Download Biology 20 Diversity of Life PowerPoint part 2.pps

Viruses
Living or non-living? This is debatable!
Living Thing? Viruses can reproduce.
Non-living thing? Viruses can only show
characteristics of a living thing (reproduce) inside a
host cell
Viruses are infectious particles made only of a
strand of DNA or RNA surrounded by protein coat.
Viruses are small or very small (50-200 nm) and
cannot be seen with a light microscope (you need
an electron microscope).
Some scientists consider viruses as complex
chemicals
Common Viral Diseases
Common cold
Influenza (flu), such as H1N1 (swine flu)
SARS
Chicken pox
Ebola
Measles
Mumps
Polio
Mad-cow disease
HIV
West Nile
HPV (Human papillomavirus)
Herpes
Rabies
Hepatitis
Viral Infections
2 types:


Lytic infection – host
cell bursts and releases
new viruses that infect
more host cells
Lysogenic infection –
virus combines it’s DNA
into the host cell’s DNA
but does not produce
viruses (dormancy stage)
but eventually viruses
are porduced.
Questions 1-2, p 551
1. Name and describe the main parts of a typical virus.
capsid: protein shell
genetic material: single-stranded or double-stranded DNA or
RNA
Some viruses have a lipid envelope covering the capsid
2. What are the differences between a lytic infection and a
lysogenic infection? Include the effects of each type of infection
on the cells of the host organism in your answer.
Lytic infection: virus replicates many times, producing many
offspring
Lysogenic Infection: virus integrates into the host cell’s DNA,
with viral genes passed to the host cell’s daughter cells during
mitosis. Lytic infection destroys the host cell after viral
replication and release of offspring, whereas lysogenic
infection generally causes no initial harm to the cell, though it
can alter some of the cell’s traits.
Questions 3-4, p551
3. Researchers studying infection can often grow
bacteria more easily than they can grow
viruses. What conditions must scientists
provide for viruses to multiply?
-
In order to replicate, viruses need living cells they
can infect
4. A wart is caused by a virus that may lie
dormant for years before any symptoms
appear. Does this resemble a lytic or
lysogenic infection? Explain.
-
Lysogenic. It is characterized by a virus that lies
dormant.
Question 5, p551
5. If the virus is a foreign invader, how is it
possible for the proteins of its capsid to
match the receptors on the host cell’s
surface? Consider natural selection in
your answer.
-
Over time, viruses that happened to have the
right protein “key” would survive and pass on
these traits to their viral offspring. Viruses
without the right proteins would not be able
to successfully infect the host and would
probably become extinct.
Questions 1-3, p554
1. Name and describe two infectious viruses and
a body’s first defense against infection.
-
Common cold, flu, SARS, HIV, chicken pox.
The skin is the body’s first defense against
infection.
2. Briefly describe how a vaccine can prevent
some viral infections.
- A vaccine is made from a weakened pathogen or
parts of a virus. When given, it stimulates the
host’s own immune system, preparing it for future
infections by the real virus.
Questions 3 – 4, p554
3. If a vaccine is in short supply, why is it often
recommended that older adults and children
get vaccinated first?
The immune system of older adults and
children are often weaker than those of the
rest of the population, so they are more
likely to become infected than a healthy
person who is not very young or very old.
4. Why might getting a flu vaccination sometimes
cause you to get a mild case of the flu?
- because you may be getting a weakened
strain of live virus in order to build up your
immune system.
Question 5, p554
5. People infected with HIV (the virus that
causes AIDS) can become unable to fight
off infections by organisms that normally
do not harm people. Why is this so?
- HIV affects the immune system of an infected
person, making him or her susceptible to
organisms that are normally harmless.
