Module 2, chapter 3, biological molecules Flashcards
biological elements water carbohydrates testing for carbohydrates lipids the structure of proteins nucleic acids DNA replication and the genetic code protein synthesis ATP
properties of simple covalent structures
- low melting and boiling points
- liquids and gases at room temp
- covalent bonds within molecules are strong but bonds between molecules are weak
important biological molecules
hydrogen
water
carbon dioxide
methane
ammonia
why is water important in biology
- it is a metabolite in many reactions
- it hydrates
- 55% of blood is made up of water
- habitat for aquatic animals
- 60 - 80% of the body is made up of water
what is a metabolite, and when is water a metabolite
a metabolite is any substance produced during metabolism, they usually serve the function of energy conversion
water is a metabolite in hydrolysis and condensation reactions
what is cohesion
when water sticks to itself
what is adhesion
when water sticks to other substances
what is the structure of water
- two hydrogen atoms contently bonded to one oxygen atom
what does polar mean and why is water a polar molecule
a polar molecule is a molecule that has differently charged regions
Water is polar, as the oxygen atom has more protons than the hydrogen atoms, so has a greater affinity for the shared electrons, making it slightly negative, this results in the hydrogen being slightly positive.
what does dipolar mean
having two differently charged regions
why can the oxygen atoms in water form hydrogen bonds
as the oxygen is slightly negative, it draws the slightly positive hydrogen atoms in
what is the result of hydrogen bonds
they mean that water molecules can bond with other water molecules, as the oxygen from one molecule attracts the hydrogen from another, this causes cohesion
what can cohesion explain
why a large amount of energy is lost before a temp/state change in water
what is surface tension caused by
cohesion at an air - water surface, it creates a solid like surface
why is water a good solvent
water had polar molecules, so is attracted to other substances that also have polar molecules, because these other substances will become part of the hydrogen bonds in water, they will dissolve and are called hydrophilic. Non polar molecules will not become part of this, so these substances will not dissolve (hydrophobic) e.g triglycerides
what is the formula of a calcium ion and what is it used for
Ca2+
nerve impulses, muscle, contractions,
what is the formula of a sodium ion and what is it used for
Na+
nerve impulses, kidney function
what is the formula of a potassium ion and what is it used for
K+
nerve impulses, stomata
what is the formula of a hydrogen ion and what is it used for
H+
catalysts, pH determination
what is the formula of an ammonium ion and what is it used for
NH4+
needed to make nitrate ions
what is the formula of a nitrate ion and what is it used for
NO3-
amino acid formation
what is the formula of a hydrogen carbonate ion and what is it used for
HCO3-
maintain blood pH
what is the formula of a chloride ion and what is it used for
Cl-
balance sodium and potassium ions in cells
what is the formula of a phosphate ion and what is it used for
PO4 3-
cell membranes, nucleic acids and ATP formation, bone formation
what is the formula of a hydroxide ion and what is it used for
OH-
catalysts
pH determination
what structures do carbohydrates exist in
monosaccharides - small simple sugars
disaccharides - large sugars
polysaccharides - long chain carbohydrates
give examples of each type of carbohydrate
mono - glucose fructose ribose and galactose
di - lactose and sucrose
poly - glycogen cellulose and starch
what is the general formula of carbohydrates
Cx(H2O)y
what is the general formula of monosaccharides
(CH2O)n, where n is 3, 4, 5, 6, 7
give the properties and structure of glucose
abundant and important
monosaccharide
six carbons (hexose sugar)
C6H12O6
highly soluble
two types - alpha and beta
what is a structural isomer
compounds that have the same number of atoms of each element but different bonds
what is the difference between alpha and beta glucose
the position of the -OH group which is attached to carbon - 1. In alpha glucose it is below the carbon, and in beta it is above
how do we make disaccharides and polysaccharides, and what happens
Condensation reactions
when two molecules are side by side, two hydroxyl groups interact. when this happens bonds are broken and others form
what are pentoses, give examples
sugars of DNA - containing 5 carbons
ribose and deoxyribose
what is the difference between ribose and deoxyribose
deoxyribose does not have an -OH group attached to carbon 2, only a hydorgen, but ribose has an OH
What is maltose and its structure,
malt sugar
two glucose molecules joined by an alpha 1-4 glycosidic bond
what is a glycosidic bond
covalent chemical bonds that link ring shaped molecules to other molecules
what is sucrose and its structure
table sugar
glucose and fructose, joined by an alpha 1 - 4 glycosidic bond
what is lactose and its structure
milk sugar
galactose and glucose joined by a beta 1 - 4 glycosidic bond
what are polysaccharides
polymers containing many monosaccharides
mainly used as energy stores in plants
starch and cellulose in plants and glycogen in animals
properties and uses of starch
made of amylopectin and amylose (alpha glucose polysaccharides)
starch doesn’t change the water potential of a cell as it is insoluble in water
usually stored as intracellular starch grains in organelles called plastids
starch is branched, but less so than amylopectin, so it doesnt take up as much space, and more starch can be stored
what is amylopectin
amylopectin is branched and made up of alpha glucose molecules joined by 1 -4 and 1- 6 glycosidic bonds
it is helical
it has a branched structure, meaning that the bonds are easily accessible for enzymes, so glucose is released quickly.
what is the structure and function of glycogen
animals store starch as glycogen
glycogen had alpha 1 - 6 glycosidic bonds
stored as small granules in the muscles and liver
less dense and more soluble than starch, so is broken down easily - this indicates the higher metabolic rates of animals
glycogen forms coils
hydrolysis reactions
opposite of condensation reactions
they break down polymers, using water molecules and enzymes (as catalysts)
what is cellulose and what are its functions
polysaccharide - straight chain of beta glucose joined by beta 1 4 glycosidic bonds
plant cell walls
most abundant organic polymer
cellulose is strong and prevents cells from bursting when they take on excess water
chains form a rope like structure called microfibrils layered to form a network - this is the reason for the strength of cellulose
what is amylose and what are its functions
linear chains of alpha glucose molecules, forming a helical structure
this allows the strands to pack closely together so this form of starch is good for storage
describe the iodine test, and what it tests for
a test for the presence of starch
iodine is used (potassium iodide)
1) if the sample is not a liquid, grind it down and mix it with water, then filter out the larger bits
2) place a sample into a test tube
3) add a few drops of iodine and watch for a colour change
what colour is iodine and what colour does it change with positive / negative results
original - orange
negative - orange
positive - blue/black
what are condensation reactions
monomer + monomer = disaccharide
called a condensation reaction as water is a by product
draw a condensation reaction (ring structure)
what is a reducing sugar
a sugar that can donate electrons to another molecule
give examples of reducing sugars
all monosaccharides (galactose, glucose, ribose, fructose
some disaccharides - lactose and maltose but not sucrose
what are lipids
fats and oils
