MPharm Cell Science: Cellular Structure 1 & 2

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of the centrosome during cell division?

Transports lipids

Forms the cell membrane

Moves chromosomes to the ends of the cell (correct)

Synthesizes proteins

What structural feature do both cilia and flagella share?

Centriole attachment

Doublet microtubules arrangement (correct)

Single cluster of microtubules

Circular configuration

Where are ribosomes primarily synthesized?

In the nucleolus (correct)

In the plasma membrane

In the endoplasmic reticulum

In the cytoplasm

Which type of endoplasmic reticulum is studded with ribosomes?

Rough E.R. Signup and view all the answers

What is the function of the smooth endoplasmic reticulum?

Lipid synthesis and detoxification Signup and view all the answers

What are centrioles primarily made of?

Microtubules arranged in triplets Signup and view all the answers

What role do cilia play in the respiratory system?

Moving mucus Signup and view all the answers

Which statement about ribosomes is correct?

They consist of rRNA and proteins. Signup and view all the answers

What function do membrane junctions serve in cells?

Linking adjacent cells together Signup and view all the answers

What is the primary component of cytosol?

Water Signup and view all the answers

What is the role of the cytoskeleton in a cell?

Maintaining cell shape and positioning organelles Signup and view all the answers

Which of the following organic molecules can aggregate for storage in cytosol?

Various organic molecules Signup and view all the answers

What characteristic distinguishes intermediate filaments from microfilaments and microtubules?

Less readily disassembled once assembled Signup and view all the answers

Which cell organelle is primarily responsible for energy production?

Mitochondrion Signup and view all the answers

What percentage of cell volume does cytosol constitute?

55% Signup and view all the answers

What is the primary function of flagella in prokaryotic cells?

Locomotion Signup and view all the answers

Which structure is not considered part of the cytoskeleton?

Endoplasmic reticulum Signup and view all the answers

Which type of bacteria are stained purple due to their thick cell wall?

Gram-positive bacteria Signup and view all the answers

Which of the following is a characteristic of eukaryotic cells?

More complex than prokaryotic cells Signup and view all the answers

What is the main structural component of the cell wall in Gram-positive bacteria?

Peptidoglycan Signup and view all the answers

What are the three main parts of a cell?

Plasma membrane, cytoplasm, nucleus Signup and view all the answers

What distinguishes Gram-negative bacteria from Gram-positive bacteria?

They stain pink due to a thin cell wall Signup and view all the answers

What is the primary function of the Golgi Complex?

Modify proteins into glycoproteins and lipoproteins Signup and view all the answers

Which cellular structure is responsible for supporting and maintaining the shape of eukaryotic cells?

Cytoskeleton Signup and view all the answers

Which cell organelle is primarily involved in the digestion of worn-out cell parts?

Lysosomes Signup and view all the answers

Which of the following organisms are classified as eukaryotic cells?

Fungi Signup and view all the answers

What characterizes the structure of peroxisomes?

Spherical or oval with a single membrane Signup and view all the answers

Which organelle is involved in detoxifying substances, particularly in the liver?

Peroxisomes Signup and view all the answers

What is the effect of a missing lysosomal enzyme in Tay-Sachs disease?

Nerve destruction Signup and view all the answers

What do proteasomes primarily function to digest?

Unneeded or faulty proteins Signup and view all the answers

Which of the following best describes the Golgi Complex's structure?

Flattened membranes with bulging edges Signup and view all the answers

What role does the sarcoplasmic reticulum (SR) play in muscle cells?

Storage of calcium ions Signup and view all the answers

What is one of the fundamental principles of cell theory?

Cells are the basic unit of both structure and function in living organisms. Signup and view all the answers

Which statement is true regarding the diversity of cells in the human body?

There are around 200 different types of cells in the human body. Signup and view all the answers

What role does the glycocalyx play in cellular interactions?

It acts as a molecular 'signature' for cell recognition. Signup and view all the answers

What is the approximate number of cells in the human body?

Approximately 3.72 x 10^13 Signup and view all the answers

Which type of junction is characterized by protein connections that allow adjacent cells to tightly adhere in areas subject to stretching?

Desmosomes Signup and view all the answers

What is the main characteristic of tight junctions?

They create a band around the entire circumference of the cell membrane. Signup and view all the answers

Which of the following statements most accurately describes a characteristic of cells?

Cells are capable of performing all vital physiological functions. Signup and view all the answers

Which type of cell is NOT typically found in the human body?

Bacterial cell Signup and view all the answers

Which proteins are involved in forming gap junctions?

Connexins Signup and view all the answers

What is the primary function of desmosomes?

To link neighboring cells together for strength. Signup and view all the answers

Which of the following best differentiates prokaryotic cells from eukaryotic cells?

