Lecture 2: Cell structure and function Flashcards
What can be seen with the unaided human eye?
tick, human heart, dog
What can be seen with the compound light microscope?
Chlamydia, rickettsia, mitochondrion, bacteria, chloroplast, RBC, large protozoa, human egg, tick
What can be seen with the scanning electron microscope?
Ribosomes, viruses, chlamydia, rickettsia, mitochondrion, bacteria, chloroplast, RBC, Large protozoa, human egg, tick
What can be seen with a transmission electron microscope?
AA’s, diameter of DNA, proteins, ribosomes, viruses, chlamydia, rickettsia, mitochondrion, bacteria, chloroplast, RBC, large protozoa, human egg
Large protozoa
eukaryotic microbe
- has euk cell structure
- larger than a prok, but smaller than a plant
- light microscope
Red blood cells
- small because they need to single file in the capillaries
- at maturity they lose mitochondria and all organelles allowing them to be small
Chloroplast
- organelle
- according to endosymbiosis theory they were prokaryotes
Chlamydia
Bacteria
- OBLIGATELY INTRACELLULAR
- smaller than bacteria (bc cell provides a lot for it)
- doesn’t juts live free in the reproductive tract but goes into reproductive tract when you 1st get the infection and then into the cytoplasm of the cell where it grows
What is similar between chlamydia and viruses?
- both organisms that go into eukaryotic cells and cause infection
- obligate intracellular
BUT
- chlamydia still have ribosomes but viruses have none of that making them smaller
Why is chlamydia small?
anything that lives inside of a cell loses what it does not need bc cell provides it a lot
But it still will have ribosomes etc stuff which viruses wont have
What should you be given if you have chlamydia?
The Dr needs to choose antibiotics that don’t just go into intracellular fluid but that go into cytoplasm of the cell
- antibiotic goes from (blood –> tissue –> ECF –> cytoplasm to find target
- antibiotic is said to have good tissue penetration
- if you choose wrong antibiotic your not helping clear the inefction
If someone had chlamydia & got a swab. After its been spread on petri dish & incubated, will there be chlamydia growth the next day?
NO IN A LAB SETTING WE CANT GROW IT
- we haven’t been able to figure out the conditions to grow chlamydia
- they have to diagnose it by nucleic acid testing
rickettsia
an INTRACELLULAR ORGANISM
- ancestor of mitochondria
- goes into a cell
- may have got trapped to act like a mitochondria (replicated)
Compound light microscope
uses visible light to illuminate the sample
- just a light bulb is used which is a low energy source so there’s limitations
What are the many different types of light microscopy?
- Bright-field
- Phase-contrast
- Dark-field
- Fluorescence
Bright-field scope
• Specimens are visualized because of differences in contrast between specimen and surroundings (dark cells on bright background)
• Two sets of lenses form the image
• Objective lens (usually 10x -100x mag.)
& ocular lens (usually 10x – 20x mag.)
Maximum magnification is ~2,000✕
Total magnification
objective
magnification ✕ ocular magnification
Why do we call the bright-field scope a compound light microscope?
b/c it compounds the magn. that the 1st lens is giving you by further magnifying it through a 2nd lens
Condenser
creates a beam of light so it’s condensed/focused to be able to move through the microscope slide
Describe the magnification light path
- Light from light source
- Condenser - focuses it into a beam so it’s interacting with the specimen
- Once the specimen comes through the objective lens (10X, 40X, or 100X (oil)), it’s inverted in position & magnified to whatever you chose
- When the specimen comes through the ocular lens (10X) it is inverted again to OG position & magnified further, so even larger
- Then you see it at either 100X, 400X, 1000X
Magnification
the ability to make an object larger
Resolution
the ability to distinguish two adjacent objects as separate and distinct
• Limit of resolution for light microscope is about 0.2 μm
(light can only get thru spaces that are at least 0.2 μm)
minimum distance 2 objects need to be apart in order for microscope to show those 2 objects
-> if objects are LESS than minimum distance that you see a blurry image
If we had a better microscope, what would we expect the limit of resolution value to be?
SMALLER - b/c then those 2 objects can be even closer together & you can still see a clear image (ex: e- microscopes)
What is relationship between wavelength and energy?
INVERSELY PROPORTIONAL
- as one increases the other decreases