Prokaryotes (Bacteria & Archaea)
Both groups are prokaryotic (lack a nucleus and
organelles)
Divided up based on need for oxygen (O2):
A. obligate anaerobes
-
cannot live in presence of O2
Some produce methane gas
Live in marshes, lake bottoms, or digestive tracts of
herbivores like cows, deer and sheep
B. obligate aerobes
-
Need O2 or will die
Many common pathogens like tuberculosis and leprosy
C. Facultative aerobe
- Can survive with or without O2
Bacteria and archaea are similar structurally but
differ in genetics and biochemistry
Both groups are small single-celled organisms
with a cell wall and cell membrane
Archaea have many shapes, bacteria have 3:
a.
b.
c.
Bacilli – (rod-shaped)
Spirochetes - (spirilla or spiral-shaped)
Cocci - (round or spherical)
Archaea and bacteria move by gliding or
using flagella (whip-like tail used for
locomotion) or pili (smaller locomotive
structures)
Typical prokaryote structure:
Archaea and bacteria differ their cell wall,
flagella and plasma membrane composition
4 main groups of Archaea:
1.
2.
3.
4.
Methanogens – produce methane
Psychrophiles – live in cold temperatures
Halophiles – live in salty environments
Thermophiles – live in extremely warm/hot
temperatures
Bacteria – two main groups:
1.
2.
Gram Positive – stain purple with a Gram stain
Gram Negative – stain red in a Gram Stain
Gram Positive / Negative Bacteria
Bacteria – benefits to humans
Bacteria help humans and other animals in their
digestive tract:


Cattle (and other ruminants) use bacteria to
breakdown their food
Human use bacteria in their intestinal track to
produce vitamins and other substances
Many foods produced by fermentation by
bacteria:




yogurt, cheese
pickles
sauerkraut
vinegar, soy sauce
Cyanobacteria – produce huge amounts
of oxygen
Nitrifying bacteria (in the soil) fix nitrogen
from the atmosphere into usable form for
plants
Bioremediation – uses microbes and
other living things to break down or
destroy pollutants. Bacteria are a key
organism is biological decay
(biodegradation)
Bacterial Diseases
acne
tuberculosis
anthrax
Lyme disease
tetanus
gangrene
botulism (as well as other forms of food poisoning,
such as salmonella)
tooth decay
strep throat, ear infections, flesh-eating disease
bacterial pneumonia
STI – syphilis, Chlamydia, etc…
Questions 1-3 page 558
1. What are the three most common shapes of
bacteria?
-
rod, spiral and sphere
2. Why are bacteria and archaea classified into
different domains?
-
Archaea are biochemically and genetically different
from bacteria
3. Prokaryotes will take up foreign DNA. How is
this characteristic used in genetic engineering?
-
Pieces of genes can be inserted into the genetic
material of prokaryotes so that they will make the
protein products encoded in the genes or copies of
the genes themselves.
Question 4-5, p558
4. Scientists estimate that only 1 percent of prokaryotes
can be grown in the lab. What does this suggest
about our knowledge of bacteria and archaea?
We do not know much about prokaryotes. Our
understanding of prokaryotes will likely change as
scientists learn more about prokaryotes that have
not been able to be cultured, or grown, in the lab.
5. Prokaryotes multiply by binary fission, which simply
divides a cell in two. Why are mutations and
conjugation important for natural selection in
prokaryotes?
Binary fission produces no variation, but mutations
and conjugation do. Natural selection requires
variation in a population.
Question 6
6. Bacteria in your mouth convert foods
containing sugar and starch into acids that can
then cause cavities in your teeth. These
bacteria will be present even if you brush your
teeth, floss, or use mouthwash. So why are
these hygiene habits so important?
-
Brushing teeth is important to keep the population
of these bacteria down and to remove the food that
the bacteria convert into acid.
Questions 1-3, p561
1. Describe two ways bacteria provide nutrients to
humans.
- Bacteria in our bodies make vitamins that we absorb,
and some bacteria are needed to make foods that
we eat, such as soy and dairy products.
