Eukaryotic Microbiology

Question 1

what is a phylogenetic tree ?

Answer 1

a diagram that represents evolutionary relationships among organisms.

Question 2

what is a mitochondria ?

Answer 2

Sub-compartments of eukaryotic cells (organelles) which generate energy, breakdown some waste products, produce chemicals the cell needs. Also have a role in apoptosis (in multicellular organisms), require oxygen.

Question 3

what is a plastid ?

Answer 3

sub-compartment of eukaryotic cells (organelles) particularly found in plants and algae. frequently contain pigments for photosynthesis (chlorophyll containing = chloroplast).

Question 4

how do you know things are related ?

Answer 4

1. similarity of shape or form
2. similarity of molecular structure
   - compare conserved structures e.g. ribosomes and ribosomal RNA

Question 5

how is the relationship of 18S rRNA genes in eukaryotes different to 16S rRNA genes in prokaryotes ?

Answer 5

Relationship of 18S rRNA genes is much less strong for eukaryotes than 16S rRNA genes are for prokaryotes

Question 6

what are the other genes that have been used to construct phylogenies ?

Answer 6

tubulin, RNA polymerase, and ATPase

Question 7

what is a eukaryotic cell ?

Answer 7

contains a membrane-enclosed nucleus and other organelles (e.g. mitochondria, Golgi complex, endoplasmic reticula, microtubules, and microfilaments)

Question 8

what is the difference between a prokaryotic and eukaryotic cell ?

Answer 8

Prokaryotic cells are smaller than eukaryotic cells and they do not contain a nucleus.

Question 9

The nucleus

Answer 9

1. contains the chromosomes
2. DNA is wound around histones to form chromatin
3. visible under light microscope without staining

Question 10

what is the nucleolus ?

Answer 10

it is within in the nucleus and it is the site of RNA synthesis

Question 11

Mitochondria

Answer 11

1. site of respiration and oxidative phosphorylation
2. 1 to over 1000 per cell
3. surrounded by two membranes: outer and inner membrane
4. outer membrane contains large number of integral porins that allow molecules of less than 5000 daltons to freely diffuse across the membrane
5. cristae = folded internal membrane
   - contains enzymes needed for respiration and ATP production
6. matrix = the inner most membrane
   - contains enzymes for the oxidation of organic compounds

Question 12

Hydrogenosome

Answer 12

• similar in size to mitochondria
• lacks TCA cycle enzymes and cristae
• present in Trichomonas and various protists including anaerobic ciliates, and fungi

Question 13

Endoplasmic reticulum (ER)

Answer 13

Two types of ER: smooth and rough

• rough contains attached ribosomes; smooth does not
• smooth ER participates in the synthesis of lipids
• rough ER is a major producer of glycoproteins

Question 14

Golgi complex

Answer 14

• modifies products of the ER destined for secretion

- addition of carbohydrates (glycosylation) and phosphates (phosphorylation)

Question 15

Lysosomes and Vacuoles

Answer 15

-membrane enclosed compartments
-contains digestive enzymes used for hydrolysis of biomolecules including:
proteins
nucleic acids
carbohydrates
lipids
cellular debris
- allow hydrolytic activity to occur within the cell without damaging other cellular components

Question 16

The Cytoskeleton

Answer 16

-helps maintain cell shape and internal organisation. Provides mechanical support so that cells can move and divide

Question 17

How many filamentous proteins is the cytoskeleton made up of and what are they called ?

Answer 17

3 sorts:

• microtubules (largest)
• actin (smallest)
• intermediate

Question 18

what is the diameter of Microtubules ?

Answer 18

25nm

Question 19

what is microtubules composed of ?

Answer 19

alpha and beta - tubulin

Question 20

what is the function of the microtubules ?

Answer 20

function in maintaining cell shape, in motility, in chromosome movement, and in movement of organelles

Question 21

what is the diameter of the microfilaments ?

Answer 21

7nm

Question 22

what is the microfilament made of ?

Answer 22

polymers of actin

Question 23

what is the function of the microfilament ?

Answer 23

function in maintaining cell shape, motility by pseudopodia and in cell division

Question 24

what is the size of the intermediate filament ?

Answer 24

8-12nm in diameter

Question 25

what is the intermediate filament made of ?

Answer 25

keratin proteins

Question 26

what is the function of the intermediate filament?

Answer 26

function in maintaining cell shape ad positioning of organelles in cell

Question 27

what is intracellular transport ?

Answer 27

is the movement of transport vesicles, organelles, chromosomes, mRNA, rafts of proteins, and substances within the cell

Question 28

why is intracellular transport unique to eukaryotes ?

Answer 28

this is because they possess membrane enclosed organelles and compartments - unlike prokaryotic cells which do not have membraneous organelles and compartments

Question 29

Flagella and Cilia

Answer 29

• allow cells to move by swimming
• cilia are short flagella
• structurally distinct from prokaryotic flagella
• bundle of 9 pairs of microtubules surrounding the central pair
• Dynein is attached to the microtubules and uses ATP
• Propel the cell using a whip-like motion

Question 30

what is primary endosymbiosis ?

Answer 30

suggested that organelles are descendants of ancient, engulfed prokaryotic cells

Question 31

Mitochondria arose from …

Answer 31

Proteobacteria

Question 32

chloroplast arose from…

Answer 32

Cyanobacteria

Question 33

what are some of the evidence that supports the endosymbiotic theory ?

Answer 33

• mitochondria and chloroplast contain DNA
• eukaryotic nuclei contain genes derived from bacteria
• mitochondria and chloroplasts contain their own ribosomes which are more similar to bacterial ribosomes (70s)

Question 34

what is secondary symbiosis ?

Answer 34

further development and divergence of eukaryotic cells into different eukaryotic families resulted from further engulfment events