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Questions and Answers
What did Robert Hooke first observe when he used a microscope in 1667?
What did Robert Hooke first observe when he used a microscope in 1667?
Which principle of Cell Theory indicates that all living organisms are composed of cells?
Which principle of Cell Theory indicates that all living organisms are composed of cells?
What is the function of the cell membrane?
What is the function of the cell membrane?
What is referred to as the 'control center of the cell'?
What is referred to as the 'control center of the cell'?
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What term describes the composition of the cell membrane according to Singer and Nicolson?
What term describes the composition of the cell membrane according to Singer and Nicolson?
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Which of the following statements best describes protoplasm?
Which of the following statements best describes protoplasm?
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Which statement about the characteristics of cells is true?
Which statement about the characteristics of cells is true?
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Which of the following types of organisms is composed of only one cell?
Which of the following types of organisms is composed of only one cell?
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What is the primary function of lysosomes in a cell?
What is the primary function of lysosomes in a cell?
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What is the function of peroxisomes in a cell?
What is the function of peroxisomes in a cell?
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Which organelle is responsible for conducting photosynthesis in plant cells?
Which organelle is responsible for conducting photosynthesis in plant cells?
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What is the primary role of the Golgi apparatus in a cell?
What is the primary role of the Golgi apparatus in a cell?
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What distinguishes ribosomes from other organelles?
What distinguishes ribosomes from other organelles?
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What is the main structural function of the cytoskeleton?
What is the main structural function of the cytoskeleton?
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What is the role of the matrix in mitochondria?
What is the role of the matrix in mitochondria?
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Which statement about vacuoles is incorrect?
Which statement about vacuoles is incorrect?
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What is the primary function of the cytoskeleton in a cell?
What is the primary function of the cytoskeleton in a cell?
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Which of the following structures is NOT a locomotive structure of the cell?
Which of the following structures is NOT a locomotive structure of the cell?
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What type of cell has linear DNA enclosed within a nucleus?
What type of cell has linear DNA enclosed within a nucleus?
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Which statement accurately describes cilia?
Which statement accurately describes cilia?
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What is the correct classification for a cell without membrane-bound organelles?
What is the correct classification for a cell without membrane-bound organelles?
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What defines the size of eukaryotic cells compared to prokaryotic cells?
What defines the size of eukaryotic cells compared to prokaryotic cells?
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Which type of flagellar arrangement involves multiple flagella covering the entire surface of a cell?
Which type of flagellar arrangement involves multiple flagella covering the entire surface of a cell?
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What do the terms 'eu' and 'pro' refer to in cell classification?
What do the terms 'eu' and 'pro' refer to in cell classification?
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What is the main function of the nucleolus within the nucleus?
What is the main function of the nucleolus within the nucleus?
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Which component of the cell is responsible for regulating the transport of molecules between the nucleus and the cytoplasm?
Which component of the cell is responsible for regulating the transport of molecules between the nucleus and the cytoplasm?
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What distinguishes the rough endoplasmic reticulum (ER) from the smooth ER?
What distinguishes the rough endoplasmic reticulum (ER) from the smooth ER?
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Which type of cell structure is composed of a double-layer membrane that separates the nucleus's contents from the cytoplasm?
Which type of cell structure is composed of a double-layer membrane that separates the nucleus's contents from the cytoplasm?
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What is the primary component of the cell wall in plants?
What is the primary component of the cell wall in plants?
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Which organelle is commonly referred to as the 'powerhouse' of the cell?
Which organelle is commonly referred to as the 'powerhouse' of the cell?
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What is the main role of chromatin within the nucleus?
What is the main role of chromatin within the nucleus?
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Which of the following statements about the cytoplasm is true?
Which of the following statements about the cytoplasm is true?
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Which component is absent in animal cells but present in plant cells?
Which component is absent in animal cells but present in plant cells?
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What is one of the primary differences in the shape of animal and plant cells?
What is one of the primary differences in the shape of animal and plant cells?
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Which of the following is a food storage compound in animal cells?
Which of the following is a food storage compound in animal cells?
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Which structure do both eukaryotic and prokaryotic cells share?
Which structure do both eukaryotic and prokaryotic cells share?
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What is typically found in plant cells but absent in animal cells?
What is typically found in plant cells but absent in animal cells?
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Which of the following statements is true regarding the cell wall?
Which of the following statements is true regarding the cell wall?
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Which of these organelles is responsible for producing energy in eukaryotic cells?
Which of these organelles is responsible for producing energy in eukaryotic cells?
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Which type of cell typically has a larger size?
Which type of cell typically has a larger size?
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Study Notes
Introduction to Cell Biology
- Cell biology is the study of cell structure and function, focusing on the concept that the cell is the fundamental unit of life.
- The term “cell” was first introduced by Robert Hooke in 1667 while examining thin slices of cork with a microscope.
- Hooke observed "cells" which actually were the walls of dead plant cells.
Cell Theory
- There are three main principles of Cell Theory:
- Cells are the basic unit of structure and organization for all living organisms.
- All living organisms are composed of cells.
- Cells arise from pre-existing cells.
Parts of the Cell
- Protoplasm is the living matter of the cell.
- Protoplasm is made up of three main parts:
- Cell membrane: Also known as the plasma membrane, it surrounds the cytoplasm of a cell and acts as a semi-permeable barrier, controlling the entry and exit of substances.
- Nucleus: Considered the "control center" of the cell, it controls cell activities like growth, DNA replication, repair, and cell division. It is bound by a double-layered membrane.
