W9_Cell Structure and Function

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Questions and Answers

What is the primary function of flagella in prokaryotic cells?

Cell division

Protein synthesis

Nutrient absorption

Locomotion (correct)

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

Gram-negative bacteria have no cell wall.

Gram-negative bacteria always cause disease.

Gram-positive bacteria have a thinner cell wall.

Gram-positive bacteria stain purple due to a thicker peptidoglycan layer. (correct)

Which characteristic is exclusive to eukaryotic cells?

Undergoing binary fission

Containing peptidoglycan

Having a membrane-bound nucleus (correct)

Possessing a cytoskeleton

What component is not part of the general structure of a cell?

Ribosome Signup and view all the answers

What is the content of the cytoplasm composed of?

Cytosol and organelles Signup and view all the answers

Which of the following cell types does not belong to the category of eukaryotic cells?

Bacteria Signup and view all the answers

What is the function of the cytoskeleton in eukaryotic cells?

Support and maintenance of cellular structure Signup and view all the answers

Gram-negative bacteria are characterized by which of the following?

Thin peptidoglycan layer Signup and view all the answers

What is the primary function of cells according to the cell theory?

Cells are the smallest units that perform all vital physiological functions. Signup and view all the answers

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

About 3.72x10^13 cells Signup and view all the answers

Which of the following statements regarding various cell types in the human body is accurate?

The human body comprises over 200 different types of cells. Signup and view all the answers

Which of the following is NOT a part of the cell theory?

Cells can spontaneously generate from non-living matter. Signup and view all the answers

What type of cells are neurons classified as?

Nerve cells Signup and view all the answers

Which cell type is primarily responsible for carrying oxygen in the bloodstream?

Erythrocytes Signup and view all the answers

Which of the following cell types is classified as a connective tissue cell?

Osteocytes Signup and view all the answers

What is the role of the plasma membrane in a cell?

It regulates the movement of substances in and out of the cell. Signup and view all the answers

What is the structural composition of centrioles within the centrosome?

9 clusters of 3 microtubules Signup and view all the answers

Which organelle is primarily responsible for protein synthesis?

Ribosomes Signup and view all the answers

What is the main function of cilia in the respiratory system?

Move mucus Signup and view all the answers

What distinguishes rough endoplasmic reticulum from smooth endoplasmic reticulum?

Presence of ribosomes Signup and view all the answers

Which of the following is NOT a function of the smooth endoplasmic reticulum?

Protein synthesis Signup and view all the answers

What role do the basilar bodies play in relation to cilia and flagella?

Provide structural support Signup and view all the answers

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

Movement of chromosomes Signup and view all the answers

How are ribosomes produced within the cell?

Produced in the nucleolus Signup and view all the answers

How does cholesterol affect membrane fluidity at warm temperatures?

Restrains phospholipid movement Signup and view all the answers

What is the role of glycolipids in the plasma membrane?

Create an asymmetric bilayer Signup and view all the answers

What distinguishes integral membrane proteins from peripheral membrane proteins?

Integral proteins are amphipathic and closely associated with lipids Signup and view all the answers

What is one function of transmembrane proteins?

Transport ions or water across the membrane Signup and view all the answers

Where are peripheral membrane proteins found in relation to the membrane?

Bound to the polar regions of integral proteins Signup and view all the answers

What is the glycoprotein's significance in the plasma membrane?

It helps in the transmission of chemical signals Signup and view all the answers

What is the glycocalyx composed of?

Glycoproteins and glycolipids Signup and view all the answers

How does cholesterol maintain membrane fluidity at cold temperatures?

Prevents tight packing and maintains fluidity Signup and view all the answers

What distinguishes unipotent stem cells from non-stem cells?

Ability to produce only one cell type and self-renew Signup and view all the answers

Which stem cell type can give rise to nearly all cell types derived from any of the three germ layers?

Pluripotent stem cells Signup and view all the answers

What is the primary characteristic of oligopotent stem cells?

They can differentiate into a limited number of closely related cell types. Signup and view all the answers

Which of the following statements about prokaryotic cells is correct?

They are the simplest type of cell. Signup and view all the answers

What is the primary function of cell walls in prokaryotic cells?

To protect the cell and maintain shape Signup and view all the answers

Which of these is NOT a characteristic of all cell types?

Single-celled structure Signup and view all the answers

What is the relationship between totipotent and pluripotent stem cells?

Totipotent cells can develop into a complete organism, while pluripotent cells cannot. Signup and view all the answers

Which type of stem cell can differentiate into a number of cell types, but only those related to each other?

