2billion
What are the four requirements for semiconservative replication?
Four types of nucleotides, both strands act as a template, DNA polymerase and source of chemical energy
What breaks down the hydrogen bonds in semi-conservative replication?
DNA helicase
What type of molecule is ATP?
Phosphorylated macromolecules
How does ATP store energy?
Between phosphate groups- bonds have low activation energy, so they release a considerable amount of energy
How is ATP broken down?
Hydrolysis by ATP hydrolase
ATP + H2O = ADP + Pi + E
How is ATP synthesised?
Addition of a phosphate molecule to ADP:
Photophosphorylation
Oxidative phosphorylation
Substrate level phosphorylation
What enzyme catalyses ATP synthesis?
ATP synthase
What is photophosphorylation?
Chlorophyll-containing plant cells during photosynthesis
What is oxidative phosphorylation?
In plant and animal cells during respiration
What is substrate level phosphorylation?
In plant and animal cells when phosphate groups are transferred from donor molecules to ADP
Why is ATP a good short term energy store?
The energy released from ATP is less than glucose, releasing smaller ad more manageable quantities
Hydrolysis of ATP is a single immediate reaction
When is ATP used?
Metabolic processes
Movement
Active transport
Secretion
Activation of molecules
How is ATP used in metabolic processes?
Provide the energy needed to build up macromolecules from their basic units
How is ATP used in movement?
Provides the energy for muscle contraction, it gives the energy for the filaments of muscles to slide past one another and therefore shorten the overall length of a muscle fibre
How is ATP used in active transport?
Energy changes shape of the protein carrier in plasma membranes
How is ATP used in secretion?
Formation of lysosomes necessary for the secretion of cell products
How is ATP used in activation of molecules?
Inorganic phosphate released during the hydrolysis of ATP can be used to phosphorylate other compounds in order to make them more reactive, thus lowering the activation energy in enzyme-catalysed reactions
What are the properties of water?
High specific heat capacity, high latent heat of vaporisation and cohesion and surface tension
Why is high latent heat of vaporisation beneficial in water?
Sweat is an effective means of cooling
Why is cohesion a beneficial property of water?
Pull water up through xylem
When water molecules meet air they are pulled back into the body of water so it doesn’t escape
Why is water important in metabolism?
Hydrolysis
Aqueous mediums for chemical reaction
Photosynthesis
Why is water important as a solvent?
Gases dissolve, wastes dissolve, inorganic ions and enzymes dissolve, this allows transport
Why is evaporation as cooling an important feature of water?
Allows them to control their temperature
Why is water being transparent beneficial?
Aquatic plants can photosynthesise as light can pass through
What percent of jellyfish are water?
98%
What percent of mammals are water?
65%
What are lipids?
Macromolecules containing oxygen, hydrogen and carbon atoms
What is cellulose?
A polymer of long-chain beta glucose joined by glycosidic bonds
What is a carbonyl?
A carbon atom double bonded to an oxygen atom
What is a monomer?
A small basic molecular unit
What are triglycerides?
One molecule of glycerol with 3 fatty acids attached through ester bonds
What are phospholipids?
Lipids found in cell membranes , which is a glycerol bonded with two fatty acids and a phosphate group
What is an ester bond?
A hydroxyl group (OH) and carboxyl group (COOH) bonded together in a condensation reaction
What is starch?
A mixture if two polysaccharides amylose and amylopectin