1.3.3
Organelles of Eukaryotic Cells
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Cell-Surface Membranes and Cytoplasm
Eukaryotic cells have a cell-surface (plasma) membrane that separates the inside of the cell from its environment.

Structure of the plasma membrane
- The plasma membrane is made from a phospholipid bilayer.
- A phospholipid is a lipid molecule with glycerol, two fatty acid chains, and a phosphate-containing group.
- Plasma membranes have proteins and cholesterol embedded in them.
- These proteins can act as receptors. This means that the cell can respond to the external environment of the cell.

Function of the plasma membrane
- The plasma membrane controls the passage of organic molecules, ions, water, and oxygen into and out of the cell.
- Waste products (e.g. carbon dioxide and ammonia) leave the cell by passing through the plasma membrane.

Structure of the cytoplasm
- Cytoplasm is made up of organelles suspended in the gel-like cytosol.
- 70% of the cytoplasm is made up of water.
- The cytoplasm also contains proteins, sugars, ions and fatty acids.

Functions of the cytoplasm
- Many metabolic reactions take place in the cytoplasm.
- Different organelles perform specific functions within the cytoplasm.
- It is important to remember that organelles are parts of a cell.
- Organelles are NOT cells even though they often surrounded by membranes.
The Nucleus
The nucleus is a big organelle that contains the cell’s DNA. It is surrounded by a nuclear envelope.

Structure of the nuclear envelope
- The nuclear envelope is a double-membrane structure that has a number of pores.
- Both the inner and outer membranes of the nuclear envelope are phospholipid bilayers.

Function of the nuclear envelope
- The pores in the nuclear envelope control the passage of ions, molecules and RNA between the nucleoplasm and cytoplasm.

Structure of the nucleus
- The nucleoplasm is the semi-solid fluid inside the nucleus, where we find the chromatin and the nucleolus.
- In eukaryotes, the nucleus contains linear chromosomes that are made up of DNA.
- There is an area within the nucleus called the nucleolus (plural = nucleoli).

Function of the nucleus
- The nucleus controls the actions of the cell.
- DNA in the nucleus contains instructions for the synthesis of proteins.
- Ribosomal RNA is joined together with associated proteins in the nucleolus to assemble the ribosomal subunits.
Mitochondria and Chloroplasts
Mitochondria produce adenosine triphosphate (ATP) via aerobic respiration. Chloroplasts are plant cell organelles that carry out photosynthesis.

Structure of mitochondria
- Mitochondria are oval-shaped, double-membrane organelles that have their own ribosomes and DNA.
- Each membrane is a phospholipid bilayer embedded with proteins.
- The inner layer of the membrane has folds called cristae.
- The area surrounded by the folds is called the mitochondrial matrix.
- The mitochondrial matrix contains enzymes used for respiration.

Function of mitochondria
- Mitochondria make ATP via aerobic respiration.
- Muscle cells have a very high concentration of mitochondria because they are highly active and need a lot of energy to keep the body moving.

Structure of chloroplasts
- Chloroplasts have their own DNA, ribosomes and have inner and outer membranes.
- The space enclosed by the inner membrane contains a set of interconnected and stacked fluid-filled membrane sacs called thylakoids.
- Each stack of thylakoids is called a granum (plural = grana).
- Grana are linked by lamellae.
- Lamellae are flat, thin parts of thylakoid membrane.
- The fluid enclosed by the inner membrane that surrounds the grana is called the stroma.

