Biomolecules Flashcards
What are the primary functions of carbonhydrates ?
They are for fuel/energy (immediate and stored) and for structure (especially in plants).
What are polymers ?
Linked monomers
How is formed a polymer ( polymerization)?
By the removal of water. It is called a dehydration reaction or a condensation reaction.
How are polymers broken down ( depolymerization)?
By adding water, which is called hydrolysis
How is called a carbonhydrate monomer ?
A monosaccharide
How is called a carbonhydrate polymer ?
A polysaccharide
What is the formula for a monosaccharide ?
CxH2xOx
What is the formula for a disaccharide ?
CxH2(x-1)O(x-1)
How can carbonhydrates be drawn ?
As a long vertical chain (fisher projection) or as a ring.
How is called the link between two monosaccharides ?
A glycosidic link/bond
If the OH group on the first carbon sticks upwards, what is its orientation ?
It is beta
If the OH group on the fisrt carbon sticks downwards, what is its orientation ?
It is alpha
How is called the glycosidic bond in maltose (2 glucose monomers) ?
An alpha 1-4 bond/linkage
How is called the glycosidic bond in lactose (1 glucose and 1 beta-galctose) ?
A beta 1-4 bond /linkage
How is called the glycosidic bond in sucrose (1 alpha glucose, 1 fructose) ?
An alpha 1-2 bond/linkage
Of what is made glycogen ?
it is composed of glucose connected by alpha 1-4 bonds and with many branching points of alpha 1-6 bonds. It is found in animals and is stored within liver and muscles.
What is glycogen function ?
A storage for glucose that can quickly be hydrolysed (used up) thanks to its many branching points.
What is amylopectin ?
One of the two polysaccharides that forms starch. It is found in plants. It has the same types of bonds as glycogen but does not have as many branching points.
What is amylopectin function ?
Intermediate-“term” glucose storage.
Found in plants and stored as granules within choloroplast
What is amylose ?
The second component of starch. It is a continuous chain of glucose with an alpha 1-4 bond. It has no branching points.
What is amylose function ?
Long-term storage of glucose
Found in plants and stored as granules within choloroplast
What is cellulose ?
It consists of glucose with beta 1-4 bonds. It causes the chains of glucose to form step-like strands.
What is cellulose function ?
It is a major component of plant cell wall
What is the primary function of nucleic acids ?
To store genetic information.
How is called a nucleic acid monomer ?
A nucleotide
How is called the bond between two nucleotides ?
A phosphodiester bond
Of what is made a nucleotide ?
A phosphate group, a pentose sugar and a nitrogenous base.
What are the two possible pentose sugars found in a nucleotide ?
Ribose or deoxyribose
What is RNA ?
RNA (ribonucleic acid) is a polymer of nucleotides with a ribose pentose sugar.
What is DNA ?
DNA (deoxyribonucleic acid) is a polymer of nucleotides with a deoxyribose pentose sugar.
What are the two purines ?
Adenine (A) and Guanine (G)
What are the three pyrimidines ?
Cytosine (C), Thymine (T) and Uracil (U)
What purines /pyrimidines does DNA have ?
A-T and C-G
What purines /pyrimidines does RNA have ?
A-U and C-G
How many hydrogen bonds does C and G form ?
three
How many hydrogen bonds does A and T/U form ?
two
What is base stacking ?
The stacking up of the different nitrogenous bases to stabilize each other.
What controls the double-stranded nature of DNA ?
Base stacking and hydrogen bonding.
What are characteristics of RNA ?
It is usually single-stranded.
It is considered more fragile than DNA.
What are some of the functions that a protein can have ?
Accelerate certain chemical reactions (enzymatic)
Protection against disease (defensive )
Storage of amino acids (storage)
Transport of substances (transport)
Coordination of an organism’s activities (hormonal)
Response of cell to chemical stimuli (receptor)
Movement (contractile and motor)
Support (structural)
What determines the protein’s function(s) ?
The protein’s structure
How is called the bond between two amino acids ?
A peptide bond
How is called a protein’s monomer ?
