The Cell
Cells vary in size, shape, content, and
function.
Composite Cell
 3 main parts
1.nucleus
2.cell membrane
3.cytoplasm
 includes protein rods and tubules
that form a framework called
cytoskeleton
Organelles within the cytoplasm
 Endoplasmic reticulum – transportation
system for lipids and proteins
 Ribosomes – protein synthesis
 Golgi apparatus – packages
glycoproteins (sugar attached to protein)
for secretion
 Mitochondria – “powerhouse” of the cell
– releases energy from food
 Lysosomes – produces digestive
enzymes to decompose waste
 Peroxisomes – catalyze reactions, make
bile, decompose hydrogen peroxide (a
by product of metabolism), decompose
lipids, and detoxifies alcohol
 Microfilaments (made up of the protein
actin) and microtubules (made up of the
protein tubulin) – cell movement and
support and stabilization of organelles
 Centrosomes – contain centrioles that
distribute chromosomes during mitosis
 Vesicles (Vacuoles) – contain substances
that have entered the cell or are to be
secreted
 Nucleus – Control center of the cell
o Enclosed in a double layered
envelope
o Contains nucleolus – makes
ribosomes
o Contains chromatin
The Cell Membrane
 Semi-permeable – Allows some
substances through, but not others
 Composed of a Phospholipid bilayer
(phospholipid – lipid made of a
phosphate group and two fatty acids)
 The head of the phospholipid is polar
and is attracted to water (hydrophilic)
 The tail of the phospholipid is non polar
and repel water (hydrophobic)
 Integral proteins – proteins that extend
through the lipid bilayer
 Peripheral proteins – proteins that are
attached to the external surface of the
bilayer
 Some proteins transport ions such as
sodium, potassium, calcium, and
chloride
Defective ion channels
Cystic Fibrosis
 Abnormal chloride channels
 Symptoms – difficulty breathing,
frequent respiratory infections, clogged
pancreas (disrupts digestion)
 Caused by a buildup of thick mucous
secretions from salt that gets trapped
inside cells that draws moisture inside.
Movement through the Cell Membrane
Diffusion – movement from an area of high
concentration to an area of low
concentration (example – oxygen/carbon
dioxide)
Facilitated Diffusion – Special carrier
molecule moves substances (glucose and
amino acids enter this way)
 Hormone insulin promotes facilitated
diffusion of glucose
 Moves only from high to low
concentration
 Rate is limited by the number of carrier
molecules
Osmosis – Diffusion of water from high
concentration to low concentration
 Isotonic solution – the solution has the
same osmotic pressure inside and
outside the cell
 Hypertonic solution – the solution has a
lower water concentration than the cell
 Hypotonic solution – the solution has a
higher water concentration than the cell
Active Transport – molecules or ions move
from low concentration to high
concentration
 Requires energy from ATP and carrier
molecules in the cell membrane
Exocytosis – transportation of large
molecules outside the cell
Endocytosis – transportation of large
molecules into the cell
Pinocytosis – membrane engulfs droplets of
liquid
Phagocytosis – membrane engulfs solid
particles
Mitosis – cell division
 Stages
1.interphase
2.prophase
3.metaphase
4.anaphase
5.telophase
 cytokinesis - ring of microfilaments
form and constrict to pinch in cell
membrane
Cancer
 Hyperplasia – uncontrolled cell division
 Dedifferentiation – lose specialization –
develop into disorganized mass
 Invasiveness – break through boundaries
between organs
 Angiogenesis – form blood vessels to
nourish themselves and remove waste
Cell differentiation – the development of
specialized structures and functions
 Stem Cells – undifferentiated and remain
that way until acted upon
 A cell that does not divide or
differentiate may undergo apoptosis (a
form of cell death that is a normal part of
development)