Cell Biology Overview

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Questions and Answers

What is the primary function of cilia and flagella in eukaryotic cells?

They assist in cell division.

They provide movement for the cell. (correct)

They support the cell structure.

They are involved in metabolic reactions.

Which statement best describes the process of osmosis?

It requires energy to move water across a membrane.

It involves the active transport of ions only.

It is the passive movement of water across a selectively permeable membrane. (correct)

It is the movement of solutes from an area of low concentration to high concentration.

What is an endergonic reaction characterized by?

Releases energy to the surroundings.

Has a negative change in free energy.

Requires energy input to proceed. (correct)

Occurs spontaneously without the need for energy.

What are the final waste products of cellular respiration?

Carbon dioxide and water. Signup and view all the answers

Which structure in the chloroplast is primarily involved in the light-dependent reactions of photosynthesis?

Thylakoid. Signup and view all the answers

How many ATP molecules are produced during glycolysis?

2 ATP. Signup and view all the answers

What role do NAD and NADP play in cellular processes?

They function as electron carriers in metabolic reactions. Signup and view all the answers

What molecule serves as the primary reaction molecule in photosynthesis?

Carbon dioxide. Signup and view all the answers

How do autotrophs primarily obtain energy?

Through photosynthesis or chemosynthesis Signup and view all the answers

What characterizes a competitive inhibitor in enzyme reactions?

It competes with the substrate for the active site Signup and view all the answers

Which component of chloroplasts is primarily responsible for the light-independent reactions?

Stroma Signup and view all the answers

What is the primary function of phospholipids in cell membranes?

Form a bilayer that acts as a barrier Signup and view all the answers

What occurs during substrate-level phosphorylation?

ATP is formed directly from a metabolic intermediate Signup and view all the answers

Which of the following is a potential effect on enzyme function?

Changing temperature Signup and view all the answers

What distinguishes prokaryotic cells from eukaryotic cells?

Absence of a defined nucleus Signup and view all the answers

How many times must the Calvin Cycle go around to produce one molecule of glucose?

Six times Signup and view all the answers

Study Notes

Cilia and Flagella

Cilia and flagella are hair-like structures that project from the surface of cells.
Cilia are short and numerous, while flagella are long and few in number.
Both cilia and flagella are involved in cell movement.

Major Organelles of Eukaryotic Cells

Nucleus: Contains the cell's genetic material (DNA) and controls cellular activities.
Ribosomes: Responsible for protein synthesis.
Endoplasmic Reticulum (ER): A network of membranes involved in protein and lipid synthesis.
Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.
Mitochondria: The powerhouse of the cell, responsible for ATP production through cellular respiration.
Lysosomes: Contain enzymes for digesting waste products and cellular debris.
Vacuoles: Store water, nutrients, and waste products.

Phospholipids

Phospholipids are the primary building blocks of cell membranes.
Composed of a hydrophilic head (phosphate group) and a hydrophobic tail (fatty acid chains).
Form a bilayer in cell membranes, with the hydrophilic heads facing outwards and the hydrophobic tails facing inwards.

Osmosis

Osmosis is the movement of water across a semipermeable membrane from a region of high water concentration to a region of low water concentration.
This movement is driven by the difference in water potential.
Osmosis is essential for maintaining cell volume and fluid balance.

Diffusion, Passive Transport, Active Transport, and Bulk Transport

Diffusion: The spontaneous movement of molecules from an area of high concentration to an area of low concentration.
Passive transport: Movement of molecules across a membrane without requiring energy. This includes simple diffusion, facilitated diffusion, and osmosis.
Active transport: Movement of molecules across a membrane against their concentration gradient, requiring the use of energy (ATP).
Bulk transport: Movement of large molecules or particles across a membrane using vesicles. Includes endocytosis (taking material into the cell) and exocytosis (releasing material out of the cell).

Ultimate Source of Energy

The ultimate source of energy for life on Earth is the Sun.

Laws of Thermodynamics

First Law of Thermodynamics: Energy cannot be created or destroyed, only transformed from one form to another.
Second Law of Thermodynamics: Every energy transfer or transformation increases the entropy (disorder) of the universe.

Enzymes and Substrates

Enzymes: Biological catalysts that speed up chemical reactions without being consumed in the process.
Substrate: The specific molecule that an enzyme binds to and acts upon.
Enzymes have an active site where the substrate binds.

Oxidation-Reduction Reactions

Reactions involving the transfer of electrons.
Oxidation: Loss of electrons, resulting in a decrease in potential energy.
Reduction: Gain of electrons, resulting in an increase in potential energy.
Often occur together, as one molecule is oxidized while another is reduced.

Autotrophs and Heterotrophs

Autotrophs: Organisms that produce their own food from inorganic sources, such as sunlight (e.g., plants).
Heterotrophs: Organisms that obtain their food by consuming other organisms (e.g., animals).

Light Dependent and Light Independent Reactions of Photosynthesis

Light Dependent Reactions: Occur in the thylakoid membranes of chloroplasts.
Convert light energy into chemical energy in the form of ATP and NADPH.
Water is split, releasing oxygen as a byproduct.
Light Independent Reactions (Calvin Cycle): Occur in the stroma of chloroplasts.
Use ATP and NADPH produced in the light dependent reactions to convert carbon dioxide into glucose.

Thylakoids and Stroma

Thylakoids: Disk-shaped structures within chloroplasts, arranged in stacks called grana.
Contain chlorophyll, the pigment that absorbs light energy for photosynthesis.
Stroma: The fluid-filled region surrounding the thylakoids.
Contains enzymes for the Calvin Cycle.

