2- Chapter 2

Question 1

What is morphology?

Answer 1

It means cell shape

Question 2

What are the stalk and hypha shapes of bacteria?

Answer 2

Stalk is like a cylinder balloon and hypha is a balloon with a sphere on the end

Page 35 in text book

Question 3

What is the reason for upper size limits for prokaryotic cells?

Answer 3

Decreasing ability of larger and larger cells to transport nutrients
Surface area to volume ratio is very small

Higher surface are to volume ratio is better so small cells are better, means can exchange nutrients and waste products with its environment faster

Question 4

Out of the two, prokaryotes and eukaryotes, which has a better chance to adapt to its environment and why?

Answer 4

Prokaryotes since they’re smaller and express mutations quicker since they are haploid so favourable mutation survive longer and reproduce

Question 5

What is the lower limit to how small cells can be? Why?

Answer 5

0.15 μm-0.20μm

This is because there is a smallest point where the internal components of a cell need to fit

Question 6

How are sterols helpful to cytoplasmic membranes?

Answer 6

They are rigid and planar structures that strengthen the membranes of eukaryotic cells (since most lack a cell wall)
Hapanoid is a sterol like structure that does this

Question 7

How is the cytoplasmic membrane of archaea different than bacteria and Eukarya?

Answer 7

The lipids of archaea contain ether bonds between glyrcerol and a hydrophobic side chain that is NOT a fatty acid, it is repeating units of the five carbon hydrocarbon isoprene
Page 41

Question 8

What are the three major functions of the cytoplasmic membrane?

Answer 8

1. Cells permeability barrier, prevents leak of solutes on or out of cell
2. Anchored several proteins that catalyze a bunch of key cell functions
3. Bacteria and archaea membrane plays a major role in energy conservation and consumption

Question 9

What is cell lysis?

Answer 9

A process used to withstand the pressures of osmotic pressure and prevent bursting
Cell walls use this besides holding the shake of the cell

Question 10

What’s the difference structurally between gram positive and gram negative cell walls?

Answer 10

Gram positive wall is thicker and consists primarily of a single type of molecule
Gram negative wall consists of two layers

Question 11

What is peptidoglycan?

What’s the one thing that can destroy it?

Answer 11

A rigid polysaccharide that confers structural strength on the cell
Found in all bacteria that contain a cell wall
But not in cell walls of archaea or Eukarya

Lysozyme, an enzyme that cleaves glycosidic bonds in it can destroy it and penicillin

Question 12

What are teichoic acids?

What are lipoteichoic acids?

Answer 12

Acidic molecules produces by gram positive bacteria that are composed of glycerol phosphate or ribitol phosphate
Function to bond divalent metal ions (Ca, Mg) before they transport into the cell

Lipoteichoic acids are teichoic acids bonded to the lipids inside the membrane
Picture on page 45

Question 13

What is the outer membrane of a gram-negative bacteria?

Answer 13

It is a second lipid bilayer that has polysaccharides and lipids linked to form a complex called the lipopolysaccharide layer or LPS

Question 14

How is the outer membrane linked to the peptidoglycan layer in gram negative bacteria?

Answer 14

By the Braun Lipoprotein

Question 15

What is the periplasm?

What can it hold?

Answer 15

A space between the outer surface of the cytoplasmic membrane and the inner surface of the outer membrane where extracellular proteins reside
Holds hydrolytic enzymes, binding proteins, chemoreceptors, and proteins

Question 16

What are porins and where are they located in a gram-negative cell wall?

Answer 16

Proteins that function as channels for the entrance and exit of solutes
Found in the outer membrane

Question 17

What is pseudomurein?

Answer 17

Remarkably similar to peptidoglycan found in the cell walls of certain archaea
Immune from destruction by lysozymes and penicillin

Question 18

What is the S-layer in archaea and what are its functions?

Answer 18

The common cell wall in archaea that consists of interlocking molecules of protein or glycoprotein (can be hexagonal tetragonal etc)
They are strong to withstand osmotic pressure
Also acts as a passage into the cell which it can select what goes in

Question 19

What are the difference between capsules and slime layers?

Answer 19

Capsules are organized in a tight matrix that excludes small particles and is tightly attached (easy to see with microscope)
Slime layers are more easily deformed and loosely attached and will not exclude particles
(Hard to see with microscope)

Question 20

What are cell inclusions?

