Download utaccel 2010

UTACCEL 2010
Adventures in Biotechnology
Graham Cromar
Cell Biology
Cell is the basic unit of life
•
•
•
All living organisms are composed of one or more cells - the cell is the unit of
organization of Life
Most cells are very small. Exceptions? Ostrich egg is the largest cell. Nerve cell in a
leg of a giraffe may be as long as 3m, but is very thin.
Most life on the planet consists of single cells. Multicellular organisms arose
relatively recently ~ 600 million years ago.
What is a cell?
A cell is a small packet or bag of liquid. The
liquid is cytoplasm (or cytosol), which is
essentially salty water with various organic
molecules suspended in it.
Geologic Time Scale
The earth is ~4.6 billion years old
Humans < 1 mya
Dinosaurs until ~65 mya
Reptiles
Seed plants
Insects, amphibians
Land plants
Multicellular life
Eukaryotes ~600 mya
Prokaryotes, the first cells
Prokaryotes
plasmid
Lacking well-defined nuclei and membranebound organelles, and with chromosomes
composed of a single closed DNA circle. They
come in many shapes and sizes, from minute
spheres, cylinders and spiral threads, to
flagellated rods, and filamentous chains. They
are found practically everywhere on Earth and
live in some of the most unusual and
seemingly inhospitable places.
Flagellar Motor
Plasmids
Plasmids, are small, circular pieces of DNA carried by
many strains of bacteria. Unlike the chromosome, they
are not involved in reproduction. Only the chromosome
has the genetic instructions for initiating and carrying
out cell division. Plasmids replicate independently and,
while not essential for survival, appear to give bacteria a
selective advantage.
Plasmids have been shown to be instrumental in the
transmission of special properties, such as antibiotic
drug resistance, resistance to heavy metals, and
virulence factors necessary for infection of animal or
plant hosts. The ability to insert specific genes into
plasmids have made them extremely useful tools in the
fields of molecular biology and genetics, specifically in
the area of genetic engineering.
Eukaryotes
Eukaryotic cells have organelles. Organelles are
subcellular structures that provide internal
compartmentalization and other functions.
Nucleus is a large membrane-bound
organelle. Its function is to sequester the
DNA from the rest of the cell. Inside the
nucleus, DNA is organized in
chromosomes. A chromosome is a tighly
coiled and wound strand of DNA
packaged with various proteins.
Smooth endoplasmic reticulum is a
system of membranes and is involved in
carbohydrate and lipid synthesis.
Rough endoplasmic reticulum is a
system of membranes that possesses
ribosomes. Proteins are synthesized in
the rough ER.
Golgi apparatus stores and packages
various molecules. When a molecule is
needed elsewhere in the cell, a portion
of the Golgi membrane closes off and
forms a vesicle that can be transported
around the cell.
Mitrochondria
Mitochondria are found in all
Eukaryotic cells. Breakdown of glucose
begins in the cytoplasm and ends in
the mitochondria, where the final
products of the breakdown are ATP,
water, CO2 and heat. This process
requires oxygen - that is why we
breath: to provide the oxygen for the
mitochondria and to get rid of carbon
dioxide produced in the mitochondria.
ATP (adenosine triphosphate) is the
energy currency of the living world.
Every cellular process that requires
energy gets it from ATP. Thus,
mitochondria are sometimes referred
to as "factories of the cell".
Cytoskeleton
The cytoskeleton, composed of
filaments and microtubules,
anchors the organelles and gives
a cell its shape. Microtubules
move organelles, including
vesicles, within a cell. They also
move the membrane-embedded
proteins around where they are
needed.
Comparison
Prokaryotes (bacteria) have a cell membrane and cytoplasm and no other
organelles.
Eukaryotes (plants, animals, fungi, protista) have a number of different cell
organelles.
The nuclear material in Prokaryotes is a single, circular strand of DNA.
The nuclear material in Eukaryotes is organized in multiple chromosomes
contained with a nucleus.
Not just empty space!
vs
The Inner Life of the Cell
One minute paper
Take out a piece of paper.
From memory, draw and label a eukaryotic or
prokaryotic cell (your choice)
When you are done, exchange your drawing with a
partner and mark their work.
Do your cells look like these?
Eukaryotic cell structure