Photosynthesis 6 Flashcards
Photosynthesis
- anabolic process, light is converted to chemical energy
- Chemical energy is stored into large compounds ( glucose) made from low energy inorganic compounds ( CO2)
- Chlorophyll is found in phototrophic autotrophs and facilitate light absorption
- Although prokaryotes lack chloroplast, they still undergo photosynthesis due to photosynthetic pigments present
- photosynthesis occurs in all green plant cells
- Stomata: CO2 enter/ O2 exits
- H20- absorbed by the roots of the plants and transported to leaves via xylem
Purpose of photosynthesis
Process of capturing sunlight energy to power production of glucose and oxygen from carbon dioxide and water
What if there is a surplus of glucose
it is stored as a starch, transported around the plant as sucrose
Chloroplast and components in them
- A double membrane-bound organelle and the site of photosynthesis.
- Within the inner membrane of the chloroplast, there are membrane discs known as thylakoids arranged in a stack called grana.
- The membrane of thylakoid contain chlorophyll, which captures light for photosynthesis
- Stroma is the fluid that surrounds the contents of the inner membrane.
- Chloroplasts contain their own DNA and ribosomes, which suggests they were once prokaryotic cells (like mitochondria)
Evidence of bacterial origin/ endosymbiosis relationship
- Own circular DNA not enclosed in nuclear membrane( like bacteria)
- replicate through binary fission
- Own ribosomes that share characteristic with Bacteria
- Prions are present in cell membrane only prokaryotic cells
- similar size
Light independent location
Grana/ thylakoid membrane
Light independent input
6 CO2
12 NADPH
12 ATP
Light independent outputs
C6H12O6
12 NADP+
12 ADP + Pi
6 H2O
Light dependent input
12 H2O
12 NADP+
12 ADP + Pi
Light dependent output
6 O2
12 NADPH
1 2ATP
Light dependent location
Stroma
- Step in the light dependent stage
- Inside thylakoid, light energy splits water into H+, electrons and oxygen and excites electrons in chlorophyll
- , oxygen released from chloroplast and diffuse in environment or in put for CR
- H+ electrons( from water and chlorophyll are used to generate high energy co enzyme NADPH (NADP + + H+) and ATP( ADP + Pi ) . Through series of interaction with proteins in thylakoid membrane and movement of H+ down concentration gradient
- ATP and NADPH then move to light independent stage
- Steps in the light independent stage
- carbon dioxide molecules enter LID stage, powered by ATP
- NADPH formed in the LD reactions unload their hydrogen ions and electrons to produce glucose
- additional oxygen molecules from CO2 and hydrogen ions from NADPH bind together to create water
Factors that affect Photosynthesis
[CO2] : CO2 is one of the substrates and as [CO2] increases so does rate of photosynthesis to a certain pont
Light Intensity: Light intensity increases, rate of photosynthesis increases to a certain point
Enzymatic Activity [pH, temperature and concentration/availability of substrate/enzyme] à Limit rate of
photosynthesis
Draw CO2 graph and Light intensity graph
looks the same with a plateau after optimal