An amino acid or a peptide
Of what is composed an amino acid ?
An amino group, an R group side chain and a carboxyl group
How many possible R groups are there for an amino acid ?
20 different R groups
What is an hydrophobic (non-polar) side chain ?
A side chain that contains only C and H.
What is an hydrophilic (polar) side chain ?
A side chain that has an OH, SH or a carbonyl group
What is an acidic side chain ?
A side chain capable of donating a proton
What is an basic side chain ?
A side chain capable of receiving a proton
What is an amphipathic molecule ?
A molecule that has both a polar and a non-polar part.
What are some particularities of glycine ?
It has no stereoisomers, unlike the other amino acids.
It is very flexible
It is smaller than the other amino acids.
What are some particularities of proline ?
Its side chain actually links with its backbone.
It is extremely rigid.
What is a particularity of an amino acid with an hydrophobic side chain ?
It is amphipathic.
Between what is a peptide bond formed ?
Between the amino nitrogen of one amino acid and the carboxyl carbon of the next amino acid.
What is the primary protein structure ?
The written out list of amino acids that exist in the protein from the N to the C terminal.
What is the secondary protein structure ?
The specific folding of the protein. it is determined through the hydrogen bonding interactions between the backbones of the polypeptide chain.
What two types of folds can occur in a protein ?
alpha-helices (coiled tubes) and beta pleated sheets (flat “waves”)
What is the tertiary protein structure ?
The interactions between the side chains of the amino acids in the protein (such as hydrogen bonding, ionic bonds and disulfide bridges).
What is the quaternary protein structure ?
It takes into consideration when more than one polypeptide chain cluster together to form a macromolecule. It is the interaction between those different polypeptide chains that are considered the quaternary structure.
What does an enzymatic protein ?
It binds to a specific molecule and changes it (it is a catalyst).
When does protein denaturation happen ?
When the interactions that cause protein folding are intefered with.
What can influence whether a protein is in its proper structure or not ?
Temperature
pH changes
Salt concentrations
Solvent used
Is denaturation reversible ?
Yes, it usually is since the primary structure is intact.
Lipids consist primarily of what moleculels ?
Of carbon and hydrogen molecules (hydrocarbons).
What is the general formula of fatty acids ?
saturated : CxH2xO2 (no double bonds)
unsaturated : CxH2(x-n)O2 (double bond(s) )
What causes the double bond found in unsaturated fatty acids ?
It causes a kink in the hydrocarbon chain.
Of what are composed triglycerides/fats ?
Of a glycerol molecule linked to three fatty acids
Are triglycerides polar or not ?
They are non-polar.
Of what are phospholipids composed ?
Of two fatty acids, a glycerol attached to a phosphate group and a variable hydrophilic group
What are some of the propreties of phospholipids ?
They are amphipathic molecules (they have an hydrophilic head and an hydrophobic tail)
When added to water, they assemble into a bilayer
Major component of all cell membranes
What is a common feature to all steroids ?
A carbon skeleton that consists of 4 fused rings
What is one of the propreties of steroids ?
They are all amphipathic molecules,
What are examples of a steroid ?
Cholesterol
Bile acids
Vitamin D
Hormones
Monosaccharides vary in what?
Location of carbonyl group (ketoses or aldoses)
Number of C in the skeleton (usaully 3, 5 or 6)
Isomers( structural, enantiomers, strereoisomers)
What is an anomeric carbon?
The carbon on which the carbonyl group is
Why is cellulose a stable structural molecule?
Few organisms have the enzymes to hydrolyse the beta linkages in cellulose
No caloric value for most animals (insoluble fibers)
From where do almost half of our calories come from?
From starch
What is chitin?
A semi-rigid structural polysaccharide (composed of glucose + an appendage containing N -> N-acetyl glucosamine)
Where is chitin found?
In exoskeleton of arthropods
In fungi cell walls
What is the general structure of a fatty acid?
A carboxyl group attached to a hydrocarbon chain (usually between 12 to 24 C)
Under what from are unsaturated fatty acids found in nature?
