anatomy & physiology of cells · •cell theory - the cell is the fundamental organizational...
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Anatomy & Physiology of Cells Chapters 3 & 4
Anatomy & Physiology Ms. Roden
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Basic Cell Info
•Cell Theory - the cell is the fundamental organizational unit of life
Schleidon & Schwann – first to suggest that all living things are
composed of cells
•Human body – 100 trillion cells
•Cell diameter range: 7.5 micrometers (RBC) – 150 micrometers (ovum)
•Composite cell – generalized cell illustration we study that exhibits most
important characteristics of many different dinstinctive cell types;
no such cell exists in the body
•3 Main Cell Structures:
• plasma membrane
• cytoplasm (with organelles)
• nucleus
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Nuclear pore
Chromatin Cytoplasm
Plasma membrane
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Cell Structures
Plasma membrane Outer boundary of cell
Made of lipids, proteins, and other molecules
Fluid mosaic model molecules slowly float around the membrane
molecules bound tightly to form continuous sheet
molecules bound loosely to slip past one another
Chemical attractions / forces hold membrane together
Phospholipid bilayer hydrophilic heads - polar
hydrophobic tails - nonpolar
Without cholesterol (steroid lipid), membranes would break easily
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Plasma Membrane cont.
Selectively permeable Lipid-soluble molecules pass through easily
Water-soluble molecules can not pass through
Membrane proteins: how the cell controls movement of molecules
“gates” that open and close to allow things into and out of the cell
Carbohydrates attached – glycoproteins identification markers allow to distinguish between normal and
abnormal cells
attack bacteria, cancer, blood transfusions
Enzymes attached – catalyze cellular reactions
Other proteins attached – form connections between cells
Receptors – react to hormones, etc. to trigger metabolic changes; signal transduction
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Peripheral protein
Hydrophobic
Phospholipid
tail
Hydrophilic
Phospholipid
head
Integral protein
http://www.youtube.com/watch?v=owEgqrq51zY
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Types
of
Membrane
Proteins
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Nucleus
One of largest cell structures
Occupies central portion of cell
Shape and number in a cell vary (most common is one spherical nucleus)
Nuclear membrane - double membrane with pores
contains nucleoplasm
pores called nuclear pore complex (NPCs)
selectively permit molecules to enter or leave nucleus
extensions of the ER
Contains genetic material
forms 46 chromosomes in dividing cells
Remains as chromatin in non-dividing cells
Dictates structure and function of the cell
Contains nucleolus
nonmembranous
contains RNA
synthesizes ribosomal RNA (rRNA) to combine with proteins to make ribosomes
cells that make more protein have bigger nucleolus
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Cytoplasm Gel-like substance that makes up inside of cell
Contains various organelles suspended in cytosol (intracellular fluid)
Membranous organelles - specialized sacs or canals made of cell membrane
Endoplasmic reticulum
Golgi apparatus
Lysosomes
Peroxisomes
Mitochondria
Nucleus
Nonmembranous organelles - not made of a membrane; made of microscopic filaments
Ribosomes
Cytoskeleton
Fibers – microfilaments; intermediate filaments
Centrosome
Cell extensions – microvilli, cilia, flagella
Nucleolus
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Organelles
Endoplasmic Reticulum Flat, curving sacs in parallel rows
Two types
Rough ER
Contains ribosomes
Extends from nucleus
Protein synthesis and intracellular transportation
proteins move through canals to the golgi
Smooth ER
Synthesizes lipids and carbohydrates
steroid hormones, glycoproteins, membrane lipids
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Steps to processing and packaging
1. ER delivers protein via vesicles
2. Enters first cisternae
3. Chemical modifications
4. Sent to next cisternae via vesicle
5. Further modification
6. Repeated until last cisternae
7. Packaged in secretory vesicle
8. Migrates to cell surface
9. Combines with membrane
10.Secretes contents
Organelles cont.
Golgi Apparatus Membranous
Cisternae (sacs) stacked near nucleus
Processes and packages molecules for export from cell
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Organelles cont.
Lysosomes & Peroxisomes Lysosomes
Membraneous sac
Vesicles that pinched off from Golgi
Size and shape change depending on activity
Contains enzymes that if bust can kill the cell
Destroy bacteria, etc.
“digestive bags” , “cellular garbage disposals”
Peroxisomes membraneous sac
Smaller than lysosome
Contains enzymes (peroxidase, catalase)
Detoxify harmful substances
Seen in kidney and liver cells
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Organelles cont.
Mitochondria Membraneous
Double membrane
Form a sac within a sac
Cristae – inner membrane folds contain enzymes – make ATP
Membranes same structure as plasma membrane
“power house”
Liver - +1000 mitochondria
Sperm cell – 25 mitochondria
Exercise – increases number of mitochondria
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Organelles cont.
