Download Chapter 7 Section 1

Chapter 7
Explain the cell theory.
Name the basic cell structures.
Describe prokaryotes and eukaryotes.
What is the Cell Theory?
Widely accepted explanation of the
relationship between cells and living things.
The cell theory states the following:
• All living things are composed of cells.
• Cells are the basic unit of structure and
function in living things.
• All cells are produced from other cells.
Robert Hooke
“Cells are the basic unit of structure and function in living things”
• In 1665, Hooke looked at
a thin slice of cork
through one of the first
light microscopes.
• Hooke described the cork
as being made of
thousands of tiny
chambers.
• Hooke called these
chambers “cells” because
they reminded him of the
monastery’s tiny rooms
which were called cells.
All living things are composed of cells
Rudolf Virchow
“New cells are produced from existing cells”
• Studied cell
reproduction
Cell Types
Prokaryotes
Eukaryotes
• Organisms who’s cells LACK
nuclei.
• REMEMBER: Pro has no
nucleus
• Organisms whose cells have
nuclei (more advanced)
• REMEMBER: Eu do have a
nucleus
Cell Structures and functions
Cell membrane
• Function – controls what
enters and exits the cell; also
provides protection and
support for the cell.
• Structure – phospholipid
bilayer (two layers of
phospholipids with
carbohydrate chains and
protein channels). Selectively
permeable barrier.
• Found in all cells
• Similar to the gates of a gated
community, or a fence
Cell wall
• Structure – rigid structure
made up mostly of
cellulose fibers
• Function – to provide
support and protection
for the cell.
• Found only in plant,
bacteria, and fungi cells
• Similar to gates of a gated
community/fence
Nucleus
• Structure – has a nucleolus
(where the making of
proteins begins), chromatin
(grainy mixture of DNA and
protein), chromosomes
(condensed chromatin) and
nuclear envelope
• Function – controls most
cell processes and contains
the hereditary material DNA
• Found in eukaryotic cells,
plant and animal cells
• Similar to the boss, city hall,
library
Cytoplasm
• Structure – clear, thick,
jellylike material inside the
cell. Contains cytoskeleton
fibers (microtubules and
microfilaments)
• Function – supports,
protects, and helps
transport organelles inside
the cell
• Found in all cells
• Similar to the interstates,
highways, roads, and the
support beams in buildings
Ribosomes
• Structure – small bodies
free or attached to ER
and made of protein
and rRNA
• Function – synthesizes
(assembles or makes)
proteins
• Found in all cells
• Similar to a
construction site
Endoplasmic Reticulum
• Structure – network of
tubes or membranes;
connected to nuclear
envelope and cell
membrane (rough has
ribosomes/smooth doesn’t)
• Function – carries materials
through cell and aids in
making proteins, parts of
the cell membrane.
• Found in all eukaryotic cells
• Similar to a factory
Golgi Apparatus
• Structure – stacks of
flattened sacs
• Function – package and
export proteins, modify
proteins (attaches
carbohydrates and lipids
to proteins) made by the
cells in the ER.
• Found in all eukaryotic
cells
• Similar to a shipping
company (UPS/Post
Office)
Vacuoles
• Structure – fluid-filled
sacs (the largest organelle
in a plant cell)
• Function - store food,
water, and waste
• Found in eukaryotic cells;
plant cells have one large
vacuole and animal cells
have multiple small
vacuoles.
• Similar to storage
company or water tower
Chloroplasts
• Structure – green, oval
containing chlorophyll;
double membrane with
inner membrane
modified into sacs
• Function – uses solar
energy to make food
(glucose) and release
oxygen.
• Found in plants and algae
• Similar to solar energy
panels
Mitochondria
• Structure – peanut
shaped, double
membrane (outer is
smooth and inner is
folded)
• Function – breaks down
glucose (food) molecules
to release energy
• Found in all eukaryotic
cells
• Similar to MLGW or other
similar power company
Nuclear envelope
• Structure – flexible,
selectively permeable,
double membrane
• Function – controls
movement of materials
in/out of nucleus
• Found in all eukaryotic
cells
• Similar to a gate/door
Lysosome
• Structure – small, round
organelle with a single
membrane
• Function – digests old cell
parts; breaks down larger
molecules into smaller
molecules
• Found mostly in animal
cells and only occasionally
in plant cells
• Similar to a
garbage/recycling
company
Centrioles
• Structure - a cylinder of
microtubule pairs;
found in pairs near the
nucleus
• Function – separates
chromosome pairs
during cell division
• Found only in animal
cells
Transportation through the Cell
Membrane
Active transport moves
substance against the
concentration gradient
(from low concentration to
high concentration)
Passive transport moves
substances with the
concentration gradient
(from high concentration
to low)
The Cell Membrane
What are the main functions of the cell membrane?
It regulates what enters and leaves the cell and provides protection
and support
What does it mean that a cell membrane has a “lipid bilayer”?
It is composed of two “bi” layers of lipid molecules with protein
molecules that help certain substances to enter or exit the cell. It
also has carbohydrates that behave as identity markers (name tags).
What does it mean when a membrane
is selectively permeable?
• The membrane will allow only certain
materials to pass across the membrane.
Diffusion
• Diffusion is the
movement of molecules
from an area of high
concentration (where
there are many) to an
area of low concentration
(where there are few).
• This is a type of Passive
transport since it does
not require the input of
additional energy.
Osmosis
• Osmosis is the diffusion
of water molecules
through a permeable
membrane from an area
of high concentration to
an area of low
concentration.
• Because it is the diffusion
of water, it is also a type
of passive transport.
Facilitated Diffusion
• During facilitated diffusion, the
protein channels in the cell
membrane help (facilitate)
certain molecules like glucose
(which can not simply diffuse)
to pass through those protein
channels into or out of the
cell.
• Again, this is a type of
diffusion, so it is also a type of
passive transport (the
movement of molecules is
from areas of high
concentration to low
concentration)
Equilibrium
• When is equilibrium reached in a solution?
– When the concentration of the solute is the same
on both sides of the cell membrane or throughout
a solution
Endocytosis
• Endocytosis is the process of
taking material into the cell by
enfolding of the cell
membrane around large
molecules, clumps of food, or
even whole cells.
• This is a type of active
transport because it requires
the input of additional energy
and the substance is moving
against the concentration
gradient (from an area of low
concentration to high
concentration).
Exocytosis
• During exocytosis, the
membrane of the vacuole
surrounding the material
fuses with the cell
membrane, forcing the
contents out of the cell.
• Because this type of
transport requires the cell
to use energy and the
substance is moving
against the concentration
gradient, exocytosis is a
type of active transport.