Cell Biology Quiz from L02-L06 Set 1

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Questions and Answers

What are the 3 main parts shared by all eukaryotic cells?

Cell membrane, nucleus, and ribosomes

Cell membrane, cytoplasm, and nucleus (correct)

Cell wall, vacuole, and chloroplast

Cell membrane, mitochondria, and endoplasmic reticulum

What are the main components of the cell membrane?

Lipids, proteins, and carbohydrates (correct)

Proteins, lipids, and organelles

Lipids, nucleic acids, and proteins

Carbohydrates, nucleic acids, and lipids

Which model describes the structure of the cell membrane?

Fluid Mosaic Model (correct)

Lock and Key Model

Induced Fit Model

Endosymbiotic Model

What is the function of the cell membrane?

Regulates transport, reactions, and communication with the environment Signup and view all the answers

What are the categories of proteins found in the cell membrane?

Integral and peripheral membrane proteins Signup and view all the answers

What are the mechanisms of material transport in and out of the cell?

Endocytosis and exocytosis Signup and view all the answers

What is the role of specialized cell membranes in the small intestine?

Nutrient absorption and immune response Signup and view all the answers

What regulates intestinal epithelial permeability?

Tight junctions Signup and view all the answers

What is the percentage of lipids in the cell membrane?

45-50% Signup and view all the answers

What is the implication of loss of integrity in tight junctions?

Disease implications Signup and view all the answers

Which molecules mediate cell-to-cell adhesion through various binding mechanisms?

Cell adhesion molecules (CAMs) Signup and view all the answers

What is the main function of cell adhesion?

Communication and coordination among groups of cells Signup and view all the answers

Which component of the cell membrane is affected in diseases like celiac disease?

Specialized cell membranes Signup and view all the answers

Which type of transport is involved in material transport in and out of the cell?

Active transport Signup and view all the answers

What are the three broad functions of the cytoskeleton?

Enabling the cell to move and change shape, organizing the contents of the cell, connecting the cell physically and biochemically to the external environment Signup and view all the answers

How is the cytoskeleton described in terms of its structure?

Dynamic and adaptive, not a fixed structure Signup and view all the answers

Which type of cytoskeletal polymer is most flexible?

Intermediate filaments Signup and view all the answers

What is a characteristic of intermediate filaments?

They are highly conserved in sequence and molecular weight Signup and view all the answers

Where are type I and type II keratins commonly found?

Nails and hair Signup and view all the answers

Which cells form keratin intermediate fibers to resist shear stress?

Epithelial cells of the airway Signup and view all the answers

What is a common feature of intermediate filaments?

They can cross-link to microtubules and microfilaments Signup and view all the answers

What is a characteristic of the cytoskeleton modulation by pathogens?

Can occur at several points of contact between the pathogen and host Signup and view all the answers

What is the largest group of intermediate filaments?

Keratins Signup and view all the answers

What are the three main components of the cytoskeleton?

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

Which protein forms microtubules?

α- and β-tubulin Signup and view all the answers

What are the roles of microtubules in the cell?

Support beams, critical for mitosis and cell division Signup and view all the answers

What are the three main types of microtubules?

Aster/astal, interpolar, and kinetochore Signup and view all the answers

In which diseases has reduced microtubule stability been observed?

Alzheimer's, Parkinson's, and motor neuron disease Signup and view all the answers

What are microfilaments also known as?

Actin filaments Signup and view all the answers

What biological functions do actin filaments regulate in coordination with microtubules?

Focal adhesions Signup and view all the answers

What are the primary roles of actin filaments?

Cell movement, cell transport, and division Signup and view all the answers

What is the function of the tumour suppressor Adenomatous polyposis coli (APC)?

Nucleates actin filaments Signup and view all the answers

What biological processes do microtubules, microfilaments, and intermediate filaments coordinate for?

Forming contractile rings during cell division and coordinating with microtubules for cell migration Signup and view all the answers

Which organelle is described as a remnant bacteria?

Mitochondrion Signup and view all the answers

What is the size range of mitochondria?

1-2um Signup and view all the answers

Which molecule is described as the energy currency of the cell?

