everything? Flashcards
At what organelle does anaerobic cellular respiration occur?
Anaerobic cellular respiration doesn’t occur in any organelles, it occurs in the cytosol
Explain what happens when lactic acid builds up in muscles due to anaerobic respiration.
Lactic acid lowers the pH of cells which can reduce enzyme function. Once oxygen is present again, lactic acid is metabolised back into pyruvate and used for aerobic cellular respiration.
What is the equation for aerobic respiration?
Glucose + Oxygen → Carbon dioxide + Water + 30 or 32 ATP
or
C6H12O6 + 6O2 → 6CO2 + 6H2O + 30 or 32 ATP
Where does each stage of aerobic respiration take place?
Glycolysis -cytosol
Kreb’s cycle - mitochondria matrix
Electron transport chain - cristae of the mitochondria
What are the 3 key coenzymes involved in aerobic respiration?
ATP, NAD+, FAD
What factors influence enzymes?
- Temperature
- pH level
- concentration
Why are enzymes used in biological reactions?
Enzymes catalyse and speed up reactions by providing a lower energy, alternate pathway for the reaction to take place.
Explain the ‘induced fit’ model.
The induced fit model explains how enzymes are flexible and change shape slightly when a substrate binds to them, which causes a reaction to occur.
What are the inputs and outputs of glycolysis?
Inputs:
* 1 Glucose
* NAD+ + 2 H+
* 2ADP + 2Pi
Outputs:
* 2 Pyruvate
* NADH
* 2 ATP
What are the inputs & outputs of the Krebs cycle?
Inputs:
* 2 acetyl-CoA
* 2 ADP + 2 Pi
* 6 NAD+ + 6 H+
* 2 FAD + 4 H+
Outputs:
* 2 ATP
* 4 CO2
* 6 NADH
* 2 FADH2
What are the inputs & outputs of the electron transport chain?
inputs:
* 6 O2 + 12 H+
* 2 FADH2
* 10 NADH
* 26 or 28 ADP + Pi
outputs:
* 26 or 28 ATP
* 6 H2O
* 10 NAD+ + 10 H+
* 2 FAD + 4 H+
Explain why the rate of cellular respiration increases when the temperature was increased from 0 to 33°C.
The rate of cellular respiration increased due to more frequent enzyme-substrate collisions between rubisco and CO2, thus increasing the rate of fixing CO2 into organic glucose and increasing photosynthetic rate.
Why do enzymes in the cytoplasm and mitochondrial matrix have different optimal pH levels.
The pH levels of different locations vary due to the cycling of H+ ions through FAD and NAD+, and thus the enzymes that support those functions have evolved to also have the same optimal pHs as their environments.
What are two reasons why a light-saturation point can be reached?
- Enzymes within chloroplasts are operating at full capacity.
- There is another limiting factor, such as CO2 availability, temperature, water availability, light colour or etc that is restricting the rate of photosynthesis.
Plants absorb light mostly at the:
short (blue) and long (red) wavelength ends of the visible light spectrum.
when does photorespiration occur
Photorespiration occurs in hot weather when Rubisco has a greater affinity for O2 than CO2
or when the concentration of O2 is greater than CO2
how does C4 photosynthesis work
- This separation allows for higher concentrations of CO2 than O2 around RuBisCO, which increases the chances for it to bind to CO2 which reduces photorespiration and increases photosynthesis.
how does CAM photosynthesis work
- In dry habitats plants lose their turgor due to water loss via transpiration, which causes the stomata to close.
- O2 from the light-dependent stage of photosynthesis builds up, and increases the likelihood that rubisco binds to O2 rather than CO2 and initiate photorespiration.
- CAM plants open their stomata at night to bring in CO2, and store fixed CO2 in vacuoles within mesophyll cells. During the day the stomata
What are the inputs & outputs of the light-dependent stage of C3 photosynthesis?
inputs:
* 12 H2O
* 12 NADP+
* 18 ADP + 18 Pi
outputs:
* 6 O2 molecules
* 12 NADPH
* 18 ATP
What are the inputs & outputs of the light-independent stage of C3 photosynthesis?
inputs:
* 6 CO2(g) molecules
* 12 NADPH
* 18 ATP
outputs:
* C6H12O6
* 6 H2O
* 12 NADP+
* 18 ADP + 18 Pi
What is chlorophyll?
Chlorophyll is the green pigment, found in thylakoid disks within chloroplasts, that absorbs light energy for use in photosynthesis.
Where do the stages of C3 photosynthesis occur?
light-dependent - On thylakoid membranes
light-independent - In the stroma within chloroplasts
What are the factors that affect the rate of photosynthesis?
- Light intensity
- Light colour
- Water availability
- Temperature
- CO2 concentration
- O2 concentration
What are C3 plants?
C3 plants are plants that conduct photosynthesis normally and have no evolved adaptations to minimise photorespiration.
What is the equation for photosynthesis?
Carbon dioxide + water → glucose + oxygen gas
or
CO2 + H20 → C6H12O6 + O2(g)
What are the two ways water availability can affect the rate of photosynthesis?
- Water is required as an input for the light dependent stage of photosynthesis.
- Dehydrated plants lose their turgor and stomata close, which increase conc. of O2 from light dependent reactions and thus increases likelihood of rubisco binding to O2 and initiating photorespiration.
What is the role of Rubisco in photosynthesis?
Fixes inorganic CO2 into glucose
Explain C3 photosynthesis
Explain why above 33°C the rate of photosynthesis decreases significantly with reference to rubisco.
rubisco is an enzyme that denatures above 42ºC but after 33ºC it is no longer at it’s optimum working temperature thus anything above or below is less efficient or entirely ineffective
* extreme temps = denature
CRISPR-Cas9 in bacteria functions as a:
primitive adaptive immune system
temps of each step of PCR
Denaturation: occurs at 94°C
Annealing: occurs at 54°C
Elongation: occurs at 72°C
Repetition
Generally explain how CRISPR-Cas9 would be used to disrupt a gene
- Using a vector, add the CRISPR-Cas9 complex to a cell that contain the target gene.
- Guide the RNA that is manufactured to anneal to the target DNA so that it binds to the target gene.
- Cut the target gene to disrupt it.
Outline the process CRISPR-Cas9 uses to cut specific DNA
- a bacteriophage attaches to the outside of bacterial cell and injects its VIRAL DNA into the cell (reinfection)
- previously, a segment of the viral DNA has been stored as a spacer in the CRISPR region - the CRISPR sequence is TRANSCRIBED resulting in CRISPR RNA (crRNA)
- tracer RNA (trcrRNA) has a complementary sequence to the repeat DNA (NOT the spacers) - role: helps hold the gRNA in place in the Cas9 enzyme
- the specific spacer of the crRNA binds to the trcrRNA to form single guide RNA (sgRNA) - sgRNA then binds with the Cas9 enzyme → forms a Cas9-gRNA complex
- Cas9-gRNA complex scans bacteriophage (target DNA) to look for complementary bases
- once it is found, the DNA is unzipped and Cas9 cuts/cleaves the DNA the viral DNA cannot reproduce as the DNA has been disrupted