Transcript Eukaryotic Cells

Unit 2 Review
Cell Theory (Pg. 78)
• All organisms are made up of one
or more cells.
• All cells carry on life activities
• New cells arise only from other
living cells by the process of cell
division.
Introduction
There are two basic cell types:
Prokaryotic Cells:
Eukaryotic Cells:
•Lack membrane bound
organelles.
• Present in all living
things.
• Internal membrane
bound structures
•Include bacteria
Similarities between plant cells
and animal cells
Both have a cell membrane surrounding
the cytoplasm.
Both have a nucleus.
Both contain mitochondria, golgi bodies,
E.R. , ribosomes and microtubules.
Know the basic functions of the organelles
of the cell
Differences between plant cells
and animal cells
Animal cells
Plant cells
Relatively smaller in
size
Relatively larger in
size
Irregular shape
Regular shape
No cell wall
Cell wall present
Differences between plant
cells and animal cells
Animal cells
Plant cells
Vacuole small or absent Large central vacuole
No Chloroplasts
Chloroplasts Present
Nucleus at the centre
Nucleus near cell wall
Classification & Taxonomy
• Know the classification systems
developed by Aristotle and
Theophrastus, John Ray, &
Carolus Linnaeus.
• What are the current 6 kingdoms
of living things??
Naming Organisms
• A system for naming things is called
nomenclature.
• Linnaeus named each species with a genus name
followed by a species name.
• This 2 word system of identifying each organism
is called binomial nomenclature.
• Most organisms also have a common name as
well, but this is not always the best way to
describe organisms.
WHY USE SCIENTIFIC
NAMES?
• PEOPLE IN ALL PARTS OF THE
WORLD USE THE SAME NAME FOR
AN ORGANISM
• RELATIONSHIPS AMONG
ORGANISMS ARE EVIDENT IN THEIR
NAMES
• DIFFERENCES BETWEEN ORGANISMS
ARE OBVIOUS FROM THEIR NAMES
Kingdoms Archaebacteria and
Eubacteria
•
•
•
•
The kingdom formerly known as Monera
Most abundant/diverse kingdom
Prokaryotic organisms
ONLY KINGDOM lacking an organized
nucleus or membrane-bound organelles
Nostoc (cyanobacterium)
Structure
Cell Wall
Chromosomes
Cilia or Flagella
Prokaryotic Cell
Eukaryotic Cell
Yes
Yes, Plants Only
One long DNA
strand
Yes, Simple
Many
Yes, Complex
Lysosomes
No
Common
Mitochondria
Nucleus
No
Yes
No
Yes
Plasma Membrane
Yes
Yes
Bacterial Shapes
Metabolic Needs
• All prokaryotes require an energy source and a
food source.
• Most are aerobic (Require oxygen)
• Bacteria that cannot live without oxygen are called
obligate aerobes.
• Some bacteria, called faculative anaerobes, can
live in the absence or presence of oxygen.
• Some bacteria cannot live in the presence of
oxygen. These are called obligate anaerobes.
Reproduction
Bacteria reproduce by
binary fission which
is an asexual process
Bacteria usually follow a typical growth curve. Fig.30-4
The Gram Test
• This is a universal method of classifying bacteria
called Gram Staining.
• This is a staining method developed by a Danish
physicist named Hans Christian Gram.
• It classifies bacteria by how they react to the
stain.
• Bacteria are divided into 2 categories:
– Gram positive bacteria (Purple)
– Gram negative bacteria (Pink)
Pasteur and Germ Theory
•
Pasteur’s work set the ground work for what we
now know about pathogens.
1. Bacteria become so numerous that they
interfere with the functioning of normal cells.
2. They can destroy body cells and tissues.
3. They can produce poisons, or toxins, that kill
cells or interfere with their functioning. This is
usually the cause of harm.
Koch’s Postulates
1. The suspected disease-causing organism should
always be found in animals with the disease.
2. The organism must be isolated from the diseased
animal and grown in a pure culture.
3. When organisms taken from the pure culture are
injected into a healthy animal, they must cause
disease.
4. The organism must be isolated from the
experimentally infected animal and grown in pure
culture again, and it should be identified as the
same organism isolated in step 2.
Vaccines
•
Jenner’s work (smallpox) led to many other
scientist developing vaccines to prevent
disease.
Viruses are further classified based on
three structural considerations:
1) The type and size of their nucleic acid
2) The size and shape of the capsid.
3) Whether they have a lipid envelope
surrounding the capsid.
Parts of a Virus
1. Capsid - The capsid is the protein shell that
encloses the nucleic acid.
• The capsid has three functions:
1. it protects the nucleic acid from digestion by
enzymes,
2. Contains special sites on its surface that allow
the virus to attach to a host cell.
3. Provides proteins that enable the virus to
penetrate the host cell membrane and, in some
cases, to inject the infectious nucleic acid into
the cell's cytoplasm.
