Chapter 2: An Introduction to cell diversity Flashcards
In mammals, what is the function of epithelial cells? (4)
Protection
Barrier
Absorption
Secretion
In mammals, what is the function of endocrine cells?
Hormone production for communication and signalling
In mammals, what are the functions of muscle cells?
Movement (peristalsis)
Contraction
In mammals, what is the function of nerve cells?
Fast and accurate communication
In mammals, what is the function of support cells (connective tissue cells)?
Support
Organisation of tissue structure
In mammals, what is the function of germ cells?
Reproduction
In mammals what is the function of immune system cells?
Defence
In mammals, what is the function of adipocytes?
Energy
Storage
Protection
Who devised the first compound telescope?
Robert Hooke
How many micrometres in a metre?
1 000 000 or 10^6
What is the typical size of animal and plant cells?
Animal: 10–50 µm in diameter
Plant: 50–100 µm in diameter
What is the typical size of animal and plant cells?
Animal: 10–50 µm in diameter
Plant: 50–100 µm in diameter
What is endosymbiotic theory?
The theory that eukaryotic organelles like mitochondria and chloroplasts came to exist through prokaryotes that were ingested by other cells and survived, becoming symbiotic with one another and eventually becoming a singular organism.
What are the three lenses found on a conventional light microscope?
- condenser
- objective
- eyepiece
Describe how a light microscope works.
A light beam is passed through a condenser lens which focuses the light onto the specimen before passing through the objective lens which magnifies the image and passes it to the eyepiece lens which magnifies the image further, finally focusing the image onto the eye or digital detector.
Describe how a light microscope works.
A light beam is passed through a condenser lens which focuses the light onto the specimen before passing through the objective lens which magnifies the image and passes it to the eyepiece lens which magnifies the image further, finally focusing the image onto the eye or digital detector.
What does ‘resolution’ mean?
Resolution is the smallest distance between two objects that can be detected / the distance apart at which 2 objects can still be distinguished as separate
Why can light microscopy not excel past 200 nm resolution?
The resolution is dictated by the wavelength of the visible light being used, which cannot detect anything smaller than itself as it will not interact.
What is the ultrastructure of a cell?
The fine structures of a cell that can only be seen using an electron microscope.
Includes the details of intracellular structures.
What is histochemistry?
The use of chemical stains to identify cells and some of their components when using microscopy.
What is the term for the study of tissue sections in microscopy?
Histology
How would you prepare a biopsy for study using light microscopy?
- Freezing or embedment in supporting material
- Sectioning (5 - 50µm thick)
- Histochemistry / staining
Describe the process of gram staining of a bacterial sample.
- Dye smear of bacteria with ‘crystal violet’ dye
- Usage of a mordant, like a dilute iodine solution, to trap the dye within the cells
- Treat with an organic solvent that dissolves the purple stain
- Gram-positive bacteria will be able to hold onto the dye and show up purple
- Counterstain with red dye that is taken up by gram-negative bacteria
Name two chemicals that can be used to view subcellular components, what components they stain, and how they do this.
Haematoxylin binds to negatively charged molecules and stains the nuclei.
Eosin binds to positively charged molecules and stains the cytosol.
What are the steps of immunolabelling?
In a prepared sample:
1. Addition of primary antibody that binds to specific relevant molecules
2. Addition of secondary antibodies that binds to primary antigens and are labelled with a chemical or enzyme that can be detected
3. Study to localise the secondary antibodies label / expected reaction and therefore localisation of specific molecules
What are confocal microscopes able to capture?
Fluorescent labelling (in immunolabelling), different levels of the sample therefore forming a detailed analysis and a digital 3D reconstruction.
What do cells within a cell culture need to grow and live?
Suitable liquid + growth medium
Suitable surface
What is a problem with using a tissue sample for a cell culture and how can this be overcome?
Due to there being no cell supply nutrients received by the cell would completely depend on diffusion, meaning cells central in the sample may not receive suitable nutrients to survive.
The use of enzymes and gentle mechanical agitation can be used to break down extracellular adhesive molecules to separate cells, then able to be held in suspension instead with diffusion now being enough.
What are the advantages of being able to grow specific cell types in cell cultures?
- You can study the effects of exogenous agents
- You can avoid the complexity of animal studies and avoids uncertainty of secondary effects
- Reduces animal testing
Growing cells in a liquid medium or surface of nutrient agar plates is suitable for which types of organisms?
Single-celled organisms and independent cells
What are primary cells?
Cells derived from a fresh tissue sample.
Why would video and time-lapses of cell cultures be used in microscopy?
To study the movement and interactions of cells and organisms.