AQA A-level Biology - Topic 2A - Eukaryotic cells and organelles
How are fungal cells different to plant cells?
Their cell walls are made of chitin, not cellulose. They don't have chloroplasts because they don't need to photosynthesise
Describe eukaryotic cells
They are complex cells and include all animal and plant cells, as well as all algae and fungi cells.
Describe mitochondrion. Outline the functions.
They are usually oval-shaped and have a double membrane. The inner membrane is folded to form structures called cristae. Inside is the matrix, which contains enzymes involved in respiration. The site of aerobic respiration, where ATP is produced. They are found in large numbers in cells that are very active and require a lot of energy.
How are algal cells similar to plant cells?
They have the same organelles.
What are specialised cells grouped together to form?
Tissues
Name the organelles you might find in an animal cell
1)Plasma cell surface membrane 2)Rough/smooth endoplasmic reticulum 3)nucleus (nucleolus) 4)lysosome 5)ribosome 6)Golgi apparatus 7)cytoplasm 8)mitochondrion
Name the organelles you might find in a plant cell
1)Plasma cell surface membrane 2)cellulose wall 3)chloroplast 4)rough/smooth endoplasmic reticulum 5)mitochondrion 6)Golgi apparatus 7)vacuole 8)cytoplasm 9)nucleus 10) ribosome
How are epithelial cells in the small intestine specialised to absorb food efficiently?
1)The intestine walls have lots of villi, which increase surface area for absorption 2)The epithelial cells on the surface of the villi have folds in their cell-surface membrane called micro-villi, increasing SA even more. 3)They have lots of mitochondria to provide energy.
Name the components of the nucleus
1)nucleolus 2)nuclear envelope 3)nucleoplasm 4)nuclear pores 5)chromatin
What is a tissue?
A group of cells working together to perform a particular function. Different tissues work together to form organs, organs make up an organ system.
Describe the structure of the Golgi apparatus. Outline the functions.
A group of fluid-filled, membrane-bound, flattened sacs. Vesicles are often seen at the edges of the sacs. It processes and packages new lipids and proteins. It also makes lysosomes.
Describe the nucleus. Outline the functions.
A large organelle surrounded by a nuclear envelope which contains many pores. The nucleus contains chromosomes. The nucleus controls the cell's activities by controlling the transcription of DNA. The pores allow substances to move between the nucleus and the cytoplasm. The nucleolus makes ribosomes.
Describe the structure of the cell vacuole. Outline the functions.
A membrane-bound organelle found in the cytoplasm of plant cells. It contains cell-sap, a weak solution of sugar and salts. The surrounding membrane is called the tonoplast. Helps to maintain pressure and rigidity inside the cell. This stops the plants wilting. It is also involved in the isolation of unwanted chemicals inside the cell.
What is an organelle?
A part of a cell that plays a specific role.
Describe the structure of the cell wall. Outline the functions.
A rigid structure that surrounds cells in plants, algae and fungi. In plants and algae its mainly made from cellulose, but it in fungi it is made of chitin. It supports the cell and prevents them from changing shape.
Describe the structure of a lysosome. Outline the functions.
A round organelle surrounded by a membrane, with no clear internal structure. It's a type of Golgi vesicle. Contains digestive enzymes called lysozymes, that are kept separate from the cytoplasm by the membrane. They can be used to digest invading cells or the break down worn out components of the cell.
Describe the structure of a Golgi vesicle. Outline the functions.
A small fluid-filled sac in the cytoplasm, surrounded by a membrane, and produced by the Golgi apparatus. Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell via the cell surface membrane.
Describe the structure of chloroplasts. Outline the functions.
A small, flattened structure found in plant and algal cells. It is surrounded by a double membrane, and has membrane inside called thylakoid membranes. They are stacked up in some parts to form grana. Grana are linked together by lamellae. The site where photosynthesis takes place. Some parts happen in the grana, and other parts happen in the stroma. (thick fluid found in chloroplasts)
Describe the structure of the smooth endoplasmic reticulum. (SER) Outline the functions.
A system of membranes enclosing a fluid-filled space. The surface is completely smooth. Synthesises and processes lipids.
Describe the structure of the rough endoplasmic reticulum. (RER) Outline the functions.
A system of membranes enclosing a fluid-filled space. The surface is covered with ribosomes. They fold and process proteins that have been made at the ribosomes.
Describe the structure of a ribosome. Outline the functions.
A very small organelle that either floats free in the cytoplasm or is attached to the rough endoplasmic reticulum. It is made up of proteins and RNA, and is not surrounded by a membrane. It is the site where proteins are made.
What does it mean if a organism is eukaryotic?
It is a multi-cellular organism that is made up of eukaryotic cells.
Describe the cell surface plasma membrane. Outline the functions.
It is found on the inside of cells that also have a cell wall (plants), and is mainly made up of lipids and proteins. It controls the movement of substances in and out of the cell. It also has receptor molecules on it, to allow it to respond to chemicals like hormones.
