3.2.1 Cell Structure Flashcards
Types of eukaryotic cells
animal, plant, fungi,algae
Types of prokaryotic cells
Bacteria
What is the difference between plant and animal cells?
plant cells have cell wall, chloroplast and vacuole.
fungi cells
- similar to plant cells
- Don’t have chloroplasts (don’t photosynthesise)
- their cell wall is made of chitin
Algae cells
Have all the same organelles as plant cells
what is the structure and function of the nucleus?
Contain genetic material
- contains chromosomes
- protein bound DNA
- one or more nuclei
Structure and function of cell membrane
Controls entry and exit of substances (semi permeable)
- made up of proteins and lipids
structure and function of Mitochondria
Produce ATP
- appear as rod-like structures
- Have a double membrane
- Cristae (folds)
- matrix
function of chloroplasts
Site where photosynthesis takes place
Golgi apparatus
Collects and processes proteins and lipids
Golgi vessicles
Bud off and form lysosomes
Lysosomes
A type of golgi vessicle that releases the enzyme lysozyme.
Ribosomes
where protein synthesis takes place
Rough ER
Folds and processes proteins made on ribosomes
Smooth ER
Produces and processes lipids
Cell wall (plants, algae)
- made of cellulose
- supports cell and prevents shape change
Cell wall (fungi)
made of chitin
vacuole
- involved in removing unwanted chemicals from the cell
What are specialised cells?
cells that have a specific function
sc—> tissues—> organs—-> organ systems
Name some organelles that prokaryotic cells always have
- cell wall (made from murein)
- plasma membrane
- ribosome
- cytoplasm
- circular DNA
Name some organelles prokaryotic cells sometimes have
- flagellum
- capsule
- nesmosome
- plasmids
- pilli
Where is DNA found in a prokaryote?
- single circular DNA, free floating in cytoplasm
Is a virus living or non-living?
non living
what is the structure of a virus?
- Genetic material (DNA or RNA)
- capsid ( layer of fatty acid coats)
- Attachment protein (receptor to recognise cells to invade)
formula for magnification
image size/actual size
How does an optical microscope work?
use light to form an image
Advantages of using optical microscope
Can use live specimens
Disadvantages of using optical microscope
- low resolution
- can’t see smaller organelles/ in great detail
What are the two types of electron microscopes?
- scanning electron microscope
- Transmission electron microscope
How does a TEMS work?
use electromagnets to focus a beam of electrons, which is then transmitted through the specimen
Denser parts absorb more electrons, appearing draker
Advantages of TEMS
- High resolution ( can see internal structures)
Disadvantage of TEMS
- can only be used on thin specimens
how does a SEMS work?
electrons bounce off specimen and forms an image
Advantage of SEMS
- can be used on thick specimens
- form 3D structures
Disadvantage of SEMS
has a lower resolution than TEMS
Stages of cell fractionation
1) Homogenisation (break up the cell)
2) filteration (remove large tissues)
3) ultracentrifugation (seperates organelles)
Homgenisation process
Homogenised in a cold isotonic solution with same water potential as cell. breaks open plasma membrane to release the organelles into the solution.
Why is the cell homogenised in a cold solution?
To slow down/stop enzyme activity
Why is the cell homogenised in an isotonic solution?
So no osmosis takes place
Filteration process
filtered to remove larger tissues.
Centrifugation process
- spun in centrifuge at low speed
- large organelle forms pellet at bottom
- smaller organelles stay in liquid called suspendant at the top
- pellet removed and process is repeated at higher speeds each time until all organelles are seperated.
How can you identify starch grains in a plant?
use iodine in potassium iodide solution.
