Cell Biology Basics

Questions and Answers

What contributed to Antonie van Leeuwenhoek's discovery of motile free living cells in 1674?

Discovery of protoplasm

Adoption of the electron microscope

Development of more complex lens grinding techniques (correct)

Use of chemical stains to differentiate cell structures

Which of the following statements about the contribution of Hugo von Mohl is correct?

He studied animal cells and proposed that cells are the basic building units of all animals

He identified the protoplasm as the physical basis of life (correct)

He observed a multitude of tiny pores in cork and coined the term 'cell'

He added the third tenet to cell theory: all cells arise from pre-existing cells

What was Rudolf Virchow's main contribution to cell theory?

Adding the tenet that all cells arise from pre-existing cells (correct)

Proposing that cells are the basic building units of all plants

Coining the term 'cell'

Introducing the concept of the protoplasm

Who first coined the term 'protoplasm' and in what year?

J.E Purkinje in 1839 Signup and view all the answers

Which part of the cell contains hereditary information passed during cell division?

Nucleoplasm Signup and view all the answers

Who proposed that cells are the basic building units of all plants?

M.J. Schleiden Signup and view all the answers

Which microscope uses a beam of electrons to illuminate the sample?

Electron Microscope Signup and view all the answers

What best describes the function of protoplasm in the cell?

Provides the site where all cell functions take place and allows the cell to respond to stimuli Signup and view all the answers

What is the smallest unit of structure and function in a living organism?

Cells Signup and view all the answers

Who constructed the first simple microscope?

Antonie van Leeuwenhoek Signup and view all the answers

Which term describes an organism composed of only one cell?

Unicellular Signup and view all the answers

What was the maximum magnifying power of the microscopes built by Antonie van Leeuwenhoek?

What is not a characteristic shared by all known living organisms?

Visible to the naked eye Signup and view all the answers

Which of the following is true of multicellular organisms?

They are composed of trillions of cells. Signup and view all the answers

How did the invention of the microscope contribute to the discovery of cells?

It allowed cells to be magnified and resolved. Signup and view all the answers

What did scientists need in order to start studying cells?

Technology to magnify cells Signup and view all the answers

Which of the following descriptions best represents the function of the cytoskeleton?

It provides shape to the cell and facilitates movement. Signup and view all the answers

Which cell organelle is responsible for separating the interior of the cell from the external environment?

Cell membrane Signup and view all the answers

Which statement about deutoplasmic bodies is correct?

They are non-living cytoplasmic inclusions. Signup and view all the answers

What are the components that make up protoplasm?

Cytoplasm and nucleoplasm Signup and view all the answers

Which of the following substances can be classified as cytoplasmic inclusions?

Calcium oxalate crystals Signup and view all the answers

What essential role does the cytoplasm play in cell metabolism?

It acts as the site for many vital biochemical reactions. Signup and view all the answers

Which cell organelle is primarily involved in the storage of materials like starch and glycogen?

Cytoplasmic inclusions Signup and view all the answers

Which organelles are described as 'little organs' performing specific functions within the cell?

Organelles Signup and view all the answers

Which of the following organisms is considered the largest unicellular organism?

Amoeba proteus Signup and view all the answers

How do unicellular organisms obtain nutrition?

Phagocytosis Signup and view all the answers

What serves as the protective outer boundary of a cell?

Plasma membrane Signup and view all the answers

In plant cells, where is the plasma membrane located?

After the cell wall Signup and view all the answers

Which type of unicellular organism is known to possess pseudopodia for movement?

Amoeba Signup and view all the answers

Which of the following structures within a cell is responsible for housing genetic material?

Nucleus Signup and view all the answers

What is the primary way in which multicellular organisms typically develop from a single cell?

Cell Division and Differentiation Signup and view all the answers

Which cell type is specifically adapted to conduct impulses?

Neuron Signup and view all the answers

What structural characteristic do all cells share, regardless of type?

