B1.1 Flashcards
Nucleus:
- what is it’s purpose
- what does it contain (2)
+ Controls the activities of the cell
+ Contains organism’s genetic material, arranged as chromosomes
+ Contains instructions to make new cells or organisms
What happens within the mitochondria?
- what does it contain to enable this process
- how does that help the body
+ where respiration happens
+ enzymes there allow glucose and oxygen to react together
+ reactions transfer vital energy to the organism
What is the Cell membrane do?
- why may it be called a ‘sense organ’?
+ Acts as a barrier that controls which substances pass in and out of the cell
+ Membrane also contains receptor molecules
Cytoplasm
+ A ‘jellylike’ substance
+ where chemical reactions happen
Do Prokaryotic or Eukaryotic cells contain a nucleus?
Eukaryotic cells
State key facts about Eukaryotic cells
- size
- example of them
- size relative to other cells
+ between 10 μm and 100 μm (micrometers)
+ Plant and Animal cells are an example
+ They are generally large and complex
+ Larger than prokaryotic cells
State key facts about Prokaryotic cells
\+ do NOT contain a nucleus \+ genetic material floats in the cytoplasm \+ 1 μm to 10 μm \+ Bacterial cells are an example \+ Smaller than Prokaryotic cells
What is the role of Chloroplasts?
- what does it contain to enable that
- where is it found
+ where photosynthesis occurs
+ Contain green chlorophyll
+ which transfers energy from the Sun to light
+ Only in green parts of plant
What is the role of the Cell wall?
- what is it made of
+ Made of tough fibre called cellulose
+ Supports the cell from falling
What is the role of Vacuole?
- what is within it
+ Full of cell sap
+ Helps keep the cell rigid and upright
How many micrometers are in a meter?
1 μ
1,000,000
one million
State the difference between Prokaryotic and Eukaryotic cells
Eukaryotic cells have a nucleus and prokaryotic cells do not.
Eukaryotic cells are larger than Prokaryotic cells.
State the similarities and differences between animal and plant cells
Similarities - Cytoplasm, Cell membrane, Nucleus, Mitochondria
Differences - Plants have cell wall, vacuole, chloroplasts
How does a light microscope work?
Light is passed through an object on the stage and then eyepiece lenses are used to see the object in more detail
What are light microscopes used for?
To observe small structures in detail
State 7 components of a light microscope
- eyepiece lens
- objective lens
- stage
- slide
- light
- fine focus
- coarse focus
What is the first three stages to observe cells using a light microscope?
1) Move the stage to its lowest position
2) Select the objective lens with the lowest magnification
3) Place the slide (with the cells) on the stage
What are the last three stages to observe a cell using a light microscope?
4) Turn the coarse focus knob
5) Turn the fine focus knob
6) to see the cell clearer, repeat the steps using a higher magnification
What is the equation to find out the total magnification of a microscope?
eyepiece lens magnification x objective lens magnification
Why are cells stained when observed under a microscope?
- to increase the contrast
- since cells are colourless
- the stains are used to see sub-cellular features
Explain what the term “higher resolution” means
The image/cell is seen in high detail
What is an iodine solution stain used for?
makes it easier to see plant cell nuclei
What is methylene blue stain used for?
makes it easier to see the nucleus of an animal cell
What is the crystal violet stain used for?
stains bacterial cell walls
What is the resolution of a light microscope?
2 x 10^-7
2 x 10 to the power of -7
How do TEM work?
1) beam of electrons pass through a thin slice of the sample
2) Beam is focused to produce an image
How does a SEM work?
1) sends a beam of electrons across the surface of a specimen
2) the reflected electrons are collected to produce an image
What does TEM stand for?
And what dimension does it come in?
Transmission Electron Microscope
2D - ELECTRONS TRANSMIT THROUGH SAMPLE
What does SEM stand for?
And what dimension does it come in
Scanning electron microscope
3D - SCANS OVER OBJECT
State 4 advantages of a light microscope compared with an electron microscope
- Cheap to buy and operate
- Small and portable
- Specimens can be living or dead
- Natural colour of sample can be seen
State 4 qualities of a electron microscope
- High resolution ( up to 0.1nm)
- Large and difficult to move
- Expensive
- Specimens must be dead
- Black and White images produced
How has electron microscopy increased our understanding of subcellular structures?
It has allowed scientists to see detail within subcellular structures
what is the magnitude of this symbol:
μm
MICROMETER
10^-6m
what is the magnitude of this symbol:
nm
nano-meter
10^-9
define monomer
a single molecule that can be bound to many copies of itself to make a larger molecule
define polymer
a molecule composed of many repeating monomers
what are proteins made from?
amino acids
What is the formula to work out the magnification of a picture?
image size
————
actual size
i
a\m
What’s important about ribosomes?
- allow Translation to occur
- are the site of ‘protein synthesis’
Define magnification
How many times larger an image is seen through a microscope compared to a real specimen
Define resolution
The ability to distinguish between two or more objects close together
