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.

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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

http://en.wikipedia.org/wiki/Image:Biological_cell.svg

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