biological molecules chp 3 (3.1 - 3.3, 3.5 - 3.6) Flashcards
what are the 4 primary elements that make up all living things
- Carbon
- Hydrogen
- Oxygen
- Nitrogen
Phosphorus, sulfur, sodium, potassium, calcium and iron are also important
what is the number of bonds that each of the main biochemical elements can form
- carbon can form 4
- Nitrogen can form 3
- Oxygen can form 2
- Hydrogen can form 1
are hydrogen bonds strong or weak
- singularly they are weak (they break and reform during the movement of water
- if in high amounts can become very strong
what are the characteristics of water
- has an unusually high boiling point
- are small molecules
- liquid at room temperature
^ this is due to the hydrogen bonding within water - water has cohesive properties
- water also has adhesive properties
- Water acts a coolant, helping to buffer temperature changes
- water provides a constant environment for fish and other organisms to live in
Why can ice float on water
- as water is cooled below 4°C the hydrogen bonds fix the positions of H2O molecules further apart than when liquid
^this produces a giant, rigid structure - due to these reasons the same mass of water would take up more space when in solid form
what does cohesive and adhesive mean and why is it an important characteristic of water
- cohesive: molecules of the same species are attracted to one another
- Adhesive: Molecules of one species are attracted to the molecules of another
- It enables the transpiration stream in plants
- Its how straws are able to work
What are some ways that water is important for life
- polar so can dissolve polar substances (the cytosol cells is mainly water)
- acts as medium for chemical reactions
- helps transport dissolved compounds
what is capillary action
- the process by which water can rise up a narrow tube against the force of gravity (due to adhesion and cohesion)
why it is important to maintain constant temperature in cellular environments
- enzymes (needed for most cellular reactions) work most optimally in very narrow range of temps
what elements do lipids contain
carbon, hydrogen and oxygen and phosphorus in same cases
what lipids are liquid and solid at room temperature
- saturated lipids are solid
- unsaturated are liquid
Are lipids polar or non-polar and what does this mean for the molecule
- most lipids are non-polar molecules (with exception of phospholipids)
- ^ lipids are not soluble in water, a polar solvent (oil and water do not mix).
what is the structure of a triglyceride, draw the structure
- Made by combining 1 glycerol molecule with 3 fatty acids
- glycerol is an alcohol
- Fatty acids are carboxylic acids (functional group -COOH) with a hydrocarbon chain attached.
what bonds are found in lipids
ester bonds
esterfication is an example of a condensation reaction
what reaction takes place to form triglycerides, draw the reaction to form triglycerides
- esterification, a condensation reaction
what reaction occurs when triglycerides are broken down
a hydrolysis reaction occurs and 3 water molecules have to be supplied
what is a saturated fatty acid
- A fatty acid with no C=C bonds in its tail
- The carbons are ‘saturated’ with hydrogens
what is an unsaturated hydrocarbon and what are the 2 different denominations
- a fatty acid chain with a double bond is called unsaturated
- If there is just 1 double bond it is mono-unsaturated
- if there are 2 or more its poly-unsaturated
what is a unique characteristic of an unsaturated hydrocarbon
- The presence of double bonds causes the molecule to kink/bend
- ^this means that cannot pack as closely together as there saturated counter-parts
- ^This means that they are liquid at room temperature (less London forces)
what is the structure & function of phospholipids
- one of the fatty acids in a triglyceride is replaced with a phosphate group to make a phospholipid
- modified triglycerides
- they make up plasma membranes
what end of the phospholipid is hydrophobic and which end is hydrophilic
- the phosphate group is hydrophilic (attracts water)
- The fatty acids are hydrophobic (repels water) but mix readily with non-polar solvents
how do phospholipids and water interact
- form a layer on the surface of water
- ^phosphate heads (hydrophilic), fatty acid tails (hydrophobic)
- because of this they are called surface active agents (surfactants for short).
why are phospholipids important for life
- separate aqueous environments by forming plasma membranes
what are sterols
- steroid alcohols
- type of lipid found in cells
what is an example of a sterol
cholesterol
where does the body manufacture cholesterol mainly
in the liver and intestines
where is cholesterol found and what is its function.
- role in the formation of cell membranes
- found in cell membrane
- adds stability to membrane
- regulates fluidity
- ^keeps membranes fluid at low temperatures
- ^stops them becoming too fluid at high temperatures
what are the some roles of lipids
- membrane formation
- hormone production
- electrical insulation necessary for impulse transmission
- important role in energy storage.
how do you identify lipids
name the steps
- by using emulsion test
1) sample is mixed with ethanol
2)resulting solution is mixed with water and shaken
3)if white emulsion forms as layer on top of solution this indicates the presence of a lipid
- if the solution remains clear the test is negative
what are peptides
polymers made up of amino acid molecules
what elements do proteins primarily consist of
carbon, hydrogen, oxygen and nitrogen
what changes in structure to give different amino acids
- R-groups
- ^Different R-groups results in different amino acids
How many amino acids are considered non-essential and why are they considered non-essential
- 5 amino-acids
- our bodies are able to make them from other amino acids.
