Viruses And Origin Of Life

Front 1

Spontaneous generation

Back 1

Life arises regularly from non-life.

First hypothesis for life on earth.

Disproved by 3 scientists.

Front 2

Biogenesis

Back 2

Life only comes from life

Front 3

When and how did the earth form

Back 3

4.6 bya

Condensed cloud of dust and rocks that surrounded sun.

No life yet

Earth was bombarded with ice and rocks and heat from the collision evaporated the water from ice

Front 4

What was present in the first atmosphere

Back 4

Lots of water vapour and compounds of volcanic eruptions.

No oxygen

Reducing (electron adding)

Front 5

How did oceans form

Back 5

As earth started to cool water vapour condensed.

Front 6

4 steps in the theory of the origin of life

Back 6

1. Abiotic synthesis of small organic molecules

2. Synthesis of monomers into polymers (macromolecules)

3. Packaging of small molecules into protocells

4. Origin of self-replicating molecules

Front 7

Abiotic synthesis of small organic molecules

Back 7

- earths early reducing atmosphere was perfect for simple molecules to form into organic compounds

-Urey/miller experiment confirmed this

- deep sea volcanic vents + meteorites may be source for organic molecules

Front 8

Synthesis of monomers into polymers (macromolecules)

Back 8

Organic molecules change into clumps (polymers) spontaneously

Polymers were not complex but functioned as basic catalyst for chemical reactions

Front 9

Packaging of molecules into protocells

Back 9

Montmorillonite increases rate of vesicle self-assembly and produces surfaces on which molecules can concentrate.

Front 10

Origin of self replicating molecules

Back 10

First genetic material was RNA

Ribozymes=first primitive enzyme, could catalyze chemical reactions

RNA world may have existed for long time

Eventually DNA was produced(much more stable)

Front 11

What is the RNA world

Back 11

Time period where small RNA molecules were able to replicate and store information about the vesicles that carried them

Front 12

What was the source of energy for early organic molecules

Back 12

Lightning and intense UV radiation

Front 13

How did Cyanobacteria effect life on earth

Back 13

First evolved oxygen of photosynthesis.

Started in oceans and then moved to atmosphere

Changed it to an oxidizing atmosphere and aerobic organisms can increase

Front 14

What was the earliest form of life of earth

Back 14

Single celled prokaryotes- stromatolites

3.5 bya

Front 15

Order of events in the life of the planet

Back 15

1. Origin of solar system and earth

2. Prokaryotes

3. Atmospheric oxygen

4. Single-celled eukaryotes

5. Multicellular eukaryotes

6. Life moves onto land

Front 16

3 processes that give rise to emerging viruses

Back 16

1) Mutations of existing viruses

2) dissemination of a viral disease from small isolated human population (travel, blood transfusions, drugs/sex)

3) spread of existing viruses from animals to humans

Front 17

Plant viruses: horizontal vs vertical transmission

Back 17

Horizontal: infected from outside source

Vertical: inherits virus through parent

Front 18

Viroids

Back 18

Simpler than viruses

Circular RNA molecules that infect plants

Cause errors in regulatory systems controlling growth (result in abnormal development + stunted growth)

Front 19

Prions

Back 19

Misfolded proteins

Highly infectious

Transmitted through food

Long incubation period

No cure

Front 20

What are the components of a virus

Back 20

Nucleic acid (genome) surrounded by a protein coat (capsid)- shape unique to type of virus

Animal viruses have additional envelope outside capsid

Front 21

Host range

Back 21

What cell the virus will infect

Recognize and infect certain cells through lock and key method

Front 22

What is a bacteriophage/phage

Back 22

A virus that infects bacteria specifically

Front 23

Lytic cycle vs lysogenic cycle

Back 23

Lytic- Active reproductive cycle (no dormancy)

Lysogenic- virus doesn’t make new viruses, replicates it’s viral genome when host cell replicates before entering normal lytic cycle

Front 24

Steps of lytic cycle

Back 24

Viral genome enters host cell

immediately takes over host cell and uses it to replicate new viral parts

Assembly of viral parts

Bacterial cell explodes and releases new viruses

Front 25

Steps of lysogenic cycle

Back 25

Viral genome enters cell

Genome incorporates itself into host cell chromosome. Resulting chromosome= PROPHAGE

Viral genome remains dormant, every time host cell replicates, viral genome with prophage replicates with it

