Download animal cells have a plasma membrane

EXAM II
EXAM II is on MARCH 15
Covers Weeks 4, 5 and 6
What is a substrate?
• A substrate is a reactant for an enzymatic reaction.
• A substrate attaches to an enzyme at the active site.
• The substrate is the reactant in that the enzymatic reaction only occurs
once the substrate attaches with the enzyme that is specific for that
particular substrate.
• Remember, we are talking about molecules here. All of the big blobs you
see that I've drawn are representations or cartoons of what are actual
molecules.
• These molecules undergo a reaction to produce a PRODUCT. Then, that
product can be used as the reactant or SUBSTRATE for the next enzymatic
reaction.
Enzyme Active Site
In general only the “active site” of the enzyme
binds to the substrate
I.
II.
Active Site of
the Enzyme
III.
A slight change at the
active site allows
for the attachment of
the substrate
WEEK 5 Continued
Adenosine Triphosphate (ATP)
ATP is a nucleotide
The base of the nucleotide is adenine
The sugar of the nucleotide is ribose
Tri refers to the 3 phosphate groups attached to the
ribose sugar
- The last two Phosphate bonds are UNSTABLE,
easily broken
- In cells, the end phosphate is hydrolyzed to release
energy which results in ADP, adenosine diphosphate
and a Phosphate molecule
ATP and the Electron Transport Chain
ATP is produced via the electron transport chain (ETC)
Chloroplasts in plant cells use solar energy to generate
ATP using ETC
Mitochondria in animal cells use glucose to generate
ATP using ETC
The ETC is a series of transfers of electrons whereby
high energy electrons are transported through a
series of steps to release energy for the synthesis of
ATP
Energy comes from the transfer of electrons
WEEK 6
Chpt 18 (pg320-327)- Cell Evolution and
multicellularity
Chpt 20 (all)- Viruses, Bacteria and Archaea
Chpt 4 (pg68-84)- The Eukaryotic Cell
Chpt 5 (all)- Membranes and Transport
Mitochondria and Chloroplasts
Energy is created in the Mitochondria in animal
cells and in the Chloroplasts of Plant cells
How do we know this?
Using Microscopy, scientists have discovered the
organelles and molecular structures
responsible for cell structure
1- All organisms are composed of cells
2- Cells are the basic units of structure and
function in organisms
3- Cells come only from preexisting cells because
cells are self-reproducing
Fig. 4.2
Cell Size
Cells are small- approximately 1 micron (µm)
This is 1,000th of a millimeter
Cells are the smallest unit of living matter
SURFACE AREA TO VOLUME RATIOS
Fig. 4.3
Why are cells so small and
Why is having a large surface area so important?
1. A Smaller cell has more surface area per volume than a large cell
2. Small cells have more surface area for exchanging wastes for
nutrients because of its greater surface-area-to-volume ratio.
Two Types of Cells
Bacteria and Archaea
YOU ARE RESPONSIBLE FOR
UNDERSTANDING
THE DIFFERENCE BETWEEN
PROKARYOTIC
AND EUKARYOTIC CELLS
AND
HOW ANIMAL CELLS DIFFER
FROM PLANT CELLS
Chpt. 18
CELLULAR EVOLUTION
Protocell containing DNA
Genes  true cell
Plasma membrane forms
Polymers aggregate within
the plasma membrane=
protocell
Monomers joined to form
Polymers (proteins, RNA)
Abiotic Synthesis created
Small organic molecules
(ex. Amino acids, nucleotides)
4.6 BYA
Chpt. 18, page 325
First Prokaryotes arose 3.5 BYA
Eukaryotic cells arose 2.1 BYA
Eukaryotes contain Mitochondria which are believed
To have been independent , free living aerobic bacteria
The endosymbiotic theory states that a nucleated cell
Engulfed these free living aerobic bacteria which later
Became organelles or ‘MITOCHONDRIA’
Heterotrophs cannot produce
Own food and practice
Sexual reproduction
The eukarya arose from ARCHAEA
Heterotrophic protists arose when eukaryotic cells engulfed
aerobic bacteria
THE EUKARYOTIC CELL
http://www.wisconline.com/Objects/ViewObject.aspx?ID=AP11403
ANIMAL CELLS HAVE A PLASMA MEMBRANE
THE NUCLEUS
Chromosomes
Nuclear Envelope
Nucleolus
Condensed Chromatin
Surrounds Nucleus
Contains genetic information/
Genes
Composed of two layers
