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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+

Endocytosis

http://www.youtube.com/watch?v=DuDmvlbpjHQ

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