Multipotent stem cells Signup and view all the answers

Which characteristic is unique to ribosomes present in prokaryotic cells?

They do not have a membrane. Signup and view all the answers

What is indicated by asymmetric stem cell division?

A stem cell divides to produce another and a differentiated cell. Signup and view all the answers

What is NOT a function of lysosomes?

Modify proteins into glycoproteins Signup and view all the answers

Which structure is primarily involved in detoxifying harmful substances in the liver?

Peroxisomes Signup and view all the answers

What characterizes the Golgi complex?

Flattened membranes resembling stacks of pita bread Signup and view all the answers

What is the main function of proteasomes?

Digest faulty or unneeded proteins Signup and view all the answers

Which of the following conditions is linked to a missing lysosomal enzyme?

Tay-Sachs disease Signup and view all the answers

What do peroxisomes primarily utilize molecular oxygen for?

Removing hydrogen from organic molecules Signup and view all the answers

Which statement about lysosomes is accurate?

They help in the death of old cells through autolysis. Signup and view all the answers

What is the structure of a proteasome?

Cylindrical barrels containing enzymes Signup and view all the answers

Study Notes

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

The course is PHA115, Cellular Structure 1 & 2, taught by Dr. Praveen Bhugra.
The learning objectives include understanding and explaining in detail cell theory, stem cell theory, differences between prokaryotic and eukaryotic cells, differentiation between plant, animal cells and bacteria, and structure and function of plasma membrane, cytoplasm (cytosol and organelles), and the nucleus.

Cells Theory

Cells are the building blocks of all plants and animals.
All cells come from the division of pre-existing cells.
Cells are the smallest units that perform all vital physiological functions.
Each cell maintains homeostasis at the cellular level.

Cells in the human body

The human body is composed of cells.
An estimated 3.72 x 10¹³ cells exist in the human body.
A variety of cell types exist within the human body (approximately 200 types).
Cells contain organelles.

Diversity of Human Cells

Adult humans contain more than 200 different kinds of cells.
These include nerve, muscle, skin, blood, bone, and cartilage cells.
Extra-embryonic tissues like the placenta and umbilical cord are essential for embryonic development.

Stem cells

Stem cells are undifferentiated biological cells that can differentiate into specialized cells and can divide (mitosis) to create more stem cells.
Two primary types of stem cells in mammals are embryonic stem cells and adult stem cells.
Embryonic stem cells are derived from the inner cell mass of blastocysts.
Adult stem cells are found in various tissues and function in tissue repair.
In a developing embryo, stem cells can differentiate into three germ layers (ectoderm, mesoderm, and endoderm).

Stem cells potency

Totipotent stem cells can differentiate into all types of cell types (including embryonic and extra-embryonic).
Pluripotent stem cells can differentiate into nearly all cells derived from the three germ layers.
Multipotent stem cells differentiate into a number of closely related cell types.
Oligopotent stem cells differentiate into just a few closely related cell types.
Unipotent stem cells differentiate into just one cell type and have self-renewal abilities.

Stem cell division and differentiation

Stem cells divide and differentiate to produce progenitor cells and differentiated cells.
Stem cell division and differentiation can be symmetric or asymmetric and lead to progenitor cell division.
Stem cell differentiation leads to a terminal differentiated state.

Potential uses of stem cells

Stem cells have potential applications in treating various diseases and conditions (stroke, traumatic brain injury, learning defects, and others).

Stem cells potency & source developmental

Totipotent embryonic stem cells are the most versatile.
Pluripotent embryonic stem cells and induced pluripotent stem cells can generate multiple cell types.
Multipotent stem cells can generate a range of cells within a family of related cells.

Hierarchy of haemopoietin differentiation

Stem cells give rise to progenitor cells and mature cells (blood cells).
Blood cells are categorized into different lineages, with specific progenitor cells leading to distinct blood cell types.

Characteristics of all cell types

All cell types have a surrounding membrane, protoplasm, organelles, and a control center with DNA.
This leads to prokaryotic and eukaryotic cell categorization.

Characteristics of prokaryotic cells (Bacteria)

Lack a nucleus and membrane-bound organelles.
Simplest cell type with a single, circular chromosome.
The nucleoid region contains DNA.
Surrounded by a cell membrane and cell wall (peptidoglycan).
Contain ribosomes for protein synthesis.
Can be Gram-positive or Gram-negative based on cell wall structure.

