华中农业大学：《微生物学》课程教学课件（PPT讲稿，英文版）Chapter 2 Cell biology

Chapter 2 Cell Biology

Chapter 2 Cell Biology

Chapter outline 2. 1 Overview of the structure of microbial cells 2.2 Procaryotic cell wall 2. 3 Cytoplasmic membrane 2. 4 Cellular genetic information 2.5 Cytoplasmic matrix -Ribosome and Inclusions 2.6 Components external to the cell wall 2.7 Bacterial endospores 2. 8 Comparison of the prokaryotic and eukaryotic ce elI

2.1 Overview of the structure of microbial cells 2.2 Procaryotic cell wall 2.3 Cytoplasmic membrane 2.4 Cellular genetic information 2.5 Cytoplasmic matrix – Ribosome and Inclusions 2.6 Components external to the cell wall 2.7 Bacterial endospores 2.8 Comparison of the prokaryotic and eukaryotic cell Chapter outline

Overview of cell structure A procaryotic cell A eucaryotic cell

A procaryotic cell A eucaryotic cell Overview of cell structure

The prokaryotic cell 1. Their genetic material (DNA)is not enclosed within a membrane and they lack other membrane bounded organelles 2. Their dna is not associated with histidine 3. Their cell wall almost al ways contain the complex polysaccharide peptidoglycan 4. They are very small

3. Their cell wall almost always contain the complex polysaccharide peptidoglycan The prokaryotic cell 1. Their genetic material (DNA) is not enclosed within a membrane and they lack other membrane – bounded organelles 2. Their DNA is not associated with histidine 4. They are very small!!

Size: Most bacteria fall within a range from 0.2 to 2.0 um in diameter and from 2 to 8 um in length A cyanobacterium 8 x 50 um 15x4m A rod-shaped prokaryote Microorganisms in ∈ TOuSe 1>sum Is typically about 1-5 general are very small micrometers(um) long and are completely and about I um wide invisible to the naked oam d eye raueuzae C25x 1.2um

Size: Most bacteria fall within a range from 0.2 to 2.0 um in diameter and from 2 to 8 um in length A rod-shaped prokaryote is typically about 1-5 micrometers (μm) long and about 1 μm wide Microorganisms in general are very small and are completely invisible to the naked eye. A cyanobacterium 8 x 50 um

SIze comparison of microorganisms Meters Visibility scale Relative size of microbes 103 1,000um 1 mm ked eye Prokaryotes 10-4 100pm 10-5 lO um Bacillus megaterium 6 1.000 nm or Eukaryotes 1 um Escherichia coli 10-7 100nm Light microscope Mycoplasma 0810nm Virus Viruses 10-9 1 nm Electron microscope

size comparison of microorganisms Meters Visibility scale Relative size of Microbes Prokaryotes Eukaryotes Viruses Naked eye Light microscope Electron microscope

Surface area and volume relationships in cells volUme.4.2wl r Carlson a cell increases in size its surface area -to 1-2um volume ratio decreases 5rs0a=503 wore.33.5 um' Surace 15

a cell increases in size, its surface area – to – volume ratio decreases Surface area and volume relationships in cells

Shape: bacteria have a few basic shapes spherical coccus Coccus Rod-shaped bacillus spirillum

spirallum Shape: Bacteria have a few basic shapes spherical coccus Rod-shaped bacillus

Prokaryotic cell wall The cell wall of the bacterial cell is a complex semi-rigid structure that is responsible for the characteristic shape of the cell. The cell wall surrounds the underlying, fragile plasma (cytoplasmic) membrane and protects it and internal parts of the cell from adverse changes in the surrounding environment Almost all prokaryotes have cell walls

• The cell wall of the bacterial cell is a complex, semi-rigid structure that is responsible for the characteristic shape of the cell. The cell wall surrounds the underlying, fragile plasma (cytoplasmic) membrane and protects it and internal parts of the cell from adverse changes in the surrounding environment. • Almost all prokaryotes have cell walls. Prokaryotic cell wall

Schematic diagram of bacterial cell walls Grant rram Peptidoglycan 一 Peptidoglycan Membrane Membrane I Periplasm Lipopolysaccharide and protein Bacteria can be divided into two major groups, called gram-positive and gram-negative. The original distinction between gram-positive and gram-negative was based on a special staining procedure, the Gram stain

Gram+ Gram - Schematic diagram of bacterial cell walls Bacteria can be divided into two major groups, called gram-positive and gram-negative. The original distinction between gram-positive and gram-negative was based on a special staining procedure, the Gram stain