C1.2: Cell Respiration Flashcards
Describe the structure of ATP.
An RNA Nucleotide made of 3 parts:
- Nitrogenous base Adenine
- Ribose Sugar
- A tail of 3 phosphate molecules
State the name of the process where a phosphate is added to another molecule
Phosphorylation
Outline properties of ATP that make it suitable for the use as an energy currency within cells.
- ATP is soluble in water
- ATP is stable at pH levels close to neutral
- ATP can’t pass freely through phospholipid bilayer: Movement between membrane bound organelles within cells can be controlled
- 3rd Phosphate group of ATP can be easily removed (hydrolysis) and reattached (condensation): Hydrolysing ATP to ADP and phosphate releases a small amount of energy which is not wasted and is sufficient for many processes within the cell
Outline example cellular processes that require use of ATP (3)
- Synthesising macromolecules like DNA
- Pumping molecules or ions via active transport
- Movement of things within the cell such as vesicles
Define Exergonic
Energy is released into surrounding environment
Define Endergonic reaction
Energy is absorbed form surrounding environment
What does ADP stand for
Adenosine Diphosphate
Describe the ATP-ADP cycle, firstly by stating how ATP changes to ADP + Phosphate.
- Hydrolysis reaction occurs with the addition of H2O
- Bond holding 3rd phosphate to 2nd phosphate gets broken and an exergonic reaction occurs, energy is released
- This changes ATP to ADP too
Describe the ATP-ADP cycle, secondly by stating how ADP + Phosphate changes to back to ATP.
- 3rd Phosphate group is added to a molecule of ADP (Phosphorylation occurs)
- A molecule of water is removed in an endergonic reaction and energy is temporarily stored
- Energy stored is released during ATP hydrolysis at the first step which is sufficient for processes within the cell
Where can the energy required to convert ADP and Phosphate back to ATP come from
- Cell respiration: Energy is released by oxidising carbohydrates, fats or proteins
- Photosynthesis: Light energy is converted to chemical energy
- Chemosynthesis: Energy is released by oxidising inorganic substances like sulfides
State why heat is generated during the ATP-ADP cycle.
Exergonic reaction occurs when ATP is hydrolysed into ADP
Define cellular respiration.
Cellular respiration is the gradual and controlled release of energy by breaking down organic compounds to produce ATP
List reasons why cellular respiration must be continuously performed by all cells.
- ATP can’t be stored for later use
- ATP can’t be transferred from cell to cell
- When ATP’s used in cells, heat is released: This heat energy is wasted
Distinguish between cellular respiration and gas exchange (respiration).
- Cellular respiration is a complex series of metabolic pathways and cycles that break down carbon compounds which is used to produce ATP.
- Gas Exchange (respiration) is the movement of oxygen form the inhaled air into the blood and carbon dioxide from the blood into the air to be exhaled.
Define what a respiratory substrate is
Any molecule that can be broken down in respiration to release energy
List common substrates of cellular respiration.
- Glucose
- Carbohydrates
- Lipids
- Proteins (amino acids)
Compare and contrast anaerobic fermentation and aerobic respiration.
Anaerobic Fermentation:
- Occurs in the absence of oxygen
- Occurs only in cytoplasm
- Only glucose and carbs can be used as respiratory substrates
- Yield of ATP is relatively large
- Waste products lactate (lactic acid)
Aerobic Respiration:
- Occurs in the presence of oxygen
- Begins in cytoplasm but most steps occur in mitochondria
- Able to use any respiratory substrates
- Yield of ATP is small
- Waste products are CO2 and H2O
Instrument used to measure rate of respiration and how does it measure the respiration rate
Respirometer: it measures the consumption of O2
Identify the manipulated (independent), responding (dependent) and controlled variation in experiments of variables affecting the rate of cell respiration.
Independent variable:
- Temperature
Dependent variable:
- Rate of cell respiration (volume of oxygen consumed per unit time)
Controlled variables:
- same conc of substrate
- same pH level
- same duration
- same light exposure
List three approaches for determining the rate of cellular respiration.
- Oxygen uptake
- CO2 Production
- Consumption of glucose or other respiratory substrates
Describe three investigative techniques for measuring the effect of a variable on the rate of cellular respiration.
Measure O2 uptake: A capillary tube containing fluid connected to the container to measure changes in the volume of air inside the respirometer
Converting measurements to volumes: Movement of fluid in capillary tube is measured in mm and should be converted to units of volume
Calculating rates: Volume of oxygne used must be divided by time. This rate is the dependent variable in an experiment using a respirometer
Outline oxidation and reduction reactions in terms of movement of hydrogen and electrons.
Oxidation:
- E- are lost
Reduction:
- E- are accepted
Define “electron carrier.”
Substances that are able to accept and lose electrons reversibly
State the name of the electron carrier molecule used in cellular respiration. It is also known as an oxidiser
NAD (Nictotinamide Adenine Dinucleotide)