Function of chloroplasts
- Photosynthesis is the series of reactions that use carbon dioxide, water and light energy to make glucose and oxygen.
- This process happens in chloroplasts and allows plants to make their own food (e.g. sugars).
- Chloroplasts are found in plant and algal cells but not in animal or fungal cells.
1Principles of Science I
1.1Structure & Bonding
1.1.1Atomic Model1.1.2Electron Shells, Sub-Shells & Orbitals1.1.3Ionic Bonding1.1.4Representing Ionic Bonds1.1.5Covalent Bonding1.1.6Representing Covalent Bonds1.1.7Metallic Bonding1.1.8Intermolecular Forces1.1.9Intermolecular Forces 21.1.10End of Topic Test - Bonding1.1.11Relative Masses1.1.12The Mole1.1.13Molar Calculations1.1.14Molar Calculations 21.1.15Empirical & Molecular Formulae1.1.16Balanced Equations1.1.17Percentage Yield1.1.18End of Topic Test - Amount of Substance
1.2Properties of Substances
1.2.1The Periodic Table1.2.2Ionisation Energy1.2.3Factors Affecting Ionisation Energies1.2.4Trends of Ionisation1.2.5Trends in the Periodic Table1.2.6Polarity1.2.7Metals & Non-Metals1.2.8Alkali Metals1.2.9Alkaline Earth Metals1.2.10Reactivity of Alkaline Earth Metals1.2.11Redox1.2.12Transition Metals1.2.13Redox Reactions of Transition Metals
1.3Cell Structure & Function
1.4Cell Specialisation
1.5Tissue Structure & Function
1.5.1Human Gas Exchange1.5.2Blood Vessels1.5.3Atherosclerosis1.5.4Skeletal Muscle1.5.5Slow & Fast Twitch Fibres1.5.6Neurones1.5.7Speed of Transmission1.5.8Action Potentials1.5.9End of Topic Test - Neurones & Action Potentials1.5.10Synapses1.5.11Types of Synapse1.5.12Medical Application1.5.13End of Topic Test - Synapses1.5.14Chemical Brain Imbalances1.5.15Effect of Drugs on the Brain
1.6Working with Waves
1.7Waves in Communication
2Practical Scientific Procedures and Techniques
3Science Investigation Skills
3.1Scientific Processes
3.2Data Handling & Analysis
3.3Enzymes in Action
3.4Diffusion
3.5Plants & Their Environment
3.6Energy Content in Fuels
4Principles of Science II
4.1Extracting Elements
4.2Relating Properties to use of Substances
4.3Organic Chemistry
4.4Energy Changes in Industry
4.5The Circulatory System
4.5.1The Circulatory System4.5.2Blood Vessels4.5.3Blood Transfusion & the ABO Rhesus System4.5.4The Heart4.5.5The Cardiac Cycle4.5.6Cardiac Output4.5.7Coordination of Heart Action4.5.8Heart Dissection4.5.9Controlling Heart Rate4.5.10Electrocardiograms4.5.11Cardiovascular Disease4.5.12Investigating Heart Rates
4.6Ventilation & Gas Exchange
4.7Urinary System
4.9Thermal Physics
4.9.1Power & Efficiency4.9.2Work & Energy4.9.3Conservation of Energy4.9.4Pressure4.9.5First Law of Thermodynamics4.9.6Second Law of Thermodynamics4.9.7Heat Engines, Heat Pumps & Refrigerators4.9.8Non-Flow Processes4.9.9p-V Diagrams4.9.10Ideal Gases4.9.11Ideal Gases 24.9.12Thermal Energy Transfer4.9.13Thermal Energy Transfer Experiments
4.10Materials
5Contemporary Issues in Science
5.1Contemporary Issues in Science
5.2Analysing Scientific Information
Jump to other topics
1Principles of Science I
1.1Structure & Bonding
1.1.1Atomic Model1.1.2Electron Shells, Sub-Shells & Orbitals1.1.3Ionic Bonding1.1.4Representing Ionic Bonds1.1.5Covalent Bonding1.1.6Representing Covalent Bonds1.1.7Metallic Bonding1.1.8Intermolecular Forces1.1.9Intermolecular Forces 21.1.10End of Topic Test - Bonding1.1.11Relative Masses1.1.12The Mole1.1.13Molar Calculations1.1.14Molar Calculations 21.1.15Empirical & Molecular Formulae1.1.16Balanced Equations1.1.17Percentage Yield1.1.18End of Topic Test - Amount of Substance
1.2Properties of Substances
1.2.1The Periodic Table1.2.2Ionisation Energy1.2.3Factors Affecting Ionisation Energies1.2.4Trends of Ionisation1.2.5Trends in the Periodic Table1.2.6Polarity1.2.7Metals & Non-Metals1.2.8Alkali Metals1.2.9Alkaline Earth Metals1.2.10Reactivity of Alkaline Earth Metals1.2.11Redox1.2.12Transition Metals1.2.13Redox Reactions of Transition Metals
1.3Cell Structure & Function
1.4Cell Specialisation
1.5Tissue Structure & Function
1.5.1Human Gas Exchange1.5.2Blood Vessels1.5.3Atherosclerosis1.5.4Skeletal Muscle1.5.5Slow & Fast Twitch Fibres1.5.6Neurones1.5.7Speed of Transmission1.5.8Action Potentials1.5.9End of Topic Test - Neurones & Action Potentials1.5.10Synapses1.5.11Types of Synapse1.5.12Medical Application1.5.13End of Topic Test - Synapses1.5.14Chemical Brain Imbalances1.5.15Effect of Drugs on the Brain
1.6Working with Waves
1.7Waves in Communication
2Practical Scientific Procedures and Techniques
3Science Investigation Skills
3.1Scientific Processes
3.2Data Handling & Analysis
3.3Enzymes in Action
3.4Diffusion
3.5Plants & Their Environment
3.6Energy Content in Fuels
4Principles of Science II
4.1Extracting Elements
4.2Relating Properties to use of Substances
4.3Organic Chemistry
4.4Energy Changes in Industry
4.5The Circulatory System
4.5.1The Circulatory System4.5.2Blood Vessels4.5.3Blood Transfusion & the ABO Rhesus System4.5.4The Heart4.5.5The Cardiac Cycle4.5.6Cardiac Output4.5.7Coordination of Heart Action4.5.8Heart Dissection4.5.9Controlling Heart Rate4.5.10Electrocardiograms4.5.11Cardiovascular Disease4.5.12Investigating Heart Rates
4.6Ventilation & Gas Exchange
4.7Urinary System
4.9Thermal Physics
4.9.1Power & Efficiency4.9.2Work & Energy4.9.3Conservation of Energy4.9.4Pressure4.9.5First Law of Thermodynamics4.9.6Second Law of Thermodynamics4.9.7Heat Engines, Heat Pumps & Refrigerators4.9.8Non-Flow Processes4.9.9p-V Diagrams4.9.10Ideal Gases4.9.11Ideal Gases 24.9.12Thermal Energy Transfer4.9.13Thermal Energy Transfer Experiments
4.10Materials
5Contemporary Issues in Science
5.1Contemporary Issues in Science
5.2Analysing Scientific Information
Practice questions on Organelles of Eukaryotic Cells
Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.
- 1Components of a phospholipid:Fill in the list
- 2
- 3What type of molecule are cell-surface membranes made up of?Multiple choice
- 4Which of the following is found in the nucleoplasm?Multiple choice
- 5What shape are eukaryotic chromosomes?Multiple choice
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