As cis stereoisomers
What are essential fatty acids (EFA) ?
Fatty acids that cannot be synthesised in our body (must be obtained from diet)
What are eicosanoids ?
Molecules made by oxygenation of 20 carbons EFA
Signalling molecules involved in inflammation and as messengers in nervous system
Eicosanoids are either what ?
omega-3
omega-6
What is the difference between omega-3 and omega-6 ?
omega-3 are anti-inflammatory
omega-6 are pro-inflammatory
What does the balance between w-3 and w-6 in diet affect?
Triglyceride level
Blood pressure
Cardiovascular disease
Inflammatory disorders
What drugs stop the synthesis of eicosanoids?
Aspirin
Ibuprofen
What are classes of eicosanoids ?
Prostaglandins
Leukotriene
Thromboxane
In what organisms are saturated fats the most common?
In terrestrial animals
How are saturated fats produced?
By the hydrogenation of unsaturated fats
In what state are saturated fats at room temperature?
They are solid
In what state are unsaturated fats at room temperature?
They are liquid
In what organisms are unsaturated fats the most common?
Fish
Plants
What are the chemical propreties of fats?
Non-polar
Neutral
Hydrophobic
What are the main functions of fats?
Long term energy storage
What are the functions of adipose tissues?
Store fats (in mammals)
Cushion vital organs
Insulate the body
What are the particularities of phospholipids with unsaturated fatty acids?
They have a lower freezing point
They tend to aggregate less
What are the functions of cholesterol?
Temperature buffer
Regulates membrane fluidity
Where are bile acids produced?
In the liver of mammals
What is the main function of bile acids?
Digest fats (fats aren’t water soluble)
Where can vitamin D be found?
Produced when skin exposed to sunlight
Found in diet
What are some of the roles of vitamin D ?
It promotes the absorption and metabolism of Ca and P
It is involved in cancer prevention
Deficit linked to multiple sclerosis
How are waxes defined?
As a substance similar in composition and physical propreties to beeswax
What is the biological importance of waxes?
Plant cuticule
Insect waxes (ex: beeswax)
Water proofing of feathers (in birds)
Found on skin surface and in ears (earwax)
What roles do waxes play in some marine organisms?
Energy source
Insulation
Buoyancy control (flotability)
Echolocation
What do sphingolipids contain?
Sphingosine
What are the functions of sphingolipids?
Protect cell surface by forming stable structure part of the outer leaflet of phospholipid bilayer
Role in signal transmission (form lipid rafts)
Involved in cell recognition
What are glycolipids?
Lipids attached to carbonhydrates
What are the functions of glycolipids?
Recognition sites/ chemical signature of cells
Contribute to cell attachment to form tissues
Approximatively what percentage of the dry mass of most cells consists of proteins?
> 50%
What are proteins?
Polymers built from the same set of 20 amino acids
Why do amino acids differ in their propreties?
Because of their different side chains
What are zwitterions?
Amino acids that carry both a + and a - charge
What are a few propreties of zwitterions?
Form at isoelectric point
Net charge is of 0
Polar
Hydrophilic
What is the isoelectric point (pI)?
The pH at which an amino acid/protein has a net electric charge of 0
What charge will a protein have if the pH is lower than the isoelectric point?
A positive charge
What charge will a protein have if the pH is higher than the isoelectric point?
A negative charge
What happens to proteins at the isoelectric point?
They aggregate and precipitate out of the solution
In order from the weakest to the strongest, name the types of interactions between the R groups of the amino acids in a protein
Van der Waals Covalent bond (hydrophobic interactions) H-bonds Ionic bonds Disulfide bridges
Which amino acid allows the formation of disulfide bridges?
Cysteine
What are examples of proteins with a quaternary structure?
Hemoglobin
Collagen
What can be associated to several diseases?
The aggregation of misfolded protein
To what type of diseases are misfolded proteins associated to ?
Prion-related illness
Amyloid-related illness
Intracytoplasmic aggregation disease
What do prion diseases affect?
