prokaryotes and eukaryotes

Question 1

what are the 4 key processes that are common between prokaryote and eukaryote

Answer 1

• Growth
• Reproduction
• Responsiveness
• Metabolism

Question 2

what is growth in the process of life

Answer 2

-increase in size

Question 3

what is reproduction in the process of life

Answer 3

-an increase in number
•this may be accomplished sexually (using gametes, or sex cells)
•asexually (alone)

Question 4

what is responsiveness in the process of life

Answer 4

-the change of internal or external properties in response to changing environmental conditions
•The ability to move may not be common across all types

Question 5

what is metabolism in the process of life

Answer 5

-the ability to take in nutrients and utilise controlled chemical reactions to generate energy
•This energy is used to fuel the other three processes

Question 6

what do viruses do and not do

Answer 6

• Don’t grow
• Only reproduce in a host cell
• Only some are responsive to the host cell
• Uses the host cells metabolism

Question 7

what is the major difference between prokaryote and eukaryote

Answer 7

One of the major differences between the prokaryotes and eukaryotes is size
•Prokaryotes are typically 1μm in diameter
•Small size for control of metabolism in cytoplasm?•Eukaryotes can be 10-100μm
•1μm = 1 millionth of a meter, so very small.

Question 8

name and describe an exception of the difference in size between prokaryote and eukaryote

Answer 8

• In 1985, Epulopiscium fisheloni was discovered in sturgeon intestine
• Hair like structures originally thought to be cilia (eukaryotic), turned out to be bacterial flagella (prokaryotic)
• Cells are 600μm, so visible without a microscope

Question 9

difference and similarity of prokaryotes and eukaryotes

Answer 9

• Both eukaryotes and prokaryotes have a membrane bound structure capsule capable of the four processes
• However, there are differences between the organelles present
• Also differences in which organelles are present

Question 10

describe the cell structure in prokaryotic nucleus

Answer 10

• The word prokaryote comes from the Greek for before nucleus
• Prokaryotes do not have a nucleus, Eukaryotes do. •Genetic material is not surrounded by a membrane
• Bacteria may also carry additional genetic material on circular DNA molecules called plasmids
• Easily transferred between bacteria- antibiotic resistance

Question 11

describe the cell structure in eukaryotic nucleus

Answer 11

-DNA (negatively charged) wound around histones (positively charged)
•Tight packing into nucleosomes
•Chromosomes form from the nucleosomes
•In large eukaryotes, nucleus visible using light microscope (1-2um)

Question 12

is the central dogma of molecular biology the same for both eukaryotes and prokaryotes

Answer 12

yes it is same for both (picture)

Question 13

what is difference in ribosomes for prokaryote and eukaryote

Answer 13

•Assemble proteins from amino acids based on mRNA
•Contain significant amounts of RNA
•prokaryote ribosome has 70s 
-eukaryote ribosome has 80s
(picture)

Question 14

what did carl woese do

Answer 14

• He compared the gene sequences which coded for the small sub-units of RNA from:
• Methanogens
• Bacteria
• Eukaryotes
• He then looked at the association coefficients between the sequences

Question 15

the genetic material in prokaryotes and eukaryotes

Answer 15

There are differences between the genetic material and how it is stored within the Prokaryotic and Eukaryotic cell

Question 16

what are archaea

Answer 16

The Archaea are fancy Prokaryotes that are different from the Bacteria.

Question 17

where can bacteria carry genetic information that eukaryotes cannot

Answer 17

Bacteria can carry genetic information on plasmids, which eukaryotes cannot

Question 18

describe the cell wall in prokaryotes

Answer 18

Prokaryotic cells are surrounded by a cell wall.
•Provides structure, shape and some functions
•Protection from osmotic forces
•Cell adhesion (sticking together, or sticking to something else)
•Antimicrobial resistance (penicillin attacks cell walls, mammals do not have!)
•The Archaea have a cell wall, but it is different from the Bacteria

Question 19

what is the bacteria cell wall called

Answer 19

peptidoglycan

Question 20

describe the bacteria cell wall- peptidoglycan

Answer 20

-The bacterial cell wall is made from peptidoglycan
•Repeating units of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)
•NAG and NAM are covalently linked – “Glycan”
•The chains of Glycan are linked with a four amino acid cross-bridge – tetrapeptide “peptido”

Question 21

what did Hans Christian Gram come up with in 1884

Answer 21

he came up with that there are two types of common cell wall structures in a bacteria cell wall by doing the Gram Stain

Question 22

describe the gram stain and what it does (4)

Answer 22

• Crystal Violet – Stains Peptidoglycan Purple
• Iodine – ‘Fixes’ any bound crystal violet
• Ethanol – washes away any unbound crystal violet
• Carbol fuschin/safranin- Stains the cell wall

Question 23

what is Gram- Positive

Answer 23

• Thick peptidoglycan (as much as 90%)
• Teichoic acids
• Retains crystal violet

Question 24

what is Gram Negative

Answer 24

• Thin peptidoglycan
• No teichoic acids
• Outer membrane

Question 25

in the outer membrane what can lipid A do and when is it released

Answer 25

Lipid A is released on cell death, can trigger a number of responses in mammals, e.g. fever