Prokaryotic cells lack membrane-bound organelles, whereas eukaryotic cells have them. Signup and view all the answers

What limits the size of molecules that can pass through gap junctions?

The diameter of the connexin channels. Signup and view all the answers

What role do stem cells primarily play in the body?

They have the ability to differentiate into various cell types. Signup and view all the answers

Which of the following is NOT a main part of the cell structure?

Endoplasmic Reticulum Signup and view all the answers

What cellular component directly links integrins to the extracellular matrix?

Transmembrane proteins Signup and view all the answers

Which option describes the structure of tight junctions compared to desmosomes?

Desmosomes occur in a disk shape, while tight junctions form a continuous band. Signup and view all the answers

Study Notes

MPharm Programme - Cell Science - Introduction to Cellular Structure 1 & 2

This lecture introduces cellular structures, cell theory, stem cells, and the diversity of human cells.
The learning objectives are to understand and explain in detail cell theory, stem cells, differences between prokaryotic and eukaryotic cells, differentiation of various cell types (plant, animal, bacteria), and the structure and function of the cell's three main parts (plasma membrane, cytoplasm, and nucleus).

Cell Theory

Cells are the fundamental units of all living organisms, forming the building blocks of plants and animals.
All cells originate from pre-existing cells through cell division.
Cells are the smallest units that carry out all essential physiological functions necessary for life.
Each cell maintains homeostasis at the cellular level.

Cells in the Human Body

The human body contains an estimated 3.72 x 10^13 cells.
There is no single "typical" cell; the body has many different types.
While diverse, cells have common chemical and structural features.
Humans have approximately 200 different cell types.
Each cell type has roughly 20 different types of structures/organelles.

Diversity of Human Cells

Adult humans are composed of more than 200 different cell types, including nerve, muscle, skin, blood, bone, and cartilage cells.
Cells essential for embryonic development, but not incorporated into the body, include extra-embryonic tissues like placenta and umbilical cord.
All these cells originate from the fertilized egg (zygote), a totipotent cell.

Stem Cells

Stem cells are undifferentiated cells capable of differentiating into specialized cells and also producing more stem cells through mitosis.
Mammalian stem cells are broadly categorized as embryonic and adult stem cells.
Embryonic stem cells are isolated from the inner cell mass of blastocysts.
Adult stem cells and progenitor cells act as a repair mechanism for the body.
Stem cells in developing embryos can differentiate into all three germ layers (ectoderm, endoderm, mesoderm) giving rise to all tissues and organs.
Stem cells have different potency levels (totipotent, pluripotent, multipotent, oligopotent, unipotent) indicating their differentiation potential.

Stem cells potency

Totipotent stem cells can differentiate into any cell type, including embryonic and extraembryonic cell types. These are produced from the fusion of an egg and sperm cell.
Pluripotent cells can differentiate into almost all cell types. These are derived from totipotent cells.
Multipotent stem cells can differentiate into various cell types of a closely-related family.
Oligopotent stem cells can differentiate into only a few cell types.
Unipotent cells can only produce one cell type, but have the capacity for self-renewal.

Stem cell division and differentiation

Stem cells can divide symmetrically or asymmetrically to produce either more stem cells or progenitor cells.
Progenitor cells divide to form differentiated cells.
Terminal differentiation is the final stage in the development of a specialized cell.

Potential uses of stem cells

Stem cells have potential applications in treating various diseases and injuries including stroke, traumatic brain injury, learning defects, Alzheimer's disease, Parkinson's disease, missing teeth, wound healing, bone marrow transplantation, spinal cord injury, osteoarthritis, rheumatoid arthritis, and others.

Characteristics of All Cell Types

All cells have a surrounding membrane.
All cells contain protoplasm, the cell contents held within the membrane.
Organelles are specialized structures within the cell performing specific functions.
All cells have a control center containing DNA.
Cells are broadly classified as prokaryotic and eukaryotic.

Prokaryotic Cells

Prokaryotic cells lack a nucleus and membrane-bound organelles.
They are the simplest cell type.
Bacteria is a prokaryotic group.
They possess a cell wall typically made of peptidoglycan (although some lack it).
They have a single, circular chromosome, and a nucleoid region for DNA.
They contain ribosomes for protein synthesis.

Prokaryotic Cells (Bacteria)

Bacteria can be classified based on Gram staining, differentiating Gram-positive (purple) and Gram-negative (pink) types.
Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane.

Eukaryotic Cells

Eukaryotic cells have a membrane-bound nucleus.
They are more complex than prokaryotic cells.
They contain various organelles for compartmentalization and efficient function.
Eukaryotic cells have a cytoskeletal framework for support and structural integrity.
They include fungi, protozoa, plants, and animals.

Cell Structure

The three main components of a eukaryotic cell are the plasma membrane, the cytoplasm containing cytosol and organelles, and the nucleus.

