Transcript PPT - Yavapai College

Cell Structure and Function
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Cells as fundamental living unit
Prokaryotic and Eukaryotic Cells
Cell Membranes
Protein synthesis (quick overview)
Organelles and parts of a cell
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
What is Life?
• Life needs energy
• Life reproduces
• Life grows and
develops
• Life maintains a
stable condition—
homeostasis
• Life responds to
stimulus
• Life is organized
because it has
evolved
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Life Evolves
• Life is organized
hierarchically
• Evolution explains
organization at every
level of hierarchy
• All living organisms or
species can be
understood at every
level of hierarchy
• All current living species
(including humans) have
evolved and are
evolving
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Cells are fundamental unit of life
• Cells are the basic
and fundamental
unit of life
• The first life was
cellular life
• The Molecules of
Life are what cells
and all their
internal parts are
made up of
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Two types of cells
• Prokaryotic cells
– Relatively Simple
– Relatively Small
– No organelles with Molecules of Life
distributed throughout cytoplasm
– Bacteria are all prokaryotic cells
• Eukaryotic cells
– More complex
– Much bigger (100 x size of prokaryotic
cells)
– Internally organized with membrane-bound
organelles
– Multi-cellular organisms, like plants and
animals, are all made up of eukaryotic cells
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Eukaryotic cell
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Endosymbiotic origin of
mitochondria and
chloroplasts
• Eukaryotic cells evolved from fusion
or integration of prokaryotic cells
• Best evidence is in bacterial or
prokaryotic appearance of
mitochondria and chloroplasts
• These organelles are like little
bacterial cells within our cells, now
fully functionally integrated
• They perform fundamental cell
functions. Mitochondria process
sugars to produce energy;
chloroplasts make sugars by
photosynthesis
• But they maintain their own DNA and
genetic control
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Prokaryotic cells have:
• Cell membrane
• DNA molecule loose in cytoplasm
• Small Ribosomes where proteins are
assembled from DNA information
• Microtubule structures like flagella and
cilia
• Mitochondria and chloroplasts share most
of these features, including their own
independent DNA
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
Eukaryotic cells (like our human cells) have:
WHAT EUKARYOTIC CELLS HAVE:
• Cell membrane
• Nucleus
• Mitochondria (and sometimes chloroplasts for
photosynthesis)
• Larger ribosomes for protein assembly from DNA
information
• Internal membranes that organize cellular spaces and
distribution of Molecules of Life within cell (“cytoskeleton”)
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
WHAT CAN EUKARYOTIC CELLS
DO?
WHAT STRUCTURES ARE
INVOLVED?
Separate inside of cell from external
environment and control what
substances pass across membrane
Cell Membrane
Produce proteins/enzymes that
catalyze chemical reactions or control
movement across membrane
Nucleus (DNA), Ribosomes on rough
endoplasmic reticulum
Break down sugars to form energy
which is stored in phosphate bonds of
ATP
Mitochondria
Organize distribution of Molecules of
Life (macromolecules) and ions
throughout cell
Internal membrane system and
“cytoskeleton” (ER, lysosomes,
vessicles, microtubules)
Move
Flagella, cilia, pseudopods
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
A cell membrane or plasma membrane separates cell
from outside world—creates ability to regulate internal
environment (homeostasis)
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
cell membrane
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
cell membrane
What are some characteristics of
the plasma membrane?
• It is a phospholipid bilayer
• It is embedded with
proteins that move in
space
• It contains cholesterol for
support
• It contains carbohydrates
on proteins and lipids
• Selectively permeable
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
cell membrane
What does selectively permeable
mean?
• The membrane allows
some things in while
keeping other
substances out
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
cell membrane
How do things move across the
plasma membrane?
1.
2.
3.
4.
5.
Diffusion
Osmosis
Facilitated transport
Active transport
Endocytosis and exocytosis
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
cell membrane
What are diffusion and osmosis?
• 1. Diffusion is the
random movement of
molecules from a
higher concentration
to a lower
concentration
• 2. Osmosis is the
diffusion of water
molecules
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
cell membrane
How does tonicity change a cell?
• Hypertonic solutions have
more solute than the inside
of the cell and lead to lysis
(bursting)
• Hypotonic solutions have less
solute than the inside of the
cell and lead to crenation
(shriveling)
• Isotonic solutions have equal
amounts of solute inside and
outside the cell and thus does
not affect the cell
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
cell membrane
What are facilitated diffusion and
active transport?
• 3. Facilitated transport is
the transport of molecules
across the plasma
membrane from higher
concentration to lower
concentration via a
protein carrier
• 4. Active transport is the
movement of molecules
from a lower to higher
concentration using ATP
as energy; requires a
protein carrier
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College
What are endocytosis and
exocytosis?
cell membrane
• 5. Endocytosis transports
molecules or cells into the
cell via invagination of the
plasma membrane to
form a vesicle
• 6. Exocytosis transports
molecules outside the cell
via fusion of a vesicle
with the plasma
membrane
Larry M. Frolich, Ph.D.
Biology Department, Yavapai College