Characteristics of eukaryotic cells

Possess a membrane-bound nucleus.
More complex than prokaryotic cells, with compartmentalization of functions in organelles.
Possess a cytoskeleton for support and to maintain cellular structure.
Include fungi, protozoa, plants, and animals.

An animal cell and A plant cell.

Both animal and plant cells have a nucleus, cytoplasm and cell membrane.
Plant cells have a cell wall, vacuoles, and chloroplasts.

Plant cell

Plant cells have specific organelles.

Animal Cell

Animal cells are characterized by diverse organelles.

Cell Structure

The three main parts of a cell are the plasma membrane, cytoplasm (cytosol and organelles), and the nucleus.

Generalized View of Cell Structure

The cell has components that are part of its structure and their functions.

Plasma membrane

Main structural element in cells, made of a phospholipid bilayer, cholesterol, and proteins.
Proteins associated with carbohydrates are glycolipids and glycoproteins.
The functions of membranes include a barrier between inside and outside of the cell, regulation of transport of materials, and transmitting signals between different areas within and outside the cell.

Plasma membrane (Phospholipids)

Phospholipids are amphipathic molecules that form a bilayer in cell membranes.

Plasma membrane (Cholesterol)

Cholesterol plays a key role in regulating membrane fluidity at different temperatures.

Plasma membrane (Glycolipids)

Glycolipids are membrane lipids with carbohydrate groups that face the extracellular fluid.

Plasma Membrane (Protein)

Integral membrane proteins are tightly associated with the membrane and span the lipid bilayer.
Peripheral membrane proteins are loosely associated with the membrane.

Plasma Membrane (Junctions)

Various junction types connect cells.
These include desmosomes, tight junctions, and gap junctions.
Integrins are transmembrane proteins that link the membrane to the extracellular matrix.

Desmosomes

Structures that anchor cells together in tissues that undergo stretching.

Tight junctions

Link cells tightly, creating an impermeable seal that prevents the leakage of materials between cells.

Gap junctions

Protein channels that connect the cytosols of adjacent cells, allowing small molecules, ions, and signaling molecules to pass between cells.

Functions of Cell Membranes

Regulate passage of substances in and out of cells.
Detect chemical messengers.
Link adjacent cells.
Anchor cells to the extracellular matrix.

Cytoplasm (Cytosol)

The fluid component of the cytoplasm.
Consists mostly of water plus dissolved substances.

Cytoplasm (Cell Organelles)

Contains various organelles such as cytoskeleton, flagella, cilia, centrioles, endoplasmic reticulum, Golgi apparatus, mitochondria, nucleus, nucleolus, and nuclear envelope, vesicles.

Cell organelles (Cytoskeleton)

Maintains the shape of the cell.
Positions organelles.
Changes cell shape.
Includes microfilaments, intermediate filaments, and microtubules.

Cell organelles (Centrosome)

An organizing center for microtubules.

Cell organelles (Cilia and Flagella)

Specialized for motion.
Flagella are long tail-like structures, and cilia are short hair-like structures.

Cell organelles (Ribosomes)

Sites of protein synthesis, found free in the cytosol or attached to the endoplasmic reticulum.

Cell organelles (Endoplasmic Reticulum (E.R.))

Network of folded membranes involved in protein synthesis, lipid synthesis, and intracellular transport.
Types - rough and smooth.

Cell organelles (Golgi Complex)

Modifies proteins and lipids, sorts and packages materials for secretion, and forms lysosomes.

Cell organelles (Lysosomes)

Contain digestive enzymes for breaking down cellular waste.

Cell organelles (Peroxisomes)

Contain enzymes for detoxification reactions.

Cell organelles (Proteasomes)

Responsible for the breakdown of unneeded or damaged proteins.

Cell organelles (Mitochondria)

The major site of ATP production in cells.
Contain DNA and ribosomes.
Abundant in cells with high energy demands (muscle, liver, kidney).

Nucleus

The control center of the cell containing DNA and nucleolus, responsible for regulating protein synthesis.

Comparison of Bacterial, Animal and Plant cells

A table summarizing the main structural differences across bacterial, animal, and plant cells, indicating the presence or absence of various structures (cell wall, plasma membrane, flagella, DNA, etc.).

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Description

Test your knowledge on prokaryotic and eukaryotic cells with this quiz covering their structures, functions, and differences. Explore topics including flagella, cell theory, and the various types of cells in the human body. Perfect for biology students seeking to reinforce their understanding of cellular biology.