Anatomy & Physiology
Chapter 3
Cells
Eukaryotic

Prokaryotic

Cell membrane
Thin, flexible, and somewhat elastic
Selectively Permeable
 Allows some things in/out but not others
What are some things that are selectively
permeable?
Signal Transduction
 Helps signals from outer environment get
into the cell
Cell Membrane Structure
Double layer of phospholipid molecules.
The water soluble head (phosphate
group) forms the surface. The insoluble
tail (fatty acid chain) is inside the layers.
What types of particles could easily pass
through (solubility)?
Cell Membrane
Fibrous proteins
Provide structure for the cell membrane,
make it more rigid.
Globular proteins
Called integral proteins/transport proteins
imbedded in the interior.
They span the membrane channel allowing
small molecules inside (may be a pore)
Cytoplasm
The fluid that makes up the entire interior
of the cell.
Organelles are suspended in it.
Provides an area for reactions to occur,
supports the cell with osmotic pressure
Endoplasmic Reticulum
ER membrane is membrane-bound
flattened sacs, elongated canals, and
fluid filled vesicles.
Plays a role in protein and lipid
synthesis.
Transports molecules throughout the
cell.
Attachment site for ribosomes
Ribosomes
Found on the ER and floating in the
cytoplasm
composed of protein and RNA
What is it’s function?
Golgi Apparatus
Composed of a stack of 6 cisternae
Refines, packages, and delivers proteins
synthesized by the ribosomes
Why do think proteins would need
refining?
Mitochondria
Elongated fluid filled sac
Moves slowly through the cytoplasm
Reproduce by dividing
Contains small amounts of DNA
Has an outer and inner membrane layer.
Mitochondria
The enzymes and the mitochondria
control many of the chemical reactions
that release energy.
What are the molecules the
mitochondria produce?
What are the substances mitochondria
utilize to produce cellular energy?
Mitochondria
A typical cell will have about 1700
mitochondria.
What types of cells would have more
mitochondria?
Lysosomes
The cell’s garbage disposal.
Commonly appear as tiny membranous
sacs that contain powerful enzymes that
break down protein, carbohydrates, and
nucleic acids as well as foreign particles
They also destroy worn cellular parts.
Peroxisomes
The outer membrane of a peroxisome
contains 40 enzymes that perform various
duties:
synthesis of bile acids
breakdown of lipids
degradation of rare biochemicals
detoxification of alcohol
Cilia & Flagella
Cilia occur in large numbers on the
surface of some epithelial cells.
Cilia are tiny hairlike structures
Used to move substances along the
membrane
Flagella are tail-like structures that aid in
cell motility
Why would cells have cilia instead of
flagella?
Cytoskeleton
Microtubules
Provide passage ways to transport
substances throughout the cell
Similar to blood/lymphatic vessels in the
body
Microfilaments
Provide a framework of support for the cell
Similar to bones in the body
Nucleus
Directs the activities of the cell.
Enclosed by a double-layered nuclear
envelope.
Nuclear envelope consists of an inner and
outer lipid bilayer membrane.
Nucleolus
Small, dense body composed largely of
RNA and protein.
No surrounding membrane.
Site of ribosome production.
Cells may have more than one nucleolus.
Chromatin
Consists of loosely coiled fibers in the
nuclear fluid
Stores DNA and Forms chromosomes
during cell reproduction
Composed of DNA
Movement of substances
Diffusion
Moves from high concentration to low.
Osmosis – diffusion of water
No energy needed
Facilitated Diffusion
Big substance, still goes from high to low
Uses proteins
No energy needed
Active Transport
Movement of large particles by carrier
proteins from low concentration to high
concentration.
Does it require Energy?
It may use as much as 40% of a cell’s
energy supply.
Active Transport
Active transport is similar to facilitated
diffusion.
What’s the difference?
Fig 3.16 page 62
Solute pumps
Transport amino acids and most ions
Sodium-potassium pump
Essential for nerve impulses
Why could transporting ions create an
electrical impulse?
Endocytosis & Exocytosis
Molecules or particles too large to pass
through the membrane by diffusion are
actively transported into (endocytosis)
and out of (exocytosis) the cell.
