2.2.1

Introduction to Cells

Test yourself on Introduction to Cells

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Introduction to Cells

According to the cell theory, all living organisms, from bacteria to humans, are composed of cells, the smallest units of living matter.

Cell size

Cell size

  • Cells are often too small to be seen without a microscope.
  • Cells come in all sizes and shapes.
    • Their small size allows for a large surface-area-to-volume ratio that enables a more efficient exchange of nutrients and wastes with the environment.
Types of cell

Types of cell

  • There are three basic types of cells: archaea, bacteria, and eukaryotes.
  • Both archaea and bacteria are classified as prokaryotes, whereas cells of animals, plants, fungi, and protists are eukaryotes.
    • Archaea are a unique group of organisms and likely evolved in the harsh conditions of early Earth and are still prevalent today in extreme environments, such as hot springs and polar regions.
Common ancestry

Common ancestry

  • All three types of cells share features that reflect their evolution from a common ancestor.
  • These features are:
    1. A plasma membrane that separates the cell from its environment
    2. Cytoplasm comprising the jelly-like cytosol inside the cell
    3. Ribosomes that are important for the synthesis of proteins
    4. DNA to store and transmit hereditary information
Prokaryotes vs eukaryotes

Prokaryotes vs eukaryotes

  • The term “prokaryote” means “before nucleus,” and prokaryotes do not have nuclei.
  • Rather, their DNA exists as a single circular chromosome in the central part of the cell called the nucleoid.
  • Eukaryotic cells possess many features that prokaryotic cells lack, including a nucleus with a double membrane that encloses DNA.
    • In addition, eukaryotic cells tend to be larger and have a variety of membrane-bound organelles that perform specific, compartmentalized functions.
Jump to other topics
1

Unity & Diversity - Molecules

1.1

Water

1.1.1Water & Hydrogen Bonding1.1.2IB Multiple Choice - Water & Hydrogen Bonding1.1.3Extended Response - Water
1.2

DNA Structure & Replication

1.2.1DNA1.2.2RNA1.2.3DNA Replication1.2.4DNA Replication - Summary1.2.5IB Multiple Choice - DNA Replication
1.3

Transcription & Gene Expression

1.3.1Introduction to Transcription & Protein Synthesis1.3.2Types of RNA1.3.3Transcription1.3.4RNA Processing in Eukaryotes1.3.5IB Multiple Choice - Transcription
1.4

Translation

1.4.1Translation1.4.2Retroviruses1.4.3Scientific Practices: Coronavirus1.4.4IB Multiple Choice - Translation
2

Unity & Diversity - Cells

2.1

The Origin of Cells

2.1.1Origins - Endosymbiosis
2.2

Introduction to Cells

2.2.1Introduction to Cells2.2.2Cell Size & Surface Area2.2.3Surface Area to Volume Ratio2.2.4Eukaryotic vs Prokaryotic Cells2.2.5Stem Cells2.2.6Stem Cells in Disease
2.3

Ultrastructure of Cells

2.3.1Golgi, Lysosomes & Ribosomes2.3.2Cell Walls & Vacuole2.3.3Prokaryotes2.3.4Binary Fission
2.4

Cell Division

2.4.1The Cell Cycle2.4.2Mitosis2.4.3Regulation of the Cell Cycle2.4.4End of Topic Quiz - The Cell Cycle2.4.5IB Multiple Choice - The Cell Cycle2.4.6Extended Response - Mitosis
2.5

Structure of DNA & RNA

2.5.1DNA & RNA
2.6

DNA Replication, Transcription & Translation

2.6.1Protein Synthesis2.6.2Transcription & Translation2.6.3End of Topic Test - DNA, Genes & Protein Synthesis2.6.4Exam-Style Question - Protein Synthesis2.6.5End of Topic Test - Coronavirus Translation2.6.6IB Multiple Choice - Transcription2.6.7IB Multiple Choice - Translation
2.7

Cell Respiration

2.7.1Overview of Respiration2.7.2Anaerobic Respiration2.7.3End of Topic Test - Anaerobic Respiration2.7.4Respiration Experiments2.7.5End of Topic Test - Respiration2.7.6IB Multiple Choice - Respiration
2.8

