1.2 Ultrastructure of cells Flashcards
What is resolution?
The ability to distinguish between two points of an object.
When is resolution better?
When the wavelength of light is shorter
How are electron microscopes different?
- Uses electron beam as illumination
- Gives black and white image
- Higher resolution
- Cannot view any living material or processes due to vacuum
Ultrastructure
Architecture of cells and biomaterials that are only visible at high resolution
Prokaryotes
Single-celled organisms that lack a nucleus and membrane bound organelles
What does 70S mean?
It is the sedimentation rate in centrifugation
Pilli
Enable cell to attach to other surfaces and exchange DNA
Flagellum
Used for cell locomotion
Nucleoid/Plasmid
Contains DNA not enclosed by a nucleus
Process of binary fission
- Circular DNA is copied in response to replication signal
- 2 DNA loops attach to membrane
- Membrane elongates and pinches off to form 2 cells. Cytokinesis
Binary fission: Asexual or sexual?
Asexual as genetic content is exactly the same as circular DNA is replicated. (Except for mutations)
Eukaryote
Complex cell which contains a clearly defined nucleus
Advantages of compartmentalization
- Greater efficiency of metabolism as enzymes and substrates are enclosed in membrane for specific functions
- Internal conditions like pH and temp can be regulated separately
- Isolation of toxic or damaging substances in cytoplasm
- Flexibility in number and positions of organelles
Nucleus
Contains genetic material and controls cell activity.
Mitochondrion
Site of ATP production by aerobic respiration.
Nucleus structure
- Densely stained areas are chromatin
- Double membrane with pores in between
Mitochondria structure
- Smooth outer membrane
- Folded inner membrane
- Folds = cristae
- Matrix= Space in the middle of the cristae
Free ribosomes (80S)
Synthesizes protein and releases it into the cytoplasm as enzymes. Constructed in nucleolus
Ribosome structure
Usually appear as darkened granules in cytoplasm and not surrounded by a membrane. Often 20nm in diameter
Rough endoplasmic reticulum
Synthesizes protein for secretion from cell (Note: Doesn’t package or carry)
rER structure
- Cisternae: Flattened membrane sacs
- Ribosomes: Attached to cisternae
Golgi Apparatus
Processes proteins brought in by vesicles and sends to membrane for secretion
Golgi apparatus structure
- Cisternae: Not as long as rER, often curved
- No ribosomes
- More vesicles nearby
Vesicles
Small vacuoles that transport materials inside a cell