How does each organelle contribute to the life of the cell?
Describe the structure and function of the major eukaryotic cell organelles
The structure and roles of the nucleus, mitochondria, ER, Golgi, ribosomes, chloroplasts, vacuole and lysosomes, including how they cooperate to make and export proteins.
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What this dot point is asking
You need to describe the structure and function of the main organelles and explain how several of them work together, especially in producing and exporting proteins.
The major organelles
Nucleus
The nucleus is surrounded by a nuclear membrane with pores. It contains the cell's DNA as chromosomes. It controls the cell's activities by controlling gene expression and is the site of transcription. The nucleolus inside it makes ribosomes.
Mitochondria
Mitochondria are the site of aerobic cellular respiration, releasing energy as ATP from glucose. They have a double membrane; the inner membrane is folded into cristae, increasing surface area for the reactions. Cells with high energy demands, such as muscle cells, contain many mitochondria.
Ribosomes
Ribosomes are the site of protein synthesis (translation). They may be free in the cytoplasm or attached to the rough endoplasmic reticulum. They are not membrane-bound.
Endoplasmic reticulum
The endoplasmic reticulum (ER) is a network of membranes. Rough ER is studded with ribosomes and processes and transports proteins. Smooth ER has no ribosomes and makes lipids and helps detoxify substances.
Golgi apparatus
The Golgi apparatus is a stack of flattened membrane sacs. It modifies, sorts and packages proteins and other molecules into vesicles for secretion or delivery elsewhere in the cell.
Chloroplasts
Chloroplasts are found in plant cells and some protists. They contain the green pigment chlorophyll and are the site of photosynthesis. Their internal membranes (thylakoids stacked into grana) provide a large surface area for capturing light.
Vacuole
In plant cells a large central vacuole stores water, sugars and waste and maintains turgor pressure, keeping the cell firm and supporting the plant.
Lysosomes
Lysosomes contain digestive enzymes that break down worn-out organelles, food particles and invading material.
Cell membrane and cell wall
The cell membrane controls movement of substances in and out. Plant cells also have a rigid cellulose cell wall for support and shape.
Exam-style practice questions
Practice questions written in the style of SACE Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
2018 SACE Stage 21 marksWhich one of the following combinations matches an organelle with one of its structural features and one of its functions: ribosome / single membrane / RNA synthesis; Golgi body / flattened membrane sacs / protein synthesis; lysosome / membrane-bound / breakdown of proteins; or nucleolus / double membrane with pores / ribosome formation?Show worked answer →
The correct combination is lysosome / membrane-bound / breakdown of proteins. A lysosome is a single membrane-bound vesicle containing digestive enzymes that break down proteins and other molecules. The others are wrong: ribosomes have no membrane and carry out protein synthesis (not RNA synthesis), the Golgi body modifies and packages proteins rather than synthesising them, and the nucleolus (inside the nucleus) makes ribosome subunits but does not have a double membrane with pores (that describes the nuclear envelope).
2019 SACE Stage 21 marksROCK regulates a component of the cytoskeleton called actin filaments. State one function of the cytoskeleton.Show worked answer →
Any one valid function earns the mark: providing structural support and maintaining cell shape, enabling cell movement, allowing movement or transport of organelles within the cell, or anchoring organelles in place. (In the source question, the dynamic actin filaments also let dendritic spines change shape.)
2019 SACE Stage 21 marksWhich one of the following combinations of the presence or absence of cell structures in animal and plant cells is correct: vacuole present in both; cell wall present in both; lysosome absent in animal and present in plant; or mitochondrion present in animal and absent in plant?Show worked answer →
The correct combination is vacuole present in both. Both animal and plant cells contain vacuoles, though the plant cell typically has one large central vacuole. The others are wrong: a cell wall is present in plant cells but absent in animal cells, lysosomes are typically found in animal cells, and mitochondria are present in both animal and plant cells.