Contains ribosomal
RNA which
aids in production of
protein
Composed of DNA
Set number per species (humans
Have 23 pairs or 46 Chromosomes)
http://library.thinkquest.org/12413/structures.html
Has nuclear pores to permit
The passage of ribosomal
Subunits and mRNA out of the
nucleus
THE CYTOPLASM
Centrioles
Involved in
Cell division
Chloroplasts
(Plants ONLY)
Contains Green
Chlorophyll where
Photosynthesis
occurs
Cytoskeleton
Composed of microtubules
Supports cell and
Gives shape
http://library.thinkquest.org/12413/structures.html
Endoplasmic
Reticulum
Fused to Nuclear
Membrane
2 types-Smooth
Rough
Produces protein
Lysosome
Digests Proteins
Lipids, Carbs
Transports waste
to cell membrane
Made by Golgi
Mitochondria
Produces ATP
Has 2 membranes
Folds are cristae
CHAPT 4
Golgi Apparatus
Packages Protein
Near Nucleus
Cell division
Vacuoles
Store, digest and
Removes cell
Waste
Plants have a
Large Central
Vacuole
Ribosomes
Particles where
protein synthesis
Occurs
Composed of 2
Subunits (large
and small)
THE CYTOSKELETON
Intracellular protein
Matrix
Ropelike fibrous polypeptides
Now called ACTIN filaments=
Actin monomers, twisted in a helical manner
Made of tubulin- a globular protein
http://www.wisconline.com/Objects/ViewObject.aspx?ID=AP11403
ANIMAL CELLS HAVE A PLASMA MEMBRANE
PLANT CELL
(eukaryote)
PLANT CELLS HAVE A CELL WALL AND CHLOROPLASTS
THE PROKARYOTIC CELL
PROKARYOTES HAVE A CELL WALL, NO NUCLEUS!
Prokaryote fossils date to 3.5 BYA
Extremely diverse in structure and metabolic capabilities
Some prokaryotes move with the use of ‘FLAGELLA’
Flagella= strands of flagellin protein wound in a helix
Many prokaryotes adhere to cells with the use of ‘FIMBRIAE’
Fimbriae = short bristlelike fibers on the surface
Prokaryotes DO NOT HAVE A NUCLEUS
Prokaryotes have a dense area called a NUCLEOID where a
Single chromosome of circular DNA exists
Some prokaryotes also have accessory rings of DNA called Plasmids
Prokaryotes reproduce ASEXUALLY via BINARY FISSION
Generation time can be as little as 12 minutes
Prokaryotes are HAPLOID- one copy of each gene 
Mutations are highly vulnerable to Natural selection!
Prokaryotes can exchange genetic information via CONJUGATIONwhen two bacteria are temporarily linked together, genetic
information is passed from one to the other = Transduction Pg. 364 in text
BACTERIA
ARCHAEA
Found practically in every environment
on earth
Became a distinct domain in 1977 because
ribosomal RNA of Archaea differs from
Bacteria
Protected by a cell wall that contains
PEPTIDOGLYCAN-polysaccharides linked
by amino acids
Bacteria are classifed by whether they are:
1-Gram +, thick layer of peptidoglycan
2-Gram -, thin layer of peptidoglycan
3 shapes: Spirilli (spiral shaped), Bacilli (rod)
Cocci (round/spherical)
Some bacteria are:
1- Obligate anaerobes- unable to grow in the
Presence of O2
2- Facultative anaerobes- able to grow in the
Presence or absense of O2
Bacteria and Arachaea can be:
1- Photoautrotrophs 3- Chemoheterotrophs
2- Chemoautotrophs
Eukarya are more closely related to archaea
than to bacteria
Archaea contain lipids that allow them to
Exist in high temperatures
Cell walls do NOT have peptidoglycan
Types of Archaea: 1-methanogens, 2- halophiles, 3- thermoacidophiles
Methanogens- Methane makers
Halophiles- need high salt concentration to
grow, ex. The Dead Sea
Thermoacidophiles- found in hot springs,
Highly acidic conditions
Photoautotrophs- Are photosynthetic and use light energy to assemble the
organic molecules they require
-Primitive photosynthesizing bacteria us only photosystem I and DO NOT GIVE
OFF O2
-Advanced photosynthesizing bacteria (ex. Cyanobacteria) use photosys. I and II
And give off O2
Chemoautotrophs- Make organic molecules by using energy derived from the
oxidation of inorganic compounds in the environment
-Ex. Methanogens can be found at the deep hydrothermal vents, H2S
-They can produce methane from hydrogen gas and CO2
-Nitrifying bacteria oxidize ammonia (NH3) to nitrites (NO2) and nitrites to
nitrates (NO3)
Chemoheterotrophs- Most free-living bacteria are chmoheterotrophs, they take
