Chapter 2- 2.6- Prokaryotic and eukaryotic cells

Question 1

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the nucleus?

Answer 1

Prokaryotic- Not present

Eukaryotic- Present

Question 2

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the DNA?

Answer 2

Prokaryotic- Circular

Eukaryotic- Linear

Question 3

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the DNA organisation?

Answer 3

Prokaryotic- proteins fold and condense DNA

Eukaryotic- Associated with proteins called histones

Question 4

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the extra chromosomal DNA?

Answer 4

Prokaryotic- Circular DNA called plasmids

Eukaryotic- Only present in certain organelles such as chloroplasts and mitochondria

Question 5

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the organelles?

Answer 5

Prokaryotic- Non membrane-bound

Eukaryotic- Both membrane-bound and non membrane-bound

Question 6

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the cell wall?

Answer 6

Prokaryotic- Peptidoglycan

Eukaryotic- Chitin in fungi, cellulose in plants, not present in animals

Question 7

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the ribosomes?

Answer 7

Prokaryotic- smaller 70S

Eukaryotic- larger, 80S

Question 8

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the cytoskeleton?

Answer 8

Prokaryotic- Present

Eukaryotic- Present, more complex

Question 9

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the reproduction?

Answer 9

Prokaryotic- Binary fission

Eukaryotic- Asexual or sexual

Question 10

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the cell type?

Answer 10

Prokaryotic- unicellular

Eukaryotic- Unicellular and multicellular

Question 11

What is the similarity or difference between prokaryotic and eukaryotic cells in reference to the cell-surface membrane?

Answer 11

Prokaryotic- Present

Eukaryotic- Present

Question 12

Prokaryotes can be divided into two evolutionary domains what are they?

Answer 12

Archaea and Bacteria.

Which evolved from an ancient common ancestor.

Question 13

What are extremophiles?

Answer 13

The early cells were adapted to living in extremes of salinity, pH and temperature.

These organisms are known as extremophiles and they still exist today.

They can be found in hydrothermal cents and salt lakes- similar environments to those believed to have made up the early Earth.

They are usually the domain of Archaea and more recently they have been found in more hospitable environments such as soil and the human digestive system.

Question 14

Prokaryotic organisms are always unicellular with a relatively simple structure.
Explain where there DNA is, if they have few or many organelles and if they are membrane bound or not?

Answer 14

DNA is not contained within the nucleus.

They have few organelles and the organelles are not membrane bound.

Question 15

What is the difference between the structure of the DNA within prokaryotes compared to eukaryotes ?

Answer 15

They are packaged differently.

Prokaryotes generally only have one molecule of DNA, a chromosome, which is supercoiled to make it more compact.

The genes on the chromosome are often grouped into operons, meaning a number of genes are switched on or off at the same time.

Question 16

What are the differences between prokaryotic cells and eukaryotic cells in reference to ribosomes?- extended.

Answer 16

The ribosomes in prokaryotic cells are smaller than those in eukaryotic cells.

Their relative size is determined by the rate at which they settle, or form a sediment, in solution.

The larger eukaryotic ribosomes are designated 80S and the smaller prokaryotic ribosomes, 70S. They are both necessary for protein synthesis, although the larger 80S ribosomes are involved in the formation of more complex proteins.

Question 17

What are the differences between prokaryotic cells and eukaryotic cells in reference to the cell wall? - extended.

Answer 17

Prokaryotic cells have a cell wall made from peptidoglycan, also known a murein. It is a complex polymer formed from amino acids and sugars.

Question 18

What are the differences between prokaryotic cells and eukaryotic cells in reference to the flagella? - extended.

Answer 18

The flagella of prokaryotes is thinner than the equivalent structure of eukaryotes and does not have the 9+2 arrangement.

The energy to rotate the filament that forms the flagellum is supplied from the process of chemiosmosis, not from ATP as in eukaryotic cells.

The flagellum is attached to the cell membrane of a bacterium by a basal body and rotated by a molecular motor.

The basal body attaches the filament comprising the flagellum to the cell-surface membrane of a bacterium.

A molecular motor causes the hook to rotate giving the filament a whip like movement, which propels the cell.

Question 19

Explain eukarotic cells?

Answer 19

The first eukaryotic cells appeared about 1.5 billion years ago.
They are more complex than prokaryotic cells and their DNA is present within the nucleus and exists as multiple chromosomes, which are supercoiled, and each one wraps around a number of proteins called histones, forming a complex for efficient packaging.

This complex is called chromatin and chromatin coils and condenses to form chromosomes.

Eukaryotic genes are generally switched on and off individually.

Eukaryotic cells have membrane-bound organelles including mitochondria and chloroplasts.

Organisms from the plant, animal, fungi, and protoctista kingdoms are all composed of eukaryotic cells. Many are multicellular.