Cell Cycle and Its Phases Quiz

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Questions and Answers

What primarily occurs during the G1 phase of the cell cycle?

Cell division into two daughter cells

Protein synthesis and organelle production (correct)

Chromosome condensation

DNA replication

Why is the S phase important in the cell cycle?

It is the phase where DNA replication occurs. (correct)

It ensures the cell is ready for mitosis.

It is when the cell starts to divide.

It increases the cell's ploidy.

What role does the G2 checkpoint play in the cell cycle?

It activates the process of DNA replication.

It initiates cellular growth.

It ensures readiness for progression into mitosis. (correct)

It begins the process of cytokinesis.

Which of the following statements about the mitotic spindle is false?

It breaks down during the early prophase. Signup and view all the answers

What happens during cytokinesis in the cell cycle?

The cytoplasm divides into two daughter cells. Signup and view all the answers

What was a significant contribution of Robert Hooke in 1665?

Description of the cellular structure in Micrographia Signup and view all the answers

What is the primary focus of the research conducted by Paez-Espino et al. in 2016?

Characterization of Earth's virome Signup and view all the answers

Which publication discusses the difference between eukaryotic and prokaryotic cells?

The Difference Between Eukaryotic And Prokaryotic Cells Signup and view all the answers

In what context is flow cytometry discussed in 2018?

Protocol for immunology applications Signup and view all the answers

What does the endoplasmic reticulum do within cells?

Synthesizes proteins and lipids Signup and view all the answers

What is the primary purpose of the cell cycle?

To produce two daughter cells through division Signup and view all the answers

Which concept is illustrated in Griffiths et al.'s introduction to genetic analysis?

Bacterial conjugation mechanisms Signup and view all the answers

Which phase of the cell cycle is primarily focused on DNA replication?

S phase Signup and view all the answers

What characterizes the G0 phase of the cell cycle?

Cell has left the division cycle and is resting Signup and view all the answers

Which aspect of cell biology is highlighted in Lavanya's work from 2005?

Cell structure and function Signup and view all the answers

What is a key topic addressed by Doble and Gummadi's publication in 2010?

Biochemical engineering principles Signup and view all the answers

During which stage of interphase does the cell prepare itself by accumulating nutrients?

G1 phase Signup and view all the answers

Which phase follows G1 and is specifically focused on DNA synthesis?

S phase Signup and view all the answers

How long does interphase typically last in relation to the total cell cycle time?

At least 90% Signup and view all the answers

What happens during the mitotic (M) phase?

The cell divides into two daughter cells Signup and view all the answers

Which of the following cells is most likely to enter the G0 phase?

Neurons Signup and view all the answers

What is the main function of cell cycle checkpoints?

To ensure proper division and DNA integrity Signup and view all the answers

Which phase of interphase follows the DNA synthesis phase (S phase)?

G2 phase Signup and view all the answers

What component makes up the largest percentage of a typical mammalian cell's weight?

Water Signup and view all the answers

Which of the following components has the smallest percentage of total cell weight in mammalian cells?

DNA Signup and view all the answers

Who coined the term 'cell' and in what context?

Robert Hooke, observing cork cells under a microscope Signup and view all the answers

What advancement allowed scientists to identify organelles like the nucleus and mitochondria by the late 1800s?

Improvements in grinding glass into lenses and staining techniques Signup and view all the answers

What technique allows researchers to track biological processes in real time?

Chemically attaching fluorescent dyes or proteins to molecules Signup and view all the answers

What color is NOT mentioned as being part of the fluorescent labels used in modern microscopy?

Purple Signup and view all the answers

What was the title of the first book describing observations made through a microscope?

Micrographia Signup and view all the answers

What process can researchers NOT directly track using fluorescent labels?

Cell respiration Signup and view all the answers

What is the approximate percentage of cell weight attributed to proteins in a typical mammalian cell?

18% Signup and view all the answers

Which component comprises the second largest percentage of total cell weight in a mammalian cell?

Proteins Signup and view all the answers

What is the primary role of the electron transport chain in cellular respiration?

To generate ATP through oxidative phosphorylation Signup and view all the answers

Which molecule is produced as a direct result of the citric acid cycle?

