L1. What are cell & how do we see them Flashcards
define cell
the basic structural and functional unit of any living organism
Where does the variability of a cell come from
the central dogma - the flow of genetic information
what is the central dogma
- DNA -> RNA -> Protein
- Different cells have different genes and mRNAs that are produced at different levels
- Making different amount of mRNAs will change how the cell functions through proteins
define Evolution
process by which living cells become gradually modified
define genome
library of genetic information
explain the light microscope
- simplest microscope
- light is refracted and passes through an objective lens to be viewed through the eyepiece
- certain dyes can be soaked up by certain organelles/cells/tissues for visualization and differentiation
different microscopies utilizing contrast adjustments
- bright-field
- phase-contrast
- interference-contrast
Fluorescence microscopy
- Light is emitted and filters split the light by only allowing certain wavelengths of light to pass through
- Can use an antibody to detect any protein and add a fluorescent tag on it
- Can see where the tag is bc it stains a specific part of the organism
- Can take pictures using different filters to see different emissions
Fluorescence microscopy - what do you need to know
specifics on fluorochromes bc different organisms rely on different fluorochromes
Confocal microscopy
- used for staining more 3D images of tissues
- Takes different Z-stacks and can look at different layers of tissue
- It takes the different stacks and compress it into one to create a clear image
- Cannot see what is going on inside the cell
Transmission electron microscopy
- Meant for 2D imaging with high resolution
- Involves taking specimen and embedding it in heavy metal, then it gets bombarded with electrons
- Can get down to protein level
Scanning electron microscope
- Used for 3D images
- Specimen is coated and bombarded by electron, there is a detector that captures the electrons and constructs a 3D image
what is the nucleus
- enclosed within two concentric membranes that form the nuclear envelope
- contains molecules of DNA
- regulation of gene expression
what is the endoplasmic reticulum
- site where most cell-membrane components, as well as materials destined for export from the cell, are made
- can be rough or smooth
what is the rough endoplasmic reticulum
protein synthesis, translocation, folding, glycosylation, antigen processing
what is the smooth endoplasmic reticulum
lipid synthesis, steroid hormone synthesis, detoxification, storage of calcium ions
what is the Golgi complex / apparatus
- Checkpoint junction - protein sorting
- Protein modification through glycosylation, completion of glycolipid and shingomyelin synthesis
what is the mitochondria
Generation of energy in the form of ATP via oxidative phosphorylation
what is the chloroplast
Generation of energy in the form of ATP via photosynthesis
what are lysosomes
- Breaks down material
- Recycling membranes and old organelles
- antigen processing
what are Peroxisomes
- Synthesis and degradation of hydrogen peroxide
- oxidation of fatty acids
- photorespiration in plants
what are Endosomes
- Sorting of protein between endocytic and exocytic traffic
- sorting of receptors and ligands
- signaling
Bacteria
- No nucleus
- Have cell walls and cytoplasm
- DNA is attached to cell wall with ribosomes there
what did Carl Woese accomplish
Came up with the three domains of life:
- Bacteria
- Archaea
- Eucarya (eukaryotes)
Carl Woese - how did he accomplish his discovery
- took ribosomal RNA across species
- Closer the species are to each other, the more likely they will have similar sequences
- Farther they are = more likely to have differences
Care Woese - what happened as more technology improved his tree
newer tree suggests eukaryotes are more similar to archaea
Archaea
- Some have elaborate membrane-like structure/protrusions that interacts with other bacteria
- Could have taken up a bacteria and it becomes the mitochondria and nucleus develops after that
how are archaea different from bacteria
- they live in extreme environments (some have been found to live in less-extreme environments as well)
- cell walls are made of a different matter
- less standard energy production
how are bacteria different from archaea
- cell walls of peptoglycen
- cannot survive in extreme environments
- more standard energy production
similarities between bacteria and archaea
- no nucleus
- no organelles
- single celled
- prokaryotes
- evolved from a single ancestor
what is the more accepted endosymbiotic theory
- Anaerobic archaea interact with aerobic bacteria (used oxygen to make ATP)
- Ectosymbiont (bacteria) becomes endosymbiont as the aerobic bacteria becomes enclosed within the anaerobic bacteria
- Membranes of archaea fold in and enclose DNA to become nucleus – becomes more efficient but more costly (thus needs bacteria)
- Other folds become other organelles
Evolution of plant cells
- Photosynthetic bacterium interacts with early eukaryotic cells and becomes enclosed
- Bacterium then becomes chloroplast
what allowed the specialization of cell types and the evolution of milticellularity
processes and organelles evolving after the symbiotic event allowing cells to undergo contemporization
what is the cytoskeleton
- Protein components create scaffolding/roads of cell
- Helps break apart chromosomes during cell division