Photosystems

Photosystem I (PSI): Absorbs light energy and uses it to reduce NADP+ to NADPH.
Photosystem II (PSII): Absorbs light energy and uses it to split water molecules, releasing oxygen and producing ATP.

Color Not Absorbed by Green Plants

Green plants do not absorb green light, which is why they appear green.

Prokaryotic and Eukaryotic Cells

Prokaryotic cells: Simple cells lacking a nucleus and membrane-bound organelles (e.g., bacteria).
Eukaryotic cells: Complex cells with a nucleus and membrane-bound organelles (e.g., plants, animals, fungi).

Endocytosis, Exocytosis, and Receptor-Mediated Endocytosis

Endocytosis: Process of taking material into the cell by engulfing it in a membrane-bound vesicle.
Exocytosis: Process of releasing material out of the cell by fusing a vesicle with the cell membrane.
Receptor-mediated endocytosis: A specific type of endocytosis where molecules bind to receptors on the cell surface, triggering the formation of a vesicle.

Endergonic and Exergonic Reactions

Endergonic reactions: Reactions that require energy input (positive ΔG), for example, photosynthesis.
Exergonic reactions: Reactions that release energy ( negative ΔG), for example, cellular respiration

Active Site, Allosteric Site, Competitive and Non-Competitive Inhibition

Active site: The region on an enzyme where the substrate binds.
Allosteric site: A site on an enzyme that, when bound to a regulatory molecule, can alter the enzyme's activity.
Competitive inhibition: A type of inhibition where the inhibitor competes with the substrate for the active site of the enzyme.
Non-competitive inhibition: A type of inhibition where the inhibitor binds to a site other than the active site, altering the enzyme's shape and making it less active.

Factors Affecting Enzyme Function

Temperature: Enzymes have an optimal temperature range. Excessive heat can denature (destroy) the enzyme.
pH: Enzymes have an optimal pH range. Extreme pH values can denature the enzyme
Substrate concentration: Enzyme activity increases as substrate concentration increases until saturation is reached.
Cofactors and coenzymes: Some enzymes require non-protein molecules (cofactors and coenzymes) to function properly.

Function of NAD and NADP

NAD+ (nicotinamide adenine dinucleotide): A coenzyme involved in many redox reactions, carrying electrons from one reaction to another.
NADP+ (nicotinamide adenine dinucleotide phosphate): A coenzyme involved in photosynthesis, carrying electrons from one reaction to another.

Substrate Level Phosphorylation and Oxidative Phosphorylation

Substrate-level phosphorylation: The direct transfer of a phosphate group from a substrate molecule to ADP to produce ATP.
Oxidative phosphorylation: The production of ATP using the energy released from the electron transport chain and the proton gradient across the mitochondrial membrane.

Glycolysis

Glycolysis is a metabolic pathway that occurs in the cytoplasm.
It breaks down glucose into pyruvate, producing ATP.
Glycolysis can occur with or without oxygen.

Cellular Respiration

The process of breaking down glucose to produce ATP.
Aerobic respiration: Requires oxygen to produce a significant amount of ATP. Occurs in four stages: glycolysis, pyruvate oxidation, Krebs cycle/citric acid cycle, and oxidative phosphorylation.
Anaerobic respiration: Occurs in the absence of oxygen, producing a small amount of ATP.

ATP Production in Cellular Respiration

Glycolysis: Produces 2 ATP molecules.
Pyruvate oxidation and the Krebs Cycle: Produce 2 ATP molecules.
Oxidative phosphorylation: Produces about 32 ATP molecules.

Locations of Cellular Respiration

Glycolysis: Occurs in the cytoplasm.
Pyruvate Oxidation: Occurs in the mitochondrial matrix.
Krebs Cycle/Citric Acid Cycle: Occurs in the mitochondrial matrix.
Oxidative Phosphorylation: Occurs in the inner mitochondrial membrane.

Final Product of Glycolysis

Pyruvate

Final Waste Products of Cellular Respiration

Carbon dioxide and water

Equations for Photosynthesis and Cellular Respiration

Photosynthesis: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Cellular Respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + energy (ATP)

Role of Water in Photosynthesis

Water is a reactant in photosynthesis, providing electrons and protons.
Oxygen is a byproduct of splitting water molecules.

Reaction Molecule of Photosynthesis

Carbon dioxide (CO2)

Molecules Produced in the Calvin Cycle

Glucose (C6H12O6)

Photon

A tiny packet of light energy.

Number of Calvin Cycle Turns to Make One Glucose

6 turns of the Calvin cycle are required to produce one molecule of glucose.

Plant vs. Animal Cells

Plant Cells
- Have a cell wall made of cellulose that provides structural support.
- Have chloroplasts for photosynthesis.
- Have a large central vacuole for storage and maintaining turgor pressure.
Animal Cells:
- Lack a cell wall.
- Lack chloroplasts.
- Have smaller vacuoles.

Stomata

Stomata: Tiny pores on the surface of plant leaves.
Purpose: Allow for gas exchange (entry of carbon dioxide and exit of oxygen).
Regulation: Stomata open and close to regulate gas exchange and prevent water loss.

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Description

Explore the essential structures and functions of eukaryotic cells, including cilia, flagella, and major organelles. This quiz covers the roles of the nucleus, ribosomes, mitochondria, and more, highlighting their significance in cellular processes. Test your knowledge about the building blocks of cell membranes with phospholipids.