Lecture 5 - Cells Flashcards
contrast
Visible shades in the object; if all shades are similar, contrast is poor, if shades are very different contrast is high.
resolution
Minimum distance between two objects where the two objects can still be observed.
three things you need for microscopic observation
magnification, contrast, resolution
limitations of light microscopy
Light microscopes can resolve objects down to about 2000x (200nm)
cell
smallest unit of having properties of life; continuity of life arises from growth and division of single cells; all organisms are composed of one or more
properties of life
All organisms
- consist of one or more cells
- have the capacity to reproduce based on DNA
- engage in metabolism/growth
- have order
- internal regulation
- evolve
- sense and respond to the environment
why are cells small?
interior volume increases significantly faster than surface area as cell size grows, limiting cell transport processes, creating inefficiencies
prokaryote
cellular organism lacking membrane-enclosed organelles (like the nucleus)
early cells
- appeared 3.5-4.0b YPB
- earliest were prokaryotic and anaerobic
- all cells have plasma membrane, chromosomes, ribosomes, and cytoplasm
anaerobic
greek, literally means “living without oxygen”
eukaryote
have a nucleus and other organelles, split into four kingdoms: plants, protists, fungi, animals
plasma membranes
Made of phospholipid bilayers, selectively permeable, allows only small, non-polar substances through
phospholipids
hydrophilic “head” in contact with water, hydrophobic “tail” hidden from water
nucleus function
Keeps DNA separate from metabolic machinery of cytoplasm, aids in autoimmune response by shielding good DNA (yours) from defensive mechanisms designed to break apart foreign DNA
nucleolus
In eukaryotes, a structure found inside the nucleus whose function is to transcribe ribosomal RNA (rRNA) and combine it with proteins to form almost-complete ribosomes.
