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A & P 1 Chapters 1 & 3

Terms in this set (161)

Chapter 1: The Human Body- An Orientation
...
Anatomy
- The study of the structure of body parts and their relationship to one another
Physiology
- The study of the function of the body's structural machinery
Gross Anatomy (visible to the naked eye)

1. Regional
- All structures in one part of the body (such as the abdomen or the leg)
2. Systematic
- Gross anatomy of the body studied by system
3. Surface
- Study of internal structures as they relate to the overlying skin
Microscopic Anatomy

1. Cytology
- Study of the cell
2. Histology
- Study of tissues
Developmental Anatomy
- Traces structural changes throughout life
Embyrology
- Study of developmental changes of the body before birth
Specialized Branches of Anatomy

1. Pathological
- Study of structural changes caused by disease
2. Radiographic
- Study of internal structures visualized by X-Rays
3. Molecular
- Study of anatomical structures at subcellular level
Physiology
* Considers the operation of specific organ systems, such as:
- Renal: Kidney function
- Neurophysiology: Workings of the nervous system
- Cardiovascular: Operation of the heart and blood vessles

* Focuses on the functions of the body (often at the cellular or molecular level)

* Understanding physiology also requires a knowledge of physics, which explains electrical currents, blood pressure and the way muscles use bone for movement
Principle of Complementarity
* When the body performs as it is supposed to

- Function always reflects structure (ex. the shape of a muscle)
- What a structure can do depends on its specific form
Levels of Structural Organization

1. Chemical
- Atoms combined to form molecules
2. Cellular
- Cells are made of molecules
3. Tissue
- Consists of similar types of cells
4. Organ
- Made up of different types of tissues
5. Organ System
- Consists of different organs that work closely together
6. Organismal
- Made up of the organ systems
Organ Systems of the Body (11)
(for the exam: know system and general function)

1. Integumentary System
* Skin, hair, nails, etc.

- Forms external covering
- Protects deeper tissue from injury
- Synthesizes Vitamin D
- Site of cutaneous (pain, pressure, etc.), receptors and sweat and oil glands
2. Skeletal System
- Protects and supports body organs
- Provides a framework for the muscles to use to cause movement
- Blood cells are formed within bones, stores minerals
3. Muscular System
- Allows manipulation of the environment, locomotion and facial expression
- Maintain posture
- Produces/gives off heat when it works (Due to exothermic chemical reactions)
** Can use this to our advantage (Ex: When we are cold, we shiver to produce heat/warm our bodies)
4. Nervous System
- Fast-acting control system of the body (See something, react immediately) (Ex: When you stub your toe, you feel the pain right away)
- Fast, but short-lived
- Responds to internal and external changes by activating appropriate muscles and glands
** Centralized (In the Brain and Spinal Cord)
5. Endocrine System
- Glands secrete hormones that regulate processes such as growth, reproduction and nutrient use (Metabolism) by body cells
- Slower, but more long-term
- Sends chemical signals into bloodstream
** Dispersed throughout body (not centralized)
6. Cardiovascular System
- Blood vessels transport blood, which carries oxygen, carbon dioxide, nutrients, wastes, etc.
- The heart pumps blood
7. Lymphatic System
- Picks up fluid leaked from blood vessels and return it to blood
- Disposes of debris
- Houses white blood cells (lymphocytes) involved in immunity
- Immune response mounts the attack against foreign substances within the body
8. Respiratory System
- Keeps body constantly supplied with oxygen and removes carbon dioxide
- Gaseous exchanges occur through the walls of the air sacs of the lungs
9. Digestive System
- Breaks down food into absorbable units that enter the food for distribution to body cells
- Indigestible foodstuffs are eliminated as feces
10. Urinary System
- Eliminates nitrogenous wastes from the body
- Regulates water, electrolyte and acid-base balance of the blood
11. Male/Female Reproductive System
- Overall function is production of offspring
- Testes produce sperm and male sex hormones
- Ducts and glands aid in delivery of sperm to the female reproductive tract

