Biology Lecture 4: Cells and Microscopy

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Questions and Answers

What byproduct is generated during the hydrolysis of water in the light dependent reactions?

Oxygen (correct)

NADPH

Carbon Dioxide

Glucose

Which molecule is primarily responsible for carrying energy during the light independent reactions?

NADP+

Glucose

H2O

ATP (correct)

In cellular respiration, what is the main difference between aerobic and anaerobic respiration?

Anaerobic respiration uses glucose for energy production.

Aerobic respiration does not produce ATP.

Aerobic respiration is more efficient at producing ATP. (correct)

Anaerobic respiration occurs in the presence of oxygen.

What is the primary reactant converted into sugar during the light independent reactions?

Carbon Dioxide Signup and view all the answers

What drives the movement of H+ across the membrane during the light dependent reactions?

Concentration gradients Signup and view all the answers

What is the primary advantage of a light microscope compared to an electron microscope?

It can view living organisms. Signup and view all the answers

Which of the following statements correctly describes prokaryotic cells?

They have a simple structure without a nuclear membrane around their DNA. Signup and view all the answers

What part of the prokaryotic cell is responsible for regulating the entry and exit of substances?

Plasma membrane Signup and view all the answers

Which eukaryotic cell structure is responsible for dividing the cytoplasm into compartments?

Plasma membrane Signup and view all the answers

New cells arise from which of the following processes?

Cell division from pre-existing cells Signup and view all the answers

What is the main disadvantage of using a scanning electron microscope (SEM)?

It cannot view internal structures. Signup and view all the answers

What function does the capsule of a prokaryotic cell serve?

It protects the cell and helps evade the immune system. Signup and view all the answers

What is a key characteristic of eukaryotic cells that differentiates them from prokaryotic cells?

They possess a nuclear membrane around their DNA. Signup and view all the answers

Which of the following cell structures is considered an organelle involved in protein synthesis?

Ribosomes Signup and view all the answers

Which type of microscope would be best to observe the fine details inside a cell?

Transmission electron microscope Signup and view all the answers

Which type of inhibition involves substances that bind to the active site of an enzyme?

Competitive inhibition Signup and view all the answers

What is true about allosteric inhibitors?

They change the shape of the enzyme. Signup and view all the answers

Which statement is correct about exergonic and endergonic reactions?

Exergonic reactions are associated with hydrolysis. Signup and view all the answers

How do enzymes primarily lower activation energy?

By forming intermediate complexes Signup and view all the answers

What distinguishes catabolic pathways from anabolic pathways?

Catabolic pathways break down molecules. Signup and view all the answers

What are the three stages of aerobic respiration?

Glycolysis, Citric acid cycle, Oxidative phosphorylation Signup and view all the answers

Where does glycolysis occur in a cell?

Cytoplasm Signup and view all the answers

Which of the following is a product of the Krebs cycle?

All of the above Signup and view all the answers

How many ATP are produced during oxidative phosphorylation?

32-34 ATP Signup and view all the answers

What type of fermentation occurs in skeletal muscle?

Lactate fermentation Signup and view all the answers

Which process produces less ATP than aerobic respiration?

Anaerobic respiration Signup and view all the answers

What is the final electron acceptor in aerobic respiration?

Oxygen Signup and view all the answers

Which of the following correctly describes the efficiency of anaerobic respiration compared to aerobic respiration?

Less efficient and produces less ATP Signup and view all the answers

What describes an amphipathic molecule?

A molecule that is hydrophilic and hydrophobic Signup and view all the answers

Which of the following is NOT a main component of cellular membranes?

Nucleic acids Signup and view all the answers

What is the function of self-markers in cells?

To identify cells for immune response Signup and view all the answers

Which statement accurately describes moving 'with' the concentration gradient?

Substances move from a high to low concentration Signup and view all the answers

Which type of passive transport requires a protein channel?

Facilitated diffusion Signup and view all the answers

What is a characteristic of exergonic reactions?

They release free energy Signup and view all the answers

Which component is essential for freshwater protists to prevent cell bursting?

