Bio 7 Flashcards
(117 cards)
When was the cell discovered and by who?
in the 1600s (after the invention of the microscope), and by Robert Hooke
why were they named cells?
they looked like small chambers
With little know about cells, the cell theory was created, what was it?
- all living things are composed of cells
- cells are the basic unit
- new cells come from old cells
What are the different microscopes that can be used/ have been used to explore the cell?
light microscope
electron microscope
scanning tunnel microscope
scanning probe microscope
light microscope and compound light microscope
light passes through lenses to produce a magnified image
- compound light microscope: two lenses
Electron microscope
forms image of specimen using beam of ELECTRONS, placed in vacuum chamber
TWO TYPES:
- TEM (transmission electron microscope)
-SEM (scanning electron microscope)
TEM versus SEM
TEM: electron beam is aimed at a very small part of specimen coated in METAL IONS, reveals internal structure
SEM: coated in METAL and 3D image is formed
scanning tunneling microscope (STM)
can be used to study living creature, uses needle like probe to measure different things, this often means metal
What is the STM mainly used for?
looking at metal at an atomic level
What is the most common microscope?
The light microscope, it is the cheapest though still very expensive
Scanning Probe microscope
NEWEST, uses little probes that produce images by scanning surfaces, show REALLY SMALL things
Micrograph
Image made by microscope
Magnification
ability to make image appear larger (microscopes have magnification)
Resolution
Measure of clarity in an image (how clear is what I am seeing?)
Why do mitochondria and chloroplasts have a large surface area?
Because they are much more efficient. This also applies to most organelles in an organism.
Why do cells need to have a large surface area?
so that they are able to push out and take in substances quickly
Prokaryotes
A cell without a nucleus, can be a single celled organism like ameba
-they are small and adapt well
How did prokaryotes evolve into Eukaryotes? And what is this theory called?
(Endosymbiotic Theory)
Starts with two fused pros, then a photosynthetic pro fuses in.
Where is DNA found in Prokaryotes?
It is found as a single extremely long circular molecule in the cytoplasm, the region where it is is called the nucleoid
Eukaryotes
an organism whose cells have a nucleus
-plants animals fungi
Where is DNA found in Ekaryotes?
within the nucleus
Cilia versus Flagella
Cilia are hair like structures protruding from Eukaryotes, Flagella are thread like structures protruding from Prokaryotes.
Cytoskeleton
Framework of a cell
- many different microfilaments& microtubes
What is a Centriole? What could it be compared to?
There are generally two centrioles in a cell near the nucleus, they are made up of many microtubules
-Centrioles organize a cells division, for instance teachers help divide students into a class