- Ovaries produce eggs and female sex hormones
- Remaining structures serves as sites for fertilization and development of the fetus
- Mammary glands of female breasts produce milk to nourish the newborn
Organ Systems Interrelationship
** No one system can operate alone

- The integumentary system protects the body from the external environment
- Digestive and respiratory systems, in contact with the external environment, take in nutrients and oxygen
- Nutrients and oxygen are distributed by the blood
- Metabolic wastes are eliminated by the urinary and respiratory systems
Necessary Life Functions (8)

1. Maintaining Boundaries
- The internal environment remains distinct from the external
* Cellular level: Accomplished by plasma membranes
* Organismal level: Accomplished by the skin
2. Movement
- Locomotion, propulsion and contractility
3. Responsiveness
- Ability to sense changes in the environment and respond to them
4. Digestion
- Breakdown of ingested foodstuffs
5. Metabolism
- All the chemical reactions that occur in the body
6. Excretion
- Removal of waste from the body
7. Reproduction
- Cellular and organismal levels

* Cellular: An original cell divides and produces 2 identical daughter cells (replacing that which is damaged or broken)

* Organismal: Sperm and egg unite to make a whole new person
8. Growth
- Increase in size of a body part of the organism
Survival needs (5)

1. Nutrients
- Chemical substances used for energy and cell building
2. Oxygen
- Needed for metabolic reactions
3. Water
- Provides the necessary environment for chemical reactions
4. Maintaining Normal Body Temp.
- Necessary for chemical reactions to occur at life-sustaining rates (some reactions work better at certain temps.)

** Chemical reactions raise our body temp.
5. Atomspheric Pressure
- Required for proper breathing and gas exchange in the lungs
Homeostasis
* If everything is in a normal state/working as it should

- The ability to maintain a relatively stable internal environment in an ever-changing outside world
- The internal environment of the body is a dynamic state of equilibrium
- Chemical, thermal and neural factors interact to maintain homeostasis
Homeostasis Control Mechanisms

* 3 Independent components of control mechanisms
- The variable produces a change in the body

** Receptor, Control Center & Effector
1. Receptor
- Monitors the environment and responses to changes (Stimuli)

** Ex: Thermometer, Monitoring the temperature of a room
2. Control Center
- Determines the set point at which the variable is maintained

ex. Thermostat (keeps the room at a set temperature)

** In the body, this is the brain
3. Effector
- Provides the means to respond to stimulus
- Making changes based on what we found out

** Ex: Turn on the air conditioner if the room is too hot
Negative Feedback
** The output shuts off the original stimulus

Ex: Regulation of blood glucose levels
- Eat; Glucose levels increase...
- Our body releases insulin...
- Our glucose levels decrease
or
- If glucose levels are decreasing, the body releases glucagon...which raises glucose elvels

** If we cannot bring blood glucose levels back to homeostasis, we get disease (Ex: If they remain too high, we get diabetes)
Positive Feedback
** The output enhances or exaggerates the original stimulus

- Ex: Regulation of blood clotting

** Generally has to end in a big event: The original stimulus has to be gone altogether
Ex: Giving birth (original stimulus is gone because the baby is born)
Homeostasis Imbalance
- Disturbance of homeostasis or the body's normal equilibrium
- Overwhelming of negative feedback mechanisms allowing destructive positive feedback mechanisms to take over

** Disruptions in homeostasis set in motion corrective cycles (or feedback systems; positive & negative) that help restore the conditions needed for health and life)
Anatomical Position
- Standardized position from which to describe direction terms

* Standing upright
* Facing the observer, head level
* Eyes facing forward
* Feet flat on the floor
* Arms at the sides
* Palms turned forward
Directional Terms

1. Superior and Inferior
- Toward and away from the head
- Superior: Above, toward the head
- Inferior: Below, away from the head

Ex: The hair on your head is the most superior part of your body
- Your eyes are superior to your chin, your chin is inferior to your mouth
2. Anterior and Posterior
- Toward the front and back of the body
- Anterior: Toward or at the front of the body, in front of
- Posterior: Toward or at the back of the body, behind
3. Medial, Lateral and Intermediate
- Medial: Toward the midline, on the inner side of (the heart is medial to the arm)

