Prokaryotic vs Eukaryotic cells

Question 1

What is a prokaryotic cell?

Answer 1

A cell before the nucleus
e.g. Bacteria and Archae

Question 2

What is Eukaryotic cell?

Answer 2

A cell with a true nucleus
e.g.Protists, fungi, animals,
and plants

Question 3

What are the 3 domains of life?

Answer 3

Prokaryotes
* Archaebacteria - unicellular
* Eubacteria – unicellular
Eukaryotes
* Eukaryotes – unicellular and multicellular

Question 4

Characteristics of prokaryotic cells

Answer 4

• Cytoplasm (contains ribosomes,
  storage granules) bound by the plasma membrane
• No nucleus, DNA in an unbound region called the
  nucleoid
• No membrane-bound organelles
• Generally smaller than eukaryotes (1-10 um)
• Cell membrane fold inwards
• have a cell wall

Question 5

Define Osmotic pressure

Answer 5

“Osmosis” – movement of solvent (H 2O)
molecules through a selectively permeable
membrane
“osmotic pressure” – the tendency of H 2O to
move into that solution by osmosis

Question 6

Why are prokaryotes considered masters of adaptation?

Answer 6

Prokaryotes thrive almost everywhere, including places
too acidic, salty, cold, or hot for most other organisms

Question 7

Structural and functional adaptations
contribute to prokaryotic success

Answer 7

• Most prokaryotes are unicellular, although some
  species form colonies
• Most prokaryotic cells are 0.5–5 μm, much smaller than
  the 10–100 μm of many eukaryotic cells
• Prokaryotic cells come in a variety of shapes. e.g. spheres (cocci), rods (bacilli), and spirals

Question 8

Cell surface of prokaryotic

Answer 8

• Bacterial cell walls contain peptidoglycan, a
  network of sugar polymers cross-linked by
  polypeptides
• Archaea cell walls contain polysaccharides
  and proteins but lack peptidoglycan
  Peptidoglycan

Question 9

Gram-negative vs Gram-positive cell wall in bacteria

Answer 9

Gram-negative bacteria (small pink) have less peptidoglycan and an outer membrane that can be toxic, and they are more likely to be antibiotic resistant
Gram-positive bacteria (purple) have a thick layer of peptidoglycan in their cell wall

Question 10

What is a capsule?

Answer 10

A polysaccharide or protein layer called a capsule covers many prokaryotes

Question 11

What are the functions of a capsule?

Answer 11

• adherence of cells to surfaces
• protection against dehydration
• inhibition of phagocytosis
• can shield the cell from the hosts immune system
• virulence factor because it enhances the ability of
  bacteria to cause disease

Question 12

What is a bacterial fimbriae and what are its funtions?

Answer 12

Fimbriae (attachment pili) are present on some
prokaryotes
* allow bacteria to stick to substrates or other individuals in a
colony

Question 13

What is sex pilli?

Answer 13

Sex pili are longer than fimbriae and allow prokaryotes to exchange DNA

Question 14

Define motility and its use

Answer 14

Motility is the ability of an organism to move independently, using metabolic energy.
* Most motile bacteria propel themselves by flagella
that different from eukaryotic flagella
* In a heterogeneous environment, many bacteria
exhibit taxis :the ability to move toward or away
from certain stimuli

Question 15

What is the structure of the flagellum?

Answer 15

• The motor of the flagellum is the basal
  apparatus
• ATP pumps transport protons out of the cell
• The basal apparatus is powered by the diffusion
  of the protons back into the cell

Question 16

signs of Internal organisation in prokaryotic cells

Answer 16

Some prokaryotes do have specialized membranes that perform metabolic functions
These are usually infoldings of the plasma membrane

Question 17

Photosynthesis and the Oxygen Revolution

Answer 17

Most atmospheric oxygen is of biological
origin (bacteria)

Question 18

Basic features of all cells

Answer 18

• Plasma membrane
• Semifluid substance called cytosol
• Chromosomes (carry genes)
• Ribosomes (make proteins)

Question 19

Characteristics of eukaryotic cells

Answer 19

• DNA in a nucleus that is bounded by a membranous nuclear envelope
• Membrane-bound structures called organelles
• Cytoplasm in the region between the plasma membrane and nucleus
• Eukaryotic cells are generally much larger than
  prokaryotic cells

Question 20

Hypothesis of endosymbiosis

Answer 20

proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells

• The prokaryotic ancestors of mitochondria and plastids
  probably gained entry to the host cell as undigested prey or internal parasites
• In the process of becoming more interdependent, the host and endosymbionts would have become a single organism
• Serial endosymbiosis supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events

* An endosymbiont is a cell that lives within a

Question 21

Key evidence supporting an endosymbiotic origin of mitochondria and plastids:

Answer 21

• Similarities in inner membrane structures and functions
• Division is similar in these organelles and some prokaryotes
• These organelles transcribe and translate their own DNA
  which shares similarity with bacterial DNA
• Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes

Question 22

Aerobic prokaryote similarity to mitochondria

Answer 22

Some aerobic bacteria have
infoldings of the plasma membrane
function as extra surface area in
cellular respiration in similar to cristae in mitchondria

Question 23

Photosynthetic prokaryote similarity to plastids

Answer 23

Photosynthetic prokaryotes called
cyanobacteria have thylakoid
membranes similar to the thylakoid membranes
in chloroplasts