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EDUCATION
“Education is a progressive discovery
of our own ignorance.”
-Will Durant
The Amazing Cell
Chapter 3
Anatomy and Physiology
Cells
• Basic unit of life.
• Not to be confused with atoms-the basic units of
all matter
• Can exist alone as a single, free-living plant or
animal, or can combine to form elaborate and
complex organisms.
• We must understand the cell before we can
understand the anatomy and physiology of the
tissues and systems the cell makes up
Evolution of Cells
• Primitive cells are thought to have resembled
present-day bacteria and contained a single strand
of DNA in a gelatinous protoplasm.
• Prokaryotes- “before nucleus”, cells without
nucleus were thought to have developed first.
• Has DNA but not in a separate compartment
• Eukaryotes- “true nucleus”, developed later and are
found in all multicellular organisms.
• Has distinct nucleus surrounded by protective
nuclear envelope.
Size Limitations
• Size of most cells is restricted to 10-30 µm in diameter
because of relationship between surface area and volume
of a cell.
• Why is this important:
1) A small cell with proportionately larger surface area
will be able to complete its metabolic functions more
rapidly and efficiently than a large cell with a relatively
small surface area.
2) A single nucleus can control the metabolic activity of a
small cell better than a large one.
3)
Mammalian Cell Anatomy
• Essential structures:
• Cell membrane(also known as plasma
membrane).
• Separates cell from environment.
• Cytoplasm
• Everything inside the cell membrane but
outside the nucleus.
• Nucleus
• Contains the genetic material of the cell.
Other optional organelles in a cell
•
•
•
•
•
•
•
Cilia
Mitochondria
Endoplasmic Reticulum (ER)
Ribosomes
Golgi apparatus
Lysosome
Peroxisomes
Cell Membrane
• Flexible, elastic barrier between inner
cytoplasm and outer environment.
• Governs the movement of atoms and
molecules in and out of the cell.
• Consists primarily of protein,
phospholipids, cholesterol, lipids, and
carbohydrates.
Structure of the Cell Membrane
• lipid bilayer: composed of two layers of phospholipid molecules
• hydrophobic_ “heads”are on outside
• hydrophilic_“tails” are on
the inside
• Most lipid soluble molecules easily
pass through membrane
• Water-soluble molecules do not
readily pass through
Structure of the Cell Membrane
•
Structural and Functional proteins are embedded
in the membrane.
• Remember the other names for these proteins?
• Remember what they do?
• Proteins that occur within the bi-layer are called
integral proteins.
• These proteins may span the entire width of
the membrane and create channels through
which other molecules can pass.
Integral Proteins
• Channels they create may be:
• ___Selective___
• permit only certain molecules in or out of the
cell
• ___Pores______
• allow the passage of molecules freely
Peripheral Proteins
• Type of globular protein which can be
bound to the inside or outside surfaces of
the cell membrane.
• Sometimes act as enzymes
• May be involved in changing the cell’s
shape (muscle contraction).
Cell Membrane: External Surface
• __Glycocalyx___– coating on the cell surface of some
cells made of glycoprotein and glycolipids.
• Unique to each cell – provides markers for
recognition and for interactions.
• Composed of 2 groups of molecules:
• ___Cell Adhesion Molecules___
• Sticky glycoproteins that cover cell surface.
Help cells move past one another and
signaling.
• Signal circulating cells like WBCs to areas
of inflammation or infection
• ___Membrane Receptors___
• Integral proteins and glycoproteins that act
as binding sites on the cell surface.
• Involved with signaling as well.
Flagella and Cilia
• Extensions of the plasma membrane
• _Cilia____- occur in large numbers on the exposed surface
of some cells. Shorter than flagella and move synchronously
to create waves of motion for propulsion.
• Shorter than flagella and move synchoronously to create
waves of some cells.
• Functions:
• In upper respiratory tract, propel bacteria and mucus
from the lungs
• In oviduct, pulls egg from ovary into oviduct.
• __Flagella___- significantly longer than
cilia and usually occur singularly.
• Attached to individual cells and aid in
propulsion.
• Example:
• Tail of sperm is flagellum
Cytoplasm
• The inner substance of the cell, excluding
the nucleus.