- Lateral: Away from the midline of the body, on the outside of (the arms are lateral to the chest)

- Intermediate: Between a more medial and a more lateral structure (the collarbone is intermediate between the breastbone and the shoulder)
4. Proximal and Distal
- Proximal: Closer to the origin of the body part or the point of attachment of a limb to the body trunk (the elbow is proximal to the wrist)

- Distal: Farther from the origin of a body part of the point of attachment of a limb to the body trunk (the knee is distal to the thigh)
5. Superficial and Deep
- Superficial: Toward or at the body surface (The skin is superficial to the skeletal muscles)

- Deep: Away from the body surface, more internal (The lungs are deep to the skin)
Regional Terms

1. Axial
- Head, neck, trunk
2. Appendicular
- Appendages (attached) or limbs (upper and lower limbs)
Body Planes

1. Saggital
- Divides the body into right and left points
2. Midsaggital or Medial
- Sagittal plane that lies on the midline
3. Frontal or Coronal
- Divides the body into anterior and posterior parts (front and back)
4. Transverse or Horizontal (Cross sections)
- Divides the body into superior and inferior parts (top and bottom)
5. Oblique Section
- Cuts made diagonally
Anatomical Variability
- Humans vary slightly in both external and internal anatomy
- Over 90% of all anatomical structures match textbook descriptions, but....
* Nerves and blood vessels may be somewhat out of place
* Small muscles may be missing

- Extreme anatomical variations are seldom seen
Body Cavities (Open space)

1. Dorsal Cavity
- Protects the nervous system and is divided into 2 subdivisions

1. Cranial Cavity: Within the skull and encases the brain
2. Vertebral Cavity: Runs within the vertebral column and encases the spinal cord
2. Ventral Cavity
- Houses the internal organs (viscera) and is divided into 2 subdivisions

1. Thoracic Cavity: Subdivided into pleural cavities, the mediastinum and the pericardial cavity

Pleural: (2) Each houses a long

Mediastinum: Contains pericardial cavity and surrounds the remaining thoracic organs

Pericardial: Encloses the heart

2. The Abdominopelvic Cavity: Separated from the superior thoracic cavity by the dome shaped diaphragm
1. Abdominal Cavity: Contains the stomach, intestines, spleen, liver and other organs
2. Pelvic Cavity: Lies within the pelvis and contains the bladder, reproductive organs and the rectum
Ventral Body Cavity Membranes
- Panetal Serosa lines internal body walls (like the outer balloon wall)

- Visceral Serosa covers the internal organs (like the inner balloon wall)

- Serous fluid seperates the serosare (like the air)
Other Body Cavities

1. Oral and Digestive
- Mouth and cavities of the digestive organs
2. Nasal
- Located within and posterior to the nose
3. Orbital
- Houses the eyes
4. Middle Ear
- Contain bones (ossicles) that transmit sound vibrations
5. Synovial
- Joint cavities
Abdominal Regions
- Umbilical
- Epigastric
- Hypogastric
- Right and Left lumbar
- Right and Left iliac or inguinal
- Right and Left hypochandrioc

** Right and Left always related to the person you are observing, not you (Their right and left, not your own)
Abdominopelvic Quadrants
- Right upper
- Left upper
- Right lower
- Left lower
Chapter 3: Cells- The Living Units
...
Cell Theory
- The cell is the basic structural and functional unit of life
- Organismal activity depends on individual and collective activity of cells
- Biochemical activities of cells are dictated by subcellular structure
- Community of life has a cellular basis
Plasma Membrane
- Separates intracellular fluids from extracellular fluids (boundary btwn inside of cell and out)
- Regulates what comes in/out of the cell
- Glycocalyx is a glycoprotein area abutting the cell that provides highly specific biological markers by which cells recognize one another (covers the plasma membrane)
Fluid Mosaic Model (describes structure of cell membranes)
- Double bilayer of lipids with embedded, dispersed proteins
- Bilayer consists of phospholipids, cholesterol, and glycolipids (maintains the stability of the cell membrane and facilitates cellular recognition)
- Glycolipids: Lipids with carbohydrates attached to them
- Phospholipids have hydrophobic (tail) and hydrophilic (head) bipoles
* Heads poke out towards water, tails poke in
* Polar heads, nonpolar tails
Functions of Membrane Proteins
** different proteins perform different functions

