Cell Stucture - Set 2 Flashcards
Describe the structure and function of the endoplasmic reticulum (ER). Name the two types and their function.
Cisternae - Network of tubules and flattened sacs extends from cell membrane and connects to nuclear envelope.
Rough ER: many ribosomes attached for protein synthesis and transport.
Smooth ER: lipid synthesis
In what type of cells are the RER and the SER foun?
Both in animal and plant cells.
Describe the key 3 features of the RER.
- Surface covered in ribosomes
- formed from continuous fold of membrane continuous with a nuclear envelope.
- processed proteins made by the ribosomes.
Describe the two key features of the SER.
- does not have ribosomes on the surface - its function is different to the RER.
- Involved in the production of:
- lipids
- carbohydrates
- steroids
Describe the structure of the mitochondria. What shape are they usually?
- surrounded by a double membrane.
- folder inner membrane forms cristae - site of electron transport chain.
- Fluid Matrix = contains mitochondrial DNA, respiratory enzymes, lipids and fluids.
- They are usually oval-shaped.
Describe the function of the mitochondria. Where are they usually found?
Act as the site for ATP production in eukaryotes.
They are found in large numbers in cells that are very active and require a lot of energy.
Describe the structure of lysosomes.
Rough spherical sacs with no clear internal structures.
They are membrane bound and contain digestive enzymes.
What is the function of the lysosomes? How do the enzymes work?
Responsible for intercellular digestion of material taken up by endocytosis
The enzymes break down the material, faulty proteins are removed, and the waste material is exocytosed.
What is the structure of the cilia? Describe what the cross-section would look like.
Small hair- like structures found in 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 two microtubules in the middle. Known as the ‘9+2’ structure.
What is the function of the cilia?
The microtubules allow the cilia to move. This movement is used by the cell to move substance along the cell surface.
Describe the structure of the Golgi Apparatus. Where are the vesicles often seen?
Sacs of flattened sacs called cisternae, with associated vessels. Vesicles are often seen as the edges of these sacs.
Describe the role of the Golgi Apparatus.
- Vesicles modify and package proteins for export.
- Synthesise glycoproteins.
- Process and package new lipids.
- Also make lysosomes.
Describe the structure of ribosomes.
Small dense cylindrical shaped structures, made of equal portions of proteins and ribosomal RNA.
Describe the function of the ribosomes.
Act as the site of protein synthesis in the cell.
Where can ribosomes be found?
- Floating around in the cytoplasm.
- Attached to the RER.
What is the structure of the centriole? Where are the found?
Small hollow cylinders made of microtubules that are found in animal cells, but only some plant cells.
What is the function of the centrioles?
Involved with the separation of chromosomes during cell division.
What is the function of the vesicle?
A small fluid filled sac in the cytoplasm that is surrounded by a membrane.
What is the function of the vesicle? Where are they formed?
Transport substances in and out of the cell via the plasma membrane and between organelles.
Some vesicles are formed by the Golgi Apparatus or the endoplasmic reticulum, whilst others are formed at the cell’s surface.
What are the 3 components of the cytoskeleton?
- Microfilaments.
- Microtubules.
- Intermediate fibres.
What are the microfilaments made of, and what is their purpose?
- Made of the protein actin.
- Involved in cell movement and locomotion, such as crawling and muscle contraction.
What are the microtubules made off, what structure do they make, and what is their purpose?
- Made of protein Tubulin.
- Form a scaffold like structure throughout the cell.
- Form the main components of the mitotic spindle, used for cell division.
- Act as tracks for intracellular transport of vesicles and organelles.
What are the intermediate fibres, and what is their purpose?
- Maintain the position of organelles within the cell.
- Responsible for the mechanical strength of certain tissues, such as the skin and hair.
Why is the cytoskeleton important?
- provides mechanical support, via the microfilaments and microtubules.
- Aids transport within cells.
- Enables cell movement.
Describe the process of protein synthesis. (6)
- proteins are made at the ribosomes.
- Ribosomes on the RER make proteins that are excreted or attached to the cell membrane. The free ribosomes in the cytoplasm make proteins that stay in the cytoplasm.
- New proteins produced at the RER are folded and processed.
- Then transported from the RER to the Golgi Apparatus in vesicles.
- At the Golgi Apparatus, proteins under further processing.
- The protein enter more vesicles to be transported around the cell.
