20.2: Bacteria - PowerPoint PPT Presentation

1 / 24
About This Presentation
Title:

20.2: Bacteria

Description:

20.2: Bacteria Recommended reading: pp. 462-464 – PowerPoint PPT presentation

Number of Views:156
Avg rating:3.0/5.0
Slides: 25
Provided by: Michael3009
Category:

less

Transcript and Presenter's Notes

Title: 20.2: Bacteria


1
20.2 Bacteria
  • Recommended reading
  • pp. 462-464

2
Overview
  • Comparing Bacteria with Eukaryotes.
  • Bacteria and the Surrounding Environment.

3
Comparing Bacteria with Eukaryotes.
  • Bacteria outnumber all eukaryotes combined.
  • There are seven important characteristics that
    distinguish bacteria (prokaryotes) from
    eukaryotes.

4
Comparing Bacteria with Eukaryotes.
  • Internal compartmentalization bacteria lack a
    nucleus, unlike eukaryotes. Bacteria have no
    internal compartments or membrane systems.

5
Comparing Bacteria with Eukaryotes.
Prokaryotic Cell
Eukaryotic Animal Cell
6
CHECKPOINT
  • What are the two major things that prokaryotic
    cells lack when compared to eukaryotic cells?
  • Nucleus Internal Compartments

7
Comparing Bacteria with Eukaryotes.
  • Cell size Eukaryotic cells are, on average, ten
    times the size of a prokaryotic cell.

8
Comparing Bacteria with Eukaryotes.
  • Multicellularity Bacteria are single-celled.
    Bacteria can cluster but are not considered
    multicellular like eukaryotes. Bacteria cells are
    not specialized like eukaryotes.

9
(No Transcript)
10
Comparing Bacteria with Eukaryotes.
  • Chromosomes Bacterial chromosomes are a single
    piece of circular DNA as opposed to eukaryotic
    chromosomes, which are linear.

11
Comparing Bacteria with Eukaryotes.
  • Cell Division Bacteria divide by binary fission,
    however eukaryotes divide by the process of
    mitosis.

12
Comparing Bacteria with Eukaryotes.
  • Binary Fission
  • Process by which a bacteria cells reproduce.
    Bacterial DNA molecule is replicated, separated
    and attached to the cell membrane then the cell
    splits into two identical cells, each containing
    an exact copy of the original cell's DNA.

13
BINARY FISSION
14
CHECKPOINT
  • Before dividing into two IDENTICAL cells, the DNA
    in bacteria attaches itself to the _________
    _____________ ?
  • Plasma (Cellular) Membrane

15
Comparing Bacteria with Eukaryotes.
  • Binary Fission (cont)
  • Similar to mitosis, but binary fission is a much
    more simplified process, which allows bacteria to
    reproduce rather quickly.
  • E. coli can divide as often as every 20 minutes!

16
Comparing Bacteria with Eukaryotes.
  • Flagella In bacteria, these are simple
    structures composed of a single fiber of protein.
    Spins in corkscrew motion to propel bacterial
    cells into motion. More sophisticated in
    eukaryotic organisms (composition and movement).

17
Comparing Bacteria with Eukaryotes.
  • Metabolic Diversity Bacteria can perform both
    anaerobic and aerobic respiration, whereas
    eukaryotes strictly carry out aerobic
    respiration. Some bacteria can obtain energy by
    oxidizing compounds such as sulfur or fixing
    nitrogen.

18
Bacteria and the Surrounding Environment
  • Bacteria can protect themselves from harsh
    environmental stress including drought, high
    temperatures, and lack of nutrients.
  • When a cell encounters harsh conditions, the
    synthesis of an endospore occurs.

19
Bacteria and the Surrounding Environment
  • Endospore tough coating that is highly resistant
    to environmental stress.
  • Process takes about eight hours from the time
    synthesis begins.

20
Bacteria and the Surrounding Environment
  • Endospores are resistant to most agents which
    would normally kill the cells they formed from.
  • Household cleaning products generally have no
    effect.

21
Bacteria and the Surrounding Environment
  • Once favorable conditions resume, a rupture or
    absorption of the spore coat occurs (activation).

22
CHECKPOINT
  • What are factors that may cause bacteria to form
    an endospore?
  • Environmental factors such as drought or extreme
    temperatures, even lack of nutrients for survival.

23
Summary
  • Bacteria (prokaryotes) exhibit many different
    characteristics than eukaryotes.
  • Bacteria can withstand stressful environments
    through use of endospores.

24
Next Day
  • Bacteria and Energy
Write a Comment
User Comments (0)
About PowerShow.com