2. What are two roles prokaryotes play in the cycling of
elements in an ecosystem?
producing oxygen through photosynthesis, fixing
nitrogen, decomposing other organisms
3. Think of an example in which the use of bioremediation
either has improved the environment or has the
potential to do so.
Cleaning up industrial accidents, sewage and other
waste.
Questions 4, p561
4. How do prokaryotes lend to stability to an
ecosystem?
- Prokaryotes lend stability to an ecosystem through
their role as decomposers. Other organisms rely
on prokaryotes for nitrogen and other compounds
that are broken down through prokaryote
metabolic activity. Some prokaryotes also help the
stability of an ecosystem by releasing oxygen into
the environment during photosynthesis.
Question 5, p561
5. Prokaryotes in cow intestines produce more methane if
the cow is fed a diet high in grains rather than grass.
Some scientists propose that overfeeding grain to cows
contributes to global warming. How did these scientists
arrive at this hypothesis, and how could it be tested?
- Students can infer that the amount of methane
produced by the intestines of a grain-fed cow can be
compared to that produced by a grass-fed cow,
perhaps by measuring concentrations of methane in
closed environments after cows have fed and lived
inside them for some time. The effect of methane
concentration on the heat retention of the atmosphere
can also presumably be tested in a small, enclosed
space that is open to sunlight.
Domain Eukarya
all are eukaryotic (possess a nucleus
and organelles)
4 kingdoms:
 Kingdom Protista
 Kingdom Fungi
 Kingdom Plantae
 Kingdom Animalia
Kingdom Protista
Eukaryotic (cells have a nucleus and organelles)
Mostly unicellular, some are colonial
Most are microscopic, some are huge (slime
molds)!
Divided into three informal categories, based on
their food-gathering method:
 Animal-like protists: eat (ingests) their food
(heterotrophic)
 Plant-like protists: make their own food by
photosynthesis (autotrophic)
 Fungal-like protists: absorb their food
(heterotrophic)
Animal-like Protists
Sometimes called “zooplankton” or “protozoa”
4 phyla:
1. Zooflagellates (Phylum Zoomastigophora)
-
Have flagella to move around (whip-like structures)
Trypanosoma causes African Sleeping Sickness,
which is transmitted by tse tse fly
2. Sarcodines (Phylum Rhizopoda)
-
-
Have pseudopods (“false feet”) to move around
Engulfs food by surrounding it with their
pseudopods
amoebas, foraminiferans
Animal-like Protists - continued
3. Ciliates (Phylum Ciliaphora)
-
Move by cilia (hair-like projections)
Paramecium – common genus
4. Sporozoans (Phylum Apicomplexa)
-
Parasitic, reproduce using spores
Plasmodium – genus causes Malaria
Malaria passed on by Anopheles mosquitoes
Malaria kills millions of people annually
Questions 1-2, page 576
1. Name the three main groups within the kingdom
Protista. What characteristics distinguish each group
from the other two?
Protozoa (animal-like) - heterotrophic consumers
Algae (plant-like) - autotrophic producers
slime molds (fungal-like) - heterotrophic
decomposers
2. Give two reasons why protists are difficult to classify.
- Answers should include two of the following: Some
protist phyla are very distantly related, and some are
more closely related to members of other kingdoms than
they are to other protists. The definition of protists is
based on the absence of traits that characterize the
other kingdoms.
Questions 3 & 4, p576
3. What observable traits might green algae and plants
share that support the molecular evidence that these
two groups are closely related?
Both are green, have chloroplasts, are eukaryotic,
and are (sometimes) multicellular
4. At one time, scientists grouped all single-celled
organisms together. What are the main differences
between single celled protists and bacteria or
archaea?
- Protists are eukaryotic, meaning they are made up of
cells that have a nucleus and membrane-bound
organelles; bacteria and archaea are prokaryotic,
meaning their cells do not have a nucleus or
organelles.
