Cells Flashcards
What are the main features of a prokaryotic cell
- No membrane bound nucleus or organelles
- Smaller than eukaryotic cells
Structure and function of cell wall in prokaryotes
Made of of murin, maintains shape of cell and allows exchange of materials from the outside
Structure and function of slimy capsule in prokaryotes
Gelatinous layer, prevents cell drying out and important in adhesions
Structure and function of cell membrane in prokaryotes
Contains less phospholipids the eukaryotic cell membranes, selectively permeable so controls what enters + leaves cell
Structure and function of plasmids in prokaryotes
Small circular, double stranded dna molecules in cytoplasm, passed from one bacterial cell to another when they exchange genes
Structure and function of flagellum in prokaryotes
Composed of tublin, used to move cells
Structure and function of ribosomes in prokaryotes
Smaller than eukaryotic ribosomes (70s), site of protein synthesis
Structure and function of cytoplasm in prokaryotes
Contains dissolved substances, cytoskeleton present
Structure and function of nucleus in eukaryotes
Surrounded by double membrane (nuclear envelope- has nuclear pores + joins to er), contains nearly all cells genetic material + controls protein synthesis
Structure and function of nucleolus in eukaryotes
Dense spherical structure inside nucleus, not surrounded by a membrane, makes RNA and ribosomes
Structure and function of ribosomes in eukaryotes
2 subunits(rRNA and protein), dense(80s), site of protein synthesis and acts as an assembly line where MRNA is used to assemble proteins from amino acids
Structure and function of rough endoplasmic reticulum in eukaryotes
Complex system of membranes cause cisternae, covered in ribosomes, modifies proteins produced in ribosomes + transported in sacs
Structure and function of smooth endoplasmic reticulum in eukaryotes
Not covered in ribosomes, steroid synthesis, lipid synthesis + makes hormones
Structure and function of Golgi apparatus in eukaryotes
Stack of flattened sacks, had vesicles, Golgi vesicles transport molecules to different parts of the cell or outside, processes + sorts molecules from vesicles
Structure and function of mitochondria in eukaryotes
Contain own dna(plasmid) and ribosomes, has a double membrane, converts energy from food so cell can use it, contains enzymes for respiration
Structure and function of chloroplasts in eukaryotes
Double membraned, has plasmid dna, chlorophyll is found in grana, carries out photosynthesis (manufactures ATP)
Structure and function of lysosomes in eukaryotes
Spherical sacs containing enzymes, has a membrane which keep’s enzymes separate( prevents digestion of useful structures), break down unwanted cells
Structure and function of cell wall in eukaryotes
Made of cellulose,rigid, supports cell and prevents them from changing shape
Structure and function of vacuole in eukaryotes
Filled with cell sap, maintains turgidity + rigidity of cell by storing water and exerting turgid pressure against cell wall
Structure and function of cell surface membrane in eukaryotes
Provides structure to the cell + controls exchange of materials across it, made up of phospholipid bilayer
What is the function of a capsid in a viral cell
Protein coat that encloses and protects RNA, in non-enveloped viruses it facilitates the attachment and penetration of virus to the host cell
What is the function of the genetic material in viral cells
Codes for viral proteins
What is the function of attachment proteins in viral cells
Unlocks host cell by interacting with ‘lock’ receptor on the cell surface (attachment/entry to host cell)
What is the function of the lipid envelope in viral cells
Protects the capsid/genetic material
What is the source of image for a light microscope, TEM and SEM
- Light
- Electrons
- Electrons
How is the beam focussed in light microscopes, TEM, SEM
- Glass lens
- A condenser electromagnet
- A condenser electromagnet
What is the max. effective mag. of a light microscope, TEM, SEM
- x2000
- Larger than l.m
- Larger then l.m
What is the max resolution of a light microscope, TEM, SEM
- 200nm
- Higher than l.m
- Higher than l.m
Can a live specimen be used in a light microscope, TEM, SEM
- Yes
- No
- No
Section of external of specimen in light microscope, TEM, SEM
- Section
- Section
- External (3d)
What is the cost of a light microscope, TEM, SEM
- Cheaper than TEM, SEM
- more expensive then l.m
Can the image be viewed directly from a light microscope, TEM, SEM
- Yes
- No - on screen
- No - on screen
Is staining the specimen required for a light microscope, TEM, SEM
- don’t have to
- Yes (complex preparation)
- Yes (complex preparation)
What is magnification
How much bigger an object appears to be
What is resolution
The ability to distinguish between 2 separate points
Why is the max mag of a l.m x2000 when can produce higher mag
The resolution limits max useful magnification
Formula for magnification
Mag =image size/actual size
Steps of cell fractionation
- Cut tissue + put into cold, isotonic, buffered solution (reduce enzyme activity, keeps same water potential to prevent organelles shrinking, prevents ph change so enzymes don’t denature)
- Homogeniser releases organelles from cell
- Filter homogenate to remove complete cells/large debris
- Put it in centrifuge (slower speed the large fragments collect at bottom + smaller ones suspended in the supernatent
- Remove large fragments and respin the supernatent
