Transcript Cells

Cells
Mr. Mincer/Mrs. Scully
Living Environment
Life is Cellular!
• All life is made of either a single cell,
or a collection of cells
• Discovered in the mid 1600’s,
because that’s when microscopes were
invented.
• Cells can be very small and simple, or
large and complex
Cell Theory
• Cell theory has three main ideas:
– All living things are composed of cells
– Cells are the basic unit of structure and
function in living things
– New cells are produced only from
existing cells
Cells
• All cells have a few things in common:
– All contain genetic material (DNA)
– All have a cell membrane which will
selectively let certain materials through
– All need a microscope to be seen
Types of Cells
• There are two types of cells
– Prokaryote-smaller, not as well
organized
– Eukaryote -Bigger, most multi-cellular
organisms are made of eukaryotic cells
Prokaryotes
• No Nucleus
– The nucleus is the place in some cells
where the DNA is stored
• No organelles (or very few)
– An organelle is a structure within a cell
that has a specific function, like an organ
• Example: Bacteria
Eukaryotes
• Contain a nucleus and organelles
• Usually larger than prokaryotic cells
• Thought to have evolved from a
symbiotic relationship between two
prokaryotic cells
• All multi-cellular organisms are made
up of eukaryotic cells
Cells Are Factories
• In a factory, many different raw
materials are brought in and
assembled into finished products
• In a cell, the same thing happens
– Raw materials, or molecules, are
brought in and different organelles
rearrange and assemble them into the
things the cell needs
– Each organelle has a different job, just
like different workers in a factory
– The nucleus tells the other organelles
when and how much of the products they
produce
Organelles
• Nucleus-Stores DNA, which is the
blueprint for almost everything that
happens in the cell (The foreman)
• Ribosomes- Create proteins (worker)
• Endoplasmic Reticulum- Assembles
lipids and proteins (worker)
• Golgi Apparatus- Modifies, sorts and
packages proteins (shipping
department)
Organelles Cont’d
• Lysosomes- Dissolve old or broken
organelles (Janitorial Staff)
• Vacuoles- Storage spaces for the cell,
can store water, food, toxins, etc.
(Warehouse)
• Mitochondria- Convert molecules into
energy (Generators)
• Chloroplasts- Converts sunlight, CO2,
and H2O into food (Cafeteria)
Cytoskeleton
• Eukaryotic cells have a skeleton, just
like you!
• There skeleton is made of protein
fiber, or filament, which helps
support the cell, but also helps with
transportation
Cell Membrane and Walls
• Cell Wall-Plants, Fungi, and some
Prokaryotes have cell walls. Mostly
made from carbohydrates, they
provide support and protection.
• The cell membrane (which both
prokaryotic and eukaryotic cells have)
is called the lipid bilayer
– Lipids are fats, and bi means 2. So, the
lipid bilayer means 2 layers of fat
molecules
Cell Organelles
Passive vs. Active Transport
• Active Transport- The cell has to use
Energy to move something
• Passive Transport-The cell doesn’t
use any ENERGY to move something
– Diffusion
– Osmosis
– Facilitated Diffusion
Diffusion
• The process by which a fluid flows
from where it is to where it isn’t
– Or, from areas of high concentration to
areas of low concentration
– E.g. Sugar molecules will move from an
area of high concentration to an area of
low concentration
Osmosis
• Same thing as diffusion, except:
It’s Only Water Molecules!!
Facilitated Diffusion
• Same thing as diffusion, but the cell
membrane helps the process out by
using specific structures to help the
molecules make it through the
membrane.
Effects of Osmosis on Cells
• Isotonic- Same amount of water in as
out
• Hypertonic- Less water outside the
cell, so the cell shrinks from water
loss
• Hypotonic- Less water inside the cell,
so the cell swells from inflow of water
Active Transport
• Endocytosis- Folding the cell
membrane around something.
• Pinocytosis-Folding the cell membrane
around a small amount of liquid to
take into the cell
• Exocytosis-Merging the membrane of
a vacuole with the cell membrane to
expell something from the cell
• Phagocytosis- Large extensions of
cytoplasm surround another cell, or
food particle.
Endocytosis
Pinocytosis
Droplets of
fluid
Exocytosis
Phagocytosis
Cellular Respiration
• Cells need ENERGY!
• Cells get their energy from breaking
down chemical bonds.
• This process is called: Cellular
Respiration.
Cellular Respiration
• It ALWAYS starts in the cytoplasm
with a process called: GLYCOLYSIS!
• Glycolysis: Glucose is broken down
into two pyruvic acids and the cell
gains 2 ATP.
• ATP is ENERGY! It’s the molecule
that your cells use to store energy.
After Glycolysis…
• Then, if there is
oxygen AND
mitochondria…
– The process moves into
the mitochondria into
the Krebs Cycle for 2
more ATP
– Then onto the Electron
Transport Chain for 32
ATP!
– This is called:
• Aerobic Cellular
Respiration
2
2
32
Electron Transport Chain
• Yields a TON of ATP (32 per glucose
molecule!)
Cellular Respiration
• C6H12O6 + O2  CO2 + H2O + ENERGY!
+
+
+
After Glycolysis if no O2
• Alcoholic
Fermentation
– 2 pyruvic acids are
turned into 2 more
ATP and alcohol
• Lactic Acid
Fermentation
– 2 pyruvic acids are
turned into 2 more
ATP and lactic acids
Mitosis!
• Mitosis is the process by which cells
divide and end up with the same
exact amount and type of DNA as
the parent cell.
Four Phases…
• 1. Prophase-To begin mitosis, the nuclear
membrane breaks down, while the chromosomes
shorten and thicken (a chromosome is two
chromatids, bound at a point called the
centromere, making an "X" shape). The other
structures important for mitosis also form (i.e.
the centrioles).
• 2. Metaphase- Spindle fibers align the
chromosomes along the middle of the cell
nucleus. This organization helps to ensure that
in the next phase, when the chromosomes are
separated, each new nucleus will receive only
one copy of each chromosome, for a complete
set.
Last Two…
• 3. Anaphase-The paired chromosomes separate
at the centromere and move to opposite sides of
the cell. Motion results from a combination of
centromere movement along the spindle
microtubules and through the physical
interaction of polar microtubules.
• 4. Telophase-Chromatids arrive at opposite
poles of cell, and new membranes form around
the daughter nuclei. The chromosomes disperse
and are no longer visible under the light
microscope. The spindle fibers disperse, and
cytokinesis or the partitioning of the cell may
also begin during this stage.
Cytokinesis
• The process by which the cell finishes
dividing.
– Animal cells- The cell membrane pinches
closed into two daughter cells
– Plant cells- A cell plate forms, which
becomes the new cell wall for the
daughter cells, then the new cell
membrane forms.
Cancer
• Cancer is just the unregulated
division, by mitosis, of a cell.
• Your immune system catches most
cancerous cells, but the ones that it
doesn’t can become life-threatening.