B17 - Energy for biological processes Flashcards
What metabolic activities take place in individual cells?
- active transport
- essential for uptake of nitrates by root hair cells
- loading sucrose (STC)
- selective reabsorption of glucose and amino acids in kidney
- conduction do nerve impulses
- anabolic reactions
- building of polymers
- e.g. proteins, polysaccharides, nucleic acids (growth and repair)
- movement
- by cilia, flagella, contractile filaments in muscle cells
How does energy flow through living organisms?
- sun —> photosynthesis —> producers (respiration —> heat) —> decomposers/autotrophs (respiration —> heat)
- sun —> photosynthesis —> producers (respiration —> heat) —> consumers/heterotrophs (respiration —> heat) —> decomposers (respiration —> heat)
- radiation from Sun is used to fuel metabolic reactions and processes necessary to keep organisms alive
- energy is then transferred back to the atmosphere as heat
What is photosynthesis in organisms?
- organisms make use of energy in bonds of organic molecules (e.g. glucose)
- they are formed during photosynthesis in plants + other photosynthetic organism
- light is trapped by chlorophyll molecules (its energy is used to drive the synthesis of glucose from CO2 and H2O)
- production of the most biomass on earth
- equation : 6CO2 + 6H2O <—> C6H12O6 + 6O2
What is respiration in organisms?
- process by which organic molecules (glucose) are broken into smaller inorganic molecules (CO2, H2O)
- energy stored within the bonds of the organic molecules is used to synthesise adenosine triphosphate (ATP)
- ATP is needed to drive the metabolic reactions that take place in cells
- equation : C2H12O6 + 6O2 —> 6CO2 + H2O
What are endo/exothermic reactions?
- endothermic = takes in energy
- exothermic = releases energy
What is the importance of carbon-hydrogen bonds?
- atoms in small inorganic molecules (water/CO2) have strong bonds
- organic molecules like glucose/amino acids contain more bonds but are weaker and *
What are autotrophic organisms?
e.g. plants and algae
What are heterotrophic organisms?
they obtain complex organic molecules by eating other organisms e.g. animals
what is the equation for photosynthesis?
6CO2 + 6H2O –> C6H12O6 + 6O2
carbon + water –> glucose + oxygen
dioxide
what is the structure and function of chloroplasts?
- contains network of membranes to maximise surface area for absorption of light essential in the first step of photosynthesis
- membranes form flattened sacs called thylakoids which are stacked to form grana, these are then joined by channels called lamellae
- fluid enclosed in the chloroplast is the stro,a and is the site of many chemical reactions resulting in the formation of organic molecules
- they have an outer and inner membrane - the outer is more permeable than the inner which is more selectively permeable
- DNA since endosymbiotic - has all ultrastructure necessary to survive
Chlorophyll
- pigment molecules that absorb specific wavelengths and reflect others
- two types: chlorophyll a - P680 (photosystem II) and P700 (photosystem I) - (both yellow-green)
- chlorophyll b - absorbs wavelengths 400-500nm and 640nm (more often found in photosystem II)
What are photosystems?
- funnel-shaped structures held in place by proteins and at the bottom is a primary pigment reaction centre made of chlorophyll ( all other pigments are accessory pigments)
- accessory pigments include carotenoids, chlorophyll b and xanthophyll, these absorb different wavelengths of light than chlorophyll a
- these accessory pigments form a light harvesting system (antennae complex), their purpose is to absorb or harvest light energy of different wavelengths and transfer this to the reaction centre
What are the 2 stages of photosynthesis?
- light dependent - energy from sunlight is absorbed to make ATP, hydrogen from water is used to reduce coenzyme NADP to reduced NADP
- light independent - hydrogen from reduced NADP and CO2 is used to build organic molecules like glucose with ATP supplying the energy
light dependent - non-cyclic photo-phosphorylation
-involves PSII and PSI,
- the reaction centre of PSI absorbs light at a higher wavelength of 700nm than PSII at 680nm
- light excites electrons at the reaction centre and these are released from PSII and passed to an electron transport chain , ATP is produced from the process of chemiosmosis
-the excited electrons are replaces from water molecyles broken down using energy from the sun
- excited electrons released from the reaction centre of PSI are passed to another electron transport chain and ATP is produced again via chemiosmosis
- electrons released from this reaction centre are replaced by electrons that have travelled along the first transport chain after being released from PSII
-the electrons leaving the electron transport chain following PSI are accepted along with a hydrogen ion, by the coenzyme NADP, forming reduced NADP
- reduced NADP provides the hydrogen or reducing power in the production of organic molecules e.g. glucose in the light independent stage which follows
photolysis in light dependent stage
- water molecules are split into hydrogen ions, electrons and oxygen molecules using energy from the sun - photolysis
- the electrons released replace the electrons lost from the reaction centre of PSII, hence why water along with light and CO2 is a raw material from photosynthesis