- obvs all essential just not in out diet
how many amino acids are considered essential and why are they considered essential
9 are essential as they can only be obtained from what we eat
how many amino acids are said to be conditionally essential and why are they considered conditionally essential
6 amino acids are said to be conditionally essential as they are only needed by infants and growing children
how do amino acids join together
draw it
- peptide bond created when amine group and carboxylic acid groups of amino acids interact
^hydroxyl group of COOH reacts with hydrogen in the amine group (NH2)
what bond is found in protiens
peptide bonds are found in protiens
what type of reaction produces a peptide bond
A condensation reaction
this means water is produced during the reaction
when two amino acids join together what is the resultant product called
the resulting compound is called a dipeptide
what is the general structure of an amino acid
what is the name of the compound made up of more than 2 amino acids
a polypeptide
what enzyme catalyses the prodution of polypeptides
peptidyl transferase (present in ribosomes)
can the r groups of different amino acids interact
- they can interact and the interactions result in folding of polypeptides into proteins
what determines the shape of a protein
- the R-groups found in the amino acids in the primary struture of a protein influence its shape
whats the process to seperate amino acids using thin layer chromotographyy
- draw line in penicl, 2cm above bottom edge
- spot solution onto number of spots evenly spaced out (spot, dry, spot multiple times)
- make mark of known solution as comparision
- place plate in jar containing solvent (1cm depth soultion)
- leave until solution near top of plate (solvent front)
- spray plate with ninhydrin (in amino acids present purple/brown
what is thin layer chromatography
a technique used to seperate the individual components of a mixture
whats the formula for an Rf value
what is the primary structure of a protein
- the sequence of amino acids in a chain
^directed by information carried within DNA
what determines the function of a protein
The Structure of the protein determines its function
what bonds are involved in the primary structure of a protein
peptide bonds are the only bonds involved in the primary structure
define secondary structure of a protein
Atoms within amino acids form hydrogen bonds to give alpha-helixs and beta pleated sheets
How are alpha helixs formed
Hydrogen bonds form within amino acid chain pulling it into coil shape
How are beta pleated sheets formed
- polypeptide chains lie parallel to one another then join by hydrogen bonds
- forms sheet like structure
What brings about secondary structure
hydrogen bonds as they form along regions of long protein molecules depending on the amino sequences
What is tertiary structure
- folding of polypeptide into its final shape.
what brings about tertiary structure
- interactions between R-groups
- formation of alpha helix and beta pleated sheets brings R-groups closer so they can interact
^further folding occurs
what elements make up carbohydrates
carbohydrates only contain carbon, hydrogen and oxygen
carbohydrate litrally means hydrated carbon
what is a single sugar unit called
monosaccharide
examples include glucose, fructose and ribose
when 2 monosaccharrides react to form a product what is the product called
A disaccharide
examples include lactose and sucrose
when monosaccharieds are polymerised what is formed
a polysaccharide is formed
examples of this include gylcogen, cellulose and strach
what is the chemical formula of glucose
C6H12O6
due to it having 6 carbons its a hexose sugar
what is the strutuce of a alpha-glucose
what is the structure of a beta-glucose
What properties does the hydroxyl group within a glucose molecule give it
- they are polar and therefore soluble in water due to the hydrogen bonds that form with water
- important because it allows glucose to dissolve in cell cytosol
What reaction takes place to bond 2 glucose molecules together
Draw 2 alpha molecules during a condensation reaction
A condensation reaction takes place
condensation because water is a product of this reaction
what is the bond between 2 glucose molecules called
glycosidic bond (Covalent)
what specific type of bond forms between alpha glucose molecules
- 1,4 glycosidic bonds formed
^called this as bond forms between 1st and 4th carbon
what does fructose + glucose produce
sucrose is formed
which is just sugar
what does galactose + glucose form
lactose is formed
found in milk
what sugar is found in RNA and which is found in DNA
ribose is found in RNA, deoxyribose is found in DNA
what is the collective name for amylose and amylopectin
starch
starch is made up of 2 polysaccharides
what is the structure of amylose
- helix structure
- stabalised with hydrogen bonds within molecule
- is compact
How does glucose bond to form amylopectin
- forms 1,4 glycosidic bonds
- also forms branches with 1,6 glycosidic bonds
how does glucose bond to form amylose
glucose forms 1, 4 glycosidic bond
what does a 1, 6 glycosidic bond look like
in which organisms is starch found
plants
what is the structural and functional equivalent to starch in animals and fungi
glycogen
whats the structual difference between starch and glycogen
glycogen forms more branches than amylopectin, this means is more compact and less space is needed to store it.
why is it important that glycogen is more compact than starch
- due to high levels of branching lots of free ends for glucose to be taken/added on to
^especially prevelant in animals as are actie and have high metabolic demand
what are the key properties of amylopectin and glycogen
they are insoluble, branched and compact. These properties mean they are ideally suited to the storage roles they carry out.
how is glucose stored by plants
stored as starch by plants
how is glucose stored in animals and fungi
stored as glycogen by animals and fungi
what reaction is needed to release glucose for respiration and what is needed for the reaction to take place
- starch or glucose undergo hydrolysis reactions
- requiring addition of water molecules, catalysed by enzymes
what is the only way that beta glucose can join together
the only way beta glucoses molecules can join together is if alternate beta glucose molecules are turned upside down
what polysaccharide forms from beta glucose and what are characteristics of it
cellulose
it is unable to coil or form branches
- what bonds form between cellulose molecules and what is the produces
- how can these products interact with each other
- how can the product of these interactions interact
- cellulose molecules make hydrogen bonds with each other forming microfibrils
- microfibrils join together forming macrofibrils
- ^these combine to produce fibres
what are the characteristics of fibres formed from macrofibrils
strong and insoluble and are used to make cell walls
