2.1.2 Cell Structure - (Organelles) Flashcards
What is the structure of plasma membrane?
> It is the membrane found on the surface of animal cells and just inside the cell wall of plant cells and prokaryotic cells.
Its mainly made of lipids
Function of a cell surface membrane
> It regulates the movement of substances in and out of the cell
It has receptor molecules which allow it to respond to chemicals such as hormones
What is the structure of cell wall?
A rigid structure that surrounds plant cells, mainly made of carbohydrate cellulose
What is the function of a cell wall?
> Provide strength and support
Maintain cell shape
Are permeable so allow solutions to pass through
What is the structure of nucleus?
A large organelle surrounded by a nuclear envelope with nuclear pores and contains a nucleolus and chromatin (which is made from DNA and proteins)
Role of a Nucleus
> The nucleus control the cell activity (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
What is the structure of a Lysosome?
> These are formed from the Golgi apparatus
> Its a round organelle surrounded by a membrane, with no clear internal structure
Role of a Lysosome?
Contains digestive enzymes, which are kept separate from the cytoplasm by the surrounding membrane, and can be used to digest invading cells or to break down work out components of the cell
What is the structure of a Ribosome?
> A very small organelle that either floats free in the cytoplasm or is attached to the RER
Its made up of proteins and RNA in the nucleolus
Its not surrounded by a membrane
Role of a Ribosome?
The site where proteins are made
What is the structure of a RER?
> A system of membranes enclosing a fluid - filled space.
The surface is covered in ribosomes
They have large surface are for protein synthesis
Role of RER
Folds and processes proteins that have been made at the ribosomes
What is the structure of a SER?
A system of membranes enclosing a fluid - filled space. No ribosomes
Role of SER
Its got enzymes which that catalyse reactions involved with lipid metabolism, such as Synthesising and processing lipids
What is the structure of a Vesicle?
> Its a small, fluid-filled sac in the cytoplasm surrounded by a membrane
Some are formed by the Golgi apparatus or the endoplasmic reticulum, while others are formed at the cell surface
Role of a Vesicle
> Transports substances in and out of the cell (via the plasma membrane) and between organelles where fusion occurs
What is the structure of a Golgi Apparatus?
An organelle that contains membrane bound, flattened sacs with vesicles on the outside
Role of the Golgi apparatus
> Processes and packages new lipids and proteins
> Makes lysosomes
What is the structure of mitochondria
> An oval shaped organelle with a double membrane - the inner one is folded to form structures called Cristae. Inside is the matrix, which contains enzymes involved in respiration.
They are self-replicating, so more can be made if the cell’s energy needs increase
The outer membrane controls the flow of materials in and out of the mitochondria
Role of mitochondria
> The site of aerobic respiration, where ATP is produced.
> Mitochondria are found in large number in cells that are very active and require a lot of energy
What are cristae?
extensions of the inner membrane which increases the surface area for the attachment of enzymes
What is the matrix?
the matrix is found inside the mitochondria and contains, lipids, trace DNA along with enzymes for respiration
What is the structure of Chloroplast
A small, flattened structure found in plant cells. Its surrounded by a double membrane, and also has membranes inside called thylakoid membranes. These membranes are stacked up in some parts of the chloroplast to form grant. Grant are linked together by lamellae - thin, flat pieces of thylakoid membrane.
Role of Chloroplasts
Place of photosynthesis - some parts happen in the grand (stacked up membranes), and other parts happen in the storm (a thick fluid found in the chloroplasts)
What is the structure of Centriole
> Small, hollow cylinders made from microtubules. They are found in all animal cells but only some plant cells
Microtubules are made of Tubulin protein subunits
Role of Centriole
They are involved in the separation of chromosomes during cell division
What is the structure of Cilia
They are small hair-like structures found on the surface membrane of some animal cells. In cross-section, they have an outer membrane and a ring of nine pairs of protein microtubules inside, with a single pair of microtubules in the middle.
Role of Cilia
The microtubules in the cillia allow the cilia to move and this movement is used by the cell to move substances along the cell surface
What is the structure of a Flagellum?
> They are like cillia but longer.
They stick out from the cell surface and are surrounded by the plasma membrane
They have 9 microtubules in a ring and two in the centre
Role of flagellum
the microtubules contract to make the flagellum move and the flagella are used as outbouard motors to propel cells forward (e.g. when a sperm cell swims)