Photosynthesis

2.8.1Overview of Photosynthesis
2.9

Viruses

2.9.1Viruses
3

Unity & Diversity - Organisms

3.1

Diversity of Organisms

3.1.1Chromosomal Theory of Inheritance3.1.2Chromosomal Basis of Inherited Disorders3.1.3IB Multiple Choice - Chromosomal Inheritance
3.2

Evidence for Evolution

3.2.1Evidence for Evolution - Fossils & DNA3.2.2Evidence for Evolution - Anatomy & Geography3.2.3IB Multiple Choice - Evidence for Evolution3.2.4Extended Response - DNA & Evolution
3.3

Natural Selection

3.3.1Introduction3.3.2Evolutionary Fitness3.3.3Natural Selection & Variation3.3.4End of Topic Quiz - Natural Selection3.3.5IB Multiple Choice - Natural Selection3.3.6Speciation
4

Unity & Diversity - Ecosystems

4.1

Classification

4.1.1Introduction to Biodiversity4.1.2Keystone Species4.1.3Courtship & Ancestry4.1.4Classification
4.2

Cladistics

4.2.1Evolutionary Relationships4.2.2IB Multiple Choice - Species & Taxonomy
4.3

Evolution & Speciation

4.3.1Evidence for Evolution - Fossils & DNA4.3.2Evidence for Evolution - Anatomy & Geography4.3.3IB Multiple Choice - Evidence for Evolution4.3.4Extended Response - DNA & Evolution4.3.5Populations4.3.6Mutations, Genetic Drift, & Gene Flow4.3.7Speciation4.3.8Rate of Speciation4.3.9Allopatric & Sympatric Speciation
4.4

Conservation of Biodiversity

4.4.1Coming Soon!
5

Form & Function - Molecules

5.1

Carbohydrates & Lipids

5.1.1Monosaccharides5.1.2Disaccharides & Polysaccharides5.1.3Triglycerides & Phospholipids5.1.4Cellulose5.1.5Starch & Glycogen
5.2

Proteins

5.2.1Structure & Functions of Proteins
6

Form & Function - Cells

6.1

Membranes & Membrane Transport

6.1.1Passive Movement Across Membranes6.1.2Active Movement Across Membranes6.1.3Endocytosis & Exocystosis6.1.4Cell Membrane Structure & Permeability
6.2

Organelles & Compartmentalization

6.2.1Eukaryotic Cells & Organelles6.2.2Subcellular Components & Organelles
6.3

Cell Specialization

6.3.1Cell Specialization
7

Form & Function - Organisms

7.1

Gas Exchange

7.1.1Lung Structure & Alveoli7.1.2Ventilation7.1.3Lung Disease7.1.4Lung Disease Data
7.2

Transport

7.2.1The Circulatory System7.2.2The Heart7.2.3Blood Vessels7.2.4Cardiovascular Disease7.2.5Xylem Structure7.2.6Cohesion-Tension Theory7.2.7Investigating Transpiration Rate7.2.8Phloem Structure7.2.9Translocation
7.3

Muscle & Motility

7.3.1Skeletal Muscle7.3.2Sliding Filament Theory7.3.3Contraction
8

Form & Function - Ecosystems

8.1

Species, Communities & Ecosytems

8.1.1Population Dynamics8.1.2Communities & Measuring Diversity8.1.3Relationships Between Populations8.1.4Overview of Ecosystems8.1.5Nutrient Cycles8.1.6Fertilisers8.1.7Eutrophication8.1.8Chi-Squared Test
8.2

Energy Flow

8.2.1Energy8.2.2Energy Flow8.2.3Biomass & Food Chains8.2.4Heterotrophs & Autotrophs
8.3

Carbon Cycle

8.3.1Carbon Cycle
8.4

Climate Change

8.4.1Carbon Dioxide8.4.2The Greenhouse Effect8.4.3Global Warming8.4.4Maintaining Biodiversity
9

Interaction & Interdependence - Molecules

9.1

Enzymes

9.1.1Enzymes9.1.2Factors Affecting Enzyme Activity9.1.3Enzyme-Controlled Reactions9.1.4End of Topic Test - Enzymes
9.2

