the final battle part 2 Flashcards
what kind of reaction forms a glycosidic bond
condesation between carbon 1-4
what breaks a glycosidic bond
hydrolysis
which two monosaccharides make lactose
galactose and B glucose
which two monosaccharides make sucrose
fructose and glucose
describe the bonding in amylose
alpha glucose molecules joined by 1-4 glycosidic bonds
the angle of these bonds means it is a long chain of glucose which twists into a helix
these are further stabilised by hydrogen bonding within the molecule
why does the bonding of amylose aid its function
its function is as a storage molecule in plants
the straight chain with no kinks means it is more compact and takes up less space in the plant and is also
less soluble
describe the bonding of amylopectin
glycosidic bonds between carbon 1-4 with alpha glucose BUT ALSO
some glycosidic bonds between carbon 1-6 between two glucose every 25 subunits
this gives it a branched structure so takes up more space than amylose
what is the function of amylopactin
another energy source in plants
describe the structure of glycogen
animal/fungi equivalent to starch
more branched but is compact and takes up less space so is an ideal storage molecule
how does glycogens structure make it an ideal storage molecule
branched mean there are free ends for glucose molecules to be added or removed
describe the structure of cellulose
made up of beta glucose monosaccharides
which cant join in same way as alpha as hydroxyl groups on carbon 1-4 too far apart to interact so…..
beta glucose molecules are inverted.
This means Bglucose polysaccharides like cellulose can’t coil or form branches so forms a straight chain molecule
what forms when cellulose molecules make hydrogen bonds with each other
forms microfibrils»»>which join to make macrofibrils
macrofibrils make fibres which are STRONG INSOLUBLE and used to make CELL WALLS
are lipids soluble
no they are non-polar molecules
what are triglycerides made up of
1 glycerol + 3 fatty acids
glyceride is an alcohol
fatty acids belong to carboxylic acids -COOH
what kind of reaction forms triglycerides
esterfication reaction which forms an ester bond which forms 3 water molecules
hydroxyl group between glycerol and fatty acid interacts
what is a saturated fatty acid
no double bonds and maximum number of bonds with hydrogen atoms
what is an unsaturated fatty acid
double bonds
if 1 double bond = monounsaturated
more than 1 is polyunsaturated
double bond causes kink so cant pack densely
this is usually liquid at room temp like oil
what is the structure of phospholipids
made up of inorganic phosphate head PO4 3-
two fatty acid tails
one of the fatty acids from a triglyceride molecule is replaced with a phosphate group to make a phospholipid
properties of phospholipids
they are surfacants (form layer if on top of water)
they make up membranes in a bilayer structure and separate an aqueous environment in the cells
what are sterols/ steroid alcohols
a lipid but not fats or oils
-they are complex alcohols w/ 4 carbon ring structure with a hydroxyl OH group at one end which is hydrophillic, polar and soluble
what is an example of an important sterol
choleSTEROL made in liver and intestines
important as its positioned between phospholipids w/ hydroxyl group at periphery of membrane
it maintains membranes stability and fluidity
what is the role of lipids
> membrane formation and creation of hydrophobic barriers >hormone production >electrical insulation eg) myelin >waterproofing >cushion vital organs >buoyancy in whales >thermal insulation in penguins >long term energy storage (triglycerides)
how do amino acids join
when the amine group and carboxylic acid groups connected to central carbon react. (R groups not involved at this point)
>hydroxyl from the carboxyl acid group of one amino acid reacts with a hydrogen from the amine group of another amino acid to form a PEPTIDE BOND.
> water is produced too in this condensation reaction
This compound result is called a DIPEPTIDE
how is a polypeptide formed and which enzyme catalyses this
when many amino acids are joined by peptide bonds
catalysed by peptidyl transferase present in ribosomes (the site of protein synthesis)
what is the primary structure of a protein
the sequence in which amino acids are joined
which is caused by information carried in DNA
this influences how polypeptides fold
only bonds involved are PEPTIDE BONDS
what is the secondary structure of a protein
> hydrogen bonding which may form an alpha helix or beta pleated sheet
what is the tertiary structure of a protein
folding of a protein into its final shape
>can include sections of its secondary structure as coiling or folding of sections of proteins into their secondary structures brings R groups of different amino acids close enough to react so further foldig of these sections occurs.
These can be:
-HYDROPHOBIC/HYDROPHILLIC INTERACTIONS-weak interactions between polar and non-polar R groups
-HYDROGEN BONDS- weakest of bonds formed
-IONIC BONDS- stronger than H bonds and form between oppositely charged R groups
-DISULFIDE BONDS/BRIDGES - Strongest and Covalentbut only between R groups with sulfur atoms in
what is the quaternary structure of a protein
- association between 2 or more individual proteins or subunits (can be identical or different)
- similar interactions to tertiary structure but are between different protein molecules rather than within one molecule.
enzymes have 2 identical subunits
hormones like insulin have 2 different subunits
haemoglobin has 4 subunits with 2 sets of identical subunits
example of a globular protein
insulin
example of a conjugated protein
haemoglobin
catalase
example of a fibrous protein
keratin
collagen
elastin
what is the structure and properties of a globular protein like
- compact and water soluble
- form when tertiary structures folding in a way so hydrophobic R grous on amino acids are on the outside of the protein. (making them soluble)
this aids in their function as insulin needs to be dissolved into the bloodstream
-insulin needs to keep its precise shape too to fit into specific receptors on cell surface membranes.