1. Transport: Allow things to come through the cell

2. Intercellular Joining: Connecting cells

3. Enzymatic Activity: Catalyst

4. Cell to Cell Recognition: If a cell is not supposed to be there, will not fit the receptor

5. Receptors for Signal Transduction: What needs to happen within a cell, sends signals to cells

6. Attachment to the Cytoskeleton and Extracellular Matrix (ECM): Structure helps to hold them in place, structures on structures to become strong, one cell by itself isn't enough to hold up the whole structure
Plasma Membrane Surfaces
** Differ in the kind and amount of lipids they contain
- Glycolipids are found only in the outer
- 20% of all membrane lipids are cholesterol

** Membrane lipids form the double layer of the cell membrane, the lipid bilayer; Keeps the watery interior of the cell separate from the waxy exterior of the cell, control the entry and exit of other molecules and ions as part of the cell's metabolism
Membrane Junctions

1. Tight Junction
- Impermeable junction that encircles the cell

** It is like welding 2 cells together; nothing gets through
2. Desmosome
- Anchoring junction scattered along the sides of cells
- Less tight
- Structure by which 2 adjacent cells are attached
3. Gap Junction
- Directly connects the cytoplasms of two cells
- Allows chemical substances to pass between cells
- Can move substances from one cell to the next (through regulated gates between cells)
Passive Membrane Transport: Diffusion (3 Types)
** Uses Kinetic Energy
** Do not have to actively push through the membrane, no energy used
** The only thing separating things is the concentration gradient

* Substances want to travel from areas of high concentration to areas of low concentration (down the concentration gradient)
1. Simple Diffusion
- Nonpolar and lipid soluble substances
- No energy, just follows the concentration gradient
- Diffuse directly through the lipid bilayer (goes through the membrane)
- Diffuse through channel proteins
2. Channel- Mediated Facilitated Diffusion
- Transport of glucose, amino acids and ions (substances are bigger)
- Transported substances bind to carrier proteins or pass through protein channels
** Has to fit/be the right shape in order to pass through the protein channel

** Relies on molecular binding between the "cargo" and the membrane-embedded channel or carrier protein
3. Carrier- Mediated Facilitated Diffusion
- Movement of molecules through the cell membrane via special carrier/transport proteins (bind to proteins and carried across)

** Are Integral Transmembrane Proteins: Permanently attached to the biological membrane

** Show specificity for certain polar molecules including sugars and amino acids
4. Osmosis
** Water is different, it can get through
** Diffusion of water across a semipermeable membrane

- Occurs when the concentration of a solvent is different on opposite sides of a membrane
- Tries to go towards the area of higher solvents in order to dilute (from low solvent area to high solvent area)
* Goes in opposite direction than we normally think of
Osmosis Contd: Osmolarity
- Total concentration of solute particles in a solution

** More Solvents= Greater osmolarity
Osmosis Contd: Tonicity
- How a solution affects cell volume

** The relative concentration of solutes dissolved in a solution which determines the direction and extent of diffusion
** Water wants to go towards higher concentration (hypertonic)
Filtration
- The passage of water and solutes through a membrane by hydrostatic pressure (Pressure exerted by fluid)
** Filtering through a membrane, chemical pressure not enough
- Pressure gradient pushes solute- containing fluid from a higher pressure area to a lower pressure area
Effects of Solutions on Varying Tonicity

1. Isotonic
- Solutions with the same solute concentration as that of the cytosol (the watery part of the cytoplasm)
2. Hypertonic
- Solutions having a greater solute concentration than that of the cytosol
3. Hypotonic
- Solutions having a lesser solute concentration than that of cytosol
Active Transport
** Need to input energy into the system
** Requires carrier proteins
** Uses ATP to move solutes across a membrane
Active Transport: Sodium Potassium Pump
- Active diffusion
- the process of moving sodium and potassium ions across the cell membrane
- Pumps 3 sodiums (Na+) out of the cell and 2 potassiums (K+) into the cell

