3A3 Biochemistry of Life Flashcards
Explore how the biochemistry of life is dependent on processes such as cellular respiration and photosynthesis, as well as the structure of biological molecules.
What is cellular respiration?
The process by which cells convert glucose into energy.
Cellular respiration generates ATP by breaking down glucose molecules, with or without oxygen.
What are the two main types of cellular respiration?
- Aerobic Respiration
- Anaerobic Respiration
Aerobic respiration requires oxygen and occurs in plants, animals, and fungi. Anaerobic respiration occurs without oxygen, and usually occurs in bacteria, archea, and other small microorganisms.
However, in situations of low oxygen, humans and plant cells can undergo anaerobic respiration.
What is the primary energy carrier molecule produced during respiration?
ATP
(Adenosine Triphosphate)
This molecule provides energy for cellular processes.
Fill in the blank:
Aerobic respiration occurs in the __________.
mitochondria
Aerobic respiration primarily takes place in the mitochondria where oxygen is utilized for ATP production.
True or False:
Anaerobic respiration occurs in the mitochondria.
False
Anaerobic respiration occurs in the cytoplasm since it does not require the organelles involved in oxygen-dependent processes.
What is the main purpose of aerobic respiration?
To produce ATP using oxygen.
This process is highly efficient, yielding up to 38 ATP molecules per glucose molecule.
What is the main purpose of anaerobic respiration?
To generate energy without oxygen.
This process produces less ATP (2 ATP per glucose) but is faster than aerobic respiration.
What is the chemical equation for aerobic respiration?
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
Glucose and oxygen are converted into carbon dioxide, water, and energy in the form of ATP.
Fill in the blank:
Anaerobic respiration produces _____ or ______ as by-products.
lactic acid ; ethanol
Ethanol and CO₂ are by-products in yeast. When humans (and other animals) exercise strenuously, the cells do not have enough oxygen to produce energy, so lactic acid is produced.
What are the 3 stages of aerobic respiration?
- Glycolysis
- The Krebs cycle
- Electron Transport Chain
These stages collectively produce ATP and require oxygen.
What is glycolysis?
The breakdown of glucose into pyruvate.
It occurs in the cytoplasm and is the first step in both aerobic and anaerobic respiration.
True or False:
Glycolysis requires oxygen.
False
Glycolysis is an anaerobic process and can occur with or without oxygen, which is why it is the first step for both aerobic and anaerobic respiration.
Where does the Krebs cycle occur in the cell?
In the mitochondrial matrix.
This cycle processes pyruvate to produce energy-rich molecules like NADH and FADH₂.
What is the main role of the electron transport chain?
To generate ATP using high-energy electrons.
This step uses oxygen as the final electron acceptor to produce ATP.
Fill in the blank:
Oxygen acts as the final ________ ________ in the electron transport chain.
electron acceptor
Oxygen combines with electrons and protons to form water, completing the process. This explains why oxygen is necessary for aerobic respiration.
What is fermentation?
An anaerobic process that generates energy without oxygen.
This process is a type of anaerobic respiration seen in organisms like yeast and muscle cells under low oxygen conditions.
What is the ATP yield of anaerobic respiration?
2 ATP per glucose molecule.
Anaerobic respiration makes less energy when compared to aerobic respiration, but is a much quicker process.
What gas is released during aerobic respiration?
Carbon dioxide
(CO₂)
CO₂ is released during the Krebs cycle and is expelled during exhalation.
What happens to pyruvate in aerobic respiration?
It enters the Krebs cycle.
In aerobic conditions, pyruvate is converted to acetyl-CoA and processed further in the mitochondria.
What is photosynthesis?
The process by which plants convert sunlight into chemical energy.
This process occurs in chloroplasts, using light, water, and carbon dioxide to produce glucose and oxygen.
Where does photosynthesis primarily occur in plants?
In the chloroplasts of leaf cells.
Chloroplasts contain chlorophyll, which captures light energy essential for photosynthesis.
True or False:
The oxygen released during photosynthesis comes from carbon dioxide.
False
The oxygen released during photosynthesis originates from water molecules. During the light-dependent reactions, water is split through a process called photolysis, producing oxygen as a byproduct.
What is the main molecule that absorbs light energy for photosynthesis?
Chlorophyll
This molecule absorbs light, primarily in the blue and red wavelengths, while reflecting green light.