Ribosome Every cells contains thousands
rER and free in cytoplasm
Nonmembranous
Protein synthesis (cell’s “protein factory”)
Ribosomes on ER – export and cell membrane use
Free ribosomes – make proteins for domestic use
make structural and functional proteins (enzymes)
Large and small subunits each has RNA bonded to protein
rRNA
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Cytoskeleton
1. Cell’s internal supporting network
2. Made of rigid, rodlike pieces (support and movement)
3. Muscle-like groups of fibers
4. Twisted protein molecules
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Cytoskeleton Cell Fibers
Microfilaments
smallest fibers
serve as “cellular muscles”
muscle cells – proteins slide past each other
Intermediate filaments
slightly thicker than microfilaments
supporting framework
dense arrangement in cells on outer skin layer
connects everything in the cell
Microtubules
thickest cell fiber
“engines” of the cell
move things around in cell
cause movement of entire cell
movement of vesicles
movement of chromosomes in mitoses
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Cytoskeleton cont. Centrosome
Non-membraneous
Very active site
Near nucleus
Coordinates building and breaking of microtubules
“microtubule organizing center” (MOC)
Important role in cell division
Centrioles found here
form microtubular cell extensions
form spindle in cell division
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Cytoskeleton cont. Cell extensions
Microvilli
found in areas where absorption is important
increases surface area of cell
allows faster rate of absorption
found in epithelial cells that line intestines
cover surface of cell
contain microfilaments
100s/cell
Cilia
contain microtubules
main purpose – movement
cilia shorter and more numerous than flagella
line respiratory tract; cilia moves mucus to be swallowed
Flagella
contain microtubules
main purpose – movement
Only present in sperm cells
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Cell to cell contact
Gap junctions
It directly connects the cytoplasm
of two cells, which allows various
molecules and ions to pass freely
between cells.
Channel proteins connect plasma
membranes
Desmosomes
Intermediate filaments connect
plasma membranes
specialized for cell-to-cell adhesion
Ex. Skin cells
Tight junctions
join together the cytoskeletons of
adjacent cells.
http://www.youtube.com/watch?v=3
Xb0PFFGblI
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PASSIVE Cellular Transport
with concentration gradient
Moves from areas of HIGH to low concentration
Simple diffusion – movement of particles through bilayer from high to low concentration
3 main categories
Dialysis – diffusion of small solute particles through selectively permeable membrane
Osmosis – diffusion of water
Facilitated diffusion – diffusion of particles through membrane with help of carrier proteins
Diffusion http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html
1. molecules densely packed when enter water
2. molecules collide in high conc.
3. gradually move away from each other
4. toward low conc.
5. eventually evenly distributed
1.semipermeable membrane
2.left – unbalanced
3.right - homeostasis
Dialysis
Osmosis Osmotic pressure / tonicity – water pressure that develops in the solution
with the higher concentration of impermeable solute (low water
concentration)
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html
Osmosis cont.
Hypotonic Isotonic Hypertonic
Pressure Low Same High
Solute conc Low Same High
Water conc High Same Low
Cell change Swells Same Shrinks
plasmolysis crenation
Facilitated Diffusion
1. Carrier mediated
2. Attracts solute to binding site
3. Carrier protein changes shape
4. Solute can move to other side of memb
http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_facilitated_diffusion_works.html
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ACTIVE Cellular Transport against concentration gradient
From low to HIGH concentration
Non-vesicular membrane transport uses carrier protein & ATP
ATPases
ex. Sodium-Potassium pump
Vesicular membrane transport
Endocytosis
Phagocytosis - taking in of solute particles by vesicles fusing with plasma membrane
“cellular eating”
Pinocytosis – taking in of dissolved particles (fluid) by vesicles fusing with plasma membrane
“cellular drinking
Exocytosis – movement of particles out of the cell via secretory vesicles fusing with plasma membrane
Active Transport http://www.youtube.com/watch?v=yz7EHJFDEJs&list=TLrO5cc_oVqkB65MvC0EmnM0ISd8y_aUTy
Carrier protein uses ENERGY to move solute AGAINST conc gradient
3 Na+/2K+
Name Type of
Transport
Direction
Of
Movement
Conditions Examples
Diffusion
passive Towards
Lower
concentration
Concentration
gradient
Water, gases (02and
CO2), and steroid
hormones.
Facilitated
Diffusion
passive Towards
Lower
concentration
Concentration
gradient, plus
channel or carrier
proteins
Water, glucose, and
amino acids.
Osmosis passive Towards
Lower
concentration
Concentration
gradient,
Channel Proteins
optional
Water 0nly.
Active
Transport
active Towards
Higher
concentration
Carrier
protein and
ATP energy
Ions, sugars,
and amino
acids.
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Enzymes
Functional proteins
Catalyst
Lowers activation energy to start chemical reaction
Not changed in reaction or used up
Tertiary/quaternary proteins
Cofactor – inorganic, non protein
Coenzyme – organic, non protein
Active site – part of enzyme where binds to substrate
Lock-and-key model
Enzyme Function
Allosteric Effect Allosteric effector molecule binds to
allosteric site
Active site’s shape is changed
Inhibition or Activation of enzymes
Factors that have allosteric effect
pH
Temp
Cofactors being added/removed
Proenzymes – inactive enzymes
Kinases
synthesize enzymes
Convert proenzyme to enzyme
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1. Catabolism
a. net output of energy
b. Breaks down large molecules into smaller ones
c. ie. cellular respiration
2. Anabolism
a. net input of energy
b. Build large molecules from smaller ones
c. ie. synthesizing DNA
Cell Metabolism
Cellular Disease
1.Cystic fibrosis
a. Cl- pumps in membrane missing
b. Secretions (sweat, mucus) salty
c. Thick mucus causes lung infection
d. Respiratory & digestive problems
2.Diabetes mellitus/type 2
a. Adult onset
b. Non-insulin dependent
c. Obesity onset
d. Reduces insulin receptors in memb
3.Cancers
a. Abnormalities in mitosis
b. Cause tumors
c. Hyperplasia: increase in number of
cells/proliferation of cells
4.Genetic Disorders
a. Sickle-cell anemia: mutation in
hemoglobin protein
http://www.youtube.com/watch?v=7nxqcRLcml0