ATP Signup and view all the answers

What is the specific structure within mitochondria responsible for ATP production?

Cristae Signup and view all the answers

What is the main process for ATP production?

Glycolysis Signup and view all the answers

Where does glycolysis occur?

Cell's cytosol Signup and view all the answers

What is the first step of glucose oxidation?

Glycolysis Signup and view all the answers

What role does ATP play in muscle contraction?

ATP is directly involved in the release and binding of myosin heads during muscle contraction. Signup and view all the answers

What is the total number of ATP a typical human turns over per second?

900,000,000,000,000,000,000 Signup and view all the answers

What is the purpose of the breakdown of glucose in cellular respiration?

To form energy Signup and view all the answers

What is the main function of ATP in cells?

Cause conformational changes in proteins and molecules Signup and view all the answers

How many ATP are produced by substrate-level phosphorylation in glycolysis?

2 Signup and view all the answers

What is the primary way for cells to make ATP when oxygen is absent?

Glycolysis Signup and view all the answers

In which organelle does the Krebs cycle occur?

Mitochondria Signup and view all the answers

What is the main function of the rough endoplasmic reticulum?

Protein synthesis Signup and view all the answers

Where are proteins modified before being sent to various places in the cell?

Golgi apparatus Signup and view all the answers

What is the role of the mitochondria in energy production?

Synthesis of ATP from ADP, pyruvate, and oxygen Signup and view all the answers

What is the consequence of cyanide and carbon monoxide acting on complex IV?

Stopping all electrons from being passed to oxygen Signup and view all the answers

What is the main function of the smooth endoplasmic reticulum?

Lipid synthesis Signup and view all the answers

What is the role of the Electron transport chain (E.T.C) in mitochondria?

Passing electrons from NADH to complex I and from FADH2 to complex II Signup and view all the answers

What is the consequence of mitochondria using the proton gradient to generate heat?

Generation of heat in fat cells Signup and view all the answers

Which organelle is associated with severe epilepsy, developmental regression, and liver failure due to DNA depletion?

Mitochondria Signup and view all the answers

What are the main functions of the Golgi apparatus?

Protein modification and transport to different cell locations Signup and view all the answers

What is the main function of the endoplasmic reticulum?

Protein production Signup and view all the answers

What is the primary function of the nucleus in a eukaryotic cell?

Controls cell growth and multiplication Signup and view all the answers

Which of the following accurately describes the multifaceted role of DNA within the nucleus?

DNA functions as a dynamic template for protein synthesis. Signup and view all the answers

What percentage of DNA do humans share with each other?

18% Signup and view all the answers

What is the function of the ribosome in a cell?

Facilitates protein synthesis Signup and view all the answers

Which accurately identifies the components of nucleotides?

Phosphate groups, sugars, and nitrogenous bases Signup and view all the answers

Identify the correct base pairings among the options provided.

Adenine-Thymine, Guanine-Cytosine Signup and view all the answers

What accurately describes the components involved in the formation of DNA molecules?

Nucleotides, deoxyribose sugars, and complementary base pairs Signup and view all the answers

Among the options provided, which substances correctly qualify as organic bases?

Guanine, adenine, and thymine Signup and view all the answers

Replication of DNA occurs

During cell division Signup and view all the answers

A nucleotide triplet codes for:

An amino acid Signup and view all the answers

Which statement accurately represents the concept known as the 'Central Dogma' of Biology?

Genetic information flows from DNA to RNA to proteins. Signup and view all the answers

Which statement provides a comprehensive understanding of how the nucleus exerts control over cellular activities?

The nucleus governs cell behavior by orchestrating protein synthesis. Signup and view all the answers

What happens to the mRNA in the cytosol?

The job of the ribosome is to make protein Signup and view all the answers

Where are proteins modified before being sent to various places in the cell?

Golgi apparatus Signup and view all the answers

Which nitrogenous base pairs with adenine in DNA?

Thymine Signup and view all the answers

What is the specific structure within the nucleus responsible for packaging DNA into thread-like structures?

Histones Signup and view all the answers

How many pairs of chromosomes do human cells typically contain?