- Cytoplasm: The part of the protoplasm located between the cell membrane and the nucleus, containing the organelles.
Nucleus
- Parts of the Nucleus:
- Nuclear envelope: a double-layered membrane separating the nucleus from the cytoplasm.
- Nucleoplasm: the dense material within the nucleus, containing DNA and proteins.
- Nucleolus: the large structure in the nucleus of eukaryotic cells, responsible for ribosome production.
- Chromatin: a complex of DNA and proteins called "histones" that form chromosomes within the nucleus of eukaryotic cells.
- Nuclear pore: channels in the nuclear envelope that regulate the transport of molecules between the nucleus and cytoplasm.
Cytoplasm
- Cytoplasm is a gel-like substance composed of water, dissolved substances, and organelles.
Organelles
- Organelles are specialized structures within the cytoplasm that perform specific functions:
- Cell wall: a rigid organelle providing support, protection, and shape for the cell. Present in plants, fungi, and bacteria.
- Endoplasmic Reticulum (ER): a network of membranous tubules within the cytoplasm, continuous with the nuclear envelope.
- Rough ER: contains ribosomes attached to its surface, responsible for protein synthesis.
- Smooth ER: lacks ribosomes, involved in lipid synthesis.
- Mitochondrion: considered the "powerhouse" of the cell, responsible for converting oxygen and nutrients into ATP (energy).
- Vacuole: a space within a cell, lined with a membrane and filled with fluid; functions as a storage tank for food, water, and waste.
- Lysosomes: organelles containing hydrolytic enzymes enclosed in a membrane, responsible for digestion of food and cellular debris.
- Involved in cell protection and breakdown of the cell during cell death.
- Peroxisomes: small organelles containing enzymes involved in nutrient absorption and alcohol digestion.
- Chloroplast: organelles found in plant cells and some eukaryotic algae that conduct photosynthesis. Contain chlorophyll, which absorbs sunlight and uses it to produce food.
- Golgi apparatus: a complex of vesicles and folded membranes; function as the "post office" of the cell, packaging and secreting materials.
- Centrioles: minute cylindrical organelles near the nucleus in animal cells, involved in the development of spindle fibers during cell division.
Ribosomes
- Ribosomes are NOT considered organelles because they lack a membrane covering.
- They are molecular machines found in all living cells, responsible for protein synthesis.
- Ribosomes can be found in the cytoplasm and on the surface of the rough ER.
Cytoskeleton
- The cytoskeleton is a network of fibers that provides support, shape, and organization to the cell.
- It is present in all types of cells and consists of three main components:
- Microfilaments: thin fibers made of actin protein.
- Microtubules: thicker fibers made of tubulin protein.
- Intermediate filaments: fibers made of various proteins.
Cell Movement
- Cell motility is essential for many physiological processes, including cell migration, cell regeneration, and tissue development.
- Three main types of locomotive structures contribute to cell movement:
- Cilia: hair-like filaments found on the surface of tissue cells, responsible for movement.
- Flagella: whip-like structures that allow cells to move.
- Pseudopodia: cytoplasm-filled projections of the cell membrane used for movement.
Types of Cells
- There are two main types of cells:
- Eukaryotic cells: contain a true nucleus bound by a membrane.
- Prokaryotic cells: lack a true nucleus, with DNA free in the cytoplasm.
- Both types of cells have ribosomes, a cell membrane, DNA, and a cytoskeleton. Eukaryotic cells may also have a cell wall depending on their type.
Comparison of Eukaryotic and Prokaryotic Cells
-
Eukaryotic Cells:
- Size: Larger than 10 micrometres.
- DNA: Linear DNA enclosed within a nuclear envelope.
- Organelles: With organelles.
- Cell wall: Made up of cellulose or chitin (plants & fungi).
-
Prokaryotic Cells:
- Size: Smaller than 10 micrometres.
- DNA: Circular DNA located in the cytoplasm.
- Organelles: Without organelles.
- Cell wall: Made up of peptidoglycan.
Animal and Plant Cells
- Both animal and plant cells are eukaryotic:
- Share features like a cell membrane, Golgi apparatus, cytoplasm, nucleus, DNA, mitochondria, rough ER, smooth ER, lysosomes, peroxisomes, and ribosomes.
- Differences between animal and plant cells:
- Size: Plant cells are larger than animal cells.
- Shape: Plant cells have a fixed rectangular shape, while animal cells are more fluid and lack a defined shape.
- Cell wall: Plant cells have a cell wall; animal cells lack a cell wall.
- Vacuole: Plant cells have a large central vacuole; animal cells may have small vacuoles.
- Chloroplast: Plant cells contain chloroplasts; animal cells do not.
- Centrioles: Present in animal cells, absent in plant cells.
- Food storage: Animal cells store glycogen as their primary food source; plant cells store starch.
Review of Animal Cell
- Key components:
- Cell membrane
- Mitochondrion
- Lysosomes
- Golgi Apparatus
- Vesicles
- Vacuole
- Centrioles
- Nucleus
- Rough ER
- Cytoplasm
- Smooth ER
- Nuclear envelope
- Nuclear pore
- Nucleolus
- Nucleoplasm
Review of Plant Cell
- Key components:
- Cell Wall
- Cell membrane
- Chloroplast
- Vacuole
- Lysosomes
- Mitochondrion
- Cytoplasm
- Rough ER
- Smooth ER
- Golgi apparatus
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Description
This quiz covers the fundamentals of cell biology, focusing on cell structure, function, and the three principles of Cell Theory. Learn about the components of a cell and their roles in maintaining life. Perfect for introductory biology courses.
