B1.1 Cell Structures

Eukaryotic cells: Found in plants, animals, fungi and protists (single-celled organisms that don’t fit other categories). 10-100 micrometres in size. A Eukaryote is an organism made up of eukaryotic cells

Prokaryotic cells: they are 0.1-5.0 micrometres in size. A prokaryote is an organism made of prokaryotic cells. Bacteria are prokaryotes

Features of prokaryotic cells:

• Plasmids: one or more small rings of DNA, which are called plasmids. Can replicate and move between cells so that genetic information can be shared

• Lack of mitochondria and chloroplasts

• Lack of nucleus

• Cell wall and membrane

• Cytoplasm - where most of the cell’s chemical reactions take place

• Flagella - used for movements

  
  

Animal cells:

• Cell membrane

• Nucleus

• Ribosomes

• Mitochondria

• Cytoplasm

Plant cells:

• permanent vacuole

• chloroplasts

• cell wall

magnification: how many times larger an image seen through a microscope is compared to the real object.

Resolution: the ability to distinguish between two or more objects that are close together

Light microscope: passes light through a specimen and creates a magnified image using lenses. highest magnification of x400 and resolution of 0.25 micrometres

Electron microscope: electrons are passed through the specimen instead of light. resolution of 0.25 nm and magnification of x500,000

when using a light microscope a stain is used to give contrast to the features of the cells, to make them visible

use the objective lens first

1km = 10³m

1cm = 10^-2

1mm = 10^-3

1micrometre = 10^-6

1nm = 10^-9