• Components include:
• Cytosol
• Cytoskeleton
• Organelles
• Inclusions
Cytosol
• The fluid of the cell
• Viscous, semi-transparent liquid
composed of dissolved electrolytes,
amino acids, and simple sugars.
• Proteins suspended within fluid give fluid
its thick, jellylike consistency.
• Theses proteins are enzymes that are
important in metabolic activities of the
cell.
Cytoskeleton
• Three dimensional frame for the cells
• Flexible and fibrous and changes in accordance to
activities of the cell.
• Gives support and shape to the cell, enables cell to
move and provides direction for metabolic activity.
• Also anchors organelles.
• 3 types of fibers that comprise cytoskeleton:
• Microtubules
• Intermediate fibers
• Microfilaments.
• _______________
• Thickest fibers and are long and hollow
• Form cables that organelles attach too.
• Proteins move these organelles along
microtubules throughout cell.
• Can be easily disassembled and
reasembled to form new paths or take
on new direction.
• _____________________
• Woven, ropelike fibers that possess high
tensile strength and are able to resist pulling
forces on the cell by acting as internal guy
wires.
• Toughest and most permanent part of the
cytoskeleton.
• Composed of proteins
• ________________________
• Composed of actin and myosin
• Play key role in cell’s ability to change shape,
break apart during cell division and form
outpouchings and involutions.
Organelles
• “little organs”
• Membrane bound structures within
cytoplasm that have specialized functions.
• Compartmentalization is good for
metabolic processes such as food
absorption, energy production, and
excretion.
Organelles continued
• Include:
• Mitochondria
• Ribosomes
• Golgi Apparatus
• Endoplasmic Reticulum
• Lysosomes
• Peroxisomes
Mitochondria
• One of largest organelles
• Called “powerhouse of the cell” because
______________________________________
______________________________
• Nutrient molecules (i.e. glucose) are broken
down to produce intracellular fuel in the form
of ATP. This process is called cellular
respiration.
Mitochondria continued.
• Active cells have higher energy demands
so have more mitochondria.
• Example:
• Mitochondria can divide through fission-or
the pinching itself in half.
Mitochondrial shape
• Tend to be elliptical and round with
outer smooth membrane and inner
involuted membrane.
• Inner membrane forms ____________
which increase internal working area
and matrix (enzyme-rich liquid housed
in mitochondria).
• Cristae are site of ATP production
Ribosomes
• Most common organelle in the cell.
• Made of two globular subunits composed
of protein and rRNA.
• Site of _____________ synthesis.
• May be attached to the endoplasmic
reticulum (rough ER) or free in the
cytoplasm
Endoplasmic Reticulum (ER)
• Series of flattened tubes stacked on one another and
bent into crescent shape.
• Composed of single lipid bilayer
• May be __________ or ___________depending on if it
contains ribosomes or not.
• Rough ER is involved in production of protein.
• Smooth ER is connected to Rough ER and is
active in synthesis and storage of lipids.
Golgi Apparatus
• Found near nucleus and is similar in
structure to ER (composed of cisternae)
• Receives proteins produced by ER.
• Proteins are modified here as they move
from fold to fold.
• Once completed they are packages in
vesicles and travel out into cell or to cell
membrane.
Lysosomes
• Specialized vesicle formed by Golgi apparatus.
• Contains hydrolytic enzymes which engulf bacteria or
cell nutrients and digests them.
• Principal responsibility
is:______________________________________
_________________________
• Considered “stomach of the cell”.
• When cells die, lysosomes are released and digest
other portions of the cell, this is called autolysis.
• May also release enzymes outside of cell to assist
with breakdown of extracellular material.
WHATEVER YOU ARE DOING,
MAKE AN EFFORT TO DO IT WELL.
“I don’t know that there are any
shortcuts to doing a good job.”
-Sandra Day O’Connor
Peroxisomes
• Membranous sacs containing enzymes found throughout
the cell.
• Important in detoxification of various molecules.
• Remove _________________normal products of
cellular metabolism but can be harmful in large
numbers
• Carry two major enzymes:
• _______________________-assist in conversion in
free radicals to hydrogen peroxide.