Fill in the blank:
The primary products of photosynthesis are glucose and ________.
oxygen
Glucose is stored as energy, while oxygen is released into the atmosphere as a byproduct.
What are the two main stages of photosynthesis?
- Light-dependent reactions
- The Calvin cycle
Light-dependent reactions occur in the thylakoid membranes, while the Calvin cycle occurs in the stroma.
True or False:
The Calvin cycle requires light to function.
False
This cycle is light-independent but depends on energy (ATP and NADPH) produced during the light-dependent reactions.
Fill in the blank:
During the Calvin cycle, carbon dioxide is converted into ________.
glucose
The Calvin cycle uses ATP and NADPH to fix carbon dioxide and synthesize glucose.
What molecule transports high-energy electrons during photosynthesis?
NADPH
This molecule is produced in the light-dependent reactions and provides the reducing power needed for the Calvin cycle.
How is ATP produced during the light-dependent reactions?
By chemiosmosis through ATP synthase.
Chemiosmosis involves hydrogen ions moving across the semipermeable membrane down their electrochemical gradient. This creates free energy that is used by ATP synthase to convert ADP into ATP.
What enzyme is responsible for fixing carbon dioxide in the Calvin cycle?
RuBisCO
This enzyme catalyzes the reaction between carbon dioxide and RuBP, initiating the Calvin cycle.
What are biological molecules?
Molecules that are essential for life.
This includes nucleic acids, carbohydrates, proteins, and lipids, which perform various functions such as storing genetic information, providing energy, and forming cell structures.
What are nucleic acids responsible for?
Storing and transmitting genetic information.
Nucleic acids, like DNA and RNA, carry the genetic blueprint for all living organisms.
What are the building blocks of nucleic acids?
Nucleotides
They consist of a sugar, a phosphate group, and a nitrogenous base. DNA and RNA are polymers of nucleotides.
Fill in the blank:
The two types of nucleic acids are _____ and _____.
DNA ; RNA
DNA stores genetic information, while RNA plays a key role in protein synthesis.
What are carbohydrates used for in living organisms?
Providing energy and structural support.
Carbohydrates, such as sugars and starches, are vital for energy storage and structural components in plants and animals.
What is the basic unit of carbohydrates?
Monosaccharides
Examples include glucose and fructose, which are simple sugars that can form more complex carbohydrates.
True or False:
Starch is a type of protein.
False
Starch is a carbohydrate and serves as a storage form of energy in plants.
Fill in the blank:
The polymer of glucose that is used by animals for energy storage is ________.
glycogen
It is a polysaccharide stored primarily in the liver and muscles in animals.
Define:
Cellulose
A carbohydrate that provides structural support in plant cell walls.
Cellulose is a polysaccharide made of glucose units, and it is crucial for maintaining the strength and rigidity of plant cells.
What are proteins made of?
Amino acids
Proteins are polymers of amino acids, and their sequence determines their structure and function.
What are the functions of proteins?
- Catalyzing reactions.
- Providing structure.
- Regulating body processes.
Proteins are involved in almost all cellular functions, including enzyme catalysis and immune response.
True or False:
All proteins are enzymes.
False
While enzymes are proteins, not all proteins function as enzymes. Many proteins have structural or regulatory roles.
What are lipids primarily used for in organisms?
Storing long-term energy and forming cell membranes.
Lipids, such as fats and phospholipids, are important for energy storage and creating the structure of cell membranes.
What are the building blocks of lipids?
Fatty acids and glycerol.
They are made up of glycerol and fatty acid chains, forming triglycerides or phospholipids.
True or False:
All lipids are hydrophobic.
True
Lipids are generally nonpolar and do not dissolve in water, making them hydrophobic.
Fill in the blank:
The most common form of lipid used for energy storage is _________.
triglycerides
These lipids are made of three fatty acids bonded to a glycerol molecule and are stored in fat cells.
What is the role of cholesterol in the body?
- Stabilize cell membranes
- Produce hormones
Cholesterol is a type of lipid that helps maintain membrane fluidity and is used to synthesize hormones like estrogen and testosterone.
What type of bond forms between amino acids in a protein?
Peptide
Peptide bonds are covalent bonds that link the amino group of one amino acid to the carboxyl group of another.
True or False:
Enzymes are consumed in the reactions they catalyze.
False
Enzymes are not consumed in reactions; they can be reused multiple times to catalyze the same reaction.
