Cell intro Flashcards
define cell
smallest functional unit of an organism
Three parts of cell theory
- every living organism is made up of one or more cells
- the smallest living organisms are single cells, and cells are the functional units of multicellular organisms
- All cells rise from preexisting cells
elements that define cells
- bounded by phospholipid bilayer (plasma membrane)
- gathers raw materials and uses it as structural building blocks and a free energy source to create and maintain organization
- contains a heritable genetic code
- can divide and reproduce itself
sizes of cells
ranges from 0.2 um to 50 um, a typical cell in the human body (fibroblast) is 20 um
three domains of cells
bacteria
archaea
eukaryota
organization of eukaryotic cells includes
Organelles: distinct intracellular compartments
cytoplasm: organelles + cytosol
cytosol: the liquid portion of the cytoplasm
cell membranes: phospholipid bilayers
plasma membrane: the surface bilayer
the majority of a cell’s phospholipid bilayers are
intracellular
Nucleus
enclosed by two phospholipid bilayers that are perforated by nuclear pores. houses genetic material
endoplasmic reticulum
enclosed by single phospholipid bilayer. Rough ER synthesizes new proteins. Smooth ER synthesizes new lipids and sequesters/releases Ca2+ ions
Golgi apparatus
enclosed by single phospholipid bilayer. performs glycosylation (packaging) of new proteins
Mitochondria
enclosed by 2 phospholipid bilayers. synthesizes ATP, stores Ca2+ ions, beta oxidation of lipids (Endosymbiotic organelle)
Chloropoasts
enclosed by 2 phospholipid bilayers. harvests solar radiation. (Endosymbiotic organelle)
lysosome
enclosed by single phospholipid bilayer. contains hydrolytic enzymes, digests endocytose materials, involved in autophagy.
Peroxisomes
enclosed by single phospholipid bilayer. create and destroys hydrogen peroxide, neutralizes toxic compounds, synthesizes plasmalogen phospholipids found in the myelin coating of neurons
Endosomes
enclosed by single phospholipid bilayer. consists of endocytosed plasma membrane
centrosome
not enclosed in lipid bilayer. organizes mitotic spindles
cytoskeleton
not enclosed by lipid bilayer. provides scaffolding for maintaining cell shape, enables contraction of many cell types, provides tracks for molecular motors, enables chromosome separation at mitosis
Inclusions
not inclosed in lipid bilayer. includes glycogen granules, fat droplets, melanin pigment granules, ribosomes, globs of various materials, proteasomes
appendages of eukaryotic cells: Microvilli
finger-like projections from cell surface. non-motile, serves to increase cell surface area
appendages of eukaryotic cells: Primary Cilium
non-motile. sensory function. present in every cell type
appendages of eukaryotic cells: Motile Cilia
hair-like structures filled with microtubules that beat in coordinated fashion to move mucus layer across cell surface
appendages of eukaryotic cells: flagella
long, whip-like structures found only in sperm cells used for swimming.
endosymbiotic theory
mitochondria (and chloroplasts) are descendants of previously free-living prokaryotic cells. Mitochondria…
- possess their own DNA and ribosomes
- genome only encodes 37 genes
- obtains 99% of proteins from genes located within the host cell nucleus
- self reproduce by dividing within our cells
Lynn Margulis
American scientist who pushed for endosymbiotic theory
What process would the mitochondria have entered ancestral eukaryotic host cells through?
endocytosis. This process would explain why mitochondria have two phospholipid bilayers. (this also applies for chloroplasts)
