Core Concepts: Cell Structure and Organisation Flashcards
What is the function of the nucleus
Contains the DNA which codes for protein synthesis
What is the function of the nuclear envelope
Separates the DNA from the cytoplasm
What is the function of the nuclear pore
Allows passage of molecules in and out on the nucleus
What is the function of the nucleolus
Synthesis of rRNA to make ribosomes
What is the structure of ribosomes
- 2 subunits made from ribosomal RNA (rRNA) and protein:
- Large subunit
- Small subunit - Can be free or attached to rough endoplasmic reticulum (RER)
What is the function of ribosomes
Protein synthesis
What is the structure of mitochondria
- Cylindrical and 1-10 um in diameter
- Double membrane separated by the fluid-filled, inter membrane space
- Inner membrane folded to form cristae
- The interior is called the matrix and contains enzymes
- contains DNA and ribosomes (70s)
What is the function of mitochondria
- Site of aerobic respiration, synthesises ATP
- Cristae increases surface area on which part of the respiratory process takes place
- Cells with high metabolic activity contain many mitochondria
What is the RER
Rough Endoplasmic Reticulum
What is the structure of RER
- A series of membrane, which enclose flattened sacs called cisternae
- Continuous with the nuclear membrane
- Has ribosomes attached
What is the function of RER?
Transports proteins which are synthesised by the ribosomes attached
What is the structure of smooth endoplasmic reticulum
- Forms a system of flattened sacs (cisternae) which are continuous with the nuclear membrane
- May link to the Golgi apparatus
- Has NO ribosomes attached
What is the function of smooth endoplasmic reticulum
The synthesis and transport of lipids
What is the structure of golgi body
- flattened sacs of membrane called cisternae
- Surrounded by vesicles
What is the function of golgi body
- Chemically modifies proteins
- Produces lysosomes
- Produces glycoproteins
- Packages proteins for secretion out of the cell
What is the structure of vesicles
Small membrane bound organelle
What is the function of vesicles
Act as a contractile vacuole to maintain osmotic pressure
What is the the structure of vacuoles
Large membrane bound organelle surrounded by a tonoplast
What is the function of vacuoles
- Storage of ions and organic molecules (e.g. proteins)
- Maintaining osmotic pressure
What is the structure of centrioles
Two hollow cylinders positioned at right angles to one another
What is the function of centrioles
Used in spindle formation (microtubles) in cell division
What is the structure of lysosomes
- Small vacuoles formed when small portions of the Golgi body are pinched off
- Contain and isolate digestive enzymes
What is the function of lysosomes
- Release digestive enzymes and destroy organelles
- Digestion of material which has been taken into the cell
- lysosomes isolate the potentially harmful enzymes from the rest of the cell
What is the structure of chloroplast
- Have a double membrane
- The interior is made up of a fluid called stroma containing:
- ribosomes
- lipids
- circular DNA
- starch granules. - There are thylakoids - flattened sacs. these form stacks which are called granum. Each granum consists of between 2-100 thylakoids. Between the grana the thylakoids form lamellae
What is the function of chloroplasts
- Site of photosynthesis
- The thylakoids contain photosynthetic pigments such as chlorophyll
What is the structure of a cellulose cell wall
Made of cellulose microfibrils in a polysaccharide matrix
What is the function of a cellulose cell wall
- To provide mechanical strength and support
- Freely permeable to water
What is the structure of plasmodesmata
A narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells
What is the function of plasmodesmata
- Exchange of large organic materials via cytoplasmic streaming
- Allows communication between adjacent cells
What is the theory that describes the origin of chloroplasts and mitochondria
Endosymbiotic theory