The structure of the brain
Other neural tissues
What is an example of prion-related disease?
BSE ( mad cow disease)
CJD ( Creutzfeldt-Jakob disease -> in humains)
What is an example of amyloid-related disease?
Alzheimer’s
What is the leading hypothesis as to what causes Alzheimer’s ?
By the deposits of amyloid-β (Aβ) protein
It accumulates in the brain and contributes to nerve cell damage
What is an example of intracytoplasmic aggregation disease?
Parkinson’s disease
What characterizes Parkinson’s disease?
The death of brain cells
The accumulation of α-synuclein protein into the Lewy bodies in neurons
What structures are altered when protein denaturation happens?
The secondary and tertiary structures
What can cause protein denaturation?
Heat
Alcohol
Mercurochrome
How many grams of protein per kg lean body weight are there in adults?
At least 0.8g
What are the functions of dietary proteins?
Source of essential amino acids (EAA)
Source of energy
Excess converted to sugars and fatty acids
What is a common cause of health problems and mortality in developing countries?
Protein deficiency
What is a characteristic of essential amino acids (EAA) ?
They can’t be synthesized by the organism (so must obtained by diet)
What is the most important source of animal proteins for humains?
Fish
What determines the amino acid sequence of a certain protein?
Genes
Genes are sequences of what?
Of DNA
What is a nucleoside?
A nucleotide without the phosphate group
How are adjacent nucleotides joined together?
By a covalent bond between the -OH group on the 3 C of a nucleotide and the phosphate on the 5 C of the next one
The phosphate group and the pentode sugar form the backbone
What did Chargaff found?
That DNA was species specific
That %A = %T and %G = %C
What did Franklin and Wilkins discover?
That DNA was formed of two antiparallel sugar-phosphate backbones, with the nitrogenous bases paired in the molecule’s interior
What did Watson and Crick do?
They build models of a double helix for DNA
What are vitamins ?
Organic compounds required by an organism as a vital nutrient (must be obtained from diet)
Based on what are vitamins grouped?
Based on their biological activity
What is the function of vitamin B ?
Important roles in cell metabolism and respiration
What are examples of vitamin B ?
Thiamine
Riboflavin
Niacin
In what is vitamin C (ascorbic acid) involved ?
In the functionning of immune cells
What are characteristics of vitamin C
It is a cofactor (electron donor) for at least 8 enzymes
It is an antioxidant (reducing agent)
To what can lead a deficiency in vitamin C ?
To scurvy
To unstable collagen
What classes of life’ s organic molecules contain polymers ?
Carbohydrates
Proteins
Nucleic acids
What are the enantiomers of glucose and their function?
D-glucose (dextrose) : biologically active
L-glucose: not metabolized by cells in glycolysis
What condition is needed for a saccharide to be a reducing sugar?
It must have an available anomeric carbon
By what is the structure and function of a polysaccharide determined?
By the type of monosaccharide it is made of
By the position of the glycosidic linkages
What is the most abundant large organic compound on Earth?
Cellulose
What role does essential fatty acids play ?
Development of nervous system
Lowers inflammation
Deficiency associated with depression, schizophrenia, heart diseases and cancer
Where are fats stored?
In adipose cells
Triglycerides are used to make soap by what process?
By saponification
What happens when phospholipids are added to water?
Bilayer formation with hydrophobic tails pointing toward the interior
What is the main role of phospholipids?
Major component of cell membrane
Where are bile acids produced?
In the liver of mammals
What is the function of chaperonins?
They assist in protein folding
How does prion diseases propagate?
They induce properly folded proteins to misfold and convert to prion
The prions then aggregated (amyloid fold formation)
Aggregates disrupt normal tissue structure
What was done to control BSE ?
Ban on feeding cattle with meat and bone meal
Import control
Surveillance measures
What is a conjugated protein?
A protein attached to non-amino groups (prosthetic group)
What are examples of conjugated proteins ?
Lipoproteins
Hemoglobin (contains heme group)
Cytochromes ( contains heme group)
What triggers allergic reactions to certain foods?
Some proteins