23 Signup and view all the answers

What is the main target of Huntington's disease?

Histones Signup and view all the answers

What is the function of DNA replication?

To create identical double-stranded DNA molecules Signup and view all the answers

What determines the genetic code in DNA?

Sequence of bases Signup and view all the answers

Which molecule controls the production of enzymes in cells?

DNA Signup and view all the answers

What is the basic unit of inheritance?

Gene Signup and view all the answers

What is the role of DNA in controlling the production of proteins?

It determines the sequence of amino acids Signup and view all the answers

What is the specific role of DNA in nerve cells affected by Huntington's disease?

Inhibiting transcription of nerve growth factors Signup and view all the answers

What is the primary function of DNA in determining cell structures and functions?

Influencing the nature of the organism Signup and view all the answers

What is the main defining characteristic used to initially classify cells into two main classes?

Presence of a nucleus Signup and view all the answers

What is a distinguishing feature of RNA polymerase in Archaea?

Simple and contains 4 subunits Signup and view all the answers

What is a characteristic of Archaea's relationship with human bodies?

Symbiotic relationship with anaerobic bacteria Signup and view all the answers

Why are there no disease-causing archaea?

Their difficult cultivation and study Signup and view all the answers

In which diseases might archaea be involved in pathogenesis?

Periodontal disease Signup and view all the answers

What is a distinguishing feature of tRNA in Archaea?

Thymine is absent in transferase RNA Signup and view all the answers

What is a notable difference in the metabolism of Archaea compared to Bacteria?

Utilization of acetate as an e-donor and ferrihydrite as an e-acceptor Signup and view all the answers

What is a significant characteristic of Archaea's diversity compared to Bacteria?

Significantly lower diversity than bacteria Signup and view all the answers

What is responsible for their own division, have their own DNA, and produce enzymes and proteins required for their function?

Mitochondria and chloroplasts Signup and view all the answers

What does the endosymbiotic theory describe?

The dependency between a large host cell and ingested bacteria for survival Signup and view all the answers

What is evidence for theories on the evolution of living organisms?

The diversity of life Signup and view all the answers

What do similarities between eukaryotes and prokaryotes suggest?

They originate from the same common ancestor Signup and view all the answers

What comprises bacteria and archaea and typically have a diameter of 0.1–5 μm, with circular DNA in a nucleoid?

Prokaryotes Signup and view all the answers

What comprises animals, plants, fungi, and protists, have a diameter of 10-100 μm, and have membrane-bound organelles?

Eukaryotes Signup and view all the answers

What come in various shapes, sizes, and arrangements, and can be transparent under a microscope?

Prokaryotes Signup and view all the answers

What are major differences between plants and animals, and between bacteria and archaea?

The presence of cell walls and different habitats and cell division methods Signup and view all the answers

What is responsible for the production of oxygen, changing Earth's atmosphere and allowing new oxygen-breathing life forms to emerge?

Photosynthesis Signup and view all the answers

What is the implication of the similarities between eukaryotes and prokaryotes?

They share a common ancestor but have evolved independently for a long time Signup and view all the answers

What is responsible for the diversity of life as evidence for theories on the evolution of living organisms?

The diversity of life Signup and view all the answers

Which statement accurately compares the ribosomes of prokaryotic and eukaryotic cells?

Eukaryotic ribosomes consist of a single RNA molecule, whereas prokaryotic ribosomes are composed of multiple RNA molecules. Signup and view all the answers

Which of the following accurately describes the location of ribosomal RNA synthesis in prokaryotic and eukaryotic cells?

Both prokaryotic and eukaryotic cells synthesize ribosomal RNA in the nucleolus. Signup and view all the answers

What distinguishes the size of prokaryotic and eukaryotic ribosomes?

Prokaryotic ribosomes are generally smaller, with a smaller 30S subunit compared to the 40S subunit in eukaryotic ribosomes. Signup and view all the answers

How can the Gram staining process be accurately distinguished between prokaryotes and eukaryotes?

Both prokaryotic and eukaryotic cells retain the crystal violet stain in the Gram staining process, posing a challenge for differentiation. Signup and view all the answers

How does the Gram staining process exploit differences in cell wall structure between Gram-positive and Gram-negative bacteria?