• ______________________-reduce hydrogen peroxide
to water.
Inclusions
• Packaged units of metabolic products or
substances that the cell has engulfed.
• May or may not be membrane-bound.
• ______________ are larger than vesicles
but are of similar structure. These
structures act as storage units, holding
substances within the cell until its contents
can be used.
Centrioles
• Found in pairs perpendicular to one another.
• Visible during cell division near nuclear
envelope
• Help to organize ____________________during
cell division.
• May also form bases of cilia and flagella (basal
bodies).
Nucleus
• Largest organelle in the cell.
• Control center or “brain” of the cell.
• Primary functions are to maintain
hereditary information of the species and
to control cellular activities through protein
synthesis.
• Some cells may be multi-nucleated while
some are anucleated.
Nuclear Anatomy
• Divided into four parts:
• Nuclear Envelope or membrane
• Nucleoplasm
• Chromatin
• Nucleoli
Nuclear Envelope and
Nucleoplasm
• Separated from cytosol by a
nuclear envelope composed of
two lipid bilayers
• Contains nuclear poreschannel through entire
thickness.
• Allow transport of protein
and RNA.
Nucleoplasm
• The gel-like substance that fills the
nucleus.
• Resembles cytosol.
DNA, RNA and Chromatin
• DNA and RNA are composed of
nucleotides.
• What are the 5 nucleotides?
• How do they pair?
• Chromatin-fibers made up of DNA and
globular proteins called histones
• During cell division the chromatin
condenses into super-coiled x-shaped
structures called __________________
Nucleoli
• Not membrane bound
• Where ribosomal subunits are made
• Contain DNA that governs synthesis of
rRNA.
Cell Physiology
• The Cellular Environment
• Body Fluids
• Composed primarily of water
• _________________fluid found
inside cell.
• ___________________fluid outside
cell.
• ___________________fluid
contained in the tissues between the
cells.
Ions, Electrolytes, and pH
• What are ions?
• Cations
• Anions
• Electrolytes
• In sick or injured animals, electrolyte
concentrations and pH of intracellular and
extracellular fluid can become abnormally
high or low
Membrane Processes
• In order to maintain homeostasis cell must
select what it needs from extracellular fluid
and bring it into intracellular environment.
• Must excrete waste products or transport
resources needed in other parts of the
body to the extracellular compartment.
• Processes may be _______________ (do
not require ATP) OR
_______________(do use ATP).
Passive Transport Processes
• Remember: No Energy Required!
• 4 Passive Processes:
• Diffusion
• Facilitated Diffusion
• Osmosis
• Filtration
Diffusion
•
movement of molecules from _________
concentration to _____________concentration
• driven by a ______________________the
difference between the concentration of one area
and the concentration of another.
• Will continue until the molecule is evenly dispersed
throughout the solution
• Determining factors for Diffusion through a
membrane:
1. _________________– small can move through
2. _________________– lipids can pass lipid bilayer
3. _________________– ions move through special
channel proteins
4. _________________– faster in hot solution
Diffusion
Facilitated Diffusion
• Selective carrier proteins assist in
movement of molecules from higher to
lower concentration; speed of diffusion is
limited by saturation of carrier molecules.
• http://www.wisconline.com/objects/ViewObject.aspx?ID=A
P11103
Osmosis
• Passive movement of __________
through a semi-permeable membrane from
high concentration to low concentration.
• Similar to diffusion, but here, we are
referring to the movement of water
molecules rather than solute
BE RESPONSIBLE FOR YOUR
OWN HAPPINESS!
“Happiness is not in our
circumstances, but in ourselves.”
-John B. Shereen
Filtration
• ___________________(caused by the
beating heart) forces liquid and small
molecules through a membrane.
• Liquids pushed through a membrane
when the pressure on one side is
greater than that on the other side.
• Example?
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P11103
Tonicity Terminology
• ________________ : Extracellular fluid
has same concentration of dissolved
substances as intracellular fluid
• ___________________: Cytoplasm
(inside) of cell is more concentrated than
extracellular (outside) fluid
• __________________: Extracellular fluid
is more concentrated than cytoplasm
Active Transport Processes
• Remember: Requires Energy (ATP)!