up Pre-formed organic nutrients
-Bacteria produce chemicals such as ethyl alcohol, acetic acid, butyl alchol,
acetones
-Bacteria action produces butter, chees, sauerkraut, rubber, cotton, silk, coffee
CELL MEMBRANE STRUCTURE AND FUNCTION
Fig. 5.1
Chpt 5 pg 86
Plasma Membrane of
an Animal Cell
-Proteins inserted
into plasma membrane
are INTEGRAL proteins
-PERIPHERAL proteins
are on the cytoplasmic
side of the membrane
The membrane is ‘fluid’
Current model to
describe fluidity=
Fluid-Mosaic Model
Cells must be fluid and
pliable, rigidity can be
caused by cholesterol
Glycoprotein- a phsopholipid with a carbohydrate or sugar chain attached
Protects cell, facilitates adhesion btwn cells
TYPES AND FUNCTIONS OF PROTEINS (chpt 5 pg 88)
The Plasma Membrane
The plasma membrane is permeable and regulates the passage of molecules
in and out of the cell
The plasma membrane is ‘SELECTIVE’ or ‘Differentially Permeable’ or ‘Selectively Permeable’
Some molecules passively cross the plasma membrane (NO ENERGY REQUIRED) while others
are actively transported across the membrane (ATP IS REQUIRED)
Small, non-charged particles freely pass the membrane barrier:
Carbon Dioxide (CO2)
Oxygen (O2)
Glycerol
Alcohol
(These molecules follow their concentration gradient)
Water passively moves across via a protein called AQUAPORIN
Ions and polar molecules like glucose and amino acids slowly cross membrane, BUT often
need assistance by carrier proteins
PASSIVE TRANSPORT
Concentration gradient- Movement of material from an area of high concentration to
an area of low concentration
Diffusion- the movement of molecules from a higher to a lower concentration
Fig. 5.5 page 91
OSMOSIS
Diffusion is the movement of molecules from an area of high to low concentration
OSMOSIS is the movement of WATER across a membrane due to concentration differences
of solutes
OSMOTIC PRESSURE is the pressure that develops in a system due to osmosis
ISOTONIC SOLUTION
Solute and water concentration inside and outside of the cell are equal
No gain or loss of water
HYPOTONIC SOLUTION
Solutions that cause cells to swell and burst
The net movement of water is from the outside to the inside of the cell
HYPERTONIC SOLUTION
Solutions that cause a cell to shrink or shrivel due to loss of water
The net movement of water out of the cell
More Solute inside
cell swells as water
moves in to dilute
solute
Equal solute inside
and out
More Solute outside
cell Shrivels as water
moves out to dilute
solute
Fig. 5.8 page 93
Gases and small non-polar molecules can easily diffuse across the membrane
Larger molecules like glucose and amino acids need protein assistance
ACTIVE TRANSPORT
Movement of molecules or ions across the membrane AGAINST their concentration
gradient
CHEMICAL ENERGY or ATP is required for active transport
Carrier proteins are needed for active transport
Proteins that assist in the active transport of molecules across the membrane are
called ‘PUMPS’
The most studied PUMP is the ‘SODIUM-POTASSIUM PUMP’
+
Na
K+
Moves Moves
Outside Inside
Cell
Cell
IMPORTANCE OF Na+ - K+ PUMP
-Essential in maintaining the electrochemical gradient across
the cell membrane.
-The electrochemical gradient generated by transporting
Sodium OUT and Potassium IN is used in secondary active
transport
-Maintanence of osmotic balance, and most importantly
-Action potential generation and propagation in muscle and
nerve cells/ Cell
signalling.
http://wiki.answers.com/Q/Why_is_a_sodium_potassium_pump_important_in_organisims#ixzz1FwvJ9yD6
Fig. 5.10 page 95
BULK TRANSPORT- TRANSPORT OF LARGE MACROMOLECULES
Very specific form of pinocytosis
Vitamins, peptide hormones and lipoproteins can bind to the receptors
Ex. Cholesterol is taken into the cell by a coated pit
THE EXTRACELLULAR MATRIX (ECM) AND CELL JUNCTIONS
Provides protection
Collagen and Elastin
-Proteins in the ECM
-Provide structure
Integrin
- Protein connected to fibronectin
- Plays a role in cell signaling
- Influences shape and activities
of the cell
ANIMAL CELL JUNCTIONS
HOW ARE CELLS CONNECTED
TO EACH OTHER??
