Topic 1 - Biological molecules Flashcards
What is a monomer
A molecule which can be repeated to for a larger molecule (polymer)
What is a polymer
A long chain of monomers bonded together
What are carbohydrates made from
Carbon, hydrogen and oxygen
What is a monosaccharide
A simple sugar made from carbon, hydrogen and oxygen
What are 3 examples of monosaccharides
Glucose, fructose and galactose
What are isomers
Have the same molecular formula but a different structure
What are the two isomers of glucose
Alpha glucose (Carbon 1 has the H at the top and the OH at the bottom) and Beta glucose (Carbon 1 has the OH at the top and the H at the bottom)
What are disaccharides
Two monosaccharides bonded together with a glycosidic bond
What is condensation
Forming polymers and releasing a water molecules
What is hydrolysis
Breaking down polymers through the addition of water (Hydro - water, Lysis -splitting)
What are 3 examples of disaccharides
Maltose = alpha glucose = alpha glucose
Sucrose = glucose + fructose
Lactose = glucose + galactose
What is a polysaccharide
Three or more monosaccharides bonded together with glycosidic bonds
What are 3 examples of polysaccharides
Starch, glycogen and cellulose
What is the monomer for cellulose and where is it found
Beta glucose, found in plants for structural support
What is the monomer of starch and where is it found
Alpha glucose , found in plants for energy storage
What is the monomer found in glycogen and where is it found
Alpha glucose (known as animal starch) , found in animals for storage
Describe the structure of starch
Amylose - tight spirals
Amylopectin - branched
How does the structure of starch link to its function
Insoluable - doesn’t affect water potential
Large - doesn’t diffuse out cells
Amylose - very compact so can store more energy in a small space
Amylopectin - Branched so can be more easily hydrolysed by enzymes
Describe the structure of glycogen
Branched
How does the structure of glycogen link to its function
Insoluable - doesn’t affect the water potential
Large - doesn’t diffuse out of cells
Branched - Can be hydrolysed into glucose for respiration easily
Describe the structure of cellulose
Parallel links held which glycosidic bonds, chains held together by hydrogen bonds
How does the structure of cellulose link to its function
Parallel chains - increased strength
Hydrogen bonds - lots of weak bonds are overall strong which helps with structure
Exerts inward pressure to help with rigidity
What are the two main types of lipids
Triglycerides and phospholipids
What is the structure of a triglyceride
Glycerol and 3 fatty acids with a ester bond
What is the formula for a fatty acid
RCOOH
What does the R and COOH represent in RCOOH
R - hydrocarbon chain
COOH - carboxyl group
What does monounsaturated mean
There is one carbon carbon double bond
What can affect the type of fatty acid
the length of the hydrocarbon chain (4-24) and whether it is saturated or unsaturated
What does polyunsaturated mean
There is 3 or more carbon carbon double bonds
What type of bonds are found in lipids
Ester bonds
How are triglycerides adapted to store energy + an example
Lots of hydrogen bonds - stores lots of energy
lots of hydrogen vs oxygen - can release water when oxidised
Hydrophobic - don’t affect water potential
Eg. oils in seeds, desert animals
How are triglycerides adapted to insulate + an example
Slow conductors of heat and stored under the skin to help retain body heat
Electrical insulators
Eg. Seals have layers of fat, neurones myelin sheath
How are triglycerides adapted to physically protect + an example
Cover delicate organs to protect against external forces
Eg. Kidney and Heart
How are triglycerides adapted to waterproof + an example
Lipids are insoluable so will repel water so cover feathers, plants and insects
Eg. waxy cuticle on leaves and insects
What is the structure of phospholipids
Glycerol, phosphate and two fatty acids held together ester bonds
Where are phospholipids used
Cell surface membrane / membranes
Describe the head and tail of phospholipids
The head (phosphate) is hydrophilic whilst the tail (fatty acid) is hydrophobic
How are membranes formed with phospholipids
The heads are attracted to the extra cellular fluid and the cytoplasm (containing water) and for a bi-layer
Describe the test for lipids
- Add ethanol
- shake
- add water
- If lipid present a milky white emulsion will be formed
What is benedicts solution
Copper(ii) sulfate
Describe the test for a reducing sugar
- Add 1ml of benedict’s to 1ml of substance
- Heat using a water bath
- colour change from blue to green yellow orange red based on how much sugar (blue to red)
Describe the test for a non reducing sugar
- Add 0.6ml of HCl and heat to hydrolyse the glycosidic bond
- Add 0.5ml of sodium hydrogen carbonate to neutralise and test with indicator paper
- Add 1ml of benedict’s and heat
- Colour change from blue to red
Why does benedicts change colour
Reducing sugars donate an electron so copper(ii) sulfate becomes copper(i) sulfate which is a red ppt.