** This process is responsible for maintaining the large excess of Na+ outside the cell and the large excess of K+ inside the cell
** Unbalanced charge transfer; contributes to action potential of the membrane
Active Transport Types:

1. Primary
- Hydrolysis of ATP phosphorylates the transport protein, causing confirmational change

** Directly uses chemical energy (ATP) to move molecules against the concentration gradient and across the cell membrane
2. Secondary
- Use of an exchange pump (such as the sodium-potassium pump) indirectly to drive the transport of other solutes
- A transport protein couples the movement of an ion down its chemical gradient to the uphill movement of another ion or molecule against the gradient
3. Symport System (type of secondary transport)
- 2 substances are moved across a membrane in the same direction, at the same time
** Ex: Sodium and Glucose; Glucose needs the energy from all the sodiums out there to move across the membrane with sodium
4. Antiport System (type of secondary transport)
- 2 substances are moved across a membrane in opposite directions
Vesicular Transport (8 Types)
** Transport of large particles and macromolecules across the plasma membrane
1. Exocytosis
- Moves substances from the cell interior to the extracellular space (moves things out of the cell)

(out)
2. Endocytosis
- Enables large particles and macromolecules to enter the cell

(in)
3. Transcytosis
- Moving substances into, across and then out of the cell
4. Vesicular Trafficking
- Moving substances from one area in the cell to another
5. Phagocytosis
- Pseudopods engulf solids and bring them into cell's interior
- Grab it and bring it into the cell
- Ex: white blood cells
6. Fluid-Phase Endocytosis
- The plasma membrane infolds, bringing extracellular fluid and solutes into the interior of the cell
7. Receptor-Mediated Endocytosis
- Clathrin coated pits provide the main route for endocytosis and transcytosis

** a process by which cells absorb metabolites, hormones, other proteins - and in some cases viruses - by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being absorbed

**This large protein assists in the formation of a coated pit on the inner surface of the plasma membrane of the cell. This pit then buds into the cell to form a coated vesicle in the cytoplasm of the cell. In so doing, it brings into the cell not only a small area of the surface of the cell but also a small volume of fluid from outside the cell.
8. Non-Clathrin Coated Vesicles
- Cavedae that are platforms for a variety of signaling molecules (plasma membrane buds)
Membrane Potential
- Voltage across a membrane
- Resting membrane potential: the point where K+ potential is balanced by the membrane potential
* Results from Na+ and K+ concentration gradients across the membrane
*Differential permeability of the plasma membrane to Na+ and K+
* ranges from -20 to -200 mv
* Established when the movement of K+ out of the cell equals the K+ movement into the cell
- Steady State: Potential maintained by active transport of ions
Cell Adhesion Molecules (CAMs)
- Kind of like the glue between the cells
- Anchors cells to the extracellular matrix
- Assist in the movement of cells past one another
- Rally protective white blood cells to injured or infected areas
Role of Membrane Receptors

1. Contact Signaling
- Important in normal development and immunity
2. Electrical Signaling
- Voltage-regulated "ion gates" in nerve and muscle tissue
3. Chemical Signaling
- Neurotransmitters bind to chemically gated channel-linked receptors in nerve and muscle tissue
4. G-Protein Linked Receptors
- Ligands bind to a receptor which activates a G protein, causing the release of a second messenger, such as cyclic AMP
Cytoplasm
- Material between the plasma membrane and the nucleus of the cell
Cytosol
- Largely water inside the cell with dissolved proteins, salts, sugars and other solutes
Cytoplasmic Organelles
- Metabolic machinery of the cell