Similar basic structural plan Signup and view all the answers

Which of the following is a characteristic feature of cell membranes?

They regulate the movement of substances in and out of cells Signup and view all the answers

Who first added the concept that all cells arise from pre-existing cells to the cell theory?

Rudolf Virchow Signup and view all the answers

Which of the following accurately describes the smallest known cell?

Mycoplasma Signup and view all the answers

What distinguishes the cytoplasm from the nucleoplasm?

Cytoplasm is the protoplasm outside the nucleus; nucleoplasm is the protoplasm within the nucleus Signup and view all the answers

Who described protoplasm as the 'Physical basis of life'?

Huxley Signup and view all the answers

Which cell structure is primarily involved in the streaming movements known as cyclosis?

Protoplasm Signup and view all the answers

Which of the following cells are typically the largest in humans?

Egg cells Signup and view all the answers

Based on the modern cell theory, which statement is correct?

Cells contain hereditary information that is passed during cell division. Signup and view all the answers

Which scientist proposed the idea that all living cells are composed of protoplasm?

Schultze Signup and view all the answers

What is the function of protoplasm in a cell?

Site where all life functions take place Signup and view all the answers

Which cells in the human body are known to be up to a meter long?

Nerve cells Signup and view all the answers

Which group of organisms includes organisms with freely permeable cell walls?

Plants, fungi, and prokaryotic cells Signup and view all the answers

What is the primary composition of the plasma membrane that helps in maintaining the flexibility of the cell?

Proteins and lipids Signup and view all the answers

Which of the following is NOT a function of the plasma membrane?

Rigid protective outer layer in plant cells Signup and view all the answers

What distinguishes multicellular organisms from unicellular organisms?

Formation of tissues from grouped cells Signup and view all the answers

Which structure in a cell is responsible for containing genetic material?

Nucleus Signup and view all the answers

What is the defining characteristic of an organelle?

Specialized structure within the cell performing specific functions Signup and view all the answers

The cell wall allows for which type of permeability?

Freely permeability Signup and view all the answers

Which of these is an example of a unicellular organism?

Yeast Signup and view all the answers

What is the main structural difference between plant and animal cells?

Presence of cell wall in plant cells Signup and view all the answers

Which of the following descriptions correctly defines the cell membrane?

A thin, elastic, selectively permeable membrane surrounding the cytoplasm Signup and view all the answers

Which organelle is responsible for autophagy?

Lysosomes Signup and view all the answers

In which cells are centrioles absent?

Plant cells Signup and view all the answers

What is the main function of leucoplasts?

Storage of food materials Signup and view all the answers

Where is the centrosome usually located in an animal cell?

Near the nucleus Signup and view all the answers

Which plastid is referred to as the kitchen of the cell?

Chloroplast Signup and view all the answers

Which statement correctly describes the nucleus?

It transfers hereditary information to the next generation. Signup and view all the answers

What pigment is found in chloroplasts that is essential for photosynthesis?

Chlorophyll Signup and view all the answers

What is referred to as the 'control center' of the cell?

Nucleus Signup and view all the answers

In which type of cells is the nucleus commonly located at the periphery?

Plant cells Signup and view all the answers

What specialized structure within the nucleus produces ribosomes?

Nucleolus Signup and view all the answers

Which function is NOT associated with the endoplasmic reticulum?

Production of ribosomes Signup and view all the answers

Which organelle is described as the powerhouse of the cell?

Mitochondria Signup and view all the answers

What is the main component of ribosomes?

Proteins and RNA Signup and view all the answers

Which function is associated with the Golgi apparatus?

Formation of egg yolk Signup and view all the answers

Which cell organelle is described as the protein factory?

Ribosomes Signup and view all the answers

Which of the following is NOT found in both prokaryotes and eukaryotes?

Mitochondria Signup and view all the answers

Which of these is a function of lysosomes?

Removal of cell debris Signup and view all the answers

Which structure in the mitochondria contains ATP producing particles?

Cristae Signup and view all the answers

What is the main function of chromoplasts?

