1.7. Bacteria

Question 1

The earliest known fossil of prokaryotes

Answer 1

are about 3.5 billion years old

Question 2

The Earth was formed about

Answer 2

4.5 billion years ago

Question 3

Most biologists believe that eukaryotes evolved from prokaryotes about

Answer 3

2 billion years ago

Question 4

The two groups of prokaryotes are

Answer 4

Bacteria and Archaea

Question 5

The thing that distinguishes bacteria from Archaea

Answer 5

is its ability to form spores.

Question 6

What is bacterial cell wall made up of?

Answer 6

A strengthening material called peptidoglycan.

Question 7

What is peptidoglycan

Answer 7

A polysaccharide combined with amino acids

Question 8

What is peptidoglycan also known as

Answer 8

Murein

Question 9

What is benefit of cell wall being made with peptidoglycan

Answer 9

It makes the bacterial cell wall more rigid

Question 10

What are the benefits of cell walls in bacteria

Answer 10

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.

Question 11

What does the cytoplasm in a bacterium not contain

Answer 11

any double membrane bound organelles (such as mitochondria)

Question 12

What does the cytoplasm in bacterium not contain

Answer 12

any double membrane bound organelles (such as mitochondria)

Question 13

The DNA molecule in bacteria is

Answer 13

Curcular

Question 14

The DNA molecule in bacteria is found in a region called

Answer 14

Nucleoid

Question 15

What is found in nucleoid in a bacteria

Answer 15

The DNA, proteins and small amounts of RNA

Question 16

There may be more than one copy of DNA molecule in a given cell

Question 17

What is the size if bacterial ribosomes

Answer 17

70S ribosomes

Question 18

Some bacteria are able to swim because

Answer 18

They one or more flagella

Question 19

Describe the structure of bacterial flagella and its how it performs its function

Answer 19

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.

Question 20

What’s the function infolding of cell surface membrane that is found in some bacteria

Answer 20

In some bacteria, the self surface membrane falls into the cell, forming an extra surface on which certain biochemical reactions can take place.

Question 21

What are some of the biochemical reactions that can take place in certain bacteria

Answer 21

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.

Question 22

What is nitrogen fixation

Answer 22

Nitrogen fixation is the ability to convert nitrogen in the air to nitrogen containing compounds such as ammonia inside the cell.

Question 23

Why is the ability of bacterial cells to perform nitrogen fixation so crucial

Answer 23

All life depends on nitrogen fixation which the eukaryotes cannot carry out by themselves.

Question 24

some bacteria are surrounded by an extra layer outside the cell wall. This may take the form of

Answer 24

A capsule or a slime layer

Question 25

While a capsule is the definite structure made mostly of polysaccharides

Answer 25

The slime layer is more diffuse and easily washed off

Question 26

What are some of the functions of a capsule or a slime layer

Answer 26

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.

Question 27

What is a plasmid?

Answer 27

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.

Question 28

What are some useful functions that plasmids have

Answer 28

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.

Question 29

What are Pili

Answer 29

Pili are fine protein rods that vary in stiffness and length.

Question 30

How many pili may be present in a single cell

Answer 30

One to several hundred

Question 31

What are pili useful for

Answer 31

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.

Question 32

Plasmid DNA is not associated with protein and is referred to as

Answer 32

Naked DNA