Parts of a Virus
2. Envelope - Some viruses may have an
additional covering on the outside
called an envelope.
• The envelope is actually a lipid bilayer
(membrane) with proteins embedded
within the membrane.
3. Nucleic Acid - Just as in cells, the
nucleic acid of each virus encodes the
genetic information for the synthesis of
all proteins.
• The nucleic acids in a virus can be RNA
or DNA.
The Lytic Cycle
• The lytic cycle is one of the two cycles of viral
reproduction, the other being the lysogenic cycle.
• These cycles should not be seen as separate, but
rather as somewhat interchangeable.
• The lytic cycle is typically considered the main
method of viral replication, since it results in the
destruction of the infected cell.
• The lytic cycle does not involve genetic material
of the virus being integrated into the host’s DNA.
Epidemic vs. Pandemic
• An epidemic is a disease affecting or
tending to affect an atypically large
number of individuals within a
population, community, or region at the
same time
• A pandemic is a disease prevalent
throughout an entire country, continent,
or the whole world; epidemic over a
large area.
Protists are divided into 3 main
groups
1. Animal-like protists
(Protozoa)
2. Plant-like protists (Algae)
3. Fungus-like protists
Animal-like Protists
• All protozoa are heterotrophic
• Some absorb nutrients through their
cell membrane, whereas others
“engulf” larger food particles.
• Most protozoa are motile and are
divided into phyla based on their means
of locomotion.
Animal-like Protists
• Classified based on ____________?
• Phylum Sarcodina (amoebas)
• Phylum Ciliophora (Paramecium)
• Phylum Zoomastigina
(zooflagellates – African Sleeping
Sickness)
• Phylum Sporozoa – Plasmodium
(Malaria)
CONJUGATION
Plant-like Protists
• Also known as Algae.
• Algae are eukaryotes
• Algae are photosynthetic, like plants:
– Have 4 kinds of photosynthetic pigments
– Many accessory pigments – blue, red,
brown, gold
• Require moist environments because they
lack a waxy cuticle. A cuticle prevents
water loss in terrestrial plants.
Three Body Plans
1. Single Celled: Eg. Euglena (p. 646),
Chlamydomonas (p.649), Diatoms (p.
648)
2. Colonial: group of unspecialized
cells. Eg. Volvox (p. 99), Spirogyra
(p. 426).
3. Multicellular: specialized division of
labour. Eg. Kelp
Classification of Algae
•
1.
2.
3.
4.
5.
6.
Classification of Algae is based on:
Color of major pigments
Method of storing food (starch, oil, sugars).
Cell structures: Cell wall, pellicle.
Body plan
Flagella
Reproduction
Plantlike Protist Phyla
•
•
•
•
•
•
Phylum Euglenophyta (Euglena)
Phylum Chrystophyta (Diatoms)
Phylum Dinoflagellata
Phylum Rhodophyta (red algae)
Phylum Phaeophyta (Kelps & Brown algae)
Phylum Chlorophyta (Green algae)
•
1.
2.
3.
•
1.
2.
a)
Reproduction
Asexual:
Fission
Fragmentation
Asexual spores (resistance to drought)
Sexual:
Conjugation – Spirogyra (p. 426)
Sex Cells
Isogamy – union of gametes of same size and
shape; different DNA
b) Heterogamy – union of unlike sex cells in size and
shape. Specialized large ♀ egg cell and small
motile ♂ sperm.
Reproduction
• Algae have an alternation of generations:
– Gametophyte Generation – Largest most
obvious part of the life cycle (n).
– Sporophyte Generation – Short lived less
conspicuous part of the life cycle (2n).
Fungi-like Protists
• These protists are similar to the fungi in
some ways. These protists have some
stages in their life cycle that are similar to
those of protozoa.
• All fungus like protists are heterotrophic,
most are decomposers and a few are
parasites.
Three major phyla of fungus like
protists
1. Myxomycota (acellular slime molds)
(feeding stage called a plasmodium)
2. Acrasiomycota (cellular slime molds)
3. Oomycota (water molds and downy
mildews)
Fungal Characteristics
• Eukaryotic
• Multicellular (with one exception)
• Heterotrophic
• Absorb nutrients - may be
saprobes (absorb from dead
material), parasites, or mutualistic
symbionts (with algae make
lichen).
The Body Plan of Fungi
• Vegetative body consists of
mycelia made up of networks of
hyphae
• Hyphae - Long threads of cells
designed to maximize surface
area and also transport nutrients
Fungal Phyla
•
•
•
•
Zygomycota – Conjugation Fungi – Bread Mold
Ascomycota – Sac fungi – Truffles & yeast
Basidiomycota – Club Fungus – mushrooms
Deuteromycota – Imperfect Fungus – Athlete’s
foot, pennicillium
• Named for their sexual spore producing
structures: Zygomycota – Zygospores;
Ascomycota – Ascospores; Basidiomycota –
Basidiospores; Deuteromycota – sexual
reproduction unknown.