Principles of Cell Theory

Questions and Answers

What occurs after mRNA leaves the nucleus?

It is degraded immediately

It forms ribosomes

It gets converted back to DNA

It is translated into protein (correct)

Intermediary metabolism refers to the processes of building larger molecules from smaller ones only.

False

What are the cylindrical structures that organize microtubules during cell division called?

Centrioles

Match the following types of metabolism with their definitions:

Anabolic = Building larger molecules from smaller ones Catabolic = Breaking down larger molecules into smaller ones Intermediary metabolism = Chemical reactions involving organic molecules Enzyme = Catalyst that speeds up chemical reactions Signup and view all the answers

The process of _______ involves breaking down larger molecules into smaller simpler ones.

catabolism Signup and view all the answers

Where do amino acids go through folding before becoming proteins?

In the cytosol Signup and view all the answers

Cilia and flagella are formed by centrioles to aid in cellular respiration.

False Signup and view all the answers

What is the primary function of microtubules during cell division?

To form the mitotic spindle Signup and view all the answers

ATP is produced during the _______ of nutrients in the cell.

metabolism Signup and view all the answers

Which is NOT a component of intermediary metabolism?

Formation of DNA Signup and view all the answers

What are the primary components of the cytoskeleton?

Microtubules, microfilaments, intermediate filaments Signup and view all the answers

The cytosol is the living substance inside the cell that includes all organelles.

False Signup and view all the answers

What is the function of ribosomes?

To synthesize proteins. Signup and view all the answers

The smallest elements of the cytoskeleton are called __________.

microfilaments Signup and view all the answers

What is the primary energy currency for cells?

Adenosine Triphosphate (ATP) Signup and view all the answers

Match the following cellular structures with their functions:

Nucleus = Contains genetic material Golgi Complex = Modifies and distributes proteins Smooth ER = Synthesizes lipids Microtubules = Acts as a transport highway Signup and view all the answers

Lysosomes are responsible for storing energy in the form of phosphates.

False Signup and view all the answers

Which statement best describes the function of the plasma membrane?

Controls movement of molecules into and out of the cell. Signup and view all the answers

Microtubules are involved in muscle contraction.

False Signup and view all the answers

What must happen to the chemical energy stored in ingested food before it can be used by cells?

It must be extracted and converted into ATP. Signup and view all the answers

The breakdown of _____ provides energy that can be stored in ATP.

glucose Signup and view all the answers

What is the primary role of the endoplasmic reticulum?

To produce and transport proteins and lipids. Signup and view all the answers

Match the following cell organelles with their functions:

Lysosomes = Digestive system of the cell Peroxisomes = Contain oxidative enzymes ATP = Energy currency of the cell Hydrolytic enzymes = Break down macromolecules Signup and view all the answers

The __________ provides the genetic blueprint during cell replication.

nucleus Signup and view all the answers

Which of the following is NOT a function of the cytoskeleton?

Stores excess nutrients Signup and view all the answers

Which organelle contains powerful hydrolytic enzymes for breaking down organic molecules?

Lysosomes Signup and view all the answers

ATP synthesis occurs without the need for any cellular machinery.

False Signup and view all the answers

What holds immense power in ATP and why is it important?

The third phosphate group, because it stores potential energy. Signup and view all the answers

Cells 'cash in' ATP to pay for _____ related to structure, function, and growth.

energy Signup and view all the answers

How is energy primarily harnessed by cells from the breakdown of organic molecules?

Using the carbon bonds from food Signup and view all the answers

What is produced during the conversion of pyruvate to Acetyl CoA?

2 NADH and 1 CO2 Signup and view all the answers

What is the starting substance in the Citric Acid Cycle?

Oxaloacetate Signup and view all the answers

Which of the following accurately describes the total carbon dioxide produced during the Citric Acid Cycle?

4 CO2 during two cycles Signup and view all the answers

How many ATP molecules are produced per cycle during the Citric Acid Cycle?