Cellular Processes
The cell depends on proteins more than
any other compound
For this reason the cell has it’s own
method of creating proteins that it needs
Protein Synthesis
Broken into two parts:
Transcription (DNA -> RNA) and
Translation (RNA -> Protein)
Transcription
Producing a strand of messenger RNA
(mRNA) from the DNA strand
mRNA uses one strand of DNA and is
complementary to that DNA
Except in RNA Uracil (U) takes the place of
Thymine (T)
RNA polymerase moves along DNA strand
and adds nucleotides to mRNA strand
Transcription
Occurs in the nucleus
When finished:
DNA winds back up
mRNA is sent out of nucleus to be used for
translation
mRNA now contains instructions on how
to build protein (codons)
Translation
Building the protein from the mRNA strand
Done at the ribosome
Codons used to indentify amino acid
sequence
All three types of RNA must come together
to build the protein
rRNA prepares ribosome
tRNA brings amino acid (contains anticodon)
mRNA brings the instructions
Translation
tRNA brings amino acid and binds to
mRNA
Enzymes remove the amino acid from that
tRNA and attach it to the growing chain
When complete:
The A.A. chain is released from the
ribosome, folds and becomes a protein
The mRNA and ribosome is reused to make
more of the same protein
Metabolism
What does metabolism mean to you?
The sum/total of all chemical reactions
within the cell.
There are two types of metabolic
reactions:
Anabolism
Catabolism
What do you think each one means?
Anabolism
Where have you heard anabolic before?
Anabolism- larger molecules are
constructed from smaller ones,
requiring the input of energy
Anabolic metabolism provides all
substances required for cellular growth
and repair.
Catabolism
Process of breaking down larger molecules
into smaller ones.
What will the breaking down of larger
molecules do?
Provide Energy!
An example of catabolic metabolism is digestion
What can be said about weight gain/loss and
the balance between catabolism and
anabolism?
Metabolic Rates
Basal metabolic rate - the amount of energy
expended when the body is at rest
BMR for an average adult (155 lbs)
60-72 Cal/hour
What are factors that affect the BMR?
Surface area, Age, Gender, Emotions
Total Metabolic Rate – Total calories the body
must consume to fuel activities
Small increases in muscular activity causes large
jumps in TMR
Enzymes
Metabolic reactions must be carefully controlled!
How are these controlled?
ENZYMES!
Most reactions will not occur without them
Enzymes are required in only small amounts
Why might this be?
They are not used up during the reaction.
Does one enzyme control all reactions?
No, enzymes only act on a particular rxn.
 One that contains their substrate.
Enzymes
How does an enzyme recognize its
substrate?
Shape – the way the enzyme is folded
The enzyme then binds to the substrate
at the active site
This is the action that causes the reaction
to occur and the cell to metabolize
substances
Example: lock and key
Cancer
Cells that divide uncontrollably
Why?
Oncogene
Tumor-suppressor gene
Oncogenes must be turned on while
tumor-suppressor genes are turned off
Mutations cause this to happen
Cancer
What are mutations caused by?
Usually not caused by genetic errors a
person is born with.
But you can be genetically more susceptible
What does this mean?
Primary Cause - Carcinogens
Radiation – from radioactive materials, UV,
etc.
Chemicals – Pollutants, tobacco, consumer
Stages of Cancer
Hyperplasia - first abnormal growth
Excess of normal appearing cells
Dysplasia - cells begin to appear abnormal
Localized cancer - ball of abnormal cells
and blood nourishment
A.K.A Tumor
Two types of Tumors
Benign - will not spread to surrounding
tissues
Stages of Cancer
If Malignant:
Invasion into adjacent tissue
Metastasis - invasion of lymph and blood
vessels
Leads to spreading to other parts of body
Let’s say colon cancer spreads to the lungs,
what type of cancer is it?
Still considered colon cancer because it still
shows same abnormalities and
characteristics as original
Most common causes of
death due to cancer
Women
Lung
Breast
25%
17%
Colon/rectum
10%
Leukemia/Lymphoma
8
Ovary
6
Pancreas
5
Uterus/cervix
5
Most common causes of
death due to cancer
Men
Lung
32%
Prostate
14%
Colon/rectum
9%
Leukemia/Lymphoma
9%
Kidney/Bladder
5%
Pancreas
5%
Why is Cancer so serious
As a tumor gets larger, it will begin to
grow its own blood supply
This steals nutrients and oxygen,
eventually choking off surrounding tissues
Surrounding tissues then begin to fail
Treatment
3 most common
Surgery
Ususally best option
da Vinci surgical system
Radiation
Internal and external
Used to shrink tumor, usually combined with other
treatments
Chemotherapy-anticancer medicine
Targets all fast growing cells
Delivered to all body tissues
Problem?
Treatment
Vaccine - HPV (human papillomavirus)
causes most cervical cancer cases
Hormone therapy
Gene therapy