what is the structure of a conjugated protein
> globular proteins BUT they contain a non-protein prosthetic group. (proteins without this group are called simple proteins)
different types of prosthetic groups:
lipids/carbohydrates combine with proteins so make
glycoproteins or lipoproteins
also metal ions derived from vitamins can form prosthetic groups like Fe2+
describe the structure of haemoglobin
> made from 4 polypeptides with 2 alpha and 2 beta subunits
each subunit contains a prosthetic haem group
the Fe2+ ions can combine reversibly with oxygen
describe the structure of fibrous proteins
> long insoluble molecules due to high proportion of amino acids with hydrophobic R groups in primary structure
quite repetitive amino acid with limited range of A.As
which leads to organised structures which are NOT folded into comlex 3D shapes like globular proteins
describe the properties and function of keratin
> hair skin and nails
hair has fewer bonds making it more flexible than nails
(bonds being strong disulfide bonds)
describe the properties and function of elastin
> fibres that are present in walls of blood vessels and alveoli of lungs
structures give them flexibility to expand when needed
but also return to their normal size
quaternary protein made of many stretchy molecules of tropoelastin
describe the properties and function of collagen
> connective tissue found in skin, tendons, ligaments and nervous system
made up of 3 polypeptides wound together in a long rope like structure
this makes it flexible
use of calcium ions in body Ca2+
nerve impulse transmission
muscle contraction
use of sodium ions Na+
nerve impulse transmission
kidney function
use of potassium ions K+
nerve impulse transmission
stomatal opening
use of hydrogen ions H+
catalysis of reactions
pH determination
use of ammonium ions NH4+
production of nitrate ions by bacteria
use of nitrate ions NO3-
nitrogen supply to plant for amino acid and protein formation
use of hydrogen carbonate ion HCO 3-
maintainance of blood pH
use of chloride ions Cl-
balance positive charge of sodium and potassium ions in cells
use of phosphate ions PO4 3-
cell membrane formation
nucleic acid and ATP formation
bone formation
use of hydroxide ions OH-
catalysis of reaction
pH determination
how are nucleotides joined
joined by condensation reactions to form a polynucleotide
-phoshphate joined on 5C of pentose sugar forms a covalent bond with hydroxyl group on 3C of pentose sugar on adjacent nucelotide
THESE ARE CALLED PHOSPHODIESTER BONDS whch form sugar phosphate backbone and are proken by hydroglysis
what holds the two strands of the double helix together
hydrogen bonds between bases
these 2 parallel strands run in opposite directions and so are antiparallel
each strand in one chain of polynucleotides which coil into a double helix
what does complementary base pairng ensure
-reduces occurance of mutation
-minimise errors in replication
-allows DNA to be copied and transcribed
T with A and C with G
-allows reformation of hydrogen bonds
-conserving genetic information so it is passed onto next generation with accuracy
which enzyme forms phosphodiester bonds
DNA ligase
describe the structure of ATP
-nitrogenous base adenine, pentose sugar and 3 phosphates
difference between structure of atp and dna
3 phosphate groups
nitrogenous base always adenine
properties of ATP and way it acts
not long term energy store due to instability of phosphate bonds
formed in phosphorylation reaction (condensation)
good immediate energy store as is rapidly reformed
hydrolysed into ADP and Pi
structure of ADP compared to ATP
2 phosphates in ADP adenosine DIphosphate
why is DNA replication semi conservative
consists of one old conserved strand and one newly synthesised strand
origional strand acts as template for new strand
what does semi conservative replication ensure?
ensure genetic continuity between generations of cells meaning genetic information is passed from one generation to the next
what is the role of helicase
DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
what is the role of DNA polymerase
DNA polymerases are responsible for synthesizing DNA: they add nucleotides one by one to the growing DNA chain, incorporating only those that are complementary to the template.
20 different amino acids are commonly used for protein synthesis. in this theory we would only need 20 different base combinations
explain the use of the remaining 44 combinations
several triplets/ codons code for 1 amino acid
some codons are used as stop/start
mutations can be silent or not change amino acid
whtat does it mean that the genetic code is degenrate
because a single amino acid may be coded for by more than one codon.
what does it mean that the genetic code is non-overlapping
genetic code does not overlap, meaning that each nucleotide is part of only one codon-a single nucleotide cannot be part of two adjacent codons.
describe how a nucleotide base sequence in a gene is used to synthesise a polypeptide
(transcription and translation)
> DNA/Gene transcribed into mRNA
RNA nucleotides line up with complementary base pairs A-U and C-G on template DNA strand
catalysed by RNA polymerase
translation - where mRNA leaves nucleus to ribosomes
>tRNA molecules bind to mRNA
>anticodons bind to codons
>specific amino acid is attached to tRNA
>there is a formation of a PEPTIDE bond between amino acids (not polypeptide)
what is the role of RNA polymerase
RNA polymerase is an enzyme that is responsible for copying a DNA sequence into an RNA sequence in transcription
what is the role of mRNA
short section of DNA transcribed into messenger RNA which is able to leave the nucleus to be translated at ribosomes ribonucleic acid (not deoxyribose)
what is the role of tRNA
involved in translation of mRNA and has anticodon complementary to codon
what is the role of rRNA
rRNA is in protein synthesis – in binding to messenger RNA and transfer RNA to ensure that the codon sequence of the mRNA is translated accurately into amino acid sequence in proteins.