1 Signup and view all the answers

What role do hydrogen atoms play in the electron transport chain?

They carry electrons and provide energy. Signup and view all the answers

Which statement about the electrons extracted from NADH and FADH2 in the ETC is correct?

They are utilized to produce ATP. Signup and view all the answers

What is the main product of glycolysis?

Pyruvate Signup and view all the answers

What is the final product of the reaction between oxaloacetate and Acetyl CoA in the Citric Acid Cycle?

Citrate Signup and view all the answers

How many ATP molecules are produced directly during glycolysis?

2 ATP Signup and view all the answers

What molecule is pyruvate converted into during pyruvate decarboxylation?

Acetyl CoA Signup and view all the answers

What is the primary purpose of the oxidative phosphorylation stage in cellular respiration?

To synthesize ATP. Signup and view all the answers

In the context of cellular respiration, where does the conversion of citrate back to oxaloacetate take place?

In the mitochondrial matrix Signup and view all the answers

Which of the following diseases results from an absence of the enzyme needed to convert glycogen to glucose?

McArdle disease Signup and view all the answers

How many NAD+ molecules are reduced to NADH during glycolysis?

2 NAD+ Signup and view all the answers

Which molecule is produced from the breakdown of a glucose molecule in glycolysis?

Pyruvate Signup and view all the answers

In glycolysis, which process uses energy from broken chemical bonds to produce ATP?

Substrate-level phosphorylation Signup and view all the answers

What type of molecule is glucose before it is broken down during glycolysis?

A hexose Signup and view all the answers

During glycolysis, what type of reaction converts glucose into pyruvate?

Oxidation-reduction Signup and view all the answers

Pyruvate enters which part of the cell for further processing after glycolysis?

Mitochondrial matrix Signup and view all the answers

What is the primary role of NADH and FADH2 in cellular respiration?

To transport high-energy electrons to the electron transport chain Signup and view all the answers

What is the significance of oxidative phosphorylation in cellular respiration?

It relies on oxygen to generate ATP through the electron transport chain Signup and view all the answers

How many ATP are typically produced from one NADH molecule during cellular respiration?

2-3 ATP Signup and view all the answers

What mechanism do electrons use when passing through the electron transport chain?

They fall to lower energy levels, releasing free energy Signup and view all the answers

What happens to NADH and FADH2 when they are oxidized during cellular respiration?

They regenerate NAD+ and FAD, enabling the cycle to continue Signup and view all the answers

During which phase of cellular respiration does oxidative phosphorylation take place?

Electron Transport Chain Signup and view all the answers

Which statement is true regarding the electron transport chain (ETC)?

It facilitates the transfer of electrons through a series of carriers Signup and view all the answers

What is the average yield of ATP produced from one FADH2 molecule?

1.5 ATP Signup and view all the answers

What energy transformation occurs as electrons move through the electron transport system?

High-energy electrons release free energy Signup and view all the answers

Where is the intermembrane space located in relation to the mitochondrion?

Between the inner membrane and outer membrane Signup and view all the answers

What is the primary role of the proton gradient created by electron transport complexes?

To facilitate the return of H+ to the matrix through ATP synthase Signup and view all the answers

Which pathway provides the most ATP per glucose molecule during aerobic respiration?

Oxidative phosphorylation Signup and view all the answers

What occurs to NADH during anaerobic respiration?

NADH is converted into NAD+ for glycolysis to continue Signup and view all the answers

How many ATP are typically generated from one glucose molecule during aerobic cellular respiration?

32 Signup and view all the answers

What can occur with the buildup of lactic acid in muscles during heavy exercise?

Muscle function is impaired and may stop Signup and view all the answers

In aerobic respiration, what is the final electron acceptor in the electron transport chain?

Oxygen Signup and view all the answers

What process primarily occurs when oxygen is limited or unavailable?

Fermentation to lactate Signup and view all the answers

What is the net ATP yield from glycolysis when oxygen is present?