Cytosol

The cytosol is the fluid portion of the cytoplasm, making up 55% of the total cell volume.
This fluid is mainly water that contains dissolved organic and inorganic substances, including ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, and waste products.
It also contains cellular structures that aggregate for storage, or for other roles, appearing and disappearing at different stages of a cell's life cycle.
Many important chemical reactions vital to cell function occur in cytosol.

Cytoplasm (Cell Organelles)

The cytoplasm consists of the cytosol and various organelles.
These include cytoskeleton, flagella, cilia, centrioles, endoplasmic reticulum, Golgi apparatus, mitochondria, nucleus, nucleolus, nuclear envelope, and vesicles such as lysosomes.

Cell Organelles (Cytoskeleton)

The cytoskeleton is a network of protein filaments (microfilaments, intermediate filaments, microtubules) that maintains cell shape, positions organelles, and changes cell shape.
Microfilaments, associated with actin, are dynamic components for cell shape and movement.
Intermediate filaments provide stiffness and resistance to tension.
Microtubules are involved in cell division, organelle transport, and cell shape.

Cell Organelles (Centrosomes)

Centrosomes that contain centrioles and pericentriolar material contain microtubules that play a crucial role during mitosis.
These structures are important for cell division.

Cell Organelles (Cilia and Flagella)

Cilia and flagella are hair-like structures consisting of microtubules.
They function in cell movement.
Flagella (e.g., sperm) are long, whip-like structures.
Cilia (e.g., respiratory system) are short hair-like structures in groups.

Cell Organelles (Ribosomes)

Ribosomes are located inside the cell, on the endoplasmic reticulum (bound ribosomes) or free in the cytoplasm (free ribosomes).
They consist of rRNA and proteins and are the protein synthesis machinery of the cell.

Cell Organelles (Endoplasmic Reticulum)

The endoplasmic reticulum (ER) includes rough ER (studded with ribosomes), and smooth ER (lacking ribosomes).
Rough ER is involved in protein synthesis and modification.
Smooth ER is involved in lipid synthesis, detoxification, and calcium storage.

Cell Organelles (Golgi Apparatus)

The Golgi apparatus consists of flattened membranous sacs (cisterns).
It modifies, sorts, packages, and exports proteins and lipids.
It is involved in the production of lysosomes and vesicles.

Cell Organelles (Lysosomes)

Lysosomes are spherical or oval structures containing digestive enzymes.
They help digest worn-out cellular components and foreign materials.
They are involved in autophagy (cell self-destruction).
Some genetic disorders involve missing lysosomal enzymes, leading to cellular damage.

Cell Organelles (Peroxisomes)

Peroxisomes are oval-shaped organelles with a single membrane; they contain enzymes to consume molecular oxygen and neutralize potentially harmful substances like fatty acids, alcohol, and even toxic compounds.
They are abundant in the liver and play a crucial role in detoxification.

Cell Organelles (Proteasomes)

Proteasomes are barrel-shaped structures containing proteases (enzymes that break down proteins).
They degrade unneeded and faulty proteins, playing a role in cellular maintenance and preventing protein accumulation.

Cell Organelles (Mitochondria)

Mitochondria have a double membrane, with folded inner membranes (cristae).
Mitochondria are the powerhouse of the cell, producing ATP (adenosine triphosphate) through cellular respiration.
They contain their own DNA and ribosomes, involved in protein synthesis.

Nucleus

The nucleus is a round or oval-shaped structure bounded by a nuclear envelope with pores.
Chromatin is a network of protein-bound DNA.
The nucleolus produces ribosomes.

Plasma Membrane

Phospholipids arrange in a bilayer, with hydrophilic heads facing outwards and hydrophobic tails facing inwards.
Cholesterol is interspersed in the membrane; it regulates membrane fluidity.
Membrane proteins (integral and peripheral) are embedded in the phospholipid bilayer.
Glycolipids and glycoproteins form the glycocalyx that enables cellular recognition.

Plasma Membrane (Junctions)

Cells are joined by desmosomes, tight junctions, and gap junctions.
These junctions link the cells together, and allow for passage of molecules between them.
Integrins are transmembrane proteins that link the extracellular matrix, and the membrane protein complex on adjacent cells.

Comparison of Bacterial, Animal, and Plant Cells

A table contrasting structural features (presence or absence of cell wall, plasma membrane, interior structures like organelles, nucleus) of bacterial, animal and plant cells.

Studying That Suits You

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

Description

Explore the intricate details of cellular structures and cell theory in this MPharm programme quiz. Understand the differences among prokaryotic and eukaryotic cells, learn about stem cells, and delve into the functions of the plasma membrane, cytoplasm, and nucleus. Test your knowledge of human cells and their vital roles.