1.7. Bacteria Flashcards
The earliest known fossil of prokaryotes
are about 3.5 billion years old
The Earth was formed about
4.5 billion years ago
Most biologists believe that eukaryotes evolved from prokaryotes about
2 billion years ago
The two groups of prokaryotes are
Bacteria and Archaea
The thing that distinguishes bacteria from Archaea
is its ability to form spores.
What is bacterial cell wall made up of?
A strengthening material called peptidoglycan.
What is peptidoglycan
A polysaccharide combined with amino acids
What is peptidoglycan also known as
Murein
What is benefit of cell wall being made with peptidoglycan
It makes the bacterial cell wall more rigid
What are the benefits of cell walls in bacteria
The cell wall protects the bacterium and is essential for its survival. It prevents the cell from blowing and bursting if water enters the cell by osmosis.
What does the cytoplasm in a bacterium not contain
any double membrane bound organelles (such as mitochondria)
What does the cytoplasm in bacterium not contain
any double membrane bound organelles (such as mitochondria)
The DNA molecule in bacteria is
Curcular
The DNA molecule in bacteria is found in a region called
Nucleoid
What is found in nucleoid in a bacteria
The DNA, proteins and small amounts of RNA
There may be more than one copy of DNA molecule in a given cell
What is the size if bacterial ribosomes
70S ribosomes
Some bacteria are able to swim because
They one or more flagella
Describe the structure of bacterial flagella and its how it performs its function
The bacterial flagellum is a simple hollow cylinder made of identical, protein molecules. it is a rigid structure, so it does not band unlike the flagella in eukaryotes. It is wave shaped and works by rotating at its base like a propeller to push the bacteria through its liquid environment. As a result, the bacterium moves forward with Corkscrew shaped motion.
What’s the function infolding of cell surface membrane that is found in some bacteria
In some bacteria, the self surface membrane falls into the cell, forming an extra surface on which certain biochemical reactions can take place.
What are some of the biochemical reactions that can take place in certain bacteria
In blue green bacteria, the infolded membranes contain for synthetic pigments which allow photosynthesis to take place
In some bacteria, nitrogen fixation takes place on the enfolded membrane.
What is nitrogen fixation
Nitrogen fixation is the ability to convert nitrogen in the air to nitrogen containing compounds such as ammonia inside the cell.
Why is the ability of bacterial cells to perform nitrogen fixation so crucial
All life depends on nitrogen fixation which the eukaryotes cannot carry out by themselves.
some bacteria are surrounded by an extra layer outside the cell wall. This may take the form of
A capsule or a slime layer
While a capsule is the definite structure made mostly of polysaccharides
The slime layer is more diffuse and easily washed off
What are some of the functions of a capsule or a slime layer
Both help to protect the bacteria from drying out
A capsule helps protect some bacteria from antibiotics.
Some capsules prevent white blood cells, known as phagocytes from engulfing disease causing bacteria.
What is a plasmid?
A plasmid is a small circle of DNA separate from the main DNA of the cell. It contains only a few genes. Many plasmids may be present in a given cell.
What are some useful functions that plasmids have
plasmids contain genes that give resistance to particular antibiotics, such as penicillin. Plasmids can copy themselves independently of the chromosomal DNA and can spread rapidly from one bacterium to another.
What are Pili
Pili are fine protein rods that vary in stiffness and length.
How many pili may be present in a single cell
One to several hundred
What are pili useful for
They are used for attachment and interactions with other cells (they allow the transfer of genes, including plasmids, from one bacterium to another during conjugation) or surfaces.
Plasmid DNA is not associated with protein and is referred to as
Naked DNA
