A1. Eukaryotic Cells and Organelles Flashcards
Plant cells
Plant cells have the same organelles as animal cells, but with a few added extras: (3 things)
- a cellulose cell wall with plasmodesmata (‘channels’ for exchanging substances between adjacent cells),
- a vacuole (fluid-filled compartment),
- and of course good old chloroplasts (the organelles involved in photosynthesis).
Algal cells
Algae carry out photosynthesis, like plants, but unlike plants they can be unicellular (e.g. Chlorella) or multicellular (e.g. seaweed).
Algal cells are a lot like plant cells they have all the same organelles, including a cellulose cell wall and chloroplasts. However, the chloroplasts in many algal cells are a different shape and size to plant chloroplasts. For example, some algae have one large chloroplast rather than several smaller chloroplasts.
Algae carry out photosynthesis, like plants, but unlike plants they can be unicellular (e.g. Chlorella) or multicellular (e.g. seaweed).
Algal cells are a lot like plant cells they have all the same organelles, including a cellulose cell wall and chloroplasts. However, the chloroplasts in many algal cells are a different shape and size to plant chloroplasts. For example, some algae have one large chloroplast rather than several smaller chloroplasts.
Fungal cells
Fungi can also be multicellular (e.g, mushrooms) or unicellular (e.g. yeast). Fungal cells (Figure 5) are also a lot like plant cells, but with two key differences:
- their cell walls are made of chitin, not cellulose.
- they don’t have chloroplasts (because they don’t photosynthesise).
Cell-surface membrane (Also called the plasma membrane) (2D, 2F)
Description
- The membrane found on the surface of animal cells and just inside the cell wall of other cells.
- It’s made mainly of lipids and protein.
Function
- Regulates the movement of substances into and out of the cell.
- It also has receptor molecules on it, which allow it to respond to chemicals like hormones.
Nucleus (2D, 3F)
Description
- A large organelle surrounded by a nuclear envelope (double membrane), which contains many pores.
- The nucleus contains chromosomes (which are made from protein-bound linear DNA) and one or more structure(s) called a nucleolus.
Function
- The nucleus controls the cell’s activities (by controlling the transcription of DNA). DNA contains instructions to make proteins.
- The pores allow substances (e.g. RNA) to move between the nucleus and the cytoplasm.
- The nucleolus makes ribosomes
Mitochondrion (2D, 3F)
Description
- They have a double membrane - the inner one is folded to form structures called cristae.
- Inside is the matrix, which contains enzymes involved in respiration.
Function
- The site of aerobic respiration.
- Aerobic respiration produces ATP - a common energy source in the cell.
- Mitochondria are found in large numbers in cells that are very active and require a lot of energy.
Chloroplast (5D, 2F)
Description
- A small, flattened structure found in plant cells and algal cells.
- It’s surrounded by a double membrane
- Granum also has membranes inside called thylakoid membranes.
- These membranes are stacked up in some parts of the chloroplast to form grana.
- Grana are linked together by lamellae - thin, flat pieces of thylakoid membrane.
Function
- The site where photosynthesis takes place.
- Some parts of photosynthesis happen in the grana, and other parts happen in the stroma (a thick fluid found in chloroplasts).
Golgi apparatus (1D, 2F)
Description
- A group of fluid-filled membrane-bound flattened sacs. Vesicles are often seen at the edges of the sacs.
Function
- It processes and packages new lipids and proteins.
- It also makes lysosomes
Golgi vesicle (1D, 1F)
Description
- A small fluid-filled sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus.
Function
- Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell (via the cell-surface membrane).
Lysosome (1D, 2F)
Description
- A round organelle surrounded by a membrane, with no clear internal structure.
Function
- Contains hydrolytic enzymes. These are kept separate from the cytoplasm by the surrounding membrane
- They can be used to digest invading cells or to break down worn out components of the cell.
Ribosome (3D, 1F)
Description
- A very small organelle that floats free in the cytoplasm or is attached to the rough endoplasmic reticulum.
- It’s made up of proteins and RNA.
Function
- The site where proteins are made.
Rough endoplasmic reticulum (RER) (1D, 1F)
Description
- A system of membranes enclosing a fluid-filled space. The surface is covered with ribosomes.
Function
- Folds and processes proteins that have been made at the ribosomes.
Smooth endoplasmic reticulum (SER) (1D, 1F)
Description
- Similar to rough endoplasmic reticulum, but with no ribosomes.
Function
Synthesises and processes lipids.
Cell wall (2D, 1F)
Description
- A rigid structure that surrounds cells in plants, algae and fungi. In plants and algae it’s made mainly of the carbohydrate cellulose.
- In fungi, it’s made of chitin.
Function
- Supports cells and prevents them from changing shape.
Cell vacuole (plants) (2D, 3F)
Description
- A membrane-bound organelle found in the cytoplasm.
- It contains cell sap - a weak solution of sugar and salts.
- The surrounding membrane is called the tonoplast.
Function
- Helps to maintain pressure inside the cell and keep the cell rigid.
- This stops plants wilting.
- It’s also involved in the isolation of unwanted chemicals inside the cell.