• Relies on a carrier protein with a specific binding
site for ATP
• Does not require a concentration gradient
• __________________– substances are moving in
the same direction
• ___________________ – substances are moved
in opposite directions
• Include:
• Active Transport
• Endocytosis
• Phagocytosis
• Pinocytosis
• Receptor mediated
• Exocytosis
Active Transport
• Active movement of molecules by specific
carrier protein; molecules may move
against concentration gradient.
Endocytosis
• ____________________
• Cells engulf solid substances
• _____________________
• Cells engulf liquid substances
• ________________________
• Specialized protein receptors bind to
ligands.
• Ligand-small molecules that bind to
receptors or larger molecules.
Exocytosis
• Excretion of waste products and secretion
of manufactured substances.
• Packaged in secretory vesicles which fuse
with cell membrane and are ejected to
extracellular space.
Life Cycle of the Cell
• Two types of division of cells.
• ________________- Reduction division
• Found in reproductive cells. End up
with half of what we start with.
• ______________- exact replication of cell.
• We will focus mainly on Mitosis for this
chapter.
Mitosis
• Life cycle has been divided into two major periods:
• _______________
• When cell is growing, maturing, and
differentiating.
• Cells spend majority of time in this phase.
• ________________
• When cell is actively dividing.
• Composed of 5 stages:
• _________________
• _________________
• _________________
• _________________
Interphase
• Period between cell divisions.
• Nucleus and nucleoli are visible and
chromatin is arranged loosely throughout
the nucleus.
• Divided into three subphases:
• Growth 1 (G1)- metabolic activity and
cell growth; time variable (min-yrs)
depending on cell type
• Synthetic (S)- DNA replication
• Growth 2 (G2)- very brief; synthesis of
enzymes and proteins needed for
mitosis
DNA Replication
• Many cells are continually replicating to maintain body tissues,
to heal wounds, or to enable growth
• DNA must be replicated before the cell can divide – a copy of
DNA is made to be passed to the daughter cell
• Occurs during Interphase
Mitotic Phase- Cell Division
• Prophase
• Chromatin coils and are
composed of two identical
chromatids
• Spindle apparatus appears
• Normal synthetic processes
cease.
• Nuclear envelope disintegrates
• Metaphase
• Chromosomes are lined up
in center of spindle.
• Centromere of each
chromosome is attached to
a spindle fiber.
• Anaphase
• Centromeres split apart and each
chromatid becomes its own
chromosome.
• Spindle fiber separates, and
chromosomes are pulled away from
each other.
• Cytoplasm constricts along metaphase
plate.
• Telophase
• Final stage of mitosis
• When chromosomal movement stops
• Chromosomes reach poles and begin
to unravel.
• New nuclear envelope appears as well
nucleoli.
• Cytokinesis ends telophase.
• New daughter cells enter interphase.
Control of Cell Division
• Some cells divide rapidly others not so
fast.
• Examples of each
• Normal cells stop dividing when they come
into contact with surrounding cells.
• Called Contact inhibition
• Division can be controlled once numbers
reach a certain point.
• Proteins can also allow cells to enter
mitotic phase
Protein Synthesis
• Protein synthesis is essential for life.
• Begins in nucleus
• DNA information is first transcribed
• Transcription-Genetic information in DNA is
copied onto messenger RNA (mRNA)
• Codon- series of 3 RNA nucleotides.
• mRNA sends information to cytoplasm
• Translation- Ribosomes (rRNA) bind to
mRNA strand.
• New protein building as codes are
translated from nucleotides to amino acids
by tRNA
Genetic Mutations
• A genetic error.
• Mutations may be so severe that cell dies, but may
also cause no issues whatsoever.
• Some can be repaired by repair enzymes.
• May occur spontaneously or due to mutagens.
• Viruses
• Ionizing radiation
• Certain chemicals
• What is cancer?
• What is chemotherapy?
Cell Differentiation and
Development
• Differentiation- The progressive acquisition
of individual characteristics by cells to
enable them to perform different functions.
• Differentiation is important as it keeps cells
focused on a particular function.
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GiupM
• http://www.youtube.com/watch?v=y8gZCTj
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