Question 26

what is the capsule attached to in bacteria

Answer 26

Firmly attached to the cell wall in a tight matrix

Question 27

how are slime layers bound

Answer 27

loosely bound

Question 28

describe the capsule and slime layer in bacteria

Answer 28

* Polysaccharide based * Play a role in adhesion to surfaces – environmental and pathogenic purposes * Biofilms * Resistance to phagocytosis * Resistance to desiccation

Question 29

what is the fimbriae

Answer 29

protein filaments that allow sticking to surfaces for biofilms

Question 30

describe fimbriae

Answer 30

- bristle-like - present in multiple numbers - adhere to host tissues

Question 31

what is the pili

Answer 31

they are similar to fimbriae but longer. •Facilitate genetic exchange between prokaryotic cells. •Colonisation of surfaces •Motility

Question 32

describe pili

Answer 32

- bristle- like - longer than fimbriae - present singly or in pairs

Question 33

what are bacteria that lack cell wall referred to as

Answer 33

protoplasts

Question 34

give an example of a protoplast and describe it

Answer 34

an example of protoplast is Mycoplasma pneumonia •Membranes are ‘tougher’ to resist osmotic change •Pathogen, can bind to cilia in the respiratory tract, killing the cell and preventing mucus removal.

Question 35

describe archaeal cell walls

Answer 35

Not peptidoglycan based •Classification as different from bacteria •Reflect extreme environments (Term 2 lectures)•For instance, halophiles have SO4- incorporated to bind Na+

Question 36

what are archaeal cell walls based on

Answer 36

* Based on: * Pseudomurein * Polysaccharides * Glycoproteins

Question 37

what do eukaryotes cell wall do

Answer 37

Some Eukarya have cell walls •Fungi, algae, plants and some protozoa •Provides shape and protection from the external environment (e.g. osmotic pressure)

Question 38

what are eukaryotes cell wall made up of

Answer 38

* Made of various polysaccharides * Plants – cellulose * Fungi – cellulose, chitin and/or glucomannan * Algae – various, cellulose, protein, agar, carrageenan, silicates, algin, calcium carbonate

Question 39

some organisms don't have a cell wall - which organisms? - what do they have instead

Answer 39

* Animal and most protozoan cells lack a cell wall * Instead they have carbohydrate glycocalyces attached to the plasma membrane * Helps anchor cells together * Protection from dehydration * Recognition and communication * Similar to the Slime layer and capsule of prokaryotes, which are also generally referred to as glycocalyces

Question 40

what are the other names called to cell membrane

Answer 40

- plasma membrane | - cytoplasmic membrane

Question 41

what are cytoplasmic membranes composed off

Answer 41

* Composed of a phospholipid bilayer * In bacteria, hydrocarbons are linked to glycerol by ester linkages * In archaea, there are no phosphate groups and have ether linkages.

Question 42

describe the function of the membrane

Answer 42

* Separates the cell contents from the external environment * Controls the contents of the cell and substances that move through it * Bilayer is impermeable to most substances * Proteins allow transport across the cell * Can be either passive or active. * Active requires energy.

Question 43

what are the four types of passive processes in a cytoplasmic membrane

Answer 43

- diffusion - facilitated diffusion - osmosis - other channels called permeases

Question 44

what is diffusion

Answer 44

Diffusion – moves across the cell membrane from high concentration to low concentration. Only occurs for small (e.g. oxygen) or lipid soluble molecules (e.g. alcohols) -goes through the phospholipid bilayer

Question 45

what is facilitated diffusion

Answer 45

Facilitated diffusion - bilayer blocks the movement of large or electrically charged molecules. Proteins act as channels that are non specific -goes through non-specific channel proteins

Question 46

describe facilitated diffusion through permeases

Answer 46

Other channels, called permeases are specific to certain substrates and has a binding site for that substrate -facilitated diffusion through a permease specific for one chemical; binding of substrate causes shape change in channel protein

Question 47

osmosis in cytoplasmic membranes

Answer 47

Osmosis – diffusion is based around the movement of solutes (things dissolved in water). Should there be no transporter for a solute, then water will move instead to balance the concentration e.g. If there is a high concentration of an impermeable substance outside the cell, water will move out of the cell to lower the concentration.

