2.1.2: Organelles Flashcards
What is the structure of the Nucleus?
Nuclear enevelope - double membrane
Nuclear pores
Nucleolus - Smaller sphere inside which is the site of rRNA production and makes ribosomes
Chromosomes - protein head, linear DNA
What is the function of the nucleus?
- Site of DNA replication and transcription (making mRNA)
- Contains the genetic code for each cell
- Site of ribosome synthesis
What is the structure for the flagella?
Whip like structure
What is the function of the flagella?
For mobility, and sometimes as a sensory organelle for chemical stimuli
What is the structure of the cilia?
Hairlike projections out of cells
What is the function of the cilia?
- Can be mobile or stationary
- Mobile cilia help move substances in a sweeping motion
- Stationary cilia are important in the sensory organs such as the nose
What is the structure of the centrioles?
- Made of microtubules
- Occur in pairs to form a centrosome
What is the function of centrioles?
Involved in the production of spindle fibre and organisation of chromosomes in cell division
What is the structure of the cytoskeleton?
A network of fibres found within the cytoplasm all over a cell
Consists of microfilaments, microtubules and intermediate fibres
What is the function of the cytoskeleton?
- Provides mechanical strength to cells, helps maintain shape and stability of a cell. Many organelles are bound to the cytoskeleton
- Microfilaments are respsonsible for cell movement
- Microtubules are responsible for creating a scaffold-like structure
What is the structure for the endoplasmic reticulum
- Rough and smooth ER both have folded membranes called cisternae
- RER have ribosomes on the cisternae
What is the function of the endoplasmic reticulum?
- RER - protein synthesis (site of)
- SER - it is where lipids and carbohydrates are created and stored
What is the structure of the golgi body and vesicles?
- Folded membranes making cisternae
- Secretory vesicles pinch off from the cisternae
What is the function of golgi body and vesicles?
- Modifies proteins and lipids before packaging them into Golgi vesicles
- The vesicles then transport the proteins and lipids to their required destination
- Proteins that go through the Golgi apparatus are usually exported (e.g. hormones such as insulin), put into lysosomes (such as hydrolytic enzymes) or delivered to membrane-bound organelles
What is the structure of lysosomes?
Bags of digestive enzymes - can contain 50 different enzymes
What is the function of lysosomes?
- Hydrolyse phagocytic cells
- Completely break down dead cells (autolysis)
- Exocytosis - release enzymes outside of the cell to destroy materials
- Digest worn out organelles for reuse of materials
What is the structure of the mitochondria?
- Double membrane
- Inner membrane called the cristae
- Fluid centre called the mitochondrial matrix
- Loop of mitochondrial DNA
What is the function of the mitochondria?
- Site of aerobic respiration
- Site of ATP production
- DNA to code for enzymes needed in respiration
What is the structure of ribosomes?
- Small, made up of two sub-units of protein and rRNA
- 80s - large ribosome found in eukaryotic cells (25nm)
- 70s - smaller ribosome found in prokaryotic cells, mitochondria and chloroplasts
What is the function of ribosomes?
Function of protein synthesis
What is the structure of chloroplasts?
- Surrounded by a double membrane
- Contains thylakoids (folded membranes embedded with pigment)
- Fluid filled stroma contains enzymes for photosynthesis
- Found in plants
What is the function in chloroplasts?
Site of photosynthesis
What is the structure of the cell wall?
In plants and fungi cells
- Plants - made of microfibrils of the cellulose polymer
- Fungi - made of chitin, a nitrogen containing polysaccharide
What is the function of the cell wall?
Provides structural strength to the cell
