2 MOLECULAR BIOLOGY Flashcards
What property of carbon makes it the base of organic life?
- it can form 4 covalent bonds (can form complex molecules)
- bonds between carbon atoms are stable
Name 4 classess of carbon compounds and their function.
carbohydrates - energy, signalling (glycoproteins), structural (DNA, RNA, cell wall)
lipids - signalling (steroids), structural (phospholipids, cholesterol), energy storage (fats)
nucleic acids - DNA (code for proteins), RNA (takes part in protein synthesis), structural (ribosome)
proteins - metabolic processess (enzymes), signalling (peptide hormones)
Explain how thermal properties of water make it a good coolant.
- sweat is produced by skin in response to heat
- water has a high latent heat of vaporization due to hydrogen bonds
- a lot of energy is required to evaporate water , because hydrogen bonds between water molecules have to be broken
- evaporation of water cools down the body
Explain the importance of hydrogen bonding for living organisms.
a. water molecules stick together (cohesion)
b. cohesion helps transport under tension of water in the xylem - maintains transpiration pull
c. adhesion between water and cell walls
d. adhesion/capillary action helps water to rise in plants in xylem
e. solvent properties (due to hydrogen bonds) can dissolve polar molecules such as glucose in blood
g. high latent heat of evaporation - a lot of energy required for evaporation so water useful as coolant in sweat
h. high specific heat capacity so water temperature changes less
i. base pairing between nitrogenous bases in DNA by hydrogen bonding
k. proteins have hydrogen bonding in secondary structure/α helix/β pleated sheet
l. proteins have hydrogen bonding between R groups/in tertiary structure/to maintain conformation
m. habitats because water is liquid due to high boiling point/due to water freezing on the surface
n. habitats on water surface due to surface tension
Explain the solvent properties of water.
- water molecule is polar
- it dissolves polar substances
- positive pole of water is attracted to negative ions
- i.e. glucose dissolves because it is polar
- sodium chloride dissolves because ions are attracted to water
Describe the structure in 3 polysacharides.
cellulose: 1-4 beta glycosidic bonds
starch: (amylose 1-4 alpha and amylopectin 1-4, 1-6 alpha)
glycogen: 1-4, 1-6 alpha
Contrast lipids and carbohydrates as energy storage.
S - storage (carbohydrates - short term, fats- long term)
O- osmotic (carbohydrates have more effect on osmotic pressure than fats)
D - digested (carbohydrates more easily digested)
A - ATP yield ( lipids store twice as much energy per gram)
S - solubility ( water soluble as monomers, lipids carried in lipoproteins)
BMI
body mass index
kg/m2
- not valid for pregannt women and athletes with atypical muscle to fat ratios
List protein functions with examples of each.
S - structure (collagen, spider silk)
H - hormones (insulin)
I - immunity (immunoglobulins)
T - transport (hemoglobin)
S - sensation (rhodopsin)
M - movement (actin)
E - enzymes (rubisco)
Explain why the size of the proteome is larger than genome.
- mRNA is spliced so different proteins may be produced from one gene
- post-translation modifications (i.e phosporylation or sth)
Outline the effect of temperature, pH and substrate concentration on the rate of enzymatic activity.
- enzymes have active sites that bind specific substrates
- catalyse reaction by lowering activation energy
TEMPERATURE
- rate increases with temperature up to an optimum temperature
- sharp decline in activity above the optimum temperature due to denaturation (hydrogen bonds broken and tertiary structure disrupted, shape of active site changed)
pH
- rate declines at a pH above and below the optimum pH (due to denaturation, change in charge of the protein, tertiary stucture, shape of active site changed)
SUBSTRATE CONCENTRATION
- rate increases sharply as substrate concentration goes up;
- above a certain concentration, the rate reaches a plateau;
INHIBITORS
- competitive inhibitor - enzyme requires higher concentration to achieve maximum rate
- non-competitive inhibitor - enzyme activity is lower at all substrate concentrations
Describe the process of the production of lactose-free milk and state its benefits.
added benefits of treating milk with lactase
- lactase bound to a column of alginate beads
- milk poured through several times
- it allows for easier separation of products
- enzymes can be reused
BENEFITS:
- lactose- intolerant people can drink it
- milk is sweeter
- less crystalisation of ice cream as monosaccharides are more soluble
- less time needed for fermentation of cheese because bacteria ferment faster with monosaccharides
Compare and contrast structure of RNA and DNA
- number of strands (DNA - 2/ RNA -1)
- pentose sugar (deoxyribose/ribose)
- nitrogenous bases ( A G C T/ A G C U)
Explain how genes can be transferred between species. What allows them? Give an example.
-universality of the genetic code (same codons code for same aminoacids)
- gene for insulin extracted from a human
- spliced into bacterial plasmid
- bacteria grown in a culture where they replicate and produce insulin
- insulin harvested, purified and packaged for human use i.e. diabetics
Explain what the Rf values represent in chromatography.
- Rf= distance travelled by the pigment/ distance travelled by the solvent
- each pigment has a specific Rf value
- which depends on its solubility in the solvent, density or polarity
- Rf value can be used to identify the pigment