NADH Signup and view all the answers

What is a significant outcome of oxidative phosphorylation?

Synthesis of adenosine triphosphate (ATP) Signup and view all the answers

What is the end product of the citric acid cycle, which is regenerated at the end of the cycle?

Oxaloacetate Signup and view all the answers

Which compound serves as the primary electron donor in the electron transport chain?

NADH Signup and view all the answers

What are the components of the mitochondrial inner membrane important for the electron transport chain?

Transport proteins and ATP synthase Signup and view all the answers

Which process is directly linked to the functioning of the electron transport chain?

Chemiosmosis Signup and view all the answers

Which of the following is an initial substrate for the citric acid cycle?

Acetyl-CoA Signup and view all the answers

What drives the synthesis of ATP during oxidative phosphorylation?

Proton gradient across the mitochondrial membrane Signup and view all the answers

Which enzyme complex is responsible for ATP synthesis in the mitochondria?

ATP synthase Signup and view all the answers

Study Notes

Cell Biology I - Course Notes

This course is for third-level biochemistry students at Helwan University
Course code: BCh3105
Lecturer: Dr. Rania EL-Lethy Abdelhamed EL-Lethy
Department of Biochemistry, Chemistry Department
Faculty of Science, Helwan University

Cell Biology - Definition

Cell biology, also known as cytology or cytobiology, is a branch of biology
It studies the different structures and functions of cells
It focuses on the cell as the basic unit of life
It explains cell structure, organization of organelles, physiological properties, metabolic processes, and signaling pathways
It studies the life cycle and interactions with the environment
This field includes both microscopic and molecular levels.
The scope encompasses both prokaryotic and eukaryotic cells

Cell Structure and Function

Cells are the fundamental and functional units of all living organisms
The body contains trillions of cells, organized into over 200 major types
Cells carry out various jobs at any given time
The cells have highly skilled jobs, which include covering (skin cells), preventing sloshing (bone cells), and eliminating toxins (liver cells).
Others include making essential products such as sweat, saliva, enzymes, hormones, and antibodies.
Cells carry out various functions depending on their type (e.g., red blood cells carry oxygen; white blood cells fight infection).

Blood

Blood is the most important fluid in the body
It's bright red when oxygenated, due to hemoglobin
Blood circulates throughout the body via blood vessels, pumped by the heart
Blood accounts for 7% of the human body weight and the average adult has a blood volume of approximately 5 litres
Blood pH is kept within a narrow range (7.35 to 7.45), slightly basic
Blood below 7.35 is acidic, while above 7.45 is basic

Functions of Blood

Delivers oxygen to tissues, bound to hemoglobin in red blood cells
Transports nutrients such as glucose, amino acids, and fatty acids
Removes waste products, including carbon dioxide, urea, and lactic acid
Has immunological functions (white blood cells and antibodies)
Involved in coagulation (blood clotting)
Transports hormones

Constituents of Human Blood

Blood is composed of plasma and blood cells
Plasma is the liquid component (~55% of blood), mainly water, with dissolved proteins and nutrients such as glucose, amino acids
Blood cells include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes)

Erythrocytes (Red Blood Cells)

The most numerous blood cells in humans
Lack a nucleus and have a biconcave shape in mammals
Responsible for transporting oxygen to tissues
Have a lifespan of approximately 120 days

Leukocytes (White Blood Cells)

Responsible for the body's defense mechanisms
Less numerous than red blood cells
Classified into granulocytes (neutrophils, basophils, eosinophils) and agranulocytes (lymphocytes, monocytes)
Each type has specific functions in the immune system

Platelets (Thrombocytes)

Smallest blood cells
Involved in blood clotting by converting fibrinogen to fibrin
Short lifespan (a few hours)

Plasma

The liquid component of blood (about 55%)
Primarily water (92%), with plasma proteins (8%) and trace amounts of other materials
It carries dissolved nutrients, such as glucose, amino acids, etc
Plays a crucial role in transporting essential materials throughout the body

Counting Red Blood Cells (RBCs)

Hemocytometer is a device used to count RBCs
It consists of a thick glass microscope slide with a rectangular indentation that creates a chamber. This is divided into nine 1.0 mm squares. A cover glass is supported over the chambers for counting.

