Advanced article 2017 Flashcards
what is the definition of population?
the number of all the organisms of the same group or species, which live in a defined geographical area and have the capability to interbreed successfully
what is the aim of genetic engineering?
to introduce a new trait to an organism that does not occur naturally in the species
how do gene guns work?
DNA bound to tiny gold/tungsten particles
particles shot into plant tissue under high pressure, penetrating cell wall and CSM
DNA separates and is integrated into nuclear DNA
how does Agrobacterium tumefaciens mediate transferal of genetic information?
desired gene is incorporated into DNA plasmid and inserted into A. tumefaciens
plasmid acts as vector
A. tumefaciens infects plant roots and encourages tumour growth
incorporated gene activated + products formed
how does electroporation work?
used when plant tissue does not contain cell walls
DNA enters the plant cell through miniature pores created by electric pulses
what is the general formula of a monosaccharide?
C(x)H(2x)O(x)
what are the two types of bonds found in glycogen? where specifically are they found and why?
a. 1,4-glycosidic bond - bonds within chains
a. 1,6-glycosidic bond -bonds between chains allowing branching
how often does branching occur in glycogen molecules?
every 8 to 24 glucose molecules
what are the differences between amylose and amylopectin?
amylose:
- helical polymer of a. glucose
- ~ 20-30% of starch
- insoluble
- hydrolysed slower
amylopectin:
- branched helical polymer of a. glucose
- ~ 70-80% of starch
- soluble
- hydrolysed faster
outline some features of cellulose molecules
made from B. glucose
forms long fibrils
∴ has high tensile strength –> used in cell wall –> allows plant cell to become turgid
has inter- and intra-fibril H bonds
outline some features of RuBisCO
has 16 ppc, 8 heavy and 8 light
requires Mg2+ (prosthetic group)
optimum pH 7.9
less specific active sites - can’t distinguish between CO(2) and O(2) - they are similar in size
when does photorespiration occur? what are the consequences?
CO(2) concentration falls too low –> RuBisCO reacts with O(2) instead
carbohydrates are metabolised instead of created
how do C4 and CAM plants cope with photorespiration?
bind CO(2) using a different enzyme - phosphoenolpyruvate carboxylase (PEPC)
which has a higher affinity for CO(2) than RuBisCCO ∴ can fix it with greater efficiency
∴ stomata can be opened for shorter periods of time
what is the definition of carbon fixation?
the incorporation of inorganic carbon into organic compounds by living organisms
what are carbon dioxide concentrating mechanisms (CCMs)?
found in algae + higher plants
used to overcome low CO(2) levels (e.g. in aqueous environment)
because CO(2) is slow to equilibrate between the air and water –> CO(2) depletion
∴ CCMs increase carboxylase activity
–> increased tolerance of low external concentrations of inorganic carbon + heat/water stress
what are the three main components of algal CCM?
pyrenoid
series of transporters
series of carbonic anhydrases
outline some features of cyanobacteria
a phylum of bacteria that obtain energy through photosynthesis
prokaryotes
can produce oxygen
can fix nitrogen in anaerobic conditions
have CCMs to obtain inorganic carbon
what are carboxysomes?
a form of icosahedral bacterial micro-compartment
concentrate CO(2) inside by means of co-localised carbonic anhydrase activity (produced CO(2) from HCO(3)-)
avoids photorespiratory reactions
found in nitrobacter
outline the features of carbonic anhydrase
globular protein with quaternary structure (Zn+ prosthetic)
Zn+ changes charge of a.s. –> easier for S to bind
∴ E(a) is reduced ∴ r.o.r. increases
reversible reaction
has 14 different isoforms in mammals
plans have B. carbonic anhydrase, which helps raise CO(2) concentration inside the chloroplast ∴ C activity of RuBisCO increases
where is most of the RuBisCO in a chloroplast found?
in pyrenoids
outline the features of Nicotiana tabacum
annually-grown herbaceous plant
commercially grown for processing into tobacco
outline the features of Synechoccus elongatus
one circular chromosome and two plasmids
Gram -ve
freshwater photoautotroph that contributes significantly to primary production
outline some of the effects of GM crops on ecosystems
possibly toxic to non-target organisms
cross-species transfer/contamination
evolution of superweeds
reduces competition and ∴ biodiversity
toxic soil ecosystems
eutrophication
what is an invasive species?
a plant/fungus/animal that is not native to a specific location
has a tendency to spread to a degree that it causes damage to the environment
what is a selective advantage?
a characteristic of an organisms that enables it to survive and reproduce better than other organisms in a population in a given environment
