Chapter 3// Biological molecules Flashcards
Polar molecule
A molecule w regions of negative charge and positive charge
Solution
A liquid (solvent) w dissolved solids,liquids or gases (solutes)
Cohesion 💧
A property of water in which water molecules are attracted to each other by hydrogen bonding, allowing the molecules to move together
Adhesion 💦
A property of water in which water molecules are attracted to surfaces such as the walls of cells,vessels or tubes
What 3 types of carbohydrates are there and which one of them is not sweet tasting?
Monosaccharides, disaccharides + polysaccharides
Polysaccharides r not sweet to taste
What type of molecule is a monosaccharide
simple sugars : monosaccharides
single, soluble molecule that’s sweet to taste 🍬🍬🍬🍬
Describe the structure of a monosaccharide
Monosaccharides have NO glycosidic bonds and exist as a single ring shape or as a straight chain
Give 3 examples of monosaccharides
Hexoses (6C) e.g. Glucose,fructose,galactose 🍎🥭🍑
Pentoses (5C) e.g.
Ribose, Deoxyribose 🧬
Trioses (3C) e.g.
Glyceraldehyde
What type of molecule is a disaccharide
Complex sugars : disaccharide
Are 2 molecules covalently joined which r soluble and sweet to taste 🍰🍰🍰
Describe the structure of a disaccharide
Disaccharides have a single glycosidic bond and there structure is two rings joined
Give 3 examples of a disaccharide
Sucrose 🍬
Maltose 🍭
Lactose🥛
What type of molecule is a polysaccharide
Complex carbohydrates : polysaccharides
Are many molecules covalently joined to each other
Polysaccharides r insoluble + NOT sweet
Describe the structure of a polysaccharide
Polysaccharides have many glycosidic bonds and exist as long chains which may be branched + coiled, making them v compact
Covalent bond
A strong chemical bond formed by sharing one or more e- between two atoms, creating a molecule
Glycosidic bond
A covalent bond formed when two carbohydrate molecules are joined together by a condensation reaction
Monomer
A single small molecule that may combine w other monomers to build up larger molecules called polymers
Polymer
A large molecule built up from many similar monomers joined together by covalent bonds to form a chain or branched chain
Condensation
A chemical reaction where 2 molecules r joined together w a covalent bond forming a larger molecule and releasing 1 molecule of water 💧
Hydrolysis
A chemical reaction where the covalent bond between 2 molecules is broken w the addition of a water molecule, separating the 2 molecules
Give 3 examples of monosaccharides + there function
Glucose (6C) = source of energy as easily hydrolysed; transported in the blood of animals
Ribose (5C) = part of all types of RNA + ATP molecules, so it’s an important part of protein synthesis
Deoxyribose (5C) = part of DNA for inherited information
Explain how hydrogen bonds form between water molecules
Oxygen and hydrogen share electrons unequally when they bond.
The oxygen has a slight -ve charge and the hydrogen atoms have a slight +ve charge.
This polarity means water molecules r attracted to each other cuz the slightly +ve pole around the hydrogen atoms bonds to the slightly -ve pole of the oxygen atoms— forming a HYDROGEN BOND
Explain why water is a polar molecule
Because the oxygen draws e- from the hydrogen atoms this results in unequal sharing of electrons in bonds so
The oxygen has a slight -ve charge 💔
And the hydrogen has a slight +ve charge💚
What elements make up carbohydrates ?
C, H + O
🥖🥞🥔🥐🍞🥯
What elements make up lipids?
C, H + O
🧀🍳🥑🥥🍮
What elements make up proteins?
C, H, O, N + S
🥩🍖🍗🥓🌭
What elements make up nucleic acids?
