Cell Structure - Harder Flashcards
What does the objective lens do?
Focuses light and increases magnification.
What does the eyepiece lens do?
Increases magnification.
What does the light source do?
Shines light through a specimen so it can be seen clearer.
What is the role of an eyepiece graticule?
In eyepiece, used to measure the size of an object viewed under a microscope.
Has to be calibrated.
100 divisions with no scale.
What is the role of a stage micrometer?
- Used to calibrate eyepiece graticule.
- 1mm with 100 divisions - each division = 10 micrometers.
- Put in microscope as if it was slide.
Why is the cover slip lowered at an angle onto a slide?
To prevent bubbles.
What is differential staining?
- Using multiple stains.
- Each stain binds to different structures.
- Allows separate structures to be identified.
Advantages of staining?
Increases contrast.
Can differentiate between different cells/parts of cell.
Advantages of light microscopes?
- Cheap.
- Easy to use.
- Can observe living organisms.
Describe how a laser scanning confocal microscope works.
- Specimen treated with fluorescent dye.
- Laser causes components labelled with dye to reflect.
Advantages of laser scanning confocal microscope.
- High resolution due to the fact laser beam has small wavelength.
- Non invasive.
- Can view objects inside cells.
Structure of the nucleus
- Has membrane with pores to allow molecules in and out of nucleus.
- Stores cell’s DNA.
What is chromatin?
DNA + histones
Where are ribosomes produced?
Nucleolus
SER function
Synthesis of lipids
RER function
Protein synthesis for proteins to be outside of cell.
Golgi function
Stores, modifies and packages proteins.
Lysosome function
Contains hydrolysing enzymes
Mitochondria function
Site of aerobic respiration, where ATP production occurs.
Cytoplasm function
Site of chemical reactions in cell
Plasma membrane function
Controls what substances enter/exit cell
Centrioles function
- Assemble microtubules in spindles for mitosis
- Not in plant cells
Components in plant cell, not animal
Chloroplasts
Permanent Vacuole
Cell wall
Chloroplast function
Site of photosynthesis
Vacuole function
Contains cell sap to help support the cell.
Cell wall function
- Made of cellulose.
- Supports and maintains shape of cell.
Microfilaments function
- Cell movement
- Contraction during cytokinesis
Microtubules function
- Provide tracks for movement of organelles.
- Form spindle fibres.
Intermediate fibres function
Give mechanical strength to cells
What is prokaryote cell wall made of?
Peptidoglycan
What is yeast cell wall made of?
Chitin
Microtubules in flagella
Contract to make flagellum move.
In 9+2 formation (9 on outside, 2 in middle)
What type of ribosomes are in bacteria vs eukaryotes?
- 70S in bacteria
- 80S in eukaryotes
Which eukaryotic organelle is not membrane bound?
Ribosome
How can microtubules be prevented from functioning?
Respiratory inhibitor
Light microscope mag + resolution
x 1500
200 nm
TEM mag + resolution
- x 500,000
- 0.2nm
SEM mag + resolution
x 100,000
0.2nm
Describe endosymbiotic theory
Mitochondria and chloroplasts found in eukaryotic cells represent formerly free-living
bacteria that were absorbed into a larger cell.
Evidence for endosymbiotic theory
- Mitochondria contain ribosomes that are smaller
than those found in the cell cytoplasm. - Mitochondria are a similar size to bacteria.
- Chloroplasts have their own circular DNA.
What is cristae?
Inner membrane of mitochondrion folded to form cristae.
Describe the roles of the cytoskeleton.
- Cell support and stability
- Movement of flagella/cilia
- Movement of ribosomes