Gram-positive bacteria possess an outer membrane that repels the crystal violet stain, resulting in a colorless appearance. Signup and view all the answers

Which statement accurately describes the role of hydrogen bonds in DNA and their influence on complementary base pairing?

Hydrogen bonds exclusively connect adenine (A) with thymine (T) and guanine (G) with cytosine (C). Signup and view all the answers

In the context of DNA structure, what is the significance of the complementary base pairing phenomenon?

It allows for the accurate replication of genetic information during cell division. Signup and view all the answers

How does the concept of minor and major grooves in DNA contribute to the understanding of complementary base pairing?

The accessibility of enzymes to the DNA molecule is facilitated by the presence of minor and major grooves. Signup and view all the answers

What is the fate of the newly synthesized polypeptide chain after termination?

The polypeptide chain undergoes post-translational modifications and folding in the cytosol. Signup and view all the answers

What event triggers the termination of protein synthesis during translation?

Recognition of the stop codon. Signup and view all the answers

What is the function of transfer RNA (tRNA) during the elongation phase of translation?

tRNA brings amino acids to the ribosome, ensuring the correct amino acid is added to the growing polypeptide chain. Signup and view all the answers

What happens during the translocation phase of translation?

The ribosome moves along the mRNA in a 3' to 5' direction. Signup and view all the answers

During the initiation phase of translation, what is the role of the initiation factors?

They assemble the ribosome at the start codon of the mRNA. Signup and view all the answers

What is the primary function of ribosomes in the process of protein synthesis?

Ribosomes facilitate the translation of mRNA into a polypeptide chain. Signup and view all the answers

What is the primary function of the terminal phosphate group in ATP?

It contains high-energy bonds crucial for energy storage. Signup and view all the answers

Which enzyme is responsible for catalyzing the hydrolysis of ATP?

ATPase Signup and view all the answers

What is the consequence of ATP hydrolysis in terms of the energy state of the resulting molecules?

ADP and Pi have lower energy than ATP. Signup and view all the answers

During which cellular process is ATP directly involved in the phosphorylation of ADP?

Cellular respiration Signup and view all the answers

In what way does the regeneration of ATP contribute to cellular energy balance?

It maintains a constant supply of high-energy molecules Signup and view all the answers

What role do integral proteins play in the fluid mosaic model of the cell membrane?

They are embedded within the lipid bilayer and can move laterally, contributing to membrane fluidity. Signup and view all the answers

How does the fluid mosaic model explain the distribution of lipids and proteins in the cell membrane?

The model envisions a dynamic arrangement where lipids and proteins are interspersed, creating a flexible and adaptable structure. Signup and view all the answers

In the context of cytoskeletal filaments, what is the primary mechanism of cellular movement associated with actin filaments, particularly in the process known as treadmilling?

Actin filaments grow at the barbed end while simultaneously shrinking at the pointed end. Signup and view all the answers

What distinguishes the dynamics of microtubules from actin filaments in cellular processes?

Microtubules exhibit treadmilling, while actin filaments undergo dynamic instability. Signup and view all the answers

What makes dynamic instability a significant event in microtubules, distinguishing it from the treadmilling process in actin filaments?

Microtubules can grow significantly in length before sudden shrinkage, leading to dynamic instability. Signup and view all the answers

What is the role of lamellipodia in cell migration, and what molecular process drives their formation at the leading edge?

Lamellipodia sense the environment, and their formation is driven by signaling pathways activating actin filament nucleation. Signup and view all the answers

During cell migration, what is the function of focal adhesions, and how are they established?

Focal adhesions anchor actin filaments to the extracellular matrix, established by integrin binding and traction forces generated by myosin motor proteins. Signup and view all the answers

What is the significance of actin retrograde flow in the process of cell migration?

Retrograde flow ensures the translocation of the cell body toward the leading edge. Signup and view all the answers

How does the process of rear retraction contribute to the overall cycle of cell migration?

