Transcript CellStudentPresentations

Chapter Four
Student Presentations
The Nucleus
Section 4.4
Nucleolus
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The nucleolus is where protein and RNA molecules are being
constructed
Protein and RNA are subunits from which ribosomes are built and pass
through the pores of the nuclear envelopes and reach the cytoplasm.
Ribosomes form at times of protein synthesis in the cytoplasm.
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Nuclear Envelope
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Two outer membranes surrounding the nucleus are called the nuclear envelope
DNA is anchored to envelope which keeps it organized
Lipid bilayers (the envelope) keeps out and control the flow of water soluble
substances in and out of nucleus
Pores let in small molecules
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Chromosomes
• Chromosomes, which are defined
as DNA molecules and their
associated proteins, are found in
the nucleus. Chromatin is known
as the cells collection of DNA.
• They have two forms; when the
cell is not dividing, chromosomes
appear as thin strands inside the
nucleus. When the cell is dividing,
the chromosome condenses into
a double helix structure.
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Section 4.5: The
Cytomembrane System
By Andrew Lindquist, Nobska Goodhue, Anna Bortnick,
and Danny Flannigan (Spell checker)
The Cytomembrane System is a series of organelles in which
lipids are assembled and new polypeptide chains are
modified into final proteins. These products are shortened
and shipped to their final destinations.
Endoplasmic Reticulum
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Functions of the Cytomembrane begin in the
endoplasmic reticulum (ER)
In animal cells, the ER is continuous with the
nuclear envelope, and extends through the
cytoplasm.
Rough ER are typically observed as being
arranged into flattened sacs with many
ribosomes attached.
These ribosomes synthesize all new
polypeptide chains.
Once these chains are in the rough ER,
enzymes may attach oligosaccharides and
other side chains to them, and these final
proteins are secreted by many cells.
The smooth ER is free of ribosomes and
curves through the cytoplasm, where most
lipids are assembled.
Golgi Bodies
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Located in the cytoplasm, in eukaryotic animal
cells
Golgi bodies are where enzymes put finishing
touches on proteins and lipids for usage in the
body
Finished proteins and lipids are packaged inside
vesicles to ship to specific locations
Golgi bodies are composed of a series of flat,
membrane-bound sacs
Vesicles form as sections of the membrane of the
top sac break away into the cytoplasm
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Variety of Vesicles
• Vesicles are tiny, membrane sacs that move through the
cytoplasm
• Lysosome are organelles of intracellular digestion and
buds from the Golgo membranes of animal cells and
certain fungal cells they contain diverse enzymes that
speed the breakdown of proteins, complex
carbohydrates, nucleic acids, and some lipids
• Peroxisomes- tiny sac of enzymes that break down fatty
acids and amino acids
• Hydrogen peroxide, a potentially harmful product, forms
during the reactions, helps break down alcohol
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Mitochondria
•The barista of Eukaryotic cells
•Creates ATP molecules (coffee), which are energy carrying
nucleotides
•Mitochondria are located in the cytoplasm of a eukaryotic cell
Structure
• 2 compartments:
1. outer membrane-->holds Hydrogen Ions and
controls the flow of energy
2. inner membrane-->folds on itself, creating the cristae
-->energy releasing reactions happen here
Function
• Mitochondria break down organic compounds into
carbon dioxide, water
• They also form ATP molecules-->these are energy
carrying nucleotides
• Energy demanding cells have more mitochondria
• Power houses of eukaryotic cells
• Mitochondria require oxygen
Chloroplasts and other Plastids
•Plastids are organelles that specialize in photosynthesis or function in storage. Including:
chloroplasts, chromoplasts, amyloplasts.
•Of all eukaryotic cells only photosynthetic cells have chloroplasts. Chloroplasts are generally
oval or disk shaped.
•These organelles convert sunlight into ATP energy which is used to make sugars and other
organic compounds.
•Chloroplasts: Primarily contain chlorophylls (photosynthetic pigments which reflect green light)
•Chromoplasts: lacks chlorophylls but have an abundance of carotenoids (source of red or
yellow colors in plants).
•Amyloplasts: lack pigments.
•Chloroplasts are apart of the innermost membrane.
Plant Cell Structure
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Plastids- category of organelles that specialize in photosynthesis
Three types: chloroplasts (oval or disc shape), chromoplasts, and
amyloplasts
Only photosynthetic have plastids
Stroma (semi-liquid interior)
Stroma surrounded by two outer membrane layers
In stroma is a third membrane layer-thylakoid membrane: folded disc
shape compartments
Compartments stack. Each stack is a granum
light-trapping pigment enzymes (chlorophylls, carotenoids)
inside stroma, ATP energy is used
Central vacuole- fluid filled. stores amino acids,sugars, ions, and toxic
wastes
Photosynthesis
• Photosynthesis is the process of converting sunlight to energy
• Of all eukaryotic cells, only photosynthetic ones have
chloroplasts, which are used to convert sunlight into energy.
