biological molecules Flashcards
chap 3
4 key elements
carbon
hydrogen
oxygen
nitrogen
2 key elements in cell biochemistry
sulfur
phosphorus
What is a molecule?
non metals that are covalently bonded (eg O2)
What elements are specific to proteins and nucleic acids?
Proteins: nitrogen, sulfur
Nucleic acids: nitrogen, phosphorus
3 ions for nervous impulse transmissions
Ca 2+
Na +
K +
2 ions for determining pH in solutions
H +
OH -
2 ions for nitrogen in plants (and names)
NH4 + (ammonium)
NO3 - (nitrate)
2 ions for transport of respiratory gases (and names)
HCO3 - (hydrogen carbonate)
Cl - (chloride)
1 ion for nucleic acid and ATP formation (and name)
PO4 3- (phosphate)
Are the key ions in this module inorganic or organic? Why? Is there an exception?
Inorganic
None contain C-H bonds
HCO3 - contains carbon and hydrogen, but the carbon forms a C-O bond
What reaction joins monomers together and releases a water molecule?
Condensation
What reaction requires a water molecule to BREAK DOWN polymers?
Hydrolysis
When 2 monomers join, what do they form?
A dimer
Why is water a polar molecule? (4 points)
- 0 overall charge
- Oxygen is slightly neg region (d-)
- Hydrogen is a slightly pos region (d+)
- Bc oxygen has more protons, it attracts e- closer to it
Where are hydrogen bonds formed? Why? What do they do and what is this similar to?
- Adjacent to water molecules
- As they are pos and bond to neg oxygen
- Hold multiple molecules together like IMF
What are the 5 essential properties of water?
- Cohesion, adhesion and surface tension
- High SHC and LH of V
- Low density
- Essential to metabolism
- Acts as a solvent
What is cohesion? Due to?
tendency of water to stick together (due to hydrogen bonds)
What is capillary action? Due to?
Ability of water to be pulled up the stem and go against gravity (due to cohesion and adhesion)
What is adhesion? Due to?
Ability of water to stick to cell wall (due to hydrogen bonds)
What is surface tension?
Where water meets air, the tendency of water to be pulled back into a body of water
What does a high specific heat capacity (SHC) mean?
Takes in a lot of energy before getting hotter
What does a high specific latent heat of vaporisation (LH of V) mean?
Takes in a lot of energy before evaporating
Why is a high SHC good for water? (2 points)
- Smaller temp range so organisms’ enzymes don’t denature
- Less ice melts= less habitat loss
Why is a high LH of V good for water?
More liquid water available for organisms
Why is ice being less dense than water good?
Organisms can live on and under ice
What 3 processes does water play in metabolism?
- Hydrolysis
- Photosynthesis
- Making cell environments aqueous
How does ice maintain a stable environment?
Surface level ice= insulating layer
What kind of solvent is water and what does this mean? (4 points)
- It is a dipolar solvent
- So neg oxygen can bind to surrounding ions/molecules
- And pos hydrogen can bind to neg ends of surrounding molecules
- so it can dissolve lots of substances
What is the general formula of a carbohydrate? General ratio?
Cx(H2O)y
H:O= 2:1
3 roles of carbs (+ examples)
energy stores (glycogen +starch)
structural support (cellulose)
DNA (ribose)
Isomer
molecules with same molecular formula but different structures
Water soluble
when there are compounds outside the molecule that water can hydrogen bond to
What makes a and B glucose isomers? What carbon is this on? What saying can be used to remember this?
In a glucose, the hydroxyl group (OH) is below the plane
In B glucose, the hydroxyl group is above the plane
C1
“Beta beats alpha”
Why is glucose water soluble?
OH is polar and water can hydrogen bond to it
Why is water a good transport medium? (3 reasons (so far))
- Polar solvent
- Cohesion and adhesion
- Thermal stability
What carbohydrate polymers does glucose make up and which types?
Alpha:
- glycogen
- amylose starch
- amylopectin starch
Beta:
- cellulose
Why does the structure of glycogen differ from the structure of cellulose? Why does it have this structure? What is this due to?