Metabolism

9.2.1Molecules to Metabolism
9.3

Cell Respiration

9.3.1Glycolysis9.3.2Aerobic Respiration
9.4

Photosynthesis

9.4.1Light-Dependent Reaction9.4.2Light-Independent Reaction9.4.3End of Topic Test - Photosynthesis Reactions9.4.4Limiting Factors9.4.5Photosynthesis Experiments9.4.6End of Topic Test - Photosynthesis9.4.7End of Topic Test - Photosynthesis
10

Interaction & Interdependence - Cells

10.1

Chemical Signalling

10.1.1Coming Soon!
10.2

Neural Signalling

10.2.1Medical Application10.2.2Speed of Transmission10.2.3Synapses10.2.4End of Topic Test - Nervous Comm&Coord10.2.5Neuron Structure10.2.6Types of Synapse10.2.7End of Topic Test - Neurones & Action Potentials10.2.8Transmission of an Impulse10.2.9End of Topic Test - Synapses
10.3

Adaptation to Environment

10.3.1Coming Soon!
10.4

Ecological Niches

10.4.1Coming Soon!
11

Interaction & Interdependence - Organisms

11.1

Integration of Body Systems

11.1.1Plant Tropisms
11.2

Defence Against Disease

11.2.1Immune System11.2.2The Immune Response11.2.3Antibodies11.2.4Primary & Secondary Response11.2.5Vaccines11.2.6HIV11.2.7End of Topic Test - Immune System
12

Interaction & Interdependence - Ecosystems

12.1

Populations & Communities

12.1.1Coming Soon!
12.2

Transfers of Energy & Matter

12.2.1Coming Soon!
13

Continuity & Change - Molecules

13.1

DNA Replication

13.1.1DNA Replication
13.2

Protein Synthesis

13.2.1Protein Synthesis13.2.2Transcription & Translation13.2.3End of Topic Test - DNA, Genes & Protein Synthesis
13.3

Mutation & Gene Editing

13.3.1Genes13.3.2Mutations13.3.3DNA Technology13.3.4PCR & Gel Electrophoresis13.3.5Genetic Modification13.3.6Cloning
14

Continuity & Change - Cells

14.1

Gene Expression

14.1.1Introduction to Transcription & Protein Synthesis14.1.2Types of RNA14.1.3Transcription14.1.4RNA Processing in Eukaryotes14.1.5IB Multiple Choice - Transcription
14.2

Water Potential

14.2.1Controlling Blood Water Potential
15

Continuity & Change - Organisms

15.1

Inheritance

15.1.1Non-Nuclear Inheritance15.1.2Linked Genes15.1.3IB Multiple Choice - Non-Mendelian Genetics15.1.4Extended Response - Inheritance15.1.5Introduction to Non-Mendelian Inheritance15.1.6Chi-Squared Test15.1.7End of Topic Quiz - Inheritance15.1.8Sex-Linked Genes15.1.9Grade 4-5 (Scientific Practices) - Inheritance
15.2

Homeostasis

15.2.1Overview of Homeostasis15.2.2Blood Glucose Concentration15.2.3Controlling Blood Glucose Concentration15.2.4End of Topic Test - Blood Glucose15.2.5Type I & Type II Diabetes15.2.6Human Reproductive Systems15.2.7Hormonal Control of the Menstrual Cycle15.2.8Kidneys & Osmoregulation
16

Continuity & Change - Ecosystems

16.1

Natural Selection

16.1.1Natural Selection
16.2

Stability & Change

16.2.1Coming Soon!
16.3

Climate Change

16.3.1Carbon Dioxide16.3.2The Greenhouse Effect16.3.3Global Warming16.3.4Maintaining Biodiversity

Practice questions on Introduction to Cells

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  1. 1
    The presence of which of the following differentiates a eukaryotic cell from a prokaryotic cell? Multiple choice
  2. 2
    Which of these is NOT one of the three basic types of cells? Multiple choice
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Origins - Endosymbiosis

Cell Size & Surface Area