Describe the test for starch
- Add 2cm^3 of sample into a test tube with 2 drops of iodine
- colour change from orange to blue-black
Describe the structure of an amino acid
- Carbon is the central atom
- Amine group (H2N)
-Carboxyl group (COOH) - Hydrogen
- R group
What is formed when two amino acids join together
A dipeptide
What does the hierarchy of proteins contain
Primary, secondary, tertiary, quaternary
What bonds are found in dipeptides
Peptide bond
What is the primary section of the protein hierarchy
A linear sequence of amino acids determined by a gene
What is the secondary section of the protein hierarchy
Folding caused by weak hydrogen bonds (between N, O, F).
What structures are formed in the secondary layer f the protein hierarchy
A-helix, a coiled structure
Beta-sheets, found in structural proteins such as keratin and collagen
What is biuret’s solution made from
Sodium hydroxide and copper(ii) sulphate
Describe the test for proteins
1.Add equal volumes of sodium hydroxide and sample
2.Add dilute copper sulfate
3. Colour change from blue to purple
Why does biuret’s solution turn blue
The copper attaches to the peptide bond
What is the tertiary structure of the protein hierarchy
Further folding caused by interactions between different R groups.
What types of bonding occurs in the tertiary structure
-Disulfide bridges
-Ionic bonds
-Hydrogen bonds
What is the quaternary structure of a protein
Two or more polypeptides bonded together.
May contain prosthetics
What is meant by a prosthetic in the quaternary structure
A non protein associated to the polypeptides
What are examples of quaternary proteins
Haemoglobin - 4 polypeptides associated with a haem group
What type of proteins are formed from the tertiary structure
Globular proteins
What type of proteins are enzymes
Globular proteins
What is an enzyme
A biological catalyst
What is a catalyst and how does it work
A catalyst increases the rate of reaction by decreasing the activation energy.
-Enzymes are not used up or changed during a reaction
Describe the graph between temperature and rate of reaction
Initially the rate o reaction increases
However past the optium the rate rapidly decreases
What 4 factors affect enzyme rate of reaction
-Temperature
-pH levels
-Enzyme concentration
-Substrate concentration
Describe the graph between pH and rate of reaction
Initially the rate increases until it reaches the optimum at which is decreases again
Describe the graph between enzyme concentration and rate of reaction
Initially the increase in the rate of reaction and the enzyme concentration is directly proportional
however past a certain point the rate of reaction remains constant
Describe the graph between substrate concentration and rate of reaction
Initially the increase in the rate of reaction and the substrate concentration is directly proportional
however past a certain point the rate of reaction remains constant
Explain the graph between pH levels and rate of reaction
Less H+/OH- ions as you reach the optimum
so less bind to the structure of the protein
so less of the bonds are disturbed
so increased rate of reaction
Explain the graph between temperature and rate of reaction
The kinetic energy increases
therefore more successful collisions
therefore more E-S complexes formed
Therefore increased rate of reaction
Explain the graph between enzyme concentration and rate of reaction
Directly proportional as long as there in an excess of the substrate since there are still unoccupied
- Reaches a constant where the substrate becomes the limiting factor
Explain the graph between substrate concentration and rate of reaction
Directly proportional as long as there in an excess of the enzyme since there are still substrates to be broken down
- Reaches a constant where the enzyme becomes the limiting factor since its reached its maximum capacity
What are the two types of inhibitors
Competitive and noncompetitive
How does a competitive inhibitor work
It has a SIMILAR shape to the substrate so can bind to the active site of the enzyme
How does a non-competitive inhibitor work
It binds to the allosteric which causes the shape of the active site to change so substrate shape will no longer be complementary
What do inhibitors do
Decrease the rate of reaction
What is the monomer in polynucleotides
Mononucleotides
What are 3 examples of poly nucleotides
DNA, RNA, ATP
What are nucleotides made from
Phosphate group, pentose sugar and nitrogen containing base
What is the pentose sugar in DNA
deoxyribose
What nitrogenous bases pair together in DNA
Adenine - Thymine
Cytosine - Guanine
What bond is formed between the phosphate and pentose sugar
phophodietser
what bond holds together bases
hydrogen bonds
what is it called when multiple phosphate and pentose sugar bond together to form a polynucleotide strand
sugar - phosphate backbone
In what way do the poly nucleotide strands arrange themselves in the double helix structure
antiparallel
what is the structure of DNA
double helix
When does DNA replication occur
Mitosis and meiosis