Question 48

describe hypotonic solution

Answer 48

animals- water goes inside the cell and the cell becomes lysed plants- water goes inside the cell and the cell becomes turgid (which can be normal)

Question 49

describe isotonic solution

Answer 49

animals- water goes in and out it is equilibrium so it is normal plants- water goes in and out of the cell; it is flaccid

Question 50

describe hypertonic solutions

Answer 50

animals- water goes out of the cell so the cell has shrivelled plants- water goes out of the cell, it is plasmolysed

Question 51

name cells without a cell wall

Answer 51

e.g. mycoplasmas, animal cells

Question 52

name cells with a cell wall

Answer 52

Cells with a wall: plants, fungi and bacteria

Question 53

what is active transport and what may it involve

Answer 53

* Active transport- Similar to facilitated diffusion, only the permease requires the use of energy to transport. * May involve the transport of one substance (uniport) * Two may move in the same direction (symport) * May involve a one in, one out (antiport)

Question 54

what are the 3 ways in which u can transport with active transport

Answer 54

* May involve the transport of one substance (uniport) * Two may move in the same direction (symport) * May involve a one in, one out (antiport)

Question 55

where does group translocation only occur

Answer 55

-only occurs in some prokaryotes

Question 56

what is group translocation

Answer 56

biological process where a molecule crossing the cell membrane not only gets transported but also gets transformed in itself. Traps the altered substance in the cell (stops it moving back)

Question 57

give an example of group translocation

Answer 57

Example- accumulation of glucose, glucose is phosphorylated as it is transported to Glucose-6-phosphate. •This cannot be transported back across even if glucose concentration falls outside the cell as a result

Question 58

describe the cytoplasmic structure of a eukaryote

Answer 58

* Similar fluid mosaic structure of the cell membrane. •Contain sterols (such as cholesterol), which most bacteria lack * Sterols help maintain membrane fluidity * No group translocation

Question 59

what is the cytosol

Answer 59

* Liquid component of the cytoplasm in which everything is dissolved * Ions, carbohydrates, proteins (enzymes), lipids and waste

Question 60

what does the cytosol contain

Answer 60

-Contains the cell DNA in the nucleoid region (remember, no nucleus!) •Some chemical reactions occur •May also have deposits, called inclusions. This is where reserves of components are stored •Lipids, starch, N, P or S containing substances

Question 61

what can the cytosol store

Answer 61

Can store carbon as glycogen, or a polymer of poly-β-hydroxybutyric acid (PHB) •Chemically modified PHB can be used for producing biodegradable plastic

Question 62

what is locomotion

Answer 62

movement

Question 63

what is the locomotion for prokaryotes

Answer 63

-flagella

Question 64

what is the locomotion for eukaryotes

Answer 64

- flagella - cilia - pseudopodia

Question 65

where is the flagella

Answer 65

-outside cell wall

Question 66

what is flagella made up off

Answer 66

Made of chains of flagellin

Question 67

what is the flagella attached too

Answer 67

* Attached to a protein hook * Anchored to the wall and membrane by the basal body * Propeller motion

Question 68

what is an axial filament

Answer 68

a central often contractile filament of a flagellum : axoneme.

Question 69

what are axial filaments made up off

Answer 69

Endoflagella

Question 70

another name for axial filaments

Answer 70

spirochetes are distinguished from other bacterial phyla by the location of their flagella, called endoflagella

Question 71

where is axial filament and what does it do

Answer 71

Anchored at one end of a cell | •Rotation causes cell to move

Question 72

what is the motion on a eukaryotic flagellum

Answer 72

Rather than a propeller like motion in prokaryotes, it is a whip like motion

Question 73

what is a amoeba

Answer 73

type of cell or unicellular organism which has the ability to alter its shape, primarily by extending and retracting pseudopods.

Question 74

what does amoeba do

Answer 74

Movement or surrounding of a cell for endocytosis •Phagocytosis- if food is solid •Pinocytosis- if food is liquid

Question 75

what is the cilia

Answer 75

internal hair-like structures | •Shorter and more numerous than flagella

Question 76

what does the cilia do and how does it work

Answer 76

Beat rhythmically •Propulsion in single cells •Movement of mucus through respiratory tract

Question 77

what can eukaryotes use for movement and so can prokaryotes

Answer 77

* Both can produce flagella but the structure and movement are different * Eukaryotes may also use cilia or pseudopodia (amoeba) * For both, its okay to be non-motile

Question 78

what is reproduction

Answer 78

•Microbial growth not only refers to increase in size, but also population size

Question 79

how do prokaryotes reproduce

Answer 79

Prokaryotes reproduce by binary fission (asexual) | •Binary, since two cells arise from the original cell.

Question 80

describe the genetic exchange in prokaryotes e.g. bacteria

Answer 80

•Possible for genetic exchange to occur between bacteria •In transformation (a), when a cell lyses the DNA easily breaks down into smaller fragments •These fragments can be taken in and incorporated into the chromosome of the recipient cell •In transduction (b) a bacterial cell is infected with a virus, or phage •When repackaging new viral particles, the host DNA can be packaged instead of the viral DNA •When the phage is released and infects a new cell, the original host DNA is placed inside the new host instead of viral DNA -In conjugation (c) a donor cell attaches to the recipient via a pilus •This pulls the recipient to the donor •Transfer of plasmid or chromosomal DNA can then take place. (look at picture)

Question 81

reproduction in eukaryotes

Answer 81

* Eukaryotes can reproduce asexually * Binary fission * Budding * Fragmentation * Spore formation * Schizogeny (associated with plasmodium)

Question 82

what is sexual reproduction

Answer 82

•Many eukaryotes reproduce sexually •Involves the formation of gametes •Fusion of two gametes forms a zygote •Some algae fungi and protozoa can do both -it is through meiosis (generation of haploid cells)