1- Cell structure and microscopy Flashcards
What is a nucleus?
contains DNA base sequences that control the activities of the cell
What is a nucleolus?
A region in the nucleus where ribosomes are made
What is a nuclear envelope?
A double membrane that surrounds the nucleus. It contains pores to allow small molecules to pass to the cytoplasm.
What is rough endoplasmic reticulum?
A large surface area for ribosomes to do protein synthesis
What is smooth endoplasmic reticulum?
Synthesises lipids
What is the golgi apparatus?
Fluid filled membrane bound sacs that modify and package from RER and SER into vesicles
What are ribosomes?
Responsibe for the translation of RNA into proteins. In the RER or cytoplasm.
What is mitochondria?
The site of ATP production in aerobic respiration. It has a large SA for respiration
What are Lysosomes?
They contain digestive enzymes that engulf and destroy old and foreign materials
What are Chloroplasts?
The site of photosynthesis. Thylakoid membranes stacked into grana and linked by lamellae
What is a plasma membrane?
Phospholipid bi-later with cholesterol regulating fluidity
What are Centrioles?
Microtubules that form spindle fibres in mitosis
What is a Cell wall?
Made of cellulose (plants), chitin (fungi) or murein (prokaryotes) and provides support to the cell
What is Flagella?
A tail structure made of microtubules (sperm)
What is cilia?
Microtubukes contract to allow movement (epithelial cells)
What is a vacuole?
An organelle that stores cell sap and keeps a plant cell turgid
What do ribosomes do? Where are they located?
Translate mRNA into a polypeptide chain. Located on RER or in cytoplasm
What does RER do to polypeptide chains?
Folds them and transports them to golgi in vesicles
What does the Golgi apparatus do?
Modifies and processes proteins before packaging and sending them to where they are required
What is the cytoskeleton?
A network of protein threads arranged into microfilaments and microtubules.
What does the cytoskeleton help with?
Strengthening cell and maintaining shape
4 main differences between eukaryotes and prokaryotes
1) Prokaryotes have no membrane-bound organelles; eukaryotes do
2) Prokaryotes are smaller than eukaryotes
3) Prokaryotes have circular DNA; eukaryotes are wrapped around chromosome
4) Prokaryotes have smaller ribosomes (70s) than eukaryotes (80s)
What are plasmids?
Small circular rings of DNA in a prokaryote
What are mesosomes?
Folded portions of a prokaryotes inner membrane
What are pilli?
Hair-like structures on a plasma membrane for cellular communication
What are the features of a light microscope?
- 1500x actual size
- 0.2um resolution
- 2D image
- Can’t see smaller organelles
-Can visualise living cells
What are the features of a laser-scanning confocal microscope?
- Clearer images
- Uses laser beam
What are the features of a transmission electron microscope (TEM)?
- 1,000,000x actual size
- 0.0002um resolution
- living cells cannot be seen
- 2D
What are the features of a scanning electron microscope (SEM)?
- 500,000x actual size
- 0.002um resolution
- Living cells cannot be seen
- 3D
What is the magnification?
How many times larger the image is compared to the actual object
What is the resolution?
How well a microscope can distinguish between two points close together
What is the magnification equation?
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What are the steps to calibrating the eyepiece graticule?
1) Place stage micrometer on stage so you can see divisions
2) Align eyepiece graticule with stage micrometer
3) Take away stage micrometer and add sample
What are the steps to preparing a specimen to view?
1) Add a drop of water to the slide and add thin layer of cells
2) Add a drop of a stain to visualise cells
3) Add a cover slip
4) Place on the stage and select the lowest objective lens
5) Use coarse adjustment to focus
6) Select increasingly higher magnification until you can visualise the structures you are interested in