** Specialized Cellular Components

1. Membranous:
- Mitochondria, peroxisomes, lysosomes, endoplasmic reticulum, and Golgi Apparatus

2. Non-Membranous:
- Cytoskeleton, centrides and ribosomes
Inclusions
- Chemical substances such as glycosomes, glycogen granules and pigment
Mitochondria
** Powerhouse of the cell
- Provides most of the cell's ATP/energy via aerobic cellular respiration
- Double membrane structure with shelf-like cristae
- Contain their own DNA and RNA
Ribosomes
** Site of protein production
- Makes what the cell needs
- Granules containing protein and rRNA
- Free ribosomes produce soluble proteins
- Membrane-bound ribosomes produce proteins to be incorporated into membranes
Endoplasmic Reticulum (ER)
- Interconnected tubes and parallel membranes enclosing cisternae
- Continous with the nuclear membrane
- 2 Varieties: Rough and Soft ER
Rough ER
** Manufacture and package all secreted proteins
- External surface studded with ribosomes
- Responsible for the synthesis of integral membrane proteins and phospholipids for cell membranes
Smooth ER
- Tubules arranged in a looping network
** Catalyzes the following reactions in various organs of the body:

1. In Liver: Lipid and cholesterol metabolism, breakdown of glycogen and, along with the kidneys, detoxification of drugs

2. In Testes: Synthesis of steroid-based hormones

3. In the Intestinal Cells: Absorption, synthesis and transport of fats

4. In Skeletal and Cardiac Muscle: Storage and release of calcium
Golgi Apparatus
** Proteins are sent here/pass through
** Secretory vesicles leave the Golgistack and move to designated parts of the cell
- Stacked and flattened membranous sacs
- Functions in modification, concentration and packaging of proteins
Lysosomes
** Serves as storage for cellular products
- Spherical membranous bags containing digestive enzymes
- Digest ingested bacteria, viruses and toxins
- Degrade nonfunctional organelles
- Breakdown glycogen and release thyroid hormone
- Breakdown non useful tissue
- Breakdown bone to release calcium
- Secretory lysosomes are found in white blood cells, immune cells and melanocytes
Peroxisomes
** Neutralize dangerous free radicals
(Free Radicals: Highly reactive chemicals with unpaired electrons)
** Detoxify harmful or toxic substances
- Membranous sacs containing oxidases and catalases
** Sacrifice themselves so the cell doesn't become damaged
Cytoskeleton
- The "skeleton" of the cell
- Dynamic, elaborate series of rods running throug the cytosol
- Consists of microtubules, microfilaments and intermediate filaments
Microtubules
** Found in flagella, cilia and centrosomes
** Determine the overall shape of the cell and distribution of organelles
- Dynamic, hollow tubes made of the spherical protein tubulin
Microfilaments
** Maintain the shape of the cell
- Braces and strengthens the cell surface
- Supports microvilli (minute projections from the surface of the cell)
- Dynamic strands of the protein actin
** Attach to the CAMs and function in endocytosis and exocytosis
Intermediate Filaments
** Even stronger, resist being stretched
- However, can compress
- Tough, insoluble protein fibers with high tensile strength (ie can stretch without breaking)
* Resist pulling forces on the cell and help form desmosomes
Motor Molecules
- Proteins that function in motility
* Attach to receptors on organelles
- Powered by ATP
* ATP changes its shape, allowing the motor proteins to move
Centrioles
* Need this for cilia and flagella; forms the basis of these
- Small, barrel-shaped organelles in the centrosome near the nucleus
- Pinwheel array of 9 triplets of microtubules
- Organize mitotic spindle during mitosis
Cilia
- Whiplike, motile cellular extension on exposed surfaces of certain cells (ciliated, looks like little hairs)
- Moves things along in one direction across cell surfaces
Nucleus
** Core of every cell, control center (kind of like the brain of the cell)
- Contains all the DNA/genes
- Contains nuclear envelope, nucleoli, chromatin and distinct compartments rich in specific protein sets
- Contains the genetic library with blue prints for nearly all cellular proteins
- Dictates the kinds and amounts of proteins to be synthesized
Nuclear Envelope
- Selectively permeable double membrane barrier containing pores
- Encloses jelly-like nucleoplasm, which contains essential solutes
- Outermembrane is continuous with the rough ER and is studded with ribosomes
- Inner membrane is lined with the nuclear lamina, which maintains the shape of the nucleus
- Pore complex regulates transport of large molecules into and out of the nucleus
Nucleoli
** Site of ribosome production
- Dark-staining spherical bodies within the nucleus
Cell Cycle:

