Ch-1 Introduction to Cells

May-12-2015

Bio-2600
Introduction to Cell Biology
Textbook (required)
Essential Cell Biology
FOURTH EDITION

Alberts • Bray • Hopkin • Johnson • Lewis • Raff • Roberts • Walter
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Ch-1 Introduction to Cells

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Chapter 1
Introduction to Cells
 A colony of bacteria, a butterfly, a rose, and a dolphin are all made of cells.
 They all have a fundamentally similar chemistry and operate according to the same basic principles. Cell Bio Spring-2015

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Ch-1 Introduction to Cells

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 Cells were discovered in 1665 by Robert Hooke
 Early studies of cells were conducted by
 Mathias Schleiden (1838)
 Theodor Schwann (1839)

 Schleiden and Schwann proposed the Cell Theory

Cell Theory
1. All organisms are composed of cells

2. Cells are the smallest living things
3. Cells arise only from pre-existing cells

 All cells today represent a continuous line of descent from the first living cells
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Electron microscopes
 Transmission electron microscopes transmit electrons

through the material

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Electron microscopes
 Scanning electron microscopes beam electrons onto the

specimen surface

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Basic structural similarities
1. Nucleoid or nucleus where DNA is located
2. Cytoplasm


Semifluid matrix of organelles and cytosol

3. Ribosomes


Synthesize proteins

4. Plasma membrane


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Phospholipid bilayer

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Ribosomes
 Cell’s protein synthesis machinery
 Found in all cell types in all 3 domains
 Ribosomal RNA (rRNA)-protein complex
 Protein synthesis also requires messenger

RNA (mRNA) and transfer RNA (tRNA)
 Ribosomes may be free in cytoplasm or associated with internal membranes

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Endomembrane System
 Series of membranes throughout the

cytoplasm
 Divides cell into compartments where different cellular functions occur
 One of the fundamental distinctions between eukaryotes and prokaryotes

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Prokaryotic Cells
 Simplest organisms
 Lack a membrane-bound nucleus
 DNA is present in the nucleoid

 Cell wall outside of plasma membrane
 Do contain ribosomes (not membrane-bound

organelles)
 Two domains of prokaryotes
 Archaea
 Bacteria
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Eukaryotic Cells
 Possess a membrane-bound nucleus
 More complex than prokaryotic cells
 Hallmark is compartmentalization
 Achieved through use of membrane-bound

organelles and endomembrane system

 Possess a cytoskeleton for support and to maintain cellular structure

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Nucleus
 Repository of the genetic information
 Most eukaryotic cells possess a single nucleus
 Nucleolus – region where ribosomal RNA

synthesis takes place
 Nuclear envelope
 2 phospholipid bilayers

 Nuclear pores – control passage in and out

 In eukaryotes, the DNA is divided into multiple linear chromosomes
 Chromatin is chromosomes plus protein
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