Download Cell Membrane

CELL
STRUCTURE &
FUNCTION
Ch. 7, Sec. 1-2
Pages 169-181
Section 7.1, Life is Cellular
I. Discovery of the Cell
A.
Robert Hooke, 1665
- First to use a Compound Microscope
to look at “cells.”
1.
A compound microscope has
two lenses.
(Objective lens & Eyepiece)
2.
Looked at a thin slice of cork
which had many “little rooms.”
B.
Anton van Leeuwenhoek, 1674
– Used a simple microscope
(one lens) to look at pond water.
– He saw tiny living organism which
he called “animalcules.”
II. The Cell Theory
A. What is a cell?
- The basic unit of life.
B. Schleiden & Schwann
– German scientists who stated the cell theory:
1. All living things are made of cells.
2. Cells are the basic units of structure &
function.
3. All cells are produced by existing cells.
III. Viewing Cells Close Up
A. T.E.M (Transmission Electron Microscope)
– Using a beam of electrons to view the inside of
cells & proteins.
– Can only penetrate thinly sliced specimens.
B.
S.E.M (Scanning Electron Microscope)
- Produces 3-D images of the outside
structure of cells.
IV. Prokaryotes and Eukaryotes
A. Prokaryotic Cells
– Cells that do not contain a nucleus.
– DNA is free to float inside the cell.
– All bacteria are an example of
prokaryotes.
B. Eukaryotic Cells
- Larger & more complex
- Have a nucleus that contains the DNA
- Have many “specialized” internal structures
contained within a membrane
(Organelles)
- May live as single cells or make up
multicellular organisms.
- The kingdoms - animals, plants, fungi, and
protists are all eukaryotes
Section 7.2 Eukaryotic Cell
Structure
I. Types of Eukaryotes.
- Plant, Animal, Fungus
& protist cells
II.
Organelles
- Membrane-bound structures that act like
individual organs.
- Each carries out a specific function.
Cytoplasm
- Area between the nucleus and cell
membrane.
- Contains a fluid/jelly-like substance and
cytoskeleton
- allows easy movement of wastes and raw
materials in and out of the cell
- provides place for chemical reactions
Parts of a Eukaryotic Cell
Nucleus
1. Contains all the DNA within a cell, which it is
referred to as the control center of the cell
2. Surrounded by the “Nuclear Envelope.”
- - Membrane that protects the
inside contents and also
allows for the passage of
materials in and out of the
nucleus such as RNA and
ribosomes. Movement
of materials is through pores.
Cell Barriers
A. Cell Membrane
- Found in all living things prokaryote and
eukaryote.
- Is a semipermeable lipid bilayer.
- It is a boundary that controls what goes in
and out of a cell.
B. Cell Wall
- Found in plants, algae, fungi & bacteria.
- Provides support and protection to the cell.
- Made mostly of the Carb. Cellulose.
Cell Membrane Structure
Cell Wall
Nucleolus
- Located in the center region of the nucleus and
it begins to produce ribosomes.
Chromatin
- the form DNA is in when a cell is not dividing.
(which is most of the time!)
- DNA wrapped around DNA.
- Looks like tangled spaghetti
Chromosomes
- the form DNA is in when a cell is dividing.
- Condensed chromatin – looks like X’s
Ribosomes
1.
Small grain-like particles of RNA
inside the cytoplasm or on the
Endoplasmic Reticulum
2.
Located throughout the cell
3.
Produce proteins from information
within DNA.
Endoplasmic Reticulum
1. System of passageways that
transports proteins & other materials
throughout the cell.
2. Two types of E.R.
a. Rough E.R.
- Is covered with ribosomes which
produce proteins.
b. Smooth E.R.
- Mainly responsible for making
membrane lipids and breaking down
drugs.
Golgi Body (Golgi Apparatus)
1. Proteins from the E.R. are
transported here next.
2. Modifies, or packages proteins and other
materials before they are secreted outside of
the cell.
- Puts the “finishing touches” on proteins .
proteins.
Lysosomes
1.Small organelles filled with digestive
enzymes.
- Break down food molecules that can
be used by the cell as well as waste
products.
