Unit 3 AOS 1: Photosynthesis and Cellular Respiration Flashcards
Chloroplasts
An organelle that uses light energy, carbon dioxide and water to produce glucose.
Photosynthesis Equation
Water + Carbon Dioxide = Glucose + Oxygen
Light Dependent Inputs, Outputs, Location
Inputs: Water, ADP+Pi, NADP
Outputs: Oxygen, ATP, NADPH
Location: Thylakoid/Granum
Light Independent Inputs, Outputs, Location
Inputs: Carbon Dioxide, ATP, NADPH
Outputs: Glucose, ADP+Pi, NADP
Location: Stroma
Evidence for chloroplasts having bacterial origin
- they possess DNA that consists of circular double-stranded DNA (not nuclear DNA)
- they divide via binary fission
- they contain their own ribosomes
- joined by eukaryotic cells after mitochondria because all eukaryotic cells have mitochondria, but not all have chloroplasts.
Relationship between light-dependent and light-independent reactions
The products or outputs of each reaction, becomes the inputs for the opposite reaction
Role of NADP+ in photosynthesis
Collects hydrogen ions for the transport to the light-independent stage
Role of ATP in photosynthesis
Energy carrier when charged with Pi. Energy is used in the light-independent stage
Factors affecting the rate of photosynthesis
Temperature Light availability CO2 availability O2 availability Chlorophyll availability
Main purpose of photosynthesis
The main purpose of photosynthesis is to convert radiant energy from the sun into chemical energy that can be used for food
Factors affecting ROP
Temp
- Photosynthetic enzymes and reactant molecules move more rapidly with increasing temperature
- With more collisions between enzymes and substrate a greater rate of photosynthetic reactions occur
- When temp is too hot and fine stage and rate of photosynthesis plummets
Factors affecting ROP
Light availability
- Chlorophyll requires light to conduct the light-dependent reactions of photosynthesis
- Thus as light intensity increases so does the rate of photosynthesis until a light saturation point is achieved
Factors affecting ROP
CO2 availability
- Carbon dioxide is a reactant for the light-independent stage of photosynthesis
- As carbon dioxide rises, the rate of photosynthesis will increase until the active sites of enzymes involved in photosynthetic reactions are saturated and an optimum rate is achieved
Factors affecting ROP
O2 availability
- More oxygen means a higher rate of photosynthesis, as it’s a result of the light-dependent action
Factors affecting ROP
Chlorophyll availability
- Chlorophyll absorbs the light energy required to convert carbon dioxide and water into glucose
- The more chlorophyll the higher the rate of photosynthesis
An increase in atmospheric CO2 level increases the rate of photosynthesis
The rate of photosynthesis increases because
The rate of the light-independent reactions in the stroma increases with the increase in CO2 levels.
Endosymbiotic theory of chloroplast and mitochondrial evolution
The endosymbiotic theory states that some of the organelles in eukaryotic cells were once prokaryotic microbes.
Mitochondria and chloroplasts of the same size as prokaryotic cells and divided by binary fission. Chloroplasts have their own DNA which is circular, not linear
In this theory the first eukaryotic cells probably amoeba-like so they got nutrients by phagocytosing and contained a nucleus that formed when a piece of the cytoplasmic membrane pinched off around the chromosomes.
The amoeba ate the prokaryotic cell the mitochondria formed when the bacteria are capable of aerobic respiration was ingested and chloroplast formed when photosynthetic bacteria was ingested
Evidence for the endosymbiotic theory
- Mitochondria and chloroplasts of the same size as prokaryotic cells and divided by binary fission
- Mitochondria and chloroplasts have their own DNA which is circular, not linear
- Mitochondria and chloroplasts have their own ribosomes which have 30S and 50S of subunits, not 40 and 60
Cofactors and Coenzymes
Coenzymes are small, non-protein organic molecules that carry chemical groups between enzymes e.g. NAD and FAD. Forms easily remove loose binds
A cofactor is a non-protein chemical compound that tightly and loosely bonds with an enzyme or other protein molecules.
What is the difference between anaerobic respiration in animals compared to anaerobic respiration in plants, yeast, and bacteria?
Anaerobic bacteria can sustain itself without the presence of oxygen.
