paper 1 Flashcards
what is the role of starch
store of glucose for energy
what is structure of amylose
long unbranched
angles of glycosidic bonds give it a coiled structures (compact)
structure of amylopectin
long and branched
side branches allow enzymes that breakdown the molecule to have easy access
glucose release quickly
features of starch
insoluble not affecting water potential so doesn’t swell making it good for storage
structure of glycogen
lots of side branches compact and good for storage
cellulose structure
long unbranched chains of beta glucose
straight chains joined by H-Bonds forming microfibrils
structural support provided
what are the properties of triglycerides
mainly used as energy storage molecules
long hydrocarbon tail of FA contains lots of chemical energy- released when broken down
because of these tails lipids contain twice as much energy per gram as carbs
insoluble in water doesn’t affect WP so water doesn’t enter by osmosis
Bundle together forming droplets, tails face inwards and shield themselves with glycerol heads
properties of phospholipids
make up bilayer of CM controlling what leaves and enters cell
heads are hydrophilic
tails are hydrophobic
meaning water soluble substances cant easily pass through
membrane acts as a barrier
what does a functional protein have
1 or more polypeptide chains
what is the role of hydrogen bonds in protein structure
form bond between partially neg oxygen and partially pos nitrogen make it coil or fold more (secondary structure)
what is the role of ionic bonds in protein structure
tertiary structure
more bond form between different parts go polypeptide chain, further coiling and folding the chain
what is the role of disulphide bridges in protein structure
form whenever 2 molecules of aa cysteine come close together, sulphur of one bonds to sulphur of the other S=S
structure of enzyme relating to function
spherical tightly folded polypeptide chains
soluble and have a role in metabolism
structure of antibodies relating to function
involved in immune response
2 light chain and 2 heavy chains
variable regions
structure of structural proteins relating to function
physically strong
consist of a long-polypeptide chains lying in parallel with cross-links
how many pp chains does collagen have
3
tightly coiled
what can enzymes do (not basic definition)
enzymes catalyse a wide range of intra/extracellular reactions that determine structures and functions from cellular to whole organism
involve in hydrolysis and DNA replication
what bonds form between 2 nucleotides
phosphodiester bond
is rna short of long
short
what is pi used for
when inorganic phosphate is released during hydrolysis of atp can be used to phosphorylate other compounds and make them more reactive
inorganic ions occur….
in solution in the cytoplasm and bodily fluids of organisms
some in high conc and some in low
iron inorganic ions
Fe2+
haemoglobin large protein that carries o2 around the body in RBC’s
made up of 4pp chains with fe2+ at the centre
fe2+ binds to oxygen in Hb when fe2+ binds to oxygen fe3+ until o2 released
hydrogen ions inorganic ions
ph is calculated based on the conc of h+ in environment
more h+ means its more acidic
enzyme controlled reactions affected by pH
sodium ions inorganic ions
glucose and amino acids need a bit of help crossing CM
glucose/AA transport into a cell (co-transport)
phosphate ions inorganic ions
attached to another molecule
DNA, RNA and ATP have phosphate allowing nucleotide to join yp to form
polynucleotides
nucleus structure and function
jelly-like nucleoplasm
nucleolus
nuclear envelope
nuclear pore
chromatin
control cell activities (by controlling transcription of DNA)
pores allow substances t9 move between cytoplasm and nucleus
prokaryotic features
much smaller
smaller ribosomes
cell wall contains murine (glycoprotein)
what does the xylem do
cohesion tension theory, water and dissolved mineral ions moves from the roots to the stem and leaves
what does the phloem do
carry organic substances (sucrose) source to the sink
structure of xylem
hollow tubes
formed from dead cells joined
one way
and no end walls
lignin providing structural support for plant
whats cohesion
water molecules attracted to others by hydrogen bonding
whats a transpiration stream
water and dissolved mineral ions through xylem vessels from roots to leaves
whats transpiration
evaporation of water from plants surface especially leaves
whats cohesion tension theory
1) water transpires from leaves, decreasing water potential in leaf cells so water drawn out xylem by osmosis
2) creating tension more water down up through xylem
as h2o cohesive due to hydrogen bonding, water moves as a continuous column
3) allows more water to enter roots by osmosis (water potential at roots decreases)
increased light intensity effect on transpiration
increases stomata open due to more co2 for photosynthesis increased water vapour leaving
increased humidity effect on transpiration
decreases as decreased conc gradient of water vapour in and out so slower diffusion in and out
increased temp effect on transpiration
increases h2o has increased KE so more h2o evaporates increasing conc gradient of water vapour so faster diffusion
increased wind effect on transpiration
increases h2o removed from around stomata increasing conc gradient and increased diff rate
whats source
where sucrose produced
whats sink
where sucrose needed (roots as they cant photosynthesise)
phloem structure
column with sieve tube elements containing no nucleus and few organelles they are living cells that are elongated and join to the end to form long tubes
companion cells carry out living functions for sieve cell (energy for AT)
what maintains conc gradient in phloem
enzymes
conc gradient of solutes between source and sink by regulating conc of solutes at sink by hydrolysis them
mass flow hypothesis
source: sucrose AT from cells in source into phloem by companion cells, which have mitochondria
decreased water potential at phloem
water enters phloem by osmosis and high hydrostatic pressure at phloem (volume of water increase)
sink: sucrose AT out phloem into sink cells
water potential of sink cells decrease so water enters by osmosis
decreased hp at sink
overall pressure gradient pushes solutes to sink
ringing trees
removing section of the bark (which contains phloem)
so solutes accumulate above the removed area as no phloem for them to flow through to sink creating a bulge
pressure applies from above sucrose accumulates
radioactive tracers
plant supplied with co2 containing radioactive c14, often done in air tight container
radioactive carbon incorporated into glucose when plants photosynthesise covering glucose to sucrose (moved by translocation)
movement traced using radioactive tracers (black)
evidence against mass flow hypothesis
organic materials have to reach sink to flowers so how can sap move up and down plant at the same time
sucrose rate of movement doesn’t change no matter how steep conc gradient is