Contractile vacuole Signup and view all the answers

What role do enzymes play in chemical reactions?

They lower the activation energy Signup and view all the answers

What effect do non-competitive inhibitors have on enzyme function?

They alter the shape of the enzyme Signup and view all the answers

Which of the following statements about metabolic pathways is true?

They are typically regulated by enzymes Signup and view all the answers

Study Notes

Cell Theory

All living organisms consist of cells.
Cells are the smallest unit of life.
New cells originate from pre-existing cells through division.

Microscopy

Two main types:
- Light microscope: Uses light for illumination, magnification up to 1000-2000x; can view living organisms but has limited magnification for small structures.
- Electron microscope: Uses a beam of electrons for illumination, magnification up to 20,000-100,000x.
Scanning Electron Microscope (SEM): High magnification view, but only surface details.
Transmission Electron Microscope (TEM): Views internal structures of cells, but requires thin slices.

Cell Structures

All cells contain four essential structures: plasma membrane, cytoplasm, genetic material, and ribosomes.
Organelles, termed "little organs," perform specific functions within the cell.

Basic Cell Types

Prokaryotic cells ("before the nucleus"):
- Simple structure, lack a nuclear membrane.
Eukaryotic cells ("true nucleus"):
- More complex, possess a nuclear membrane around DNA.

Prokaryotic Cells

Two categories:
- Bacteria: Small (1 μm – 10 μm), diverse, mostly non-harmful, but some cause diseases.
- Archaea: Similar size, less common, often found in extreme environments.
Structure includes:
- Plasma membrane: Regulates substance exchange.
- Cytoplasm: Contains internal components.
- Nucleoid region: Location of genetic material.
- Ribosomes: Synthesize proteins.
- Cell wall: Provides rigidity and shape.
- Capsule: Offers protection and helps evade immune response.
- Pili and Flagella: Functions in attachment and locomotion respectively.

Eukaryotic Cells

Vary in shape, size, and organization based on type and species.
DNA is enclosed within the nucleus.
Membrane-bound organelles compartmentalize cellular functions.

Structures:

Plasma membrane: Controls substance movement, facilitates cell adhesion, and signal transduction.
Cytoplasm: Composed of cytosol and organelles.

Cellular Respiration

Two types:
- Aerobic respiration: Requires oxygen, highly efficient for ATP production.
- Anaerobic respiration: Occurs without oxygen, less efficient, primarily in some prokaryotes.

Aerobic Respiration Stages:

Glycolysis: Occurs in the cytoplasm, breaks glucose into two molecules, yielding 2 ATP.
Krebs Cycle: Takes place in mitochondria, converts pyruvate into ATP and electron carriers (NADH, FADH2).
Oxidative Phosphorylation: Involves a series of proteins in the inner mitochondrial membrane, producing 32-34 ATP by creating a proton gradient.

Anaerobic Respiration:

Uses different final electron acceptors other than oxygen; produces 2 ATP.
Includes:
- Lactate fermentation in muscles.
- Alcoholic fermentation in yeast.

Energy, Enzymes, and Metabolism

Energy types: kinetic, potential, chemical, and free energy.
Chemical reactions:
- Exergonic: Release free energy (e.g., ATP hydrolysis).
- Endergonic: Consume free energy (e.g., ATP formation).

Enzymes:

Serve as biological catalysts, speeding up reactions without being consumed.
Specific to substrates and affected by environmental conditions (temperature, pH).
Inhibitors can block enzyme activity through competitive or non-competitive mechanisms.

Metabolic Pathways

Series of enzyme-catalyzed reactions leading to specific products.
Can be influenced by the concentration of substrates and inhibitors, impacting reaction rates.

Exam Review Points

Key concepts of cellular respiration including formulas, processes, and component functions.
Understanding amphipathic molecules, cellular membrane components, transport mechanisms, and types of endocytosis.

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Description

Explore the fundamentals of cell theory and the types of microscopes in this quiz. Understand how all living organisms are made of cells, which are the basic units of life, and learn about the differences between light and electron microscopes. Test your knowledge on the magnification capabilities and advantages of these essential scientific tools.