2 Signup and view all the answers

How is energy generated during the TCA cycle?

By reducing electron carriers NAD+ and FAD Signup and view all the answers

Which statement about ATP synthase is correct?

It utilizes the H+ gradient to create ATP Signup and view all the answers

What is the main role of cholesterol in the plasma membrane?

Contribute to fluidity and stability Signup and view all the answers

Membrane proteins can either span the membrane or be peripheral and do not span it.

True Signup and view all the answers

What term describes the movement of lipids and proteins within the plasma membrane?

Fluid Mosaic Model Signup and view all the answers

_________ molecules allow the passage of specific ions across the membrane.

Channel Signup and view all the answers

Match the following types of membrane proteins with their functions:

Channels = Allow specific ions to pass Carrier proteins = Transfer larger specific substances Receptors = Facilitate communication with the extracellular fluid Docking-marker acceptors = Match with secretory vesicles during exocytosis Signup and view all the answers

Which statement is true about the composition of the plasma membrane?

Lipid molecules outnumber protein molecules roughly 50 to 1. Signup and view all the answers

Peripheral proteins cross the plasma membrane.

False Signup and view all the answers

What is the effect of enzyme activity on phospholipid head and tail configurations?

They switch spots. Signup and view all the answers

The __________ model describes the ever-changing pattern of proteins embedded in the lipid bilayer.

Fluid Mosaic Signup and view all the answers

What describes the process in which cells release substances using vesicles?

Exocytosis Signup and view all the answers

What is the main function of the plasma membrane?

To control the movement of molecules in and out of the cell Signup and view all the answers

Phospholipids in the plasma membrane have a hydrophilic head and a hydrophobic tail.

True Signup and view all the answers

What are the primary components of the plasma membrane?

Phospholipids, proteins, and cholesterol Signup and view all the answers

The plasma membrane separates the __________ fluid from the intracellular fluid.

extracellular Signup and view all the answers

Match the following components of the plasma membrane with their descriptions:

Phospholipids = Make up the bilayer structure Cholesterol = Provides fluidity to the membrane Proteins = Facilitate communication and transport Carbohydrates = Involved in cell recognition Signup and view all the answers

How do phospholipids organize in the plasma membrane?

In a lipid bilayer Signup and view all the answers

The plasma membrane acts only as a mechanical barrier for the cell.

False Signup and view all the answers

What property of the plasma membrane allows it to be fluid and not rigid?

Presence of unsaturated fatty acid tails in phospholipids Signup and view all the answers

The head of a phospholipid is negatively charged and therefore __________ with water.

polar Signup and view all the answers

Match the following substances to their roles in the plasma membrane:

Ions = Nutrient transport Nutrients = Cellular energy source Waste products = Cellular waste disposal Secretory products = Material export Signup and view all the answers

What is the primary function of tight junctions in epithelial tissue?

Acting as an impermeable barrier Signup and view all the answers

Gap junctions allow for the passage of large molecules between connected cells.

False Signup and view all the answers

What type of junction is responsible for the synchronized contraction of muscle tissue?

Gap junctions Signup and view all the answers

Tight junctions are primarily found in ________ tissue.

epithelial Signup and view all the answers

Match the following types of cell junctions with their functions:

Tight Junctions = Impermeable barrier Desmosomes = Intercellular filament connection Gap Junctions = Communication between cells Adherens Junctions = Cell adhesion Signup and view all the answers

Which junction provides a communication pathway between adjacent cells?

Gap Junctions Signup and view all the answers

Desmosomes are primarily responsible for making cell membranes impermeable.

False Signup and view all the answers

Name the small structures that allow for communication between cells in gap junctions.

connexons Signup and view all the answers

The ________ junctions allow cells to touch and form a barrier against substances.

tight Signup and view all the answers

What type of molecules do gap junctions primarily allow to pass?

Small, water-soluble particles Signup and view all the answers

What are the three different means by which cells are held together?

