Title: 20.2: Bacteria
120.2 Bacteria
- Recommended reading
- pp. 462-464
2Overview
- Comparing Bacteria with Eukaryotes.
- Bacteria and the Surrounding Environment.
3Comparing Bacteria with Eukaryotes.
- Bacteria outnumber all eukaryotes combined.
- There are seven important characteristics that
distinguish bacteria (prokaryotes) from
eukaryotes.
4Comparing Bacteria with Eukaryotes.
- Internal compartmentalization bacteria lack a
nucleus, unlike eukaryotes. Bacteria have no
internal compartments or membrane systems.
5Comparing Bacteria with Eukaryotes.
Prokaryotic Cell
Eukaryotic Animal Cell
6CHECKPOINT
- What are the two major things that prokaryotic
cells lack when compared to eukaryotic cells? - Nucleus Internal Compartments
7Comparing Bacteria with Eukaryotes.
- Cell size Eukaryotic cells are, on average, ten
times the size of a prokaryotic cell.
8Comparing 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.
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10Comparing Bacteria with Eukaryotes.
- Chromosomes Bacterial chromosomes are a single
piece of circular DNA as opposed to eukaryotic
chromosomes, which are linear.
11Comparing Bacteria with Eukaryotes.
- Cell Division Bacteria divide by binary fission,
however eukaryotes divide by the process of
mitosis.
12Comparing 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.
13BINARY FISSION
14CHECKPOINT
- Before dividing into two IDENTICAL cells, the DNA
in bacteria attaches itself to the _________
_____________ ? - Plasma (Cellular) Membrane
15Comparing 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!
16Comparing 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).
17Comparing 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.
18Bacteria 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.
19Bacteria and the Surrounding Environment
- Endospore tough coating that is highly resistant
to environmental stress. - Process takes about eight hours from the time
synthesis begins.
20Bacteria 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.
21Bacteria and the Surrounding Environment
- Once favorable conditions resume, a rupture or
absorption of the spore coat occurs (activation).
22CHECKPOINT
- 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.
23Summary
- Bacteria (prokaryotes) exhibit many different
characteristics than eukaryotes. - Bacteria can withstand stressful environments
through use of endospores.
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