Tight Junction
Membrane proteins attach
to each other
Desmosome
Cells joined by Intracellular
filaments
Gap Junction
Occurs when identical plasma
membrane proteins join
together
HOW DO PLANT CELLS COMMUNICATE?
Plasmodesmata- narrow, membrane-lined
Channels that pass through the cell wall.
http://www.mcb.uct.ac.za/tutorial/virusentplant.htm
VIRUSES
VIRUSES
Viruses are found in plants, animals and bacteria and are
Associated with diseases in all 3.
Viruses have an RNA or DNA genome, but THEY ONLY
REPRODUCE BY USING THE METABOLIC MACHINERY
OF A HOST CELL
Viruses cannot reproduce on their own
Viruses are noncellular
Virus= poison, (Latin root)
Family= Viridae
Subfamily= Virinae
Suffix= Virus
Species hard to classify due to high mutation rates
LOUIS PASTEUR (1822-1895)
French Chemist
Believed something smaller than
a bacteria was the cause of rabies
First coined the term, “virus”
DIMITRI IVANOWSKY (1864-1920)
Russian Microbiologist
Studied viral diseases in tobacco
leaves
Filtered infected extract of tobacco
leaves through a porcelain filter that
retains bacteria leaves still got
disease  something smaller than
bacteria was causing disease
1950’s - ELECTRON MICROSCOPY
Uses a particle beam of electrons to magnify specimens.
Avian flu virus, shown in this scanning electron microscope image from
3DScience.com
VIRAL STRUCTURES
VIRAL STRUCTURE
Size- 10-400 nm. About the size of a large protein
Genome- 3-100 genes
Envelope - Covers capsid (not all viruses have an envelope, viruses w/o are “naked
- Is usually a piece of the host cell’s plasma membrane, contains viral
glycoprotein spikes
Outer Capsid- Composed of protein subunits
Inner Core- Contains nucleic acid, either DNA or RNA
- Contains Various proteins (ENZYMES)
Bacteriophage
HIV
Human Papillomavirus
Non-enveloped DNA Virus
Double stranded circular DNA
Infects skin and mucosal tissue
Some forms of HPV are cancer causing
or cause genital warts and are sexually
Transmitted
Other forms cause warts on the skin
Ex. Plantar warts
Only known host for HPV is human
TYPES OF VIRUSES
Enteric Viruses
-Viruses that infect the GI
tract
Respiratory Viruses
-Viruses that infect the
respiratory system
-Obtained by inhalation
ex. Orthomyxoviridae
(influenza)
Arboviruses
-Viruses from insects
-Arthropod-born (mosquitos,
flies etc.
ex. Bunyaviridae
Oncogenic Viruses
-Cell transforming viruses
-Target specific tissues
-some are zoonotic (from animals)
ex. Herpesviridae, papoviviridae
FAMILIES OF VIRUSES
Herpesviridae- dsDNA, lytic cycle, replicates in
Nucleus Ex. Chickenpox, shingles, cytomegalovirus,
Epstein Barr Virus and Herpes Simplex 1&2
Retroviridae- ssRNA, integrates into host genome in nucl.,
Has own reverse transcriptase gene, Ex. HIV
Papovaviridae- dsDNA, ex. HPV
Adenoviridae- dsDNA, lytic, human and horse hosts
Paramyxidae- ssRNA, replicates in cytoplasm, nonLytic/budding ex. MUMPS and MEASLES
Orthomyxoviridae- ssRNA, replicates in nucleus and
Cytoplasm, non-lytic/budding ex. INFLUENZA
Rhabdoviridae- ssRNA, replicates in cytoplasm,
Lytic and buds from membrane. Ex. Rabies
Bunyaviridae- ssRNA, replicates in cytoplasm, nonLytic ex. Hantavirus (rift valley fever)
Arenaviviridae- ssRNA, replicates in cytoplasm, nonLytic ex. Lassa Virus (West African fever)
Parvovaviridae- ssDNA, replicates in nucleus, ex.