Rear retraction completes the cycle of cell migration by disassembling actin filaments at the trailing edge. Signup and view all the answers

Study Notes

Cell Membrane Structure and Functions

The cell membrane is a double-layered membrane composed of lipids (45-50%), proteins (45-50%), and carbohydrates (4-8% - outer surface only).
It encapsulates all contents of the cell and separates the interior of the cell from the outside environment.
Lipids in the membrane include phospholipids, cholesterol, and sphingosine-based lipids, while proteins are categorized as integral or peripheral membrane proteins.
The Fluid Mosaic Model and Lipid Rafts are models that describe the structure of the cell membrane.
The cell membrane functions as a barrier, regulates transport, reactions, communication with the environment, cell recognition, adhesion, and transport.
Active transport regulation includes endocytosis (phagocytosis, pinocytosis, receptor-mediated) and exocytosis for material transport in and out of the cell.
Cell adhesion is essential for communication and coordination among groups of cells, mediated by integrins and other adhesive proteins.
Cell adhesion molecules (CAMs) include cell-cell adhesion molecules and cell matrix adhesion molecules and mediate cell-to-cell adhesion through various binding mechanisms.
Specialized cell membranes in the small intestine, affected in diseases like celiac disease, play a crucial role in nutrient absorption and immune response.
Tight junctions regulate intestinal epithelial permeability, and their loss of integrity can lead to disease implications.
The text provides an overview of eukaryotic cell structure, plasma membrane models, general functions, specialized cell membranes, and their implications in disease.
The text also offers multiple-choice questions for testing understanding of cell membrane concepts and provides a contact email for further questions.

The Cytoskeleton and Its Components

The cytoskeleton is composed of microtubules, microfilaments, and intermediate filaments, which are similar to LEGO pieces that fit together to form larger structures.
Microtubules form a dense network across the cell, acting as support beams to prevent collapse and are made up of α- and β-tubulin dimers.
Microtubules can rapidly switch between growing and shrinking states and are critical for mitosis and cell division, forming distinct centrosomes in animal cells.
There are three main types of microtubules: aster/astal, interpolar, and kinetochore, which serve as extensive highways for transport within the cell and are critical for neuronal survival.
Reduced microtubule stability has been observed in neurodegenerative diseases such as Alzheimer's, Parkinson's, and motor neuron disease.
Microfilaments, also known as actin filaments, are smaller and less rigid than microtubules, primarily involved in cell movement and highly dynamic in nature.
Actin filaments play crucial roles in cell transport, migration, and division, and coordinate with microtubules to regulate biological functions such as focal adhesions.
Actin filaments are involved in endocytosis, cell division, and cell migration, protruding in response to signals downstream of cell surface receptors.
The cytoskeleton and its components are essential for various biological processes, including forming contractile rings during cell division and coordinating with microtubules for cell migration.
Microtubules, microfilaments, and intermediate filaments are the three main components of the cytoskeleton, with microtubules being the largest and strongest structures.
The cytoskeleton and its components, analogous to LEGO, are assembled into a wide range of structures, disassembled, and reassembled into different shapes, playing critical roles in maintaining cell structure and function.
The tumour suppressor Adenomatous polyposis coli nucleates actin filaments, and actin filaments are critical in various biological processes, including cell transport, migration, and division.

