Download Cells part 1 - Amanda Bohnert

Cells part 1
BELL RINGER 9/1:
W H AT A R E T H E 4 E L E M E N T S T H AT M A K E U P
LIFE? (ONE IS CARBON)
OVERVIEW of Cellular Life
 Cells are made up of:
 Mostly Carbon, nitrogen, hydrogen, oxygen
 Mostly protein in the structure
 Trace elements are also really important
Calcium- needed for blood clotting
 Iron- needed in hemoglobin to carry oxygen
 Iodine- needed to make thyroid hormone which controls
metabolism

 Interstitial fluid: salt-water solution that surrounds
all cells

Derived from blood and all exchanges between cells and blood
are made through this fluid
OVERVIEW of Cellular Life
 Cells vary dramatically in length


2 micrometers ( 1/12,000th of an inch) in smallest cell
Over a meter (3 feet) in the nerve cells that cause you to wiggle your toes
 Cells also differ in shape


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Disk-shape (red blood cells)
Threadlike (nerve cells)
Toothpicks (smooth muscle cells)
Contain head and tail (Sperm)
General Anatomy of a Cell
 Even though cells are so diverse in structure and
function, they DO share many similar structures
 Three main regions of a cell
 Nucleus
 Cytoplasm
 Plasma membrane
General Anatomy: Nucleus “Headquarters”
 Contains all the genetic material
 DNA- blueprint for building the body
 More specifically- DNA has blueprints for building PROTEINS
 Most often circular but the nucleus can conform to the shape
of the cell (muscle cell nuclei are elongated)
General Anatomy: Nucleus “Headquarters”
 Three regions of the nucleus
 Nuclear envelope
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

Nucleoli (aka Nucleolus)


double membrane barrier that surrounds the
cell. Aka Nuclear Membrane
Between the membranes is a nuclear moat
filled with fluid that contain pores (nuclear
pores) that aid in passing substances in and
out of the cell.
small dark bodies where ribosomes are
assembled
Chromatin

when the cell isn't dividing, DNA is
compacted into loose threads called
chromatin. When the cell is dividing, these
coil/condense to create chromosomes
General Anatomy: The Plasma Membrane
 Fragile, transparent barrier surrounding the cell
 Sometimes also called a cell membrane HOWEVER all cell
organelles have membranes so we will call the outer barrier the
plasma membrane.
 Structure is important for many cellular activities
General Anatomy: The Plasma Membrane
 Structure:

Two lipid layers arranged “tail to tail”



Mostly phospholipids but some of it is cholesterol
“lipid bilayer”
Protein molecules “float” between the tails
General Anatomy: The Plasma Membrane
 Polar heads


Hydrophilic (water loving)
Attracted to water

Main component of intracellular
and extracellular fluid
 Nonpolar tails


Hydrophobic (water fearing)
Lineup inside the membrane
 This structure is self orientating and allows for quick
reseal if the membrane is torn
General Anatomy: The Plasma Membrane
 Proteins are scattered throughout the membrane
 Many are receptors for hormones or for other chemical messengers
 Some are binding sites to anchor to other surfaces
 MOST have a transport function for items going in and out

Protein channels
General Anatomy: The Plasma Membrane
 Glycoproteins
 Proteins have branching
sugar groups
 Think of them like tiny
fuzzy structures all over
the cell
 Functions



Determine your blood type
Act as receptors for certain
types of
bacteria/toxins/viruses
can bind to
Act as signaling towers for
that other cells recognize
Specialties of the Cell Membrane
 Microvilli!
 “little shaggy hairs”
 Tiny fingerlike projections that line the hollow organs
 Increase the cell surface area for more absorption ability

This also speeds up the absorption process
Specialties of the Cell Membrane
 Membrane junctions – where the membranes meet
 Tight junctions- impermeable junctions that bind cells
together - you shall not pass!

Desmosomes- button-like anchoring junctions that prevent
cells from being torn apart.


Normally membranes are thickened in these areas
Gap junctions- allows communication through membrane with
chemical molecules (ions, nutrients, hormones etc)

Neighboring cell connected with a connexon! – hollow tube
composed of proteins
We made it to Cytoplasm!
 Cytoplasm- the cellular material outside the nucleus
and inside the plasma membrane
 Three components
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

Cytosol
Organelles
inclusions
Components of Cytoplasm
 Cytosol
 Semitransparent fluid that suspends the other components
 Mostly water
 Inclusion bodies (proteins that miss fold)
 Most are stored nutrients or products from the cell
 Lipid drops in fat cells, glycogen abundant in liver and muscle cells,
pigments such as melanin in skin and hair cells, mucus and other
secreted products etc.
 Aggregate inside the cell and can be used sometimes as markers for
disease

Aggregates of inclusion bodies in the brain = markers for dementia or
Parkinson's
Organelles
Organelles- Mitochondria
 “Power-house” of the cell
 Inner membrane has shelf-
like structures called cristae.
 Enzymes dissolved in the
fluid within the
mitochondria carry out
reactions to break down
food.


Energy will be released as
this occurs and most is lost
as heat
What isn't lost is used to
form ATP molecules
Organelles- Mitochondria
 Cells that are metabolically “busy” like liver and
muscle cells require a lot of ATP and so have A
LOT of mitochondria in the cells
Organelles- Ribosomes
 Tiny bodies made
of protein
 Ribosomes are the
site of protein
synthesis
 Some float free in
the cytoplasm and
make protein
 Others are bound
to membranes (like
the endoplasmic
reticulum)
Organelles- Endoplasmic Reticulum
 “ER” – system of fluid
filled canals used as a
“circulatory system”
to carry proteins
around the cell



Rough ER- has
ribosomes bound to it
Proteins made on the
ribosome and
transported via the
rough ER
Smooth- no protein
making but does help in
lipid break down and
breakdown of
drugs/pesticides- liver
cells are full of rough
ER
Organelles- Golgi Apparatus
 Stack of flattened sacs
close to nucleus and is
the “traffic director” for
cellular proteins sent
from the ER

Modifies, packages, and
ships proteins
Organelles- Lysosomes
 “break down bodies”-
different sizes within cell
 Bags full of digestive
enzymes that breakdown
foreign material and nonusable cell structures

Demolition sites in the cell
 Abundant in phagocyte
cells that engulf
debris/bacteria
Organelles- Cytoskeleton
 Elaborate protein network
throughout the cytoplasm




“cells bones” – internal
framework
Intermediate filaments- form
desmosomes to resist pulling
apart
Microfilaments (actin/myosin)
are involved in cell motility
Microtubules- determine shape
of the cell and how organelles
are distributed
Organelles- Centrioles
 Are close to the
nucleus
 Rod shaped
structures that create
microtubules for cell
division