LEC 7 Flashcards
CELL THEORY/STRUCTURE
Cell Theory (3)
- All living things are composed of cells and cell products.
- A single cell is the smallest unit that exhibits all the characteristics of life.
- All cells come only from preexisting cells.
Eukaryotic cell (4)
- Has cell membrane
- Membrane-bound nucleus with DNA
- Cytoplasm (with gel-like fluid called cytosol)
- Membrane-bound organelles designed for specialized functions
Prokaryotic cell
- Simplest cells
- Nucleoid - DNA containing inner region (not membrane bound)
- Cell membrane & rigid cell wall
- No membrane bound organelles
- Divide rapidly
All cells do what 4 things?
- Gather raw materials
- Excrete wastes
- Make macromolecules
- Grow and reproduce
Why are all cells small?
the larger the cell gets, the more likely that its growth and metabolism will be limited by its ability to supply itself across the plasma membrane
Smaller is more efficient!!!
Microvilli
Microscopic projections that extend outwards from the cell
Increase surface area
Types of microscopes
Light microscope
Transmission electron microscope
Scanning electron microscope
Light microscope
can magnify a sample up to 1000 times
Transmission electron microscope (2)
makes 2D image of the outer surface using electrons
Can magnify up to 100,000 times
Scanning electron microscope (2)
makes the 3D image of the outer surface using electrons
Can magnify up to 100,000 times
Nucleus (2)
control centre of the cell
has most the genetic material
Parts of Nucleus (3)
1.Nuclear membrane
2. Nucleolus
3. Nuclear pores
Nucleolus (2)
Dense region inside nucleus
Components of ribosomes form here and pass through pores to enter cytoplasm
Nuclear membrane (2)
Double layer of phospholipids
Surrounds the DNA & keeps it inside the nucleus
Nuclear pores (2)
Selectively allows materials (ribosomes, proteins and RNA) to move in/out
Too small for DNA to leave through
Ribosomes def
Involved in assembling amino acids in the correct sequence (primary structure) into specific protein chains
Where are ribosomes found? (2)
- Float in cytoplasm
- Attach to the rough ER
How are ribosomes formed? (3)
- Parts of RNA and ribosomal proteins are formed
- Parts leave the nucleus via nuclear pores
- Enter the cytoplasm and are assembled into ribosomes
Where are ribosomes formed?
nucleolus
Endomembrane System (4 organelles)
- Rough Endoplasmic Reticulum (production)
- Smooth Endoplasmic Reticulum (packaging)
- Golgi Apparatus (labelling)
- Specialized vesicles (shipping)
Endoplasmic Reticulum def
Works with ribosomes to synthesize most of the chemical compounds made in the cell
Endoplasmic Reticulum structure
- Repeated folded membrane structure
- Fluid filled
- some of it is connected to the nuclear membrane
- form transport vesicles to move synthesized materials out of the cell
Endoplasmic Reticulum types
rough ER
smooth ER