Cellular Respiration and Protein Synthesis

The Krebs cycle, also known as the Tricarboxylic acid cycle or Citric acid cycle, was discovered by Hans Krebs in 1937 and occurs in the inner membrane of the mitochondria, generating energy through the oxidation of acetyl CoA.
Glucose is transferred into ATP through three separate stages: Glycolysis, Krebs cycle, and Electron transport chain (E.T.C).
The Electron transport chain (E.T.C) comprises a series of protein complexes (complex I to complex IV) and two mobile carriers (Ubiquinone and Cytochrome c), where electrons are passed from NADH to complex I and from FADH2 to complex II, and protons are pumped out into the intermembrane space (IMS).
Cyanide and carbon monoxide act on complex IV, stopping all electrons from being passed to oxygen, leading to symptoms such as lactic acidosis and a lack of ATP affecting the central nervous system and heart.
Mitochondria produce energy by using the proton gradient to generate heat, and they can act as miniheaters, producing heat in fat cells through electron flow.
Mitochondria have a main function in the inner membrane, which is the synthesis of ATP from ADP, pyruvate, and oxygen, resulting in the production of carbon dioxide and water.
Mitochondrial diseases vary greatly in symptoms, one example being Alpers’ Syndrome, which is associated with severe epilepsy, developmental regression, and liver failure due to mitochondrial DNA depletion caused by mistakes in the POLG gene.
The endoplasmic reticulum (ER) includes rough and smooth parts, with the rough ER involved in protein synthesis and the smooth ER in lipid synthesis and detoxification of drugs and toxins.
Proteins destined to be exported from the cell pass through the rough ER and Golgi, where they undergo post-translational modifications before being sent to various places in the cell.
The Golgi, resembling a stack of pancakes, receives transport vesicles from the rough ER, modifies proteins, and sends them to different cell locations such as endosomes, lysosomes, plasma membrane, and mitochondria.
Protein synthesis involves mRNA export, ribosome binding, protein production, and secretion signal recognition, followed by delivery to the ER translocon and further processing in the Golgi before reaching their final destinations in the cell.
The process of cellular respiration and protein synthesis involves complex biochemical pathways and organelles, such as the mitochondria, endoplasmic reticulum, and Golgi, each with specific functions and roles in energy production and cellular protein regulation.

Understanding DNA: Key Facts and Concepts

DNA, or deoxyribonucleic acid, is present in the nucleus of all living organism cells and controls all chemical changes within cells.
DNA is a large molecule made up of nucleotides, which consist of a sugar, phosphate group, and nitrogen-containing base.
The nitrogenous bases in DNA are adenine, thymine, cytosine, and guanine, and they pair up in specific ways (adenine with thymine, and cytosine with guanine).
DNA replication involves the unwinding and separation of DNA strands, followed by the addition of appropriate nucleotides to create identical double-stranded DNA molecules.
The sequence of bases in DNA forms the genetic code, with a triplet of bases controlling the production of a particular amino acid in the cell's cytoplasm.
Each amino acid is coded for by a specific triplet of bases, and the sequence of amino acids determines the protein being produced.
DNA controls the production of enzymes, which in turn determine the reactions that take place in cells.
Chromosomes, made of DNA and containing genes, are packaged into thread-like structures called histones in the nucleus of each cell.
Human cells typically contain 23 pairs of chromosomes, comprising 22 autosomes and the sex chromosomes, X and Y.
A gene is the basic unit of inheritance, consisting of a sequence of nucleotides, and every person has two copies of each gene inherited from each parent.
Huntington's disease targets histones through a process called deacetylation, leading to destruction of nerve cells and inhibiting transcription, particularly important in nerve cells that transcribe nerve growth factors.
DNA and enzymes are crucial in determining cell structures, functions, and reactions, ultimately influencing the nature of the organism.

Evolution and Diversity of Prokaryotes and Eukaryotes

Photosynthesis led to the production of oxygen, changing Earth's atmosphere and allowing new oxygen-breathing life forms to emerge
Symbiosis and endosymbiosis describe how different species benefit from living or working together, and how one organism lives inside the other
Mitochondria and chloroplasts are responsible for their own division, have their own DNA, and produce enzymes and proteins required for their function
The endosymbiotic theory describes the dependency between a large host cell and ingested bacteria for survival
The diversity of life is evidence for theories on the evolution of living organisms
The increase in antibiotic-resistant bacteria and comparison of protein sequences are key factors in understanding the evolution of life
Similarities between eukaryotes and prokaryotes suggest they originate from the same common ancestor
Eukaryotes and prokaryotes share some features like cytoplasm, cell membrane, and ribosomes but have evolved independently for a long time
Prokaryotes comprise bacteria and archaea and typically have a diameter of 0.1–5 μm, with circular DNA in a nucleoid
Eukaryotes comprise animals, plants, fungi, and protists, have a diameter of 10-100 μm, and have membrane-bound organelles
Prokaryotes come in various shapes, sizes, and arrangements, and can be transparent under a microscope
Major differences between plants and animals, and between bacteria and archaea, include the presence of cell walls and different habitats and cell division methods

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