Question 5, p 576
5. Organisms that get their food by ingesting
it called heterotrophs, while those that
make their own food are called
autotrophs. Categorize animal-like, plantlike, and fungus-like protists using these
two terms.
-
Animal-like protists and fungus-like are
heterotrophs. Plant-like protists are
autotrophs.
Questions 1-2, p580
1. Name and describe the three basic means of movement used by
animal-like protists.
- flagella: tail-like extensions of cytoplasm that are used in a whip like
motion to propel the organism forward
- Pseudopods: the plasma membrane and cytoplasm extend to form
a bulge that anchors to the surface and pulls the rest of the
organism along; cilia: short hair like structures on the surface of the
organism that wave.
2. Describe how the parasite Plasmodium causes disease in
humans.
- The bite of a mosquito carrying Plasmodium transmits sporozoites
into a human‘s bloodstream. The sporozoites enter the liver, where
they develop and then move to red blood cells. They reproduce
asexually until the red blood cells burst open, releasing
Plasmodium cells that can then be ingested by mosquitoes that
bite the infected host. Symptoms include severe fever, vomiting,
and possibly liver and kidney problems.
Questions 3-4, p 580
3. In what ways are cilia and flagella similar?
How are they different?
- Cilia and flagella are both used for movement in
protists. Both are formed from the cell
membrane and are permanent structures.
However, cilia are shorter and more hair like
and can be in rows or clusters that cover parts
of a cell or the entire cell. Flagella are longer,
and there are usually only one or two per cell.
4. Why do amoebas form pseudopods only when
they need them?
- because pseudopod formation requires energy
Question 5, p580
5. The flagella of eukaryotes and
prokaryotes serve the same function, but
they are structurally very different. What
does this suggest about the evolution of
flagella?
- The flagella of eukaryotes and prokaryotes
arose separately and are an example of
convergent evolution
Plant-like Protists (Algae)
- Was classified in the plant kingdom in the past,
are not any more because they lack roots,
stems, leaves or specialized tissues
- Can be single-celled or multicellular
- along with photosynthetic bacteria are
sometimes called phytoplankton
(photosynthesis)
- Provide about half of the earth’s oxygen supply!
- Base of aquatic food chains as the producers
- Most are autotrophic (make their own food by
photosynthesis
Plant-like Protists – 6 phyla
1. Euglenoids (phylum Euglenophyta)
-
Swim by flagella, yet they photosynthesize!
Mostly freshwater species, some marine
Commonly green in colour
Euglena
Most are autotrophic, some are heterotrophic
2. Dinoflagellates (phylum Dinoflagellata)
-
-
Most species are marine (90%)
Have two flagella
Some species produce toxins (cause “red tide”) –
kill large numbers of fish, can contaminate shellfish
(can kill people!)
3. Diatoms (phylum Bacillariophyta)
-
-
Covered by delicate glass-like shells
Freshwater or marine species, unicellular
Release huge amounts of the earth’s atmospheric
oxygen
Diatomaceous earth – used in many things like
tooth paste, swimming pool filters, insulation
materials
4. Green Algae (phylum Chlorophyta)
-
-
-
Most species are aquatic, some live on land in
moist environments
Some unicellular, some colonial, some
multicellular
Ancestor to land plants
5. Brown Algae (phylum Phaeophyta)
-
6.
-
Kelps that form underwater forests
multicellular
Mostly marine species
Red Algae (phylum Rhodophyta)
Mostly marine, some freshwater
Multicellular
Carrageenan - thickening agent from red
algae used dairy product like milkshakes
and ice cream
- Agar – used in bacterial culture plates
Fungal-like Protists
1. Slime Molds (phylum Myxomycota /
Acrasiomycota)
-
eukaryotic, can move around
2. Water Molds (phylum Oomycota)
-
-
Many are decomposers, some are parasites on
plants and fish
One species caused the Irish potato famine – klled
millions of people in Ireland “Great Potato Famine”