Photosynthesis Signup and view all the answers

Which structure contains enzymes that can digest all organic materials?

Lysosomes Signup and view all the answers

Which process is primarily associated with the rough endoplasmic reticulum (RER)?

Protein synthesis Signup and view all the answers

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

Forming the outer boundary of the cell Signup and view all the answers

What differentiates the smooth endoplasmic reticulum (SER) from the rough endoplasmic reticulum (RER)?

SER synthesizes lipids and steroids Signup and view all the answers

Which of the following substances are considered cytoplasmic inclusions?

Crystals Signup and view all the answers

What is the main purpose of the cell wall?

To give the cell a definite shape and rigidity Signup and view all the answers

Cytoplasm contains several living and non-living structures. Which of the following are living structures?

Endoplasmic reticulum Signup and view all the answers

Which cell organelle is directly involved in the synthesis of lipids?

Smooth endoplasmic reticulum Signup and view all the answers

Which statement best describes the role of the cytoskeleton?

It provides shape to the cell and facilitates movement Signup and view all the answers

Which of the following structures is continuous with the outer nuclear membrane?

Endoplasmic reticulum Signup and view all the answers

Which cell organelle is primarily involved in cellular transport by forming transport vesicles?

Smooth endoplasmic reticulum Signup and view all the answers

What distinguishes eukaryotic cells from prokaryotic cells?

The presence of a membrane-bound nucleus in eukaryotic cells Signup and view all the answers

Which of the following is NOT a function of the nucleus in a cell?

Storing waste products Signup and view all the answers

During which phase are chromosomes organized into chromatin?

Interphase Signup and view all the answers

Which structure is prominent in plant cells but not typically found in prokaryotic cells?

Plastids Signup and view all the answers

Which type of cells contains large and prominent vacuoles?

Plant cells Signup and view all the answers

What organelles are absent in prokaryotic cells?

Nuclear membrane Signup and view all the answers

What type of storage is NOT typically considered a cytoplasmic inclusion?

Ribosomes Signup and view all the answers

What component surrounds the vacuole in plant cells?

Tonoplast Signup and view all the answers

What term describes the basic structural, functional, and biological unit of all known living organisms?

Cell Signup and view all the answers

Who manufactured the first simple microscope using a single biconcave lens?

Antonie van Leeuwenhoek Signup and view all the answers

Study Notes

The Cell - The Basic Unit of Life

The cell is the smallest unit of structure and function of a living organism.
Cells are made up of building blocks called cells, which are the basic units of life.

Discovery of Cells

The discovery of cells became possible only after the invention of the microscope.
Antonie van Leeuwenhoek constructed the first simple microscope in 1674.
Robert Hooke discovered the cell in 1665 and coined the term "cell".

Cell Theory

The cell theory states that:
- All living organisms are made up of one or more cells.
- The cell is the smallest unit of structure and function of all living beings.
- All cells arise from pre-existing cells.
- Cells contain hereditary information which is passed from cell to cell during cell division.
- The chemical composition and metabolic activities of all cells are fundamentally similar.

Protoplasm

Protoplasm is the living substance of the cell.
It is a translucent, granular, slimy, semi-fluid or viscous fluid.
Protoplasm is divided into two parts: cytoplasm and nucleoplasm.
Functions of protoplasm:
- Provides the site where all cell functions take place.
- Allows cells to respond to various stimuli.

Diversity in Cells

Cells show great variations in shape and size.
Size of cells can vary from 5 to 20 µm (1µm = 1/1000 mm = 10-6 m).
The smallest cells are bacteria or prokaryotic cells (0.2-0.5 µm).

Unicellular and Multicellular Organisms

Unicellular organisms:
- Are known as single-celled organisms.
- Examples include Amoeba, Paramecium, Euglena, Yeast, and Bacteria.
- The process of life is carried out in the cell.
Multicellular organisms:
- Consist of more than one cell.
- Examples include plants, animals, and some algae.
- Arise from a single cell and grow into a multicellular organism.

