Topic 5 Flashcards
Photsynthesis
process in which green plants trap light energy and transform it into chemical energy
photosynthesis equation
6CO2+6H20————(light energy, chlorophyll) C6H12O6+6O2
Chloroplast structures
thylakoids-membranous fluid-filled flattened discs
grana- thylakoids aggregated into stacks
chlorophyll-light-trapping pigment embedded in thylakoid membranes
enzymes- located in thylakoid membranes (1st stage)
-stroma contains some enzymes involved in second stage of photosynthesis
stroma- fluid inside chloroplast that bathes grana
-DNA and ribosomes-the stroma contains ribosomes and DNA
Light dependent reaction
- requires light energy
- occurs in thylakoids of chloroplast- arranged in stacks called grana
- involves absorption of light energy by chlorophyll into chemical energy
inputs/outputs light dependent reaction
inputs: water, ADP+Pi, NADP+
Outputs: Oxygen, ATP, NADPH
Light dependent reaction process
- trapping or energy of sunlight occurs in chloroplasts
- when light energy strikes molecules of chlorophyll, it excites electron, which leaves the chlorophyll- enters electron transport chain- flow of electrons is initiated
- absorption of light also splits water molecules-electrons from water replace electrons removed from chlorophyll
- oxygen produced from splitting of water is waste product- released to outside environment or environment within cytosol- used during cellular respiration
- as electrons move down transport chain, lose energy to form ATP from ADP+Pi
- electrons and H+ are transferred to produce NADPH- carries H+ to next stage of photosynthesis-light independent reaction
- NAPH+ is also called terminal electron acceptor
Light independent reaction
- does not require light
- take place in solution in the stroma of chloroplasts
- involves reduction of CO2
inputs/outputs of Light independent reaction
inputs: CO2, ATP, NADPH
outputs: C6H12O6, ADP+Pi, NAPH+
- ATP formed during light-dependent reaction is used as energy source when combining CO2 and H to form glucose and water
- NADPH is energised electrons source and reducing power that reduces carbon dioxide and builds it into glucose
Factors affecting rate of photosynthesis
- amount of light
- temperature
- CO2 concentration
- water
- time of day
- colour of light
- enzyme/chlorophyll/NADP concentration
limiting factors of photosynthesis
light intensity, temperature and CO2 availability
what is a limiting factor
occurs when supply of factor is in short supply such that it restricts rate of photosynthesis.
Cellular respiration purpose
transfer chemical energy from glucose into chemical energy of ATP for use by cells
- energy required for making ATP comes from releasing chemical energy stored in bonds of glucose molecules
- glucose to ATP is not direct-occurs via shuttles called acceptors- transfer electrons and H+ to oxygen atoms and ultimately energy from glucose to ATP
where does energy from ATP come from
- release of energy from the bond attaching last phosphate group to ATP
- requires ATPase for reaction to proceed
how is ATP formed
- free energy from exergonic reactions, can be used to add phosphate group to ADP to form ATP- process of phosphorylation
- this reaction requires ATP Synthase
phosphorylation
addition of a phosphate group to organic molecule
Mitochondrion structure
cristae- highly folded inner membrane
enzymes- aerobic respiration enzymes gather in matrix along cristae
matrix- fluid-filled material-contains ribosomes and DNA.
Glycolysis
- occurs in cytosol of cell
- inputs: glucose, NAD+, 2 ADP+Pi
- outputs: 2 pyruvate, NADH, 2 ATP
Krebs Cycle
- occurs in matrix of mitochondrion
- inputs: 2 pyruvate, NAD+, FAD+, 2 ADP+Pi
- outputs: 6 CO2, NADH, FADH2, 2 ATP
Electron transport chain
occurs in cristae of mitochondrion
- inputs: 6O2, NADH, FADH2, 32 ADP+Pi
- outputs: 6H2O, NAD, FAD, 32 ATP
anaerobic respiration
occurs in cytosol in enzyme controlled, multi stepped process- enzymes present determine products formed
- pyruvate is converted to lactic acid in animals
- converted to alcohol(ethanol) and CO2 in plants and microorganisms such as yeasts
difference between aerobic respiration and anaerobic respiration
aerobic- requires oxygen, produces 36 ATP, occurs in cytosol and mitochondrion, sugars completely down into CO2 and H2O
anaerobic- doesn’t require oxygen, produces 2 ATP, occurs in cytosol of cell, sugars are not completely broken down- lactic acid or ethanol/CO2
Limiting factors of aerobic respiration
oxygen
glucose
concentration of enzymes involved in reaction
temperature and pH
availability of unloaded acceptors ( NAD+ and FAD)
limiting factors of anaerobic respiration
glucose
concentration of enzymes involved in reaction
temperature and pH
availability of unloaded acceptors ( NAD+ and FAD)
plants compensation point
- when rate of photosynthesis is equal to rate of respiration, therefore not net gain/loss of carbohydrate (glucose)
- oxygen being used during respiration equals amount being produced by photosynthesis
difference between photosynthesis and cellular respiration
photosynthesis-endergonic process (needs energy) by converting solar energy into chemical energy, requires CO2, requires chlorophyll, requires water, occurs during sunlight, produces oxygen
-cellular respiration- exergonic process(released energy,) converts chemical energy into other forms, produces CO2, no chlorophyll required, produces water, occurs at all times in all living things, needs oxygen.
evolution of mitochondria
- few billion years ago, mitochondria evolved from primitive eukaryote engulfing, but not digesting prokaryotic cell- through endophagocytosis
- could perform aerobic respiration, most efficient way of producing ATP.
- with prokaryote inside it, primitive eukaryote would have advantage over neighbouring cells- beneficial association between prokaryote and eukaryote lived on as they produced offspring
- over time cells lost ability to live independently, thus evolution of mitochondria
evolution of chloroplasts
- after eukaryotes acquired mitochondria, chloroplast evolved from primitive eukaryote engulfing, but not digesting prokaryotic cell- through endophagocytosis
- could perform photosynthesis
- with prokaryote inside it, primitive eukaryote would have advantage over neighbouring cells- beneficial association between prokaryote and eukaryote lived on as they produced offspring
- over time cells lost ability to live independently, thus evolution of chloroplasts