Cell Biology: Additional Information

The cell, in biological terms, is the fundamental unit of life encompassing all living things.
It plays a critical role as a self-contained unit, capable of metabolizing its own nutrients, synthesizing various types of molecules, providing energy, and replicating itself.
Within multicellular organisms, cells exhibit high levels of specialization through differentiation into different specialized cells
Cells interact with each other, forming tissues, organs, and, ultimately, entire organisms, all organized to carry out specific tasks.

Organelles

Key components found within cells
Mitochondria are responsible for energy transactions
Lysosomes digest unwanted materials within the cell.
Endoplasmic reticulum and golgi apparatus play key roles in the internal organization of the cell, including synthesis, sorting of molecules.
In plant cells, chloroplasts are used for photosynthesis (converting CO2 and H2O into carbohydrates using sunlight energy).
The cytosol, the liquid part of cytoplasm, contains an organized cytoskeleton, giving the cell shape and enabling movement, is crucial for various metabolic pathways.
Cells, whether animal, plant, or bacterial, demonstrate variations in their constituent organelle, which is well illustrated by diagrams and figures.

Cell Membrane

The cell membrane is a crucial component of cell biology, serving as a protective boundary.
It is primarily a phospholipid bilayer, controlling the passage of materials into and out of the cell.
The membrane is semipermeable.

Nucleus

The nucleus is a membrane-bound organelle that houses the cell's genetic material.
The nucleus is a crucial component, including the nucleolus, chromosomes and chromatin
Its major role is containing the genetic information necessary for cell growth and reproduction.

Endoplasmic Reticulum (ER)

Rough ER contains ribosomes (sites of protein synthesis)
Smooth ER plays a role in various metabolic processes such as lipid synthesis, detoxification.

Ribosomes

Ribosomes are the protein synthesis machinery of a cell.
They are responsible for reading mRNA and synthesizing proteins.

Golgi Apparatus

Golgi complex plays a role in processing and sorting of molecules within cells
Processes and modifies proteins, including the addition of sugar groups for proper function.

Lysosomes

Membrane bound sacs which contain various hydrolytic enzymes.
Responsible for breaking down and recycling cellular components.

Mitochondria

Membranes contain folds (cristae), providing a large surface area for the cellular activities that take place inside the organelle.
Contain their own DNA and ribosomes.
Energy production is a major role of these organelles - Cellular respiration is used to convert nutrient energy into a usable energy form called ATP.

Centrosome (Centrioles)

This is the central microtubule-organizing center, involved in cell division and movement.

Chloroplasts

Found in plant cells
Involved in photosynthesis, transforming light energy into chemical energy.

Peroxisomes

Contain enzymes that detoxify harmful substances.
Involved in breaking down fatty acids and certain amino acids.

Cell Cycle and Checkpoints

The series of events a cell goes through to divide and produce two identical daughter cells
Interphase, a preparatory phase that encompasses the G₁, S, and G₂ steps before mitosis.
Mitosis, the division of the nucleus, and cytokinesis, the division of the cytoplasm.
These phases include prophase, metaphase, anaphase and telophase
Checkpoints are critical control mechanisms that ensure the cell cycle proceeds accurately.

Cell Death

Apoptosis is a highly organized type of programmed cell death, crucial for development and maintaining homeostasis
Necrosis is a more disordered form of cell death, often resulting from external factors—such as injury or damage.

Genes

Oncogenes
Genes that promotes cell division
Tumor suppressor genes
Genes that inhibit cell division

Enzymes

Enzymes are protein catalysts that accelerate the rate of chemical reactions without being consumed in the process in the body.
The presence of enzymes is critical for directing metabolic events and facilitating numerous biochemical pathways.
They have an active site, which is a special pocket or cleft uniquely designed to bind substances (substrates) in specific ways, thus promoting reaction between the substrate molecules, that result in products.
Enzymes exhibit a high level of specificity
Enzymes usually have a specific coenzyme that facilitates proper function and is involved in the process.

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Description

Test your knowledge on the cell cycle phases including G1, S, G2, and mitosis. Explore key processes like cytokinesis and the roles of various cellular structures. This quiz also touches on historical contributions and modern research in cell biology.