B-19 virus=Human hemolytic anemia
Poxvirdidae- dsDNA, replicates in cytoplasm,
Budding and lytic ex. Smallpox, monkeypox
Example of how Zoonotic Viruses are transferred to Humans
Fig. 20A page 360 in your text
VIRUSES ARE PARASITIC
Viruses are ‘OBLIGATE INTRACELLULAR PARASITES’
*They can NOT reproduce outside of a living cell
A virus canNOT duplicate its own genetic material
A virus must infect a living cell to reproduce
When the infected cell duplicates, the viral genetic material is also duplicated
Viruses are HOST SPECIFIC – They infect many kinds of cells, but certain viruses
only infect certain kinds of cells!
Ex. Bacteriophages only infect Bacteria
Rabdinoviridae (Rabies Virus) only infects mammals
Human Immunodeficiency Virus (HIV) only enters certain blood
cells
Scientists can study viral behavior and infection in the laboratory by:
- Using live chicken eggs- inoculating eggs with live viral particles
- Infecting ‘CELL LINES’ (ex. From the ATCC-American Type Culture
Collection)
VIRUSES ARE CONSTANTLY MUTATING
Viral reproduction is highly imperfect
Many ‘mistakes’ are reproduced leading to mutation
The mutation rates in eukaryotes and in bacteria are
Around 1 mutation per 100,000,000 base pairs or 10-8 per
generation
The mutation rate in DNA viruses is approx. 1/1,000,000
(10-6) to 1/100,000,000 (10-8)
The mutation rate in RNA viruses is approx. 1/1,000 (10-3)
to 1/100,000 (10-5)
BREAKOUT SESSION #1
Every year, the Influenza or Seasonal Flu virus infects thousands of people
Of the thousands of people who get the flu, an average of 36,000 people actually
die from flu associated symptoms!!
Although we are vaccinated every year, some people still get the flu.
WHY DO PEOPLE STILL GET THE FLU AND WHY MUST WE GET VACCINATED EVERY
YEAR??
VIRAL REPRODUCTION- Bacteriophages
Bacteriophages or phages- VIRUSES THAT PARASITIZE BACTERIA
Bacteriophages have two life cycles 1) Lysogenic 2) Lytic
STEP 1
Bacteriophage attaches to a
Bacterial cell, ex. E. coli
The bacteriophage injects
Its DNA into the bacterial
cell
Fig. 20.3
VIRAL REPRODUCTION- Bacteriophages
Prophages can be toxic ex. Scarlet Fever
VIRAL REPRODUCTION- Animal Viruses
1- Attachment and fusion of virus to animal host cell or
Viruses taken in by endocytosis
2- Virus is uncoated-capsid and envelope removed
3- The viral genome is released and biosynthesis/duplication of genome occurs
4- Newly synthesized viruses are released via budding or lysis of the cell
3.
1.
4.
2.
This is a non-lytic
Budding virus example
The viral genetic material is
Duplicated in the cytoplasm
Fig. 20.4 page 361
Ex. of Retrovirus Replication (ex. HIV)
1. Attachment
2. Entry
3. Virus uses its own Reverse Transcriptase to
create copy DNA from ssRNA
4. ss Copy DNA (cDNA) become ds cDNA and is
incorporated into the host’s DNA
5. The host cell replicates its DNA AND THE
VIRAL DNA!!!
6. The viral DNA is transcribed from the host
DNA
7. The new viral DNA is re-packaged and the
virus is released from the cell
VIROIDS AND PRIONS
Viroids- Naked strands of RNA
not covered by a capsid
VIRUS
VIROID
Prions- Proteinaceous Infectious
Particles (a misshapen protein)
Causes TSEs (transmissible
Spongiform encephalopathies)
Disease found in tribal members
who practice cannibalism (eat
brain of deceased) in small
Tribe in Papua New Guinea
Viroids infect crops, ex. Potatoes,
Coconuts, Citruses
Misshapen prion interacts with
normal protein causing change
in shape
STILL UNDER INVESTIGATION
EXAM REVIEW
Chpt 3 (pages 37-58)-Macromolecules
Chpt 6 (pages 104-105top, 106,108-112)
Chpt 18 (pg320-327)- Cell Evolution and
multicellularity
Chpt 20 (all)- Viruses, Bacteria and Archaea
Chpt 4 (all)- The Eukaryotic Cell
Chpt 5 (all)- Membranes and Transport
EXAM REVIEW