Biological molecules (Topic 1) Flashcards
describe a biochemical test to show a solution contains non-reducing sugars
- perform the reducing sugar test if negative then
- heat with acid and neutralise
- heat with benedict’s solution
- red precipitate formed if present
explain the arrangement of phospholipids in a cell surface membrane
hydrophobic tails point away from water and hydrophilic heads point to water
describe how an ester bond is formed in a phospholipid molecule
through a condensation reaction between glycerol and fatty acid
state the property of water that helps prevent temperature increase in a cell
high specific heat capacity
how does waters high specific heat capacity prevent temperature increase in a cell
it buffers change in temperatures
explain how a phosphodiester bond is formed between two nucleotides within a DNA molecule and what catalyses the reaction
condensation reaction between phosphate and deoxyribose that is catalysed by DNA polymerase
describe how the separation of the two DNA stands occurs
•DNA helicase
•breaks H bonds between base pairs
where is amylase produced
pancreas
salivary glands
where is maltase produced
small intestine
why does an enzyme only catalyse one reaction
- active site of enzyme has specific shape
- only the substrate can bind to it
- to form an enzyme substrate complex
describe how the structure of glycogen is related to its function (4 marks)
- branched so compact
- polymer of glucose so easily hydrolysed
- branched so faster hydrolysis
- insoluble so not easily lost from cell
what enzyme breaks bonds between amino acids?
endopeptidase
all carbohydrates contain the elements….
carbon
hydrogen
oxygen
glucose is a _____ sugar
hexose
the two types of glucose are….
alpha
beta
which type of glucose has the OH group joined above the H?
beta
which type of glucose has the OH group joined below the H?
alpha
how are disaccharides formed?
by joining 2 monosaccharides through a condensation reaction
what bonds are formed when a disaccharide is formed?
glyosidic
what is released when disaccharides are formed?
water
sucrose is formed from…
glucose and fructose
maltose is formed from…
two alpha glucose
lactose is formed from…
glucose and galactose
what is the test for reducing sugars?
- heat sample with benedicts reagent
- sample forms brick red precipitate
- if reducing sugar present
polysaccharides form when…
more than two monosaccharides are joined by a condensation reaction
what is amylose formed from?
lots of alpha glucose molecules
polysaccharides are broken down by…
hydrolysis
plants store excess glucose as….
starch
when a plant needs more energy it….
breaks down starch to release glucose
starch is a mixture of two polysaccharides which are:
amylose
amylopectin
is starch soluble in water?
no
why is it important for starch to be insoluble in water?
so that it doesn’t affect water potential and water doesn’t move into the cells via osmosis causing them to swell
animals store excess glucose as…
glycogen
what are the benefits of glycogen being branched?
stored glucose can be released quickly
what is the benefit of glycogen being compact?
good for storage
cellulose is made of….
long, unbranched chains of beta glucose
cellulose chains are held together by __ bonds. to form strong fibres called….
hydrogen bonds
microfibrils
cellulose provides….
structural support for cell walls
what is the test for starch?
- add iodine dissolved in potassium iodide solution to the sample
- if starch is present sample turns from browny-orange to blue-black
lipids are made from…
proteins and carbohydrates
triglycerides contain…
glycerol
3 fatty acids
fatty acids have ____ tails and ______ heads
hydrophobic
hydrophilic
saturated fatty acids don’t have….
double carbon bonds
unsaturated fatty acids have….
which cause….
double carbon bonds
the chain to kink
what kind of reaction forms triglycerides?
condensation reaction
phospholipids consist of…
a phosphate group
glycerol
2 fatty acids
2 properties of triglycerides…
- insoluble in water
- long hydrocarbon tails with lots of chemical energy
what is the emulsion test for lipids?
- shake substance with ethanol then pour it into water
- lipid will show up as a milky solution
proteins are made of….
one or more polypeptides
amino acid functional groups are
NH2 and COOH
dipeptides and polypeptides are formed by…
condensation reactions
the bonds between amino acids are called…
peptide bonds
primary protein structure is…
the sequence of amino acids in the polypeptide chain
secondary protein structure is…
hydrogen bonds form between amino acids to make alpha helix or beta pleated sheet
tertiary protein structure is…
hydrogen bonds, ionic bonds and disulfide bridges form to fold and coil them further
quaternary protein structure is….
the way polypeptide chains are assembled together
what is the test for proteins?
- add NaOH solution TO THE SMAPLE
- add copper (II) sulfate solution
- if present solution turns purple
enzymes are…
biological catalysts
what are the models for enzyme action?
lock and key
induced fit
how can you measure enzyme activity?
how fast product is made
how fast the substrate is broken down
what factors effect enzyme activity?
temperature
pH
substrate concentration
enzyme concentration
what are competitive inhibitors?
they bind to the active site of the enzyme so no substrate can bind to the enzyme
what are non competitive inhibitors?
molecules that fit onto the molecule away from the active site causing a positive change in the enzymes active site
nucleotide consist of…
a phosphate
pentose sugar
nitrogenous base
nucleotide chains join together to form_______ via a ________ reaction. This forms a ________ bond. The chain of phosphates and sugars is known as the ______ backbone
polynucleotides
condensation
phosphodiester
sugar-phosphate
the sugar in RNA is…
ribose
the sugar in DNA is….
deoxyribose
how many hydrogen bonds form between adenine and thymine?
2
how many hydrogen bonds form between cytosine and guanine?
3
polynucleotide strands run _____ to each other
anti parallel
DNA is replicated by…..
semi-conservative repliaction
the 4 steps of DNA replication are:
- DNA helicase breaks H bonds, separating strands
- Free nucleotides are attracted by complementary bases
- Condensation reaction catalysed by DNA polymerase
- Two strands are produced
in the experiment which proves semi-conservative replication light nitrogen…
settles at the top of the tube
in the experiment which proves semi-conservative replication heavy nitrogen…
settles at the bottom of the tube
in the experiment which proves semi-conservative replication the tube…
has one band midway in the tube
give the 5 properties of water….
- its a metabolite
- has high latent heat of vaporisation
- resists temp changes
- is a good solvent
- strong cohesion between water molecules
ATP consists of…
an adenine base
a ribose sugar
3 phosphate groups
give the reaction for resynthesis of ATP
ADP + P –> ATP
catalysed by ATPase
give the equation for when energy is broken down
ATP –> ADP + P
catalysed by ATP hydrolase