• The first stages of photosynthesis starts at a thylakoid
membrane, where pigments, enzymes and other proteins trap
light, and convert it and store it in the form of ATP.
• The most abundant photosynthetic pigments are chlorophylls,
which reflect or transmit green light.
• Inside the stroma, ATP energy is used to make sugar, starch
and other organic compounds.
• The abundances of certain photosynthetic pigments determine
what color a plant is. An example would be carotenoids which, in
abundance can make a plant appear red, yellow, or green.
Cytoskeleton
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Interconnected system of fibers,
threads and lattices between
nucleus and plasma membrane of
eukaryotic cells
Gives cells internal organization,
shape and capacity to move
Two classes of cytoskeletal
elements: microtubules and
microfilaments
Animal cells also have intermediate
filament—imparts mechanical
strength to cells and tissues
Microtubules and
Microfilaments
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MICROTUBULES
Long, hollow, cylinder—25
nanometers wide
Made of tubulin monomers
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Largest cytoskeletal
element
Tubulin: protein of 2
chemically distinct
polypeptides folded into a
globular shape
Function:
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Govern the division of cells
and some aspects of their
shape as well as many cell
movements
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MICROFILAMENTS
Thinnest cytoskeletal
element
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5-7 nanometers wide
Made of two polypeptide
chains helically twisted
together
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Take part in movements,
especially those that affect
the cell surface
Contribute to development
and maintenance of
animal cell shape
Myosin and Intermediate
Filaments
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MYOSIN
Monomers of other proteins can
be attached to the tubulin and
actin that make up the
microtubules and microfilaments
– Ex: Monomers of myosin,
dynein, or other motor protein
attach to surface of
microtubules and
microfilaments in ways that
cause cell movement
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INTERMEDIATE FILAMENTS
Most stable part of the
cytoskeleton
8-12nm wide
6 known groups: desmins,
vimentins, lamins, cytokeratins
are 5
Mechanically strengthen cells
Present in only certain animal
tissue
– Can be used to identify cells
The Structural Basis of Cell
Motility
Chapter 4.9
By Diva, Olivia, and Timmy
Mechanisms of Cell Movements
• Microfilaments, microtubules, or
both take part in most aspects of
mobility through three mechanisms
• 1. Length of a microtubule or
microfilament can grow or diminish
by the controlled assemble or
disassembly of its subunits
• 2. Parallel rows of microfilaments
or microtubules actively slide in
specific directions
• 3. Microtubules or microfilaments
shunt organelles or parts of the
cytoplasm from one location to
another
• Pseudopods: temporary lobe-like
protrusions from the body inside
each lobe, microfilaments
Flagella and Cilia
• Flagellum and Cilia: structures for
cell mobility
• Have a ring of nine pairs or
microtubules and a central pair
• System of spokes and links
stabilize the array
• Centriole: barrel shaped structure
that is one type of microtubule
producing center
• Basal body: refers to the location
of the centriole
• Flagella - longer and less profuse,
sperm use the flagella as a tail to
move
• Cilia - stir air and fluids
Flagella, Cilia and the Basal Body
Centriole
Eukaryotic Cell Walls
-The cell wall is a structural component, which wraps entirely around the plasma membrane.
-Not only does it offer support physically to the cell owner, but it also protects it.
-The wall is porous so that water and solutes can move to and from the membrane easily.
-The primary wall consists glue-like secretions (polysaccharides, glycoproteins, and cellulose)
which combine together to form the wall. This wall is thin and plyable.
-Deposits on the primary wall’s inner surface combine to form a rigid, secondary wall, which
reinforces cell shape.
Matrixes Between Animal
Cells
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Animal cells don’t have cell walls. Therefore…
Matrixes are composed of cell secretions and materials from
surroundings. These are the ‘walls’
Cartilage is made up of scattered cells, this forms collagen fibers in a
‘ground substance’ of modified polysaccharides
An extensive matrix yields a wide separation of cells
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Cell-to-Cell Junctions
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The only contact a cell has with the outside world is through its plasma membrane
In plant cells tiny channels connect adjacent cell’s cytoplasm
In animal cells there are three junctions; Tight junctions, adhering junctions, and
gap junctions
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– Tight junctions link cells in the epithelial tissue, they prevent water soluble
substances from leaking through
– Adhering junctions join cells in organs subjected to stretching
– Gap junctions link the cytoplasm of neighboring cells allowing for a quick
transfer of signals and substances