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26 Cards in this Set

  • Front
  • Back
Organelle That contains DNA

• Mitochondria are cellular

• Contain circular DNA

• Sites for chemical
reactions called
oxidative metabolism

• The organelle is
surrounded by two
Organelle that contains DNA

• Chloroplasts are the
location for

• The organelle is also
surrounded by two

• Inside a series of
membrane are fused to
form Thylakoids, site of

• Contain circular DNA• Chloroplasts are the
location for

• The organelle is also
surrounded by two

• Inside a series of
membrane are fused to
form Thylakoids, site of

• Contain circular DNA
Organelles That Contain DNA
• Both mitochondria and chloroplasts
possess circular DNA that is not found
elsewhere in the cell

• They cannot be grown free of the cell

- they are totally dependent on the cells within
which they occur
The theory of endosymbiosis is...
- states that some organelles evolved from a symbiosis
in which one cell of a prokaryotic species was
engulfed by and lived inside of a cell of another
species of prokaryote

- the engulfed species provided their hosts with
advantages because of special metabolic activities

- the modern organelles of mitochondria and
chloroplasts are believed to be found in the eukaryotic
descendants of these endosymbiotic prokaryotes
Evidence Supporting Endosymbiosis theory:
• In addition to the double membranes and
circular DNA found in mitochondria and
chloroplasts, there is a lot of other evidence
supporting endosymbiotic theory

- mitochondria are about the same size as modern

- the cristae in mitochondria resemble folded
membranes in modern bacteria

- mitochondrial ribosomes are similar to modern,
bacterial ribosomes in size and structure

- mitochondria divide by fission, just like modern
The Cytoskeleton: Inferior framework of the cell.
• The cytoskeleton is an internal framework of
protein fibers that

- anchor organelles to fixed locations

- support the shape of the cell

- helps organize ribosomes and enzymes needed for
synthesis activities

• The cytoskeleton is dynamic and its components
are continually being rearranged (formed and
Three different types of protein fibers comprise
the cytoskeleton
-intermediate filaments
• thick ropes of intertwined protein

• Mechanical strength


• hollow tubes made up of the protein tubulin

• Intracellular transport, stabilization cell structure

- microfilaments

• long, slender microfilaments made up of the protein

• Cell movement
Microtubules provide a means to transport
material inside the cell efficiently over long
Centrioles are complex structures that assemble
microtubules in animal cells and the cells of most

- they anchor locomotory structures, such as flagella or cilia

- they assemble microtubules near the nuclear envelope

- Involved in cell division
Cell Movement
Cell movement is associated with the
movement of actin microfilaments and/or

- some cells “crawl” by coordinating the
rearrangement of actin microfilaments

- some cells swim by coordinating the beating
of microtubules grouped together to form
flagella or cilia
Outside the Plasma Membrane: Cell Movement
• found in plants, fungi,
and many protists

• comprised of different
components than
prokaryotic cell walls

• function in providing
protection, maintaining
cell shape, and
preventing excessive
water loss/uptake
Extracellular Matrix
Extracellular matrix (ECM)

• takes the place of the cell wall in animal cells and is comprised by a
mixture of proteins secreted by the cell

• collagen and elas(n proteins form a protec4ve layer over the cell surface

• fibronectin protein connects the ECM to the plasma membrane

• the fibronectin molecules also connect to integrins, proteins that extend
into the cytoplasm of the cell

– this extracellular‐intracellular connec4on allows the ECM to influence cellular
behavior and to coordinate groups of cells functioning as tissues
Diffusion and Osmosis Definition
Movement of water and nutrients into a
cell or elimination of wastes out of cell is
is essential for survival
Diffusion and osmosis: Movement occurs in 3 ways:
This movement occurs across a biological
membrane in one of three ways
• diffusion
• membrane folding
• protein transport
Diffusion: Difuse: duh!
• Molecules move in a random fashion but there is
a tendency to produce uniform mixtures

• The net movement of molecules from an area of
higher concentration to an area of lower
concentration is termed diffusion

• Molecules diffuse down a concentration gradient
from higher to lower concentrations

-diffusion ends when equilibrium is reached
Only certain substances undergo diffusion
across the plasma membrane
• Only certain substances undergo diffusion
across the plasma membrane

- molecules like oxygen, carbon dioxide, and nonpolar

- ions and polar molecules cannot cross the interior of
the membrane

• Water, although polar, is able to diffuse freely
across the plasma membrane

- aquaporins are selective channels that permit water
to cross
• Water moves down its concentration
gradient in moving into or out of a cell
through a process called osmosis

- the movement of water is dependent on the
concentration of other substances in a

- the greater the amount of solutes that are
dissolved in a solution, then the lesser the
amount of water molecules that are free to
Osmotic Concentration
• The concentration of all molecules dissolved
in a solution is called the osmotic
concentration of the solution

• Osmotic concentrations of different solu4ons
can be compared relative to each other
Bulk Passage into and out of Cells
• Bulky substances are contained within
vesicles as they are moved into and out of
a cell

- endocytosis is the engulfing of substances
outside of the cell in order to form a vesicle
that is brought inside the cell

- exocytosis is the discharge of substances
from vesicles at the inner surface of the cell
Forms of Endocytosis
• Phagocytosis is
endocytosis of
particulate (solid)

• Pinocytosis is
endocytosis of liquid
Selective Permeability
Selective permeability allows cells to
control specifically what enters and leaves

- involves using proteins in the membrane for
transporting substances across

- transport can be down a concentration
gradient (i.e., diffusion) or against a
concentration gradient (i.e., active transport)
Selective Permeability
- Selective diffusion
proteins act as open channels for whatever is
small enough to fit inside the channel

• this form of diffusion is common in ion transport
Selective Permeability
- Facilitated diffusion
• proteins act as carriers that can bind only to
specific molecules to transport

• transport is limited by the availability of carriers

• if there are not enough carriers, then the transport
is saturated
Selective Permeability
-Active Transport
Selective Permeability

• Active transport

- utilizes protein channels that open only when energy is supplied

- energy is used to pump substances against or up their
concentration gradients

-allows cells to maintain high or low concentration of certain

• recall that diffusion always ends in equilibrium

• There are two kinds of channels that perform active
transport in cells

- sodium-potassium pump

- proton pump
How the sodium-potassium pump
• The result of the Na+-K+ pump is to
generate a concentration gradient with
more Na+ outside of the cell than inside

• Cells exploit this gradient in key ways

-for the conduction of signals along nerve cells

- for the transportation of important molecules
into the cell against their concentration
Selective Permeability
-Coupled Transport
• the cell membrane has many facilitated diffusion
channels for Na+ but it is only transported if
partnered with another substance

-this is called coupled transport

• The concentration gradient favoring the entry of
Na+ into the cell is so strong that a coupled
substance will be transported even if it is against
the concentration gradient

-coupled transport is a common way for cells to
accumulate sugars and amino acids