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 pores- channel 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 through2. _________________– lipids can pass lipid bilayer3. _________________– ions move through special
channel proteins4. _________________– 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.wisc-online.com/objects/ViewObject.aspx?ID=AP11103
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?
• http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP11103
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=dA5RfoGiupM
• http://www.youtube.com/watch?v=y8gZCTjAbVs&feature=related