Almost all animals and humans are obligate aerobes that require oxygen for respiration, whereas anaerobic yeast is an example of facilitative anaerobe bacteria. Individual human cells are also facilitative anaerobes: They switch to lactic acid fermentation if oxygen is not available.
Mitochondria
Membrane-bound organelles that generate most of the chemical energy needed to power the cell’s biochemical reactions. Chemical energy is produced by the mitochondria is stored in a small molecule called ATP.
Cellular respiration equation
Glucose + Oxygen = Carbon Dioxide + Water + ATP
Cellular respiration
The complete breakdown of glucose to provide energy for cells. Specifically, it refers to the second aerobic stage that occurs in the mitochondria and produces 36-38 ATP per molecule of glucose.
Glycolysis
Location: Cytosol
Inputs: Glucose, ADP+Pi, NAD+
Outputs: Pyruvate, ATP, NADH
ATP yield: 2
Krebs Cycle
Location: Matrix
Inputs: Pyruvate, ADP+Pi, NAD+, FAD+
Outputs: CO2, ATP, NADH, FADH
ATP yield: 2
Electron Transport Chain
Location: Cristae
Inputs: Oxygen, ADP+Pi, NADH, FADH
Outputs: Water, ATP, NAD+, FAD+
ATP yield: 32
Factors affecting the rate of cellular respiration
Glucose availability
Temperature
Oxygen Concentration
Factors affecting ROCR
Glucose availability
If there is no glucose, all stages of cellular respiration will slow down or stop as glycolysis will not begin without glucose there is no cellular respiration
Factors affecting ROCR
Temperature
- Lower the temperature = slower the reactions
- Doesn’t often affect humans (or other warm-blooded organisms); seen more often
in cold-blooded organisms
Factors affecting ROCR
Oxygen concentration
If there is no oxygen available, the cell won’t be able to respire aerobically and will instead have to aspire anaerobically and all slow down aerobic respiration
Anaerobic respiration equation in animals
Glucose + ADP+Pi = ATP + Lactic acid
ATP yield: 2
Anaerobic respiration equation in plants and yeasts
Glucose + ADP+Pi = ATP + Ethanol + Carbon Dioxide
ATP yield: 2
Consider the reactions of photosynthesis. Why would it be important to maintain the temperature within narrow limits in a commercial greenhouse? Justify your answer
It’s important to maintain the temperature within narrow limits in a commercial greenhouse because photosynthesis is regulated by enzymes and all enzymes have an optimum temperature which allows them to work at their best. Enzymes will denature at high temperatures and will operate very slowly at low temperatures, hence the greater the rate of reaction, the more growth in the greenhouse will occur.
Scientists are developing a new material to cover greenhouses, which can split incoming light and convert the rays from green wavelengths into red wavelengths.
Explain how this new material increases crop yields.
This new material will increase crop yields as green plants will reflect the incoming green light and/or not use it for photosynthesis whereas the red light can be used in photosynthesis which therefore increases the availability of light for photosynthesis, hence the more glucose produced, the greater the rate of photosynthesis.
In plants and algae, photosynthesis is carried out in chloroplasts. It is thought that chloroplasts originated from bacteria.
Describe two features of chloroplasts that support the theory that chloroplasts originated from bacteria.
Two features of chloroplasts that support the theory that chloroplasts originated from bacteria include that chloroplasts have their own circular DNA, similar to what you would find in bacteria, as well as they have their own ribosomes to synthesise proteins as they did when it was a prokaryote
Anaerobic respiration
Anaerobic cellular respiration occurs exclusively in oxygen - deprived conditions.
Therefore, when oxygen availability is low, cells will rely on the process of anaerobic cellular respiration
Purpose of photosynthesis
To convert solar energy into chemical energy via the reduction of CO2 to glucose, and to store this glucose for future use
Purpose of cellular respiration
Breaks down high energy compounds (such as glucose) to produce the molecule, ATP, which is more useable form of energy
Chloroplasts
- Site of photosynthesis
- Result of endosymbiosis
Evidence for mitochondria
- mitochondria have their own cell membranes just like prokaryotic cells
- each mitochondrion have its own circular DNA genome
- they multiply by pinching in half just like binary fission
- lack a cytoskeleton
Evidence for mitochondria
- mitochondria have their own cell membranes just like prokaryotic cells
- each mitochondrion have its own circular DNA genome
- they multiply by pinching in half just like binary fission
- lack a cytoskeleton