Cell Adhesion Molecules, Extracellular Molecules, Specialized cell junctions Signup and view all the answers

Collagen is the most abundant protein in the body and provides tensile strength.

True Signup and view all the answers

What is the primary function of fibronectin in tissues?

To promote cell adhesion and hold cells in position. Signup and view all the answers

The strongest fiber found in the extracellular matrix is __________.

collagen Signup and view all the answers

Match the specialized cell junctions with their characteristics:

Desmosomes = Strongest cell-to-cell junction, found in stretchy tissues Tight junctions = Prevent leakage of fluid between cells Gap junctions = Allow for communication between adjacent cells Signup and view all the answers

What type of protein fiber is elastin known for?

It has rubber-like properties. Signup and view all the answers

The extracellular matrix is located exclusively on the inside of cells.

False Signup and view all the answers

What fluid provides a pathway for diffusion of nutrients and wastes between blood and tissue cells?

Interstitial fluid Signup and view all the answers

Scars are formed by __________ tissue, which produces collagen.

connective Signup and view all the answers

Which cell junction acts like 'spot rivets' to anchor two adjacent cells?

Desmosomes Signup and view all the answers

Study Notes

Principles of Cell Theory

Theodor Schwann established that the cell is the smallest structural and functional unit of life.
Functional activities of cells are determined by their specific structural properties.
All organisms' cells exhibit fundamental similarities in structure and function.
Cells are the building blocks of plants, animals, and bacteria.

Cell Structure and Function: Cytoskeleton

The human body contains trillions of cells classified into approximately 200 types.
Three main components of the cytoskeleton: Microtubules, Microfilaments, Intermediate Filaments.

Microtubule

Largest component, composed of long, hollow tubes made of tubulin.
Maintain cell shape, coordinate movements, and serve as transport highways for cellular components.
Form cilia and flagella, enabling movement.

Microfilaments

Smallest components, formed of actin in helical chains, present in all cell types.
Crucial for muscle contraction and cellular movement (amoeboid movement in white blood cells).
Provide mechanical support for structures like microvilli, enhancing surface area.

Intermediate Filaments

Irregular, threadlike proteins offering mechanical strength.
Composed of keratin, found in hair and nails.

Cell Structure and Function: Organelles

Nucleus: Double-layered membrane housing DNA, serving as the genetic blueprint during replication.
Plasma Membrane: Thin layer enclosing the cell, composed mainly of a phospholipid bilayer; selectively permeable.
Cytosol: Viscous fluid inside cells, facilitating intracellular reactions and containing enzymes for metabolic processes.

Golgi Complex

A stack of membrane-enclosed sacs, closely tied to the endoplasmic reticulum (ER).
Modifies, packages, and sorts newly synthesized proteins for transport.

Endoplasmic Reticulum (ER)

Fluid-filled membranous system functioning as a protein and lipid production factory.

Rough ER

Studded with ribosomes, synthesizes proteins for secretion and incorporation into membranes.

Smooth ER

Lacks ribosomes, packages secretory productions for transport to the Golgi complex, abundant in lipids.

Ribosomes

Sites of protein synthesis that transcribe DNA to RNA and translate mRNA into proteins.

Cellular Metabolism

Encompasses all chemical reactions involving the breakdown (catabolism) and building (anabolism) of molecules within cells.
Intermediary Metabolism: Involves the transformation of small organic molecules, occurring in the cytosol with the aid of numerous enzymes, facilitating degradation, synthesis, and transformation of nutrients.

Centrioles

Cylindrical structures that organize microtubules during cell division and assembly of the mitotic spindle.
Essential for the formation of cilia and flagella, contributing to cellular mobility.

ATP

Primary energy currency of the cell, produced during metabolic processes.### Energy Production in Cells
The body's energy source is derived from the chemical energy in carbon bonds of food.
Energy must be extracted and converted into a usable form, specifically high-energy phosphate bonds in Adenosine Triphosphate (ATP).
The third phosphate in ATP holds significant energy potential, facilitating cellular energy transactions.
Glucose, a six-carbon molecule, undergoes breakdown to harness energy through ATP production.

