Cloned from: Tour of the Cell

by Noojin


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Cell
A membrane-enclosed unit  filled with concentrated water-based solution of chemicals (cytoplasm) that is able to create copies of itself by growing and dividing in two
Hallmark Charactertistics of Cells
Build from proteins, nucleic acids, carbohydrates and lipids/fats

Could grow, develop and divide Maintain constant environment inside the cell

Exchange nutrients and signals with other cells and the environment

Could differentiate and fulfill specialized functions
All Cells are:
Surrounded by cellular membrane

Full of cytoplasm

Contain specialized organelles, i.e. “machines” to do things


Contain DNA with the genetic program of the cell
Prokaryotic Cells
Smaller (1-10 micrometers)

Older (~3.5 billion years)

Simpler


Lack nucleus

Minimal number of organelles


No organelles containing membranes
Eukaryotic Cells
Bigger (10-100 micrometers)

Younger (~ 2.2 billion years)


Complex


Have nucleus

Specialized organelles

Endomembrane system
What do both Eukaryotes and Prokaryotes have in common?
Plasma membrane (cellular membrane)

Cytoplasm

Ribosomes

Genetic material
Plasma Membrane
The plasma membrane separates the living cell from its nonliving surroundings

Controls the import of nutrients and the export of waste

Receives and transmits signals from the environment
Cytoplasm
The internal content of the cell

Cytosol – water–based solution of chemicals

Cytoplasmic organelles – distinct structures specialized to fulfill specific function(s)
Ribosomes
Not limited from  a membrane

Differences in size and composition between prokaryotes and eukaryotes


Many antibiotics kill bacteria by binding to their ribosomes and stopping protein synthesis
Mitochondria
Double membrane organelles

Have its own ribosomes and genome (prokaryote-like)


Sites of cellular respiration, i.e. the production of ATP from food molecules.
Chloroplasts
Double membrane organelles: outer and inner membrane

Have its own ribosomes and genome (prokaryote-like)

Sites  of photosynthesis, i.e. the conversion of light energy to chemical energy ; carbohydrates synthesis
Rough ER
Produce proteins that are secreted, inserted into membranes, or transported in vesicles to other organelles
Smooth ER
Synthesizes lipids

Processes toxins and drugs in liver cells


Stores and releases calcium ions in muscle cells
Goldgi Apparatus
Works in partnership with the ER

Finishes, stores, and distributes the chemical products of cells

Synthesis of some carbohydrates
Lysosomes
membrane-enclosed sacs with digestive enzyme breakdown of macromolecules from food or damaged cellular structures
Vacuoles
Vacuoles are membranous sacs full with fluid

Involved in  cellular movement (protists, contractile vacuoles), maintenance of the plant turgidity (plant central vacuole) or storage
Cell Wall Plants vs Animals
Plants:
build from cellulose fibers


maintains cell shape
prevents

cells from absorbing too much water


Animals:
“soft” extracellular matrix, build mainly from glycoproteins

helps hold cells together in tissues

protects the integrity of the plasma membrane
Cytoskeleton
reinforce the cell and maintain cellular shape

give the cell rigidity

provide anchors for organelles and act as tracks for organelle movement


build the mitotic spindle during cell division
Animal Cell Image
Endoplasmic Reticulum Image
Rough Endoplasmic Reticulum Image
Eukaryotic Cell Image
Nucleus Image
Prokaryotic Cell Image

Cell Membrane
Free Nucleic Acid
Cell Membrane
Cytoplasm with Ribosmes
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