Cell Theory
Cells are the basic structural & functional unit of life. |
Viruses do not qualify as living. |
All living organisms are composed of cells. |
No cellular structures, |
All cells arise from pre-existing cells. |
don't metabolize, |
Spontaneous generation does NOT occur. |
not motile, |
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don't reproduce w/o a host cell |
Nucleus
Double phospholipid bilayer membrane (nuclear envelope)
Biggest organelle in most cells
Ancestral prokaryote membrane folded in on itself, trapping DNA and protecting it
Nucleus cont.
The nuclear envelope is very restrictive |
Contains most eukaryotic DNA (some DNA in chloroplasts and mitochondira) |
Organizes DNA with chromosomal territories separated by proteins |
Nucleolus is the site of ribosomal RNA (rRNA) synthesis and assembly |
Protein structures and RNA can fit through nuclear pores to leave the nucleus |
rRNA is the most abundant form of RNA, and is part of the ribosome |
Golgi Apparatus
Functions to process, sort, and ship molecules synthesized in ER |
"Post office" of the cell |
Made up of Cisternae - all separate flattened membranes for vesicular transport |
Cis side- ["same"] side facing ER |
Trans side- ["opposite"] side facing away from ER |
Vesicular transport can be tracked in a laboratory with a Green Fluorescent Protein (GFP) |
Lysosomes
["breaking body"] |
Acidified organelle specializing in digestion |
pH=4.5-5 |
degrades material via endocytosis |
(bring into cell, phagocytosis is a type of endocytosis) |
enzymes work in the acidified environment to digest |
they break down intracellular materials |
Aid in Autophagy- ["self-eating"] |
recycle things like mitochondria that are 'expired' to use material for other metabolic functions |
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Cell Diversity
Measured in micrometers |
1x103µm = 1mm |
1x106µm = 1m |
bacteria= 1-10 µm |
plant/animal= 10-100 µm |
round, rod, or spiral shape |
shape is linked to function |
Form Fits Function |
Aerobic= needs oxygen |
Anaerobic= without oxygen or oxygen is toxic |
Prokaryote vs. |
Eukaryote |
>no membrane bound organelles |
>membrane bound organelles |
>Domains Bacteria & Archaea |
>Domain Eukaryota |
>Eukaryotes stress compartmentalization, using organelles with different functions and specialized roles.
>Protists are included in Eukaryota, being single celled Eukaryotes.
Ribosomes
Composed of rRNA and protein - rRNA does the actual translating |
Performs protein synthesis (translation) |
Possessed by ALL cells |
Not membrane bound |
2 different populations in eukaryotes: |
Free (cytosolic)- floating around, makes cytoplasmic proteins |
Bound to endoplasmic reticulum (ER)- makes ER proteins, cell membrane proteins |
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Exists inside chloroplasts and mitochondria (to translate cpDNA and mtDNA) |
cpDNA= chloroplast DNA
mtDNA= mitochondrial DNA
Smooth ER
site of synthesis of membrane lipids (phospholipids, cholesterol) |
Ca2+ storage for muscle cell contraction |
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> Ca2+ is a signalling molecule, kept in the smooth ER until needed for muscle contraction |
Mitochondria
Site of cell respiration |
(citric acid cycle, e- transport) |
has endosymbiotic origins: |
>double phospholipid bilayer membrane |
>ancestral eukaryote with nuclear envelope and ER phagocytized an ancestral prokaryote that was good at cell respiration |
Matrix- aqueous solution inside mitochondria |
Cristae- inner membrane of mitochondria |
this increases surface area for cell respiration to occur |
Key to initiation of apoptosis- programmed cell death |
occurs when there is DNA damage, metabolic stress, or oxidative stress |
Cytoskeleton
the cell's 'muscles and bones' |
Filamentous proteins- 'bones', structure, support, shape |
Motor proteins- 'muscles', contraction, cell movement |
Functions: |
>contributes to eukaryotic cell shape |
>controls all aspects of eukaryotic cell motility |
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Organelles
Cell Wall |
Cell Membrane |
possessed by most organisms: bacteria, protists, fungi, plants |
possessed by every cell |
provides structure and shape, |
functions as: control entry and exit from cell (semi-permeable), |
protection against hypotonic environment, |
cell communication, |
very porous to permit passage of nutrients. |
adhesion to other cells (anchored with protein complexes). |
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Phospholipid bilayer moves laterally and fluidly, composed of small pieces |
Endoplasmic Reticulum
The ER is a physical extension directly connected to the outer membrane of the nuclear envelope.
> proteins in the nuclear membrane can diffused directly into the ER
Lumen= space in between membrane of ER
Rough ER
"Rough" because of ribosomes on the surface |
site of synthesis for: |
endomembrane system proteins |
secreted proteins |
Endomembrane system: ER, golgi, lysosome, cell membrane |
Secreted proteins function outside cells (eg. antibodies) |
>nucleus/rough/smooth ER -> vesicle -> golgi -> vesicle -> lysosome or cell membrane |
Chloroplast
Site of photosynthesis (CO2 to glucose etc. using light energy) |
(plants, photosynthetic protists) |
Thylakoid- flat stacks of membrane, possess photosynthetic enzymes |
>site of light reaction |
Stroma- aqueous solution within chloroplast |
>site of dark reaction/Calvin cycle |
Double phospholipid bilayer membrane |
endosymbiotic origins: photosynthetic prokaryote became organelle in eukaryote |
Evidence of Endosymbiosis
Mitochondria and Chloroplasts possess: |
>double phospholipid bilayer membrane |
>mtDNA (mitochondrial DNA) |
>cpDNA (chloroplast DNA) |
>ribosomes |
>division that mimics that of bacteria (binary fission) |
>division is completed when 'half-life' of mitochondria/chloroplast is spent
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