C, H, O, N + Phosphorus
Function of glucose (6C) in organisms
Glucose (6C monosaccharide) = source of energy as easily hydrolysed; transported in the blood of animals
Function of ribose (5C) in organisms
Ribose (5C monosaccharide) = part of all types of RNA + ATP molecules, so it’s an important part of protein synthesis
Function of deoxyribose (5C) in organisms
Deoxyribose (5C monosaccharide) = part of DNA for inherited information
Function of maltose in organisms
Maltose (disaccharide) = energy store in plants
Function of sucrose in organisms
*bonus if u name monosaccharides it’s made of
Sucrose (disaccharide made of glucose+ fructose)
= energy storage in some plants transported in phloem
Function of lactose in organisms
*bonus if u name monosaccharides it’s made of
Lactose (disaccharide made of glucose+ galactose)
= the sugar found in milk provides nutrients for young mammals 🦙🐈🦘
Important features of monosaccharides
Small + soluble
Important features of polysaccharides
Large complex molecules which are stable + insoluble
Function of starch+ glycogen in organisms
Starch + glycogen (polysaccharides)
= energy storage in plants (starch)
energy storage in animals (glycogen)
Function of cellulose in organisms
Cellulose (polysaccharide)
= structural + v strong so forms main component in plant cell walls
Which properties of water make it an important component of the blood
- high specific heat capacity + high latent heat of vaporisation= hard to heat so maintains optimum body temp for reaction
- good solvent = important molecules such as glucose can dissolve n be carried in the blood + most biological reactions take place in solution
- water is a reactant in loads of important chemical reactions (hydrolysis reactions)
Difference between high specific heat capacity vs. High latent heat of vaporisation
High specific heat capacity is the energy required to heat water (raise its temp) = important as water is hard to heat meaning it maintains optimum temp for reactions
Whereas
High latent heat of vaporisation is the energy required for a substance to change state= important as water acts as a coolant, it takes a lot of energy to change state so e.g. when sweat evaporates it cool skin
Give 2 reasons why the high specific heat capacity of water is beneficial to organisms
water doesn’t experience rapid temperature changes which means
- it acts as a good stable habitat for organisms to live in
- it acts as a coolant in the blood, keeping a constant body temp
Meaning of coolant
Used to remove heat from something
What is a indirect energy source + give an example
An indirect energy source is one that can be stored n broken down to release energy
E.g. GLYCOGEN
N.b. Glucose is a DIRECT energy source= used straight away not stored
What sugar is present in RNA nucleotides?
RIBOSE (a pentose monosaccharide)
What is the difference between ribose n deoxyribose?
Deoxyribose lacks 1 oxygen atom whereas ribose has it
What monosaccharides make up the disaccharide maltose
Alpha glucose + alpha glucose
Maltose is found in germinating seeds
What monosaccharides make up the disaccharide sucrose
Alpha glucose + fructose
Sucrose is found in sugar cane
What monosaccharides make up the disaccharide lactose
Alpha glucose + beta galactose
Lactose is found in milk
What is a polysaccharide
Large polymers formed of many monosaccharides held together by glycosidic bonds formed thru condensation reactions
What is the difference between amylose and amylopectin
Both are starch molecules however amylose has only 1,4 glycosidic bonds whereas amylopectin has 1,4 and 1,6 glycosidic bonds
In amylopectin, how often do 1,6 glycosidic bonds form ?
In amylopectin 1,6 glycosidic bonds form once every 25 glucose subunits
Both glycogen and amylopectin are storage molecules, however why is glycogen arguably better?
Glycogen forms more branches than amylopectin, meaning it’s more compact so less space is needed for it to be stored
Give 3 similarities between amylopectin and glycogen
- both insoluble
- 1,4 + 1,6 glycosidic bonds
- both branched
- both compact
Why is glycogen easily broken down in the body ?
Because glycogen, as a result of branching, has many free ends where glucose molecules can be added or removed = this speeds up storing + releasing glucose molecules required by the cell
What glucose is glycogen made of ?
Glycogen is a polymer of alpha glucose molecules
What glucose is cellulose made of ?
Cellulose is a polymer of beta glucose molecules
How are microfibrils, macrofibrils and fibres formed in a cellulose molecule
H bonds form between the adjacent cellulose chains forming MICROFIBRILS which combine together to form MACROFIBRILS which combine to make FIBRE
These fibres r strong 💪 + insoluble which is why cellulose forms the main component of cell walls
Describes how beta glucose molecules r joined together in cellulose
Cellulose is made from beta glucose molecules joined together by condensation reactions to form glycosidic bonds. However, alternate beta glucose molecules r inverted cuz otherwise the hydroxyl (-OH) groups r too far apart to react. Because of this cellulose is a straight chain w many -OH groups on the outside
How are triglycerides formed?
Triglycerides form from ESTERIFICATION = a condensation reaction between fatty acids + glycerol forming an ester link/bond between each molecule and 3 molecules of water (one molecule for each ester link)
What’s the difference between a saturated vs. unsaturated fat
Saturated fats have NO C=C DOUBLE BONDS
Whereas unsaturated fats have one or more C=C DOUBLE BONDS ( the presence of double bonds causes the molecule to kink/bend meaning they can’t pack closely together so they’re usually oils not fats)
What is a monounsaturated fat
A unsaturated fat with only one double bond between carbon atoms
What is a polyunsaturated fat
A unsaturated fat w more than one double bond between carbon atoms
What are phospholipids
They’re modified triglycerides which contain phosphorus along w C,H + O
one of the fatty acids in a triglyceride is replaced w a PHOSPHATE
(phosphate ions r -ve so dissolve in water)
this phosphate joins w the glycerol creating a HYDROPHILLIC END (charged heads)
the remaining 2 fatty acids form the HYDROPHOBIC ENDS (non-polar tails)
What are sterols?