Structure of a Cell

A cell is made up of various components, which can be divided into three main functional regions:
1. Cell membrane or Plasma membrane, and Cell wall
2. Cytoplasm
3. Nucleus, which contains the genetic material DNA (deoxyribonucleic acid)

Cell Membrane

The cell membrane is the outer boundary of a cell.
It acts as a barrier between the inner and outer surface of a cell.
The cell membrane is selectively permeable, which helps in maintaining a constant internal environment inside the cell (Homeostasis).

Cell Wall

The cell wall is a rigid, protective layer outside the cell membrane.
It is non-living and is mainly made up of cellulose.
Found in plants, fungi, and prokaryotic cells.

Cytoplasm

The cytoplasm is a semi-fluid, gel-like substance enclosed within the cell membrane.
It lies between the nucleus and plasma membrane of the cell.
Functions of cytoplasm:
- Provides a medium for the organelles to remain suspended.
- Is a source of vital chemicals such as enzymes, vitamins, amino acids, glucose, ions, etc.

Cell Organelles

An organelle is a unique part of a cell that has a specific function.
Examples of cell organelles:
- Mitochondria
- Endoplasmic reticulum (ER)
- Golgi apparatus
- Vacuoles
- Lysosomes
- Chloroplasts (in plant cells)

Endoplasmic Reticulum (ER)

The endoplasmic reticulum (ER) is a type of organelle in the cells.
There are two types of ER:
- Rough Endoplasmic Reticulum (RER)
- Smooth Endoplasmic Reticulum (SER)
Functions of ER:
- Cellular transport
- Formation of the skeletal framework
- Formation of nuclear membrane during cell division### Cell Organelles
Ribosomes: Dense granular organelles composed of RNA and proteins, responsible for protein synthesis, found in both prokaryotes and eukaryotes except mammalian RBCs.
Mitochondria: Membrane-bound organelles, found in most eukaryotic cells, responsible for generating energy in the form of ATP, characterized by a double membrane with inner membrane folds (cristae).
Golgi Apparatus: Membrane-bound organelle, responsible for protein modification, sorting, packaging, and dispatch, found in most eukaryotes, exists as a network near the nucleus in animal cells and as dictyosomes in plant cells.
Lysosomes: Membrane-bound vesicles containing digestive enzymes, responsible for breaking down cellular waste and foreign substances, found in most eukaryotic cells.
Centrioles and Centrosomes: Found only in animal cells, responsible for cell division, composed of two centrioles that play a major role in spindle fiber formation.
Plastids: Double-membranous organelles found in plants and algae, responsible for manufacturing and storing food and photosynthetic pigments, classified into leucoplasts and chromoplasts.

Plastids

Leucoplasts: Colorless plastids, responsible for storing food materials.
Chromoplasts: Colored plastids, responsible for storing photosynthetic pigments, include chloroplasts which contain chlorophyll and are responsible for photosynthesis.

Cell Structure and Function

Nucleus: Double membrane-bound organelle, responsible for storing genetic information, controlling cell growth and reproduction, found in eukaryotic cells.
Cytoplasmic Inclusions: Diverse intracellular structures, including vacuoles, lipid droplets, and crystals, responsible for storing food, water, and waste products.

Cell Types

Prokaryotic Cells: Cells without a nucleus, found in single-celled organisms such as bacteria, characterized by a nucleoid and lack of membrane-bound organelles.
Eukaryotic Cells: Cells with a membrane-bound nucleus, found in unicellular and multicellular organisms, characterized by a larger size and presence of membrane-bound organelles.

Key Points

Cell: The basic structural, functional, and biological unit of all known living organisms.
Cell wall: Present in plant cells, pushes cytoplasm towards the periphery, and forms a thin lining against the cell wall.

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Description

Learn about the cell, the basic unit of life, its discovery, and the cell theory. Understand the structure and function of cells and their significance in living organisms.