Vacuoles
1. Sac-like structures that store water,
food and/or waste products.
- Extremely important in water storage for
plants.
Very large in
Plants
Mitochondria
1. Organelles that convert chemical energy
stored in food particles into a more useful
form.
2. Are enclosed by two membranes:
a.
Outer
- Protects the inside of the
mitochondria and allows materials to
move in and out.
b.
Inner
- Inside membrane where energy
production occurs (ATP).
Chloroplasts
1. Found only in plant cells.
- Capture energy from sunlight and convert
it into chemical energy in the process
known as “PHOTOSYNTHESIS!”
a. Creates “glucose.”
Centrioles – Organelles found in animal cells
that help the chromosomes divide during cell
division
Cell Boundaries
Chapter 7.3
I. Cell Membrane
a. Membrane that surrounds the cell and
regulates what enters and leaves the cell
as well as protects and supports the cells.
b. Found in all cells.
c. Comprised of a “lipid bilayer.”
1. Provides a flexible, but strong barrier
between the outside & inside of the cell.
d. Contains a variety of proteins (transport)
and carbohydrates (communication), all of
which perform a specific function for the cell.
Cell Membrane Diagram:
II.
Cell Wall
a. Present in all plants, and in a variety of
algae, fungi & bacteria.
b. Provides “strong support & protection” for
the cell.
c. Plant cell walls are mainly comprised of
cellulose.
III. Diffusion & Osmosis
1. Concentration
- Refers to the amount of a solute
within a solution.
a.
Solute – substance that is
dissolved in a solution.
b.
Solution – mixture of two or more
substances that are evenly
distributed.
c.
Solvent – what the solute is dissolved into
- The concentration of a solute in solution can be
critical for proper bodily function.
Ex. Sugar in blood versus Insulin levels.
2.
Diffusion
- Particles moving from an area of high
concentration to low concentration. (Cross
other things out so your notes read this!)
a.
Equilibrium – When the
concentration of solute is the same
throughout the solution.
Factors that affect the rate of diffusion:
a. Size of the Concentration Gradient.
(how concentrated the sides are)
b. Amount of surface area/ volume
c. When equilibrium is reached
(equal concentration on both sides)
d. Temperature
e. Charge of particle
3. Osmosis
- Diffusion of water across a “selectively
permeable” cell membrane.
- “Selectively Permeable” refers to how cell
membranes will sometimes not allow solute
to pass through but will freely allow water to
pass through.
Click image for
video link!
Types of Osmotic Balance:
1.
Isotonic Solution
- When solute & water are at
equal concentrations on both sides of membrane
2.
Hypertonic Solution
- When the solution a cell is in
has “more solute” than water.
(Cell will shrink by losing water!)
3.
Hypotonic Solution
- When the solution a cell is in
has “less solute” than water.
(Cell will enlarge by gaining water!)
When doing osmosis problems, know the solution,
then think of where the water will go to reach equal
water concentrations on each side (water is the only
thing that can move)
Two Types of Transport:
(this say diffusion in your notes, change to transport)
1. Passive Transport
- When particles move from high
concentration to low concentration
without the use of energy.
Click image
for video
link!
Two Types of Passive Transport:
A. Simple Diffusion
- When particles move directly through the
lipid bilayer.
Examples: Oxygen & Carbon Dioxide & Water
B. Facilitated Diffusion
- Particles cannot pass through bilayer.
- Pass through transport proteins due to
their size or charge.
Examples: H+ ions and Glucose
Click image for video link!
2. Active Transport
- Movement of substances against their
concentration gradient (Low to High).
- Requires energy (ATP) & transport
proteins to occur.
Click image
for video
link!
Endocytosis
• Type of Active transport
• The process of taking material into the cell
by means of infoldings, or pockets of the
cell membrane
Endocytosis
• 2 types of Endocytosis:
• Phagocytosis – Extensions of cytoplasm
surround a particle and package it within a food
vacuole – amoebas
• Pinocytosis – cells taking in liquid into vesicles
Exocytosis
• Also active transport
• The process of cells releasing large
amounts of material