b1 - cell structure and transport Flashcards
give four features of light microscopes
1) use a bean of light to form an image
2) can magnify objects up to 2000 times (school - 400 times)
3) used to view living objects
4) relatively cheap and easy to transport
give four features of electron microscopes
1) use a beam of electrons to form an image
2) can magnify objects up to 2,000,000 times
3) cannot be used for living objects
4) expensive and need to be kept in special conditions
give the two types of electron microscope
1) transmission electron microscope which gives 2D images
2) scanning electron microscope which gives 3D images but lower magnification
define resolving power
ability to separate small close together dots/objects
what is the resolving power of a light microscope?
200 nm
what is the resolving power of a transmission electron microscope?
0.2 nm
benefits of a transmission electron microscope over a light microscope?
- higher magnification
- better resolving power
what is 1km equal to?
1000 m
what is 1m equal to?
100 cm
what is 1cm equal to?
10 mm
what is 1 mm equal to?
1000 micrometres (um)
what is 1 um equal to?
1000 nm
give magnification formula
magnification = image size/object size
define nucleus
- diameter 10 um
- controls cell activities
define cytoplasm
- liquid gel in which the organelles are suspended
- where many chemical reactions take place
define cell membrane
controls movement of substances such as glucose and mineral ions into the cell, and other substances such as urea and hormones out of the cell
define mitochondria
where energy is transferred during aerobic respiration
define ribosomes
where protein synthesis takes place
define algae
simple aquatic organisms with features similar to plant cells
what features do plants and algae additionally have?
- rigid cell wall made of cellulose for support
- chloroplasts containing chlorophyll for photosynthesis, chloroplasts absorb light to make food
- permanent vacuole containing cell sap keeping the cell rigid and helps to support the plant
define eukaryotic
contains cell membran, cytoplasm and nucleus (nucleus contains chromosomes which are made of genetic material called DNA)
define prokaryotic
single-celled living organisms
give an example of a prokaryotic cell
- bacteria, cell membrane and cell wall surrounding cytoplasm not made of cellulose
- bacteria do not have a nucleus, genetic material is found in cytoplasm as a long circle of DNA
- some prokaryotic cells have plasmids
- some bacteria have a protective slime capsule, other have flagella for movement
- bacteria may cause stored food to decompose