Lysosomes

Lysosomes are small, membrane-bound organelles that function in degradation and digestion.
They contain powerful hydrolytic enzymes for breaking down organic molecules.
Act as the cell's digestive system, eliminating foreign substances such as viruses and cellular debris.
ATP serves as the body's common energy currency, enabling cellular processes like maintaining structure, function, and growth.

Peroxisomes

Peroxisomes are membrane-enclosed organelles that house oxidative enzymes.
Involved in various metabolic processes, including the breakdown of fatty acids and the detoxification of harmful substances.
They play a critical role in maintaining cellular health and energy balance.

Cellular Metabolism: Respiration

Glycolysis:
- Breaks down 1 glucose (6 carbon) into 2 pyruvate (3 carbon).
- Involves 10 sequential reactions, generating 2 ATP directly.
- Result: 2 NAD+ converted to 2 NADH.
- Affected by metabolic diseases like McArdle disease, which lacks the enzyme to convert glycogen to glucose.
Pyruvate Decarboxylation:
- Converts pyruvate into Acetyl CoA (2 carbon) in the mitochondrial matrix, requiring oxygen.
- Produces CO2 and 1 NADH per pyruvate, totaling 2 NADH for 2 pyruvate.
Citric Acid Cycle (Krebs Cycle):
- Consists of 8 enzymatic reactions occurring in the mitochondrial matrix.
- 2 carbon atoms are removed from citrate (6C) to regenerate oxaloacetate (4C).
- Generates 6 NADH and 2 FADH2, along with 2 ATP (1 per cycle).
- CO2 produced during this process comes from the cycle, not from breathing.
- Hydrogen atoms removed from the cycle enter the Electron Transport Chain (ETC) as NADH and FADH2.
- Energy release during this cycle is used to convert GDP to GTP.

Oxidative Phosphorylation: Electron Transport Chain (ETC)

Electrons extracted from NADH and FADH2 pass through a series of electron carriers on the inner mitochondrial membrane.
Most ATP generated here; this process is also termed oxidative phosphorylation due to the use of O2.
NADH yields 2.5 ATP on average, while FADH2 yields 1.5 ATP.
High-energy electrons drop to lower energy levels as they move through the ETC, releasing energy used to transport H+ ions into the intermembrane space.
H+ concentration gradient drives ATP synthesis through ATP synthase.
Excess electrons are accepted by oxygen, forming water.

Cellular Respiration Under Different Conditions

Aerobic Conditions:
- Total ATP generated from 1 glucose molecule averages 32.
  - Sources: 2 from glycolysis, 2 from TCA cycle, 3 from FADH2, and 25 from NADH.
- Variations in the total ATP yield may occur based on cellular conditions.
Anaerobic Conditions:
- Limited or no oxygen leads to the conversion of pyruvate into lactate instead of Acetyl CoA.
- Only glycolysis occurs, yielding less energy compared to aerobic processes.
- Glycolysis requires NAD+; during anaerobic respiration, NADH is reused to convert pyruvate into lactic acid.
- Only 2 ATP are generated under anaerobic conditions.
- Excess lactic acid buildup in muscles can impair function and is considered toxic.

Plasma Membrane Overview

Also known as the cell membrane, it surrounds every cell and regulates movement in and out of the cell.
Composed of a phospholipid bilayer, consisting of two layers of phospholipids, proteins, lipids, carbohydrates, and cholesterol.
Separates extracellular fluid (ECF) from intracellular fluid (ICF).

Functionality

Acts as a selective barrier, determining cell composition by permitting movement of ions, nutrients, waste products, and secretory molecules.
Plays a crucial role in cell-to-cell communication within the environment.

