Transcript The Amazing Cell - Dr. Roberta Dev Anand

EDUCATION
“Education is a progressive discovery
of our own ignorance.”
-Will Durant
The Amazing Cell
Chapter 3
Anatomy and Physiology
Cells
• Basic unit of _______________.
• 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
• ______________- “before nucleus”, cells without
nucleus were thought to have developed first.
• DNA is not in a separate compartment
• _______________- “true nucleus”, developed later
and are found in all multicellular organisms.
• Has distinct nucleus surrounded by protective
____________________.
Size Limitations
• Size of most cells is restricted to 10-30 µm in diameter
• Why is the small size so important:
1)
2)
3)
Mammalian Cell Anatomy
• Essential structures:
• ___________________(also known as
plasma membrane).
• Separates cell from environment.
• ___________________
• Everything inside the cell membrane but
outside the nucleus.
• ___________________
• Contains the genetic material of the cell.
Other 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
• ____________________: composed of two layers of phospholipid
molecules
• ________________ “heads”are on outside
• ________________“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.
• Proteins that occur within the bi-layer are called
__________________________.
• 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:
• ____________________
• permit only certain molecules in or out of the
cell
• _______________
• allow the passage of molecules freely
Peripheral Proteins
• Functional 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.
Cell Membrane: External Surface
• _________________– 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:
• _____________________________
• 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
• ____________________________
• 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
• ______________- occur in large numbers on the exposed
surface of some cells.
• Shorter than flagella and move synchronously to create
waves of motion for propulsion.
• Functions: to move fluid and other substances past the
cell surface
• In upper respiratory tract, propel bacteria and mucus
from the lungs
• In oviduct, pulls egg from ovary into oviduct.
Flagella and Cilia
• _______________- significantly longer
than cilia and usually occur singularly.
• Function: aid in the movement of a cell
through fluid.
• Tail of sperm is a 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
•
Framework for the cells
• Gives support and shape to the cell, enables
cell to move and provides direction for
metabolic activity.
• anchors organelles.
• 3 types of fibers that comprise cytoskeleton:
• Microtubules
• Intermediate fibers
• Microfilaments.
Cytoskeleton
• _______________
• Thickest fibers and are long and hollow
• Form cables that organelles attach to to
move throughout the cell.
Cytoskeleton
• _____________________
• Woven, ropelike fibers that are able to
resist pulling forces on the cell
• Toughest and most permanent part of
the cytoskeleton.
Cytoskeleton
• ________________________
• Composed of actin and myosin
• Play key role in cell’s ability to change shape &
break apart during cell division
Organelles
• “little organs”
• Membrane bound structures within
cytoplasm that have specialized functions.
Organelles
• 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 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.
• May be __________ or ___________depending on the
presence of ribosomes.
• 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
• Receives and modifies proteins produced by
ER.
• Once completed they are packaged in vesicles
and travel out into the cell.
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.
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 (known
as 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 have one nucleus, some
may be multi-nucleated while others 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
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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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.
• http://www.youtube.com/watch?v=dA5Rfo
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• http://www.youtube.com/watch?v=y8gZCTj
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