Transcript organelle - St. Clairsville High School

organelle
A tiny cell structure that carries out a
specific function or job within the cell.
Cell wall
A rigid layer of nonliving material that
surrounds the cells of plants and some
other organisms.
Cell membrane
The outside layer of the cell; controls
which substances enter or leave a cell.
Nucleus
The control center of the cell that
directs the cell’s activities.
Chromatin
Material in cells that contains DNA and
carries genetic information.
Cytoplasm
The thick gel-like material between the
cell membrane and the nucleus of a
cell.
Mitochondrion
Rod-shaped cell structures that produce
most of the energy needed to carry out
the cell’s functions.
Endoplasmic Reticulum
A cell structure that forms a maze of
passageways in which proteins and
other materials are carried from one
part of the cell to another.
Ribosome
A tiny structure in the cytoplasm of a
cell where proteins are made.
Golgi Body
A structure in a cell that receives
proteins and other newly formed
materials from the endoplasmic
reticulum, packages them, and
distributes them to other parts of the
cell.
Chloroplast
A structure in the cells of plants and
some other organisms that captures
energy from sunlight and uses it to
produce food.
Vacuole
A water-filled sac inside a cell that acts
as a storage area.
Lysosome
A small round cell structure that
contains chemicals that break down
large food particles into smaller ones.
Prokaryote
An organism whose cells lack a
nucleus and some other cell structures.
Eukaryote
An organism with cells that contain
nuclei and other cell structures.
The Origin of Life
 Scientists think that early Earth had a different
atmosphere than it has today.
 3.6 billion years ago the main gases were nitrogen,
water vapor, carbon dioxide, and methane. There
was no oxygen.
 Today the main gas in the atmosphere is nitrogen.
 The first life forms probably lived in the oceans.
They were unicellular and did not need oxygen.
Urey and Miller
 These two scientists designed an experiment in
which they recreated the conditions of early Earth.
They placed water (to represent the oceans), and a
mixture of gases (nitrogen, methane, carbon
dioxide) into a flask. They sent an electric current
(to represent lightning) into the flask. Within a
week a dark fluid appeared containing small
chemicals that could join to form proteins.
Fossils of bacteria-like
organisms have been found.
 The first cells were probably heterotrophs
that used chemicals in their surroundings for
energy.
 Early ancestors of today’s autotrophs had an
important effect on the atmosphere. As they
made their own food, they produced oxygen
as a waste product.
Essay question: Compare and contrast
plant, animal, and bacterial cells.
Plant, animal and bacterial cells are all living things. They
have a cell membrane, ribosomes,cytoplasm, and genetic
material. The differences are that plant and animal cells are
eukaryotes containing the genetic material in the nucleus;
bacterial cells are prokaryotes because their genetic material is
not enclosed in a nucleus. Plant cells and bacterial cells both
have a cell wall. Plant cells,
unlike animal and bacterial cells, have chloroplasts. The plant
cell vacuole is also larger than in an animal cell. Bacterial cells
are often much smaller than plant and animal cells.