- Glycogen has a higher surface area and is more compact with more extensive branching
- bc animals need more energy
- due to 1,4 and additional 1,6-glycosidic bonds
How does the structure of cellulose relate to its function? (4 points)
HINT: bonds, shape, solubility, groups
- Hydrogen bonds between chains form microfibrils–> macrofibrils–> high tensile strength fibres
- doesn’t need branches bc purely structural
- insoluble, maintaining strength
- hydroxyl group positioned above C1’, so alternate molecules must be turned upside down so chain is straight and compact
What is the structure of a triglyceride? What is the bond? Which is between what groups? (3)
- 1 glycerol + 3 fatty acids
- ester bonds
- carboxyl group om fatty acids and alcohol groups on glycerol
What is the structure of a phospholipid (3 groups)? What is special about the 2 ends of the phospholipid? Why?
- phosphate group + glycerol + 2 fatty acids
- phosphate group is hydrophilic (bc it is polar)
- fatty acids are hydrophobic (bc they’re non polar)
Functions of triglycerides (3)
- Energy source
- Insulation (adipose tissue under skin)
- Protection (adipose tissue around organs)
Function of phospholipid and how?
Forms phospholipid bi-layer (hydrophilic head faces outwards and hydrophobic tail faces inwards)
Structure of cholesterol and where is it usually?
4 carbon rings and hydrophilic hydroxyl group
between phospholipids in the cell membrane
Function of cholesterol (2)? What happens if there’s too much of it?
- controls membrane fluidity (stops them bursting open bc they’re too permeable)
- stabilizes membrane temp
- membrane becomes too stiff and impermeable so fluids cannot pass thru it
Types of bond saturation? (3) What are kinks? What do kinks do?
- saturated (no C=C), monosaturated (1 C=C), polysaturated (>1 C=C)
- kinks are bends in the chain where double bonds are
- bend molecule so they cannot pack into solids
Why are saturated molecules harder to melt?
no kinks=more layers=strong IMF between layers
What are 3 types of lipids?
Triglycerides
Phospholipids
Cholesterol
6 functions of protein
enzymes
structural
contractile
hormones
transport
antibodies
3 types of proteins + examples
globular- insulin
fibrous- collagen
conjugated- haemoglobin
What 4 things make up an amino acid?
- amine group (NH2)
- carboxyl group (-COOH)
- hydrogen
- R group
What does each structure of protein contain? (excluding tertiary)
- Primary: peptide bonds between amino acids (amino and carboxyl groups)
- Secondary: hydrogen bonds between amino group on 1 amino acid and carboxyl on another
- Quaternary: more than 1 polypeptide chain + non-amino components (eg iron)
What does the tertiary structure of a protein contain?
- ionic bonds between R groups
- ionic bonds between carboxyl/amine groups
- hydrophilic and hydrophobic interactions between polar and non polar R groups (weak)
- sometimes disulfide bridges
Structures of 3 types of protein + 3 properties of each
Globular: water soluble, folds into globe/sphere, diverse
Fibrous: elongated (sheet-like), many repeated amino acids, insoluble
Conjugated: 1 alpha and beta polypeptides, quaternary, prosthetic group (non amino component)
Functions of 3 types of fibrous proteins
- Keratin: tough (hair, tooth, nails),
- Elastin: connective tissue (tendons, skin, bones)
- Collagen: strong support and tensile strength due to hydrogen and covalent bonds (skin, tendons ligaments)
Structure + function of catalase
- Fe2+ in 4 haem groups
- allows it to break down H2O2 which is a toxic by-product of metabolism
- globular
Structure + function of insulin
- soluble and precise shape
- dissolves in blood and binds to receptors
- disulfide bridges for stability
- globular
Structure + function of haemoglobin
- 2 alpha and 2 beta polypeptides, 4 haem groups w Fe2+ ions
- which combine REVERSIBLY w O2 to allow quick pick up and release
- conjugated
True or false- conjugated proteins are entirely separate
False- conjugated proteins are just globular and fibrous proteins with prosthetic groups
