chapter 4 biology Flashcards
Cell theory
- All organisms are composed of cells
- Cells are the smallest living things
- Cells arise only from pre- existing cells
Cells
Discovered in 1665 by Robert Hooke
Leeuwenhoek - first to observe living cells
Schleiden and Schwann proposed the cell theory
Cell size limited
Most cells are relatively small due to reliance on diffusion of substances in and out of cells- waste, nutrients, molecules for biosynthesis , ect.
Require a high surface area/ volume ratio
Surface area- to- volume ratio
Organism made of many small cells has an advantage over an organism composed of fewer, larger cells
As a cells size increases, it’s volume increases much more rapidly than its surface area
Some cells overcome limitation by being long and skinny- like neurons
Muscle cells - multinucleated
Basic structural similarities
- Nucleiod( region of DNA in a prokaryotic cells) or nucleus where DNA is located
- cytoplasm- semi fluid matrix of organelles and cytosol- actual fluid
- ribosomes- synthesize proteins
Prokaryotic cells m
Simplest organisms
Lack a membrane- bound nucleus - DNA is in the nucleiod
Two domains - archea and bacteria
Pili
Don’t help attach it does help exchange genetic material
Bacteria cell walls
Strong cell wall
- composed of peptidoglycan- make up cell wall
Domain archea
Archea lack peptidoglycan
Membrane lipids are different from bacteria - monolayer- membrane can keep its integrity at high temps
Discovered in 1970s
More closely related eukarya than to bacteria
Eukaryotic cells
Posses a membrane- bound nucleus
Hallmark is compartmentlization- reaction in one apartment
Ribosomes
Cells protein synthesis machinery
Found in all cell types in all 3 domains
Made up of robosomal RNA ( rRNA ) - protien complex
Protein synthesis also requires messenger RNA and transfer RNA
Maybe free in cytoplasm and associated with internal
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