cells

Cytoplasm/Cytosol

• The cytoplasm/cytosol is the solution contained by the cell membrane.

• It contains enzymes for glycolysis/(part of) respiration and other metabolic reactions, together with sugars, salts, amino acids, nucleotides, and everything else needed for the cell to function

Organelles Found in Both Animal and Plant Cells

Nucleus

• The nucleus is the largest organelle in the cell.

• Surrounded by a nuclear envelope/double membrane containing nuclear pores/large holes containing proteins that control the exit of substances such as RNA and ribosomes from the nucleus.

• Contains nearly all of the cell’s genetic material, including chromosomes/chromatin.

• Contains the nucleolus, which synthesises/creates ribonucleic acid (RNA) and ribosomes/ribosomal subunits and is also the site of mRNA, tRNA, and rRNA synthesis.

• Directs all that goes on in the cell.

Endoplasmic Reticulum (ER)

• The endoplasmic reticulum consists of a series of membrane channels/lamellae and includes:

  • Rough Endoplasmic Reticulum (RER):

    • Studded with numerous ribosomes (giving it a rough appearance).

    • Site of protein synthesis and transport.

  • Smooth Endoplasmic Reticulum (SER):

    • Free of ribosomes.

    • Synthesises and transports lipids.

    • Involved in the detoxification of drugs and the storage of calcium ions.

Golgi Apparatus/Body

• The Golgi apparatus/body is a series of flattened membrane sacs/vesicles formed from the ER.

• Responsible for the modification of proteins received from the ER.

• Transports proteins from the RER to the cell membrane for export.

Mitochondria

• Mitochondria are double-membrane-bound structures that are the sites of cellular respiration.

• The inner membrane is folded extensively to form cristae, which surround the mitochondrial matrix.

• Produces ATP during aerobic respiration.

Lysosomes

• Lysosomes are small, single-membrane-bound organelles formed from the RER.

• Contain digestive enzymes used to break down unwanted chemicals, toxins, organelles, and even whole cells for recycling.

Ribosomes

• Ribosomes are the smallest and most numerous of the cell organelles, composed of protein and RNA.

• Manufactured in the nucleolus of the nucleus.

• Found on the rough ER, in the cytoplasm, and in mitochondria and chloroplasts.

• Sites of protein synthesis, where mRNA is translated into proteins.

Peroxisomes

• Peroxisomes in the cytoplasm contain catalase for breaking down fatty acids, lipid metabolism, and (chemical) detoxification, such as the breakdown of hydrogen peroxide.

Vesicles and Vacuoles

• Vesicles: Membrane-bound sacs used for storing or transporting substances.

• Vacuoles: Larger vesicles formed by the joining of smaller vesicles.

  • Contain water and dissolved compounds.

  • In plant cells, large central vacuoles maintain turgor pressure.

Organelles Found in Animal Cells Only

Centrioles

• Microtubules found near the nucleus.

• Important in cell division, moving chromosomes by forming spindle fibres.

Organelles Found in Plant Cells Only

Chloroplasts

• Chloroplasts are the sites of photosynthesis.

• Double-membrane structures where the inner membrane is folded into thylakoids, stacked into grana.

• Thylakoids contain chlorophyll used in photosynthesis.

Cell Wall

• A thick layer of polysaccharide/cellulose outside the cell membrane.

• Provides protection, strength, and rigidity to the cell.

Large Central Vacuole

• A membrane-bound sac containing water or dilute solutions of salts and other solutes.

• Important in maintaining turgor pressure.

Membranes

Plasma/Cell Membrane

• A thin, flexible layer around the outside of all cells.

• Composed mainly of phospholipids and proteins.

• Separates the contents of the cell from the outside environment and controls the entry and exit of materials.

Organelles Found in Animal Cells Only

Centrioles

• Centrioles are microtubules found next to the nucleus of animal cells and some protoctists.

• Centrioles are important in cell division and move chromosomes around by forming fibres called the spindle

Organelles Found in Plant Cells Only

Chloroplasts

• Chloroplasts are responsible for photosynthesis.

• Chloroplasts contain two (fluid-separated) membranes, and the inner membrane is folded into a network of flattened sacs called thylakoids that are stacked into grana/a granum.

• The thylakoids contain chlorophyll, which is used in the process of photosynthesis.

Large (Central) Vacuole

• Found in plant cells, these vacuoles are important in maintaining turgor pressure.

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Nucleus

• The largest organelle in the cell, surrounded by a double membrane called the nuclear envelope, containing nuclear pores.

• Controls cellular activities by housing genetic material (DNA).

• Contains the nucleolus, which is responsible for synthesizing ribosomal RNA (rRNA) and ribosome subunits.

Cytoplasm/Cytosol

• A solution enclosed by the cell membrane, containing enzymes for glycolysis and other metabolic reactions.

• Acts as a medium for the suspension of organelles and supports biochemical processes.

Ribosomes

• Smallest and most numerous organelles, composed of RNA and protein.

• Sites of protein synthesis, translating mRNA into polypeptides.

• Found on the rough endoplasmic reticulum (RER) and freely in the cytoplasm.

Endoplasmic Reticulum (ER)

• Rough ER (RER): Studded with ribosomes; involved in protein synthesis and transport.

• Smooth ER (SER): Lacks ribosomes; synthesizes lipids, detoxifies drugs, and stores calcium ions.

Golgi Apparatus

• A stack of flattened membrane sacs that modify, sort, and package proteins from the RER.

• Transports proteins to the cell membrane or secretes them via vesicles.

Mitochondria

• Double-membrane-bound organelles, with the inner membrane folded into cristae to increase surface area for reactions.

• Sites of aerobic respiration, producing ATP for cellular energy.

Lysosomes

• Membrane-bound sacs containing digestive enzymes.

• Break down unwanted chemicals, organelles, and materials engulfed by the cell, recycling components for reuse.

Peroxisomes

• Contain enzymes like catalase for breaking down hydrogen peroxide, lipid metabolism, and chemical detoxification.

Chloroplasts (Plant Cells Only)

• Sites of photosynthesis; contain chlorophyll in thylakoids, which are stacked into grana.

• Convert light energy into chemical energy (glucose).

Vacuoles

• Large central vacuole in plant cells maintains turgor pressure and stores nutrients or waste.

• Vacuoles in animal cells are smaller and mainly used for storage or transport.

Centrioles (Animal Cells Only)

• Microtubule structures located near the nucleus.

• Essential in cell division, forming spindle fibres that separate chromosomes.

Cell Membrane

• Composed of a phospholipid bilayer with embedded proteins.

• Regulates the entry and exit of substances, maintaining homeostasis.

Cell Wall (Plant Cells Only)

• A rigid structure made of cellulose, located outside the plasma membrane.

• Provides support, strength, and protection to plant cells