1. Interphase
G1 (gap 1): Metabolic activity and vigorous growth, just after cell was created

G0: Cells that permanently cease dividing (only allowed to do their specific job)

Synthetic (S): DNA replication

G2 (gap 2): Preparation for division
DNA Replication
- The replisome uses RNA primers to begin DNA production (RNA acts as the messenger to carry messages from DNA for controlling the synthesis of proteins)

** DNA holds the genetic information
- Each cell has a portion that is old and this is new
- Cell division requires 2 full pieces replicated DNA
- DNA polymerase III continues from the primer and covalently adds complementary nucleotides to the template
- Process is called semiconservative replication
Cell Division
- Essential for body growth and tissue repair
Mitosis
- Nuclear Division
Cytokinesis
- Division of the cytoplasm
** Cytoplasm is pinched into 2 parts after mitosis ends
Phases of Mitosis (4)
- Prophase
- Metaphase
- Anaphase
- Telephase
1. Early & Late Prophase
- Asters (star shaped, formed during the division of the nucleus) are seen as chromatin condenses into chromosomes
- Nucleoli disappear
- Centriole pairs separate and the mitotic spindle is formed
2. Metaphase
- Chromosomes cluster at the middle of the cell with their centromeres aligned at the exact center of the cell
3. Anaphase
- Centromeres of the chromosomes split
- Motor proteins in kinetochores pull chromosomes toward poles
4. Telophase and Cytokines
- New sets of chromosomes extend into chromatin (chromosomes are made of chromatin, chromatin contains DNA, RNA and proteins)
- New nuclear membrane is formed from the rough ER
- Nucleoli reappear
* Generally cytokinesis ends cell division
Control of Cell Division
- Surface to volume ratio of cells
- Chemical signals such as growth factors and hormones
- Contact inhibition
- Cyclins and cyclin-dependent kinases (CDKs) complexes
Protein Synthesis
- DNA serves as master blueprint for protein synthesis
- Genes are segments of DNA carrying instructions for a polypeptide chain (a chain of amino acids)
- Triplets of nucleotide bases form the genetic library
- Each triplet specifies coding for an amino acid
3 Types of RNA

1. Messenger RNA (mRNA)
- Carries the genetic info from DNA in the nucleus to the ribosomes in the cytoplasm
2. Transfer RNA (tRNA)
- Bound to amino acids base pair with the codons of mRNA at the ribosome to begin the process of protein synthesis
(Codon: a sequence of 3 nucleotides that together form a unit of genetic code in DNA or RNA)
Ribosomal RNA (rRNA)
- A structural component of ribosomes
Genetic Code
- RNA codons code for amino acids according to genetic code
Transcription (like writing code down)
- Transfer of info from the sense strand of DNA to RNA
- Transcription factor:
* Loosens histones from DNA in the area to be transcribed
* Binds to a promoter, a DNA sequence specifying the start site of RNA synthesis
* Mediates the binding of RNA polymerase to promoter
Initiation of Translation
- A leader sequence on mRNA attaches to the small subunit of the ribosome
- Methicrine charged iniator zRNA binds to the subunit
- The large ribosome unit now binds to this complex forming a functional ribosome
Developmental Aspects of Cells
- All cells of the body contain the same DNA, but develop into all the specialized cells of the body
- Cells in various parts of the embryo are exposed to different chemical signals that channel them into specific developmental pathways
- Cell specialization is determined by the kind of proteins that are made in the cell

** Cell Differentiation: Development of specific and distinctive features in cells

- Cell Aging:
* Wear and tear theory attributes aging to little chemical insults and formation of free radicals that have cumulative effects throughout life
* Genetic theory attributes aging to cessation of mitosis that is programmed into our genes

** Apoptosis: Programmed cell death, "cell suicide"
Info Transfer from DNA to RNA
- DNA triplets are transcribed into mRNA codons by RNA polymerase
- Codons base pair with zRNA anticodons at the ribosomes
(Anticodons: a sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA.)

- Amino acids are peptide bonded at the ribosomes to form polypeptide chains
- Start & Stop codons are used in initiating and ending translation
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