Environmental signal causes viral genome to leave host DNA

Viral genome enters active lytic cycle

Front 26

Why have viruses not destroyed bacteria

Back 26

Parasitic host relationship is in constant evolutionary flux

Lysogenic cycle

Restriction enzymes often destroy phage DNA if it is not recognized

Front 27

What is a retrovirus

Back 27

Reverse information flow from RNA to DNA using enzyme reverse transcriptase

Front 28

Hypothesis for origin of viruses

Back 28

Naked bits of cellular nucleic acids that moved from one cell the another (possibility plasmids or transposons)

Front 29

What does it mean that viruses are obligate intracellular parasites

Back 29

Viruses cannot reproduce/exist outside of their host cell

Front 30

What components of the host cell does a virus use to replicate itself

Back 30

Organelles / DNA

Front 31

Virulent vs temperate phages

Back 31

Virulent: virus that stays in lytic cycle

Temperate: uses both lytic and lysogenic cycle

Front 32

What portion of phage enters host cell

Back 32

Nucleic acid

Front 33

What is a prophage

Back 33

Nucleic compound of viral and bacterial DNA

Front 34

Prophage vs provirus

Back 34

Prophage: temporary, leaves host cell at start of lytic cycle

Provirus: permanent, never leaves host cell

Front 35

3 ways viruses make us ill

Back 35

1. Damage or kill cell using hydrolytic enzymes

2. Cause infected cells to produce toxins lead to disease

3. Have toxic molecular components

Front 36

What are protocells

Back 36

Abiotically produced vesicles that can

reproduce,

Grow without diluting their contents

metabolise (some)

maintain separate internal environment

absorb montmorillonite particles which may contain RNA

Front 37

What are plasmids

Back 37

Small circular DNA in bacteria and yeast that separate from cells DNA, replicate separately and can be passed down from cell to cell

Front 38

What are transposons

Back 38

DNA segments that can move from one location to another within a cells genome

Front 39

4 ways of classifying bacteria

Back 39

Visually (shape and arrangement)

Gram +,gram - staining

Metabolism (what nutrients they need to survive)

Colony (shape/colour/definitions)

Front 40

Endospores

Back 40

Dormant cells resistant to severe physical/chemical stress adapted to survive during unfavourable conditions

Can remain viable for millions of years

Front 41

Peptidoglycan

Back 41

Composition of bacteria cell wall

Front 42

How do antibiotics destroy bacteria

Back 42

They weaken the cell wall resulting in the wall exploding

Front 43

Chemotrophs vs autotrophs vs heterotrophs

Back 43

chemotrophs: Perform fermentation

Autotrophs: make own food (photosynthetic/chemosythetic)

Heterotrophs: obtain food from other sources

Front 44

Endospores

Back 44

Dormant cells resistant to severe physical/chemical stress adapted to survive during unfavourable conditions

Can remain viable for millions of years

Front 45

What is a colony

Back 45

Millions of identical bacteria that originate from one bacteria that did binary fission

Front 46

Peptidoglycan

Back 46

Composition of bacteria cell wall

Front 47

How do antibiotics destroy bacteria

Back 47

They weaken the cell wall resulting in the wall exploding

Front 48

Chemotrophs vs autotrophs vs heterotrophs

Back 48

chemotrophs: Perform fermentation

Autotrophs: make own food (photosynthetic/chemosythetic)

Heterotrophs: obtain food from other sources

Front 49

How do bacteria reproduce

Back 49

Primarily- binary fission

Less commonly - conjugation

Front 50

Binary fission

Back 50

Asexual, produce 2 identical daughter cells

Single bacteria copies it’s genetic material, elongates, cell membrane grows inwards and separates into 2 cells

Front 51

Conjugation

Back 51

Exchange of genetic material through pili

Always from male to female

Front 52

3 bacteria shapes

Back 52

1) bacilli: rod shaped, some form endospores

2) cocci: spherical shaped

3) spirilli: spiral shaped, forms of rod shaped bacteria

Front 53

Arrangement of bacteria

Back 53

1) Diplo: pairs

2) stept: chains

3) staphy: clusters

Front 54

Gram positive vs gram negative

Back 54

Gram + have a thick cell wall (purple)

Gram - have a thin cell wall (most bacteria)(pink)

Front 55

What is the endosymbiont theory

Back 55

Mitochondria and plastids were small prokaryotes that began living within larger cells