What are the 4 requirements for DNA replication to occur
-Free nucleotides with the bases adenine, thymine, cytosine and guanine
-Chemical energy source in the form of ATP
-Enzymes such as DNA helicase and DNA polymerase
-An original double stranded DNA to act as a template
what is the first step of DNA replication
DNA helices spilts the two strands of DNA apart by breaking the hydrogen bonds between nitrogenous bases
what is the second step of DNA replication
The free nucleotides bind to the complementary bases and form new hydrogen bonds
what is the third step of DNA replication
DNA polymerase forms phosphodiester bonds between the sugars and phosphates of the new strands
what is the last step of DNA replication
The DNA polymerase only attaches to the 3prime side so works in one direction , therefore one strand is being continuously formed whilst the other is formed in sections
What is the DNA replication model known as
Semi conservative model
Why is the DNA replication model known as the semi conservative model
Since the new strand is made from one stand of the original and one stand which is new
What nitrogenous bases pair together in RNA
-Adenine - Uracil
-Guanine - Cytosine
What is the pentose sugar in RNA
ribose
How many hydrogen bonds form between adenine and thymine
2
How many hydrogen bonds form between cytosine and guanine
3
What were the two main theories surrounding DNA replication
Conservative, semi-conservative
What were the stages in the proof of the semi-conservative model
1)Growing bacteria in N14
2)Growing bacteria in N15
3)Transfer part of original n15 to n14 and measure each generation
4 Spin in centrifuge
What part of the test tube was the n14 found in and why
At the top seeing as it is a lighter isotope
What part of the test tube was the n15 found in an why
Bottom since it is the heavier isotope
After one generation where was the DNA molecule found and why
In between the two original placements since it has one stand from each isotope
What would the make up after 2 generations be
one strand of n14 and one strand with half
What is the structure of ATP
-Adenine
-Ribose sugar
-3 phosphates
What are two differences between ATP and DNA
ATP has only an adenine nitrogenous base and has 3 phosphates instead of 1
How does ATP release energy
The bond between the last phosphate has a low activation energy and releases energy when it is broken
What type of reaction can ATP under go
A reversible reaction
When hydrolysed what does ATP break up into
ADP and an inorganic phosphate (and energy released)
Why is ATP known as an immediate source of energy
It releases small amount of energy in one go so is a short term energy source camped to carbohydrates of fats
What enzyme is used during the hydrolysis of ATP
ATP hydrolase
What enzyme is used during the synthesis of ATP
ATP synthase
Why is it good that ATP is soluble
So it can travel in the cytoplasm
In what 3 ways is energy supplied for the synthesis of ATP
-light dependant stage of photosynthesis
-aerobic respiration
-anaerobic respiration/glycolysis
What are the 5 uses of ATP (MAASS)
Movement (muscle contraction)
Activating molecules
Active transport
Synthesis of macromolecules
Secretion
What does ATP stand for
Adenosine triphosphate
What charges does a water molecules have and what does this make it
The oxygen is delta - and the hydrogens are delta positive so the molecule is DIPOLAR
What type of bonding is formed in water molecules
Hydrogen bonding
Where do hydrogen bonds form
Between the positive H on on water molecule and the negative O on another
What is the specific heat capacity of water and what is it caused by
High specific heat capacity caused by lots of hydrogen bonding
What is a benefit of the high specific heat capacity of water
It acts as a buffer against sudden temperature change (beneficial for aquatic life)
What is the latent heat of vaporisation of water
High
Why is high latent heat of vaporisation of water beneficial
Effective when cooling the body through sweating (Body heat is used to evaporate the water)
Why is the cohesion of water beneficial
Can be pulled up a tube such as the xylem vessel
Why is surface tension beneficial
Allows small bugs to travel on the surface of water
What is the importance of water in metabolism
-used in hydrolysis
-chemical reactions take place in an aqueous medium
-used in photosynthesis
What substances can be dissolved by water
Gases(oxygen and carbon dioxide), waste(urea and ammonia), inorganic ions (amino acids, monosaccharides), enzymes
What are 3 examples of important inorganic ions
Phosphate (in dna), hydrogen (determining pH), Sodium (transporting glucose in co-transport)
Why are iron ions important
Part of haemoglobin and binds to oxygen
Why are calcium ions important
Used in muscle contraction
Why are sodium ions important
Used in the cotransport of glucose and amino acids in the ileum
Why are phosphate ions important
the basis of dna and rna nucleotides and provide energy in ATP
What is the roles of ions dictated by
Their properties