Steroid alcohols = a type of lipid
4C ring structure
HYDROPHILLIC hydroxyl (-OH) group = polar end which dissolves in water
Rest of molecule hydrophobic
Where is cholesterol manufactured in the body?
Cholesterol is manufactured in the liver + intestines
What is cholesterol and name 4 of its functions
Cholesterol is a sterol= a lipid 4C ring structure steroid alcohol w a -OH HYDROPHILLIC group
Important role in:
🧀producing vitamin D
🧀producing steroid hormones
🧀producing bile
🧀providing STABILITY TO CELL MEMBRANES
Name roles of lipids due to their non-polar nature
- membrane formation + creation of hydrophobic barriers
- hormone production
- electrical insulation necessary for impulse transmission
- waterproofing e.g. birds feathers + plant leaves
Lipids, esp. triglycerides play an important role in long-term energy storage which provides :
- thermal insulation to reduce heat loss e.g. in penguins
- cushioning to protect vital organs such as heart + kidneys
- buoyancy for aquatic animals like whales
How does one test for lipids?
EMULSION TEST = mix lipid sample w an organic solvent e.g. ethanol, next add water and shake. If a white emulsion forms a layer on top it indicates the presence of a lipid
If it remains clear = test negative
R group (residual group)
A side chain that acts as a functional group as it helps to determine the internal bonds + the shape/function of the polypeptide
Peptide bond
A covalent bond that forms when 2 amino acids r joined by a condensation reaction w the loss of 1 water molecule 💧
How can a peptide bond be broken?
A peptide bond can be broken by a HYDROLYSIS reaction 💦
Polypeptide
A polymer of amino acids each joined to the other by a peptide bond
Dipeptide
2 amino acids held together by a peptide bond
Amino acids all have the same general structure, what is it?
- a carboxyl group (-COOH)
- an amino group (-NH2)
__ all attached to a carbon atom__
+ an R group (residual/variable group) which is unique to each individual amino acid
What is the smallest amino acid + what is it’s r group?
Glycine
It’s r group is a hydrogen atom
All amino acids contain the elements _ _ _ _ and some contain _
All amino acids contain the elements
Carbon, oxygen, hydrogen + nitrogen
+ some contain SULFUR
Explain what is involved in the primary structure of a protein 🔴
🔴
The primary structure is the sequence in which the amino acids r joined=
•only involves PEPTIDE BONDS•
> this sequence influences how the polypeptide folds to give its final shape
Explain what is involved in the secondary structure of a protein 🔵
🔵
In the secondary structure polypeptide chain don’t remain flat, they coil=
•as a result of HYDROGEN BONDING•
> where/how the H bonds form depends on the amino acid sequence of the protein
Either
ALPHA HELIX
Or
BETA PLEATED SHEETS
In secondary structure how do the H bonds form in an alpha helix
In alpha helix the H bonds form between amino acids in one part of the chain to those a little further down the chain
In secondary structure how do the H bonds form in beta pleated sheets
In beta pleated sheets the H bonds connect to the adjacent pleated sheet
Explain what is involved in the tertiary structure of a protein 🌕
🌕
In the tertiary structure folding of the protein into its final shape occurs thru interactions between R groups
These interactions include:
⚠️hydrogen bonds= these r the weakest of the bonds formed
⚠️ hydrophobic/hydrophillic interactions= weak interactions between polar + non-polar R groups
⚠️ionic bonds= these r stronger than H bonds n form between oppositely charged R groups
⚠️disulfide bonds= covalent + the strongest bonds, only form between R groups that contain sulfur atoms
Not all proteins have QUATERNARY STRUCTURE, but which ones do ?
Proteins that r made of more than one polypeptide chain have QUATERNARY STRUCTURE
Conjugated proteins
Conjugated proteins r GLOBULAR proteins which contain a non-protein component called a PROSTHETIC group
What are proteins without prosthetic groups called
Proteins without prosthetic groups r called SIMPLE PROTEINS
Give an example of a prosthetic group
HAEM prosthetic group found in the conjugated protein haemoglobin
What happens to the RNA molecules after protein synthesis?
After protein synthesis the RNA molecules are degraded in the cytoplasm
The phosphodiester bonds r hydrolysed + the RNA nucleotides r released and reused
Properties of ATP
- small= moves easily into + out of cells
- water soluble = energy requiring processes happen in aqueous environments
- releases energy in small quantities
- easily regenerated = can be recharged w energy
What is meant by the phrase ‘ATP contains bonds between phosphates w intermediate energy’
Bonds w intermediate energy between phosphates means the energy is large enough to be useful for cellular reactions but not so large that energy is wasted as heat
What enzyme catalyses the formation of peptide bonds (found in ribosomes)
Peptidyl transferase
What is the difference between ATP and DNA
In ATP the base is always adenine and it has 3 phosphate groups instead of one