Structure and Composition

Phospholipids are the most abundant components, with approximately 1 billion phospholipid molecules in a typical human cell membrane.
Phospholipids have a hydrophilic polar head (negatively charged, bonds with water) and two hydrophobic nonpolar fatty acid tails (repels water).
The lipid bilayer is fluid; phospholipids constantly move and rearrange within their layer.

Fluid Mosaic Model

Describes the fluid nature of the membrane and the diverse arrangement of proteins embedded within the lipid bilayer.
The membrane's fluidity allows proteins to float like icebergs in a moving sea of lipids.

Membrane Proteins

Channels: Permit water-soluble molecules, such as small ions, to pass selectively through the membrane.
Carrier molecules: Facilitate the transfer of larger specific substances like glucose.
Docking-marker acceptors: Enable secretory vesicles to fuse with the membrane for processes like exocytosis.
Membrane-bound enzymes: Participate in signal transmission and are anchored to either side of the membrane.
Receptors: Bind various molecules (e.g., growth hormones) to facilitate communication between the cell and its environment.
Cell adhesion molecules (CAMs): Enable cell-to-cell adhesion for structural integrity.
Peripheral proteins: Reside on one side of the membrane without spanning it, playing various roles without crossing the membrane.

Additional Notes

Membrane structure contains about 50 times more lipid molecules in comparison to protein molecules, but protein constitutes nearly half of the membrane's mass due to larger size.
Different proteins confer specific functions and capabilities to cells.
Cholesterol enhances the fluidity and stability of the membrane by interspersing among phospholipid molecules.

Cell to Cell Adhesion

Plasma membranes facilitate cell-to-cell adhesion.
Forms of cell adhesion include:
- Cell Adhesion Molecules (CAMs) - anchored to the membrane.
- Extracellular Molecules (ECMs).
- Specialized cell junctions.

Extracellular Matrix (ECM)

ECM consists of fibrous proteins in a gel-like interstitial fluid rich in complex carbohydrates.
Interstitial fluid allows diffusion of nutrients and waste between blood and tissue cells.
ECM occupies the space and fluid between tissue cells and surrounds all cells.

Types of Extracellular Protein Fibers

Collagen
- Strong, cable-like fibers; crucial for tensile strength and most abundant protein in the body.
- Comprises about half of total body protein weight.
- Present in skin, muscle, bone, and tissue; associated with scar formation.
Elastin
- Rubber-like protein fibers enabling stretching and recoiling.
- Common in the lungs and heart.
Fibronectin
- Promotes cell adhesion and maintains cellular positioning.
- Reduced levels are linked to tumor metastasis, aiding cancer cells in escaping and proliferating.
Proteins serve as biological glue for cells.
Scant presence in epithelial tissue; abundant in connective tissue.
Secretion by fibroblasts, specialized cells producing protein fibers.

Specialized Cell Junctions

CAMs provide tissue cohesion, functioning like "Velcro" for adjacent cells.
Types of specialized cell junctions include:
- Desmosomes
  - Strongest cell-to-cell junctions, prevalent in tissues subject to stretching (skin, liver, uterus, heart).
  - Act as "spot rivets" anchoring adjacent cells.
  - Consist of cytoplasm thickening plaques connected internally to keratin filaments and intercellular filaments linking adjacent cells.
- Tight Junctions
  - Adjacent cells tightly bind to seal off passages between them, creating an impermeable barrier.
  - Common in epithelial tissues that cover the body and line internal cavities.
  - Control the entry of substances into cells.
- Gap Junctions
  - Form tunnels allowing communication between cells without touching.
  - Enable faster communication and permit small, water-soluble particles to pass between cells while blocking large molecules.
  - Abundant in cardiac and smooth muscle to facilitate synchronized contractions through ion movement.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores the foundational concepts of cell theory, highlighting the contributions of scientists like Theodor Schwann. Understand the significance of cells as the basic units of life and their role in biological organisms. Test your knowledge on these fundamental principles.