What is the most common inclusion in prokaryotic organisms?

Answer 20

Inclusions function as energy reserves or carbon reservoirs or have special functions
Most common is poly-β-hydroxybutryic acid (PHB)

Question 21

What are magentosomes?

Answer 21

Biomineralized larricles of the magnetic iron oxides magnetite or greigite
They impart a magnetic dipole on a cell allowing it to have a magnetic field

Question 22

What are gas vesicles?

What is it composed of?

Answer 22

Structures that confer buoyancy and allow the cells to position themselves in regions of the water column that best suit their metabolism
Cyanobacteria forming blooms in lakes is an example

Two distinct proteins compose gas vesicles: GvpA forms shell and GvpC strengthens shell

Question 23

What are endospores?

Answer 23

Cells produced by bacteria that are extremely resistant to heat, harsh chemicals, and radiation
Function as survival structures

Question 24

What happens when an endospore germinates?

Answer 24

Happens by a loss of refractility of the endospore and a loss of resistance to heat and chemicals

Question 25

What is sporulation and it’s staged briefly?

Answer 25

It is the form of cellular differentiation
It is asymmetric cell division where an endospore in made in a mother cell then grows until it is freed from mother can can germinate into a vegetative cell

Question 26

What is polar flagellation, peritrichous flagellation, and lophotrichous flagellation?

Answer 26

Polar flagellation- the flagella are attached to one or both ends of a cell
Peritrichous flagellation- the flagella are inserted around the cell surface
Lophotrichous flagellation- means a rift of flagella present at only one point on bacteria cell

Question 27

What is the Archaella?

Answer 27

The flagella in archaea
Half the diameter of the flagella
Is one tenth the speed of flagellum

Question 28

What is chemotaxis and phototaxis?

Answer 28

Taxis is when cells of bacteria and archaea encounter physical or chemical agents in nature and have evolved an ability to respond by moving towards or away
Chemotaxis is a response to chemicals
Phototaxis is a response to light

Question 29

What is aerotaxis, osmotaxis, and hydrotaxis?

Answer 29

Aerotaxis- response to oxygen
Osmotaxis- response to ionic strength
Hydrotaxis- response to water

Question 30

What happens when a flagella rotates counterclockwise? Clockwise?

Answer 30

Counterclockwise- pushes bacterium in a direction

Clockwise- bundle of flagella push apart which stops motion and causes cell to tumble

Question 31

What is scotophobotaxis and how does it differ from phototaxis?

Answer 31

Scotophobotaxis- when ohitotropic bacterium happens to swim outside the illuminated field of view into darkness (on microscope)

Phototaxis differs in that cells move up a light gradient from lower to higher intensities

Question 32

How is DNA within the nucleus wound up?

Answer 32

Wound up into positively charged proteins called histones

Question 33

What is the mitochondria in eukaryotic cells?

Answer 33

Respiration occurs here

Contain folded internal membranes called Cristae which contain the enzymes needed for respiration and ATP production

Question 34

What are hydrogenosomes in eukaryotic cells?

Answer 34

Some eukaryotic organisms are killed by oxygen and live an anaerobic lifestyle
These cells lack mitochondria and contain hydrogenosomes instead
Carry out fermentative metabolism

Question 35

What are chloroplasts in the eukaryotic cell?

Answer 35

Carry out photosynthesis
Inside is the stroma that contains the enzyme for converting Co2 to organic compounds
Also has flattened membrane discs called thylakoids where chlorophyll and all other components needed for ATP synthesis are located

Question 36

What is the endosymbiotic hypothesis?

Answer 36

The idea of symbiotic bacteria as he ancestors of the mitochondria, hydrogenosome, and chloroplast

Question 37

What is the endoplasmic reticulum, golgi complex, and lysosomes?

Answer 37

Endoplasmic reticulum- network of membranes continuous with the nuclear membrane
Golgi complex- stack of membrane bound sacks called cisternae and it chemically sorts and modifies products of the ER
Lysosomes- contain digestive enzymes that hydrolyzs proteins

Question 38

What are microtubules, microfilaments, and intermediate filaments?

Answer 38

Microtubules are hollow tubes that maintain cell shale and cell motility by cilia and flagella
Microfilaments are smaller than microtubules and maintain or change cell shape and cell division helper
Intermediate filaments are keratin proteins that maintain cell shape and position organelles in the cell