|
Announcements
&
Assignments
Lecture
Objectives
Why Study
Cells
Web
Resources
Cells Are the
Basic Unit of Life
Prokaryotic
Cells
Eukaryotic
Cells
Membrane
Structure
and Function
Coordination
Organelle Function
Lecture
Syllabus
IB 100/101 Home
Page
|
|
Text Readings in Life, Lewis et al.
Chapters 4, Cells: Units of Life and 5, the Cell Surface and
Cytoskeleton
The "Reviewing Concepts" boxes are valuable summaries of the main
ideas in these sections of the text.
You have open access (no log-in or password needed) to instructional
materials on the Text web site. Select the text chapter you want and
use the links to the e-learning modules or other available materials.
There is also a collection of study materials called the "Essential
Study Partner" that you may find useful.
Web Crossing
You may also ask questions and see answers to your classmates'
questions in Web Crossing in the "Talk to Carl and Ed" discussion.
Objectives:
The content of today's lecture will help you answer questions 1
and 2 on this assignment:
After studying this material you should be able to:
- Explain how a single cell meets the basic criteria that
differentiate living organisms from nonliving objects or chemical
reactions.
- Draw sketches of prokaryotic and eukaryotic cells (plant and
animal), pointing out the distinguishing characteristics of each of
these types of cells.
- Describe the basic structure of the membranes in the cells you have
drawn and describe the roles of these membranes in determining the
organization and functions of cells and their organelles.
Include the following in your description:
| phospholipid bilayer |
transport proteins |
receptor proteins |
sugar molecules |
| diffusion |
osmosis |
facilitated diffusion |
active transport |
- Describe the role of each cell organelle and membrane system
involved in the production and secretion of milk from a mammary gland
cell. (Read the text section "Organelles Interact to Secrete Substances"
starting on pg 54 (Chapter 4 of the Life text). Understand the
relationships among the organelles illustrated in figures 4.11, pg.
55)
Include the following in your description:
| Chromosomes |
DNA |
messenger RNA |
nucleus |
| cytoplasm |
endoplasmic reticulum
(rough & smooth) |
ribosomes |
protein |
| vesicles |
Golgi bodies |
fat droplets |
outer cell membrane |
As you study the unit on cells, can you figure out how the cell
membrane systems, organelles, and other components in the right-hand
side of the table below are involved in maintaining the characteristics
of living organisms in the left-hand side of the table? (Lecture
Objective #1)
| Characteristics of Living Organisms (From Lecture #1) |
Cell Membrane Systems,
Organelles, and Other Components |
- Life is organized
- Life requires energy
- Living things must maintain an internal constancy
-homeostasis: the ability to maintain chemical constancy (i.e., to stay
the same)
- Living things react to environmental change (i.e., their
surroundings)
- Living things reproduce, grow, and develop
- Living things adapt
|
| cell wall |
plasma membrane |
| phospholipid bilayer |
membrane proteins |
fluid mosaic
membrane model |
transport proteins |
| nucleus |
nuclear membrane (envelope) |
| nuclear pores |
chromosomes |
| DNA |
nucleolus |
| receptor proteins |
golgi bodies |
| vesicles |
mitochondria |
| chloroplasts |
ribosomes |
| endoplasmic reticulum (ER) |
lysosomes |
| cytoskeleton |
microtubules |
| vacuole |
|
|
Why should we study cells?
- Cells are the basic structures of almost all living things,
including us. There are maybe 10 to 100 trillion of them in each of our
bodies. (But most aren't "Human Cells")
- Cells do all the chemical activity that happens in our bodies (our
meaning - all types of organisms).
- They process energy, digest our food, capture CO2, release CO2,
release heat
- When cells get "out of whack" we get sick.
- Stem cells may one day help us recover from inherited and other
types of illness or injury.
Cell Biology Web Resources
- Interesting Video showing the level of movement within cells
Cells as the "Basic Unit of
Life"
- Cells are common to all organisms from bacteria to fungi, plants,
and animals.
- Cells were "discovered" as the basic unit of living organisms in
the nineteenth century.
- Early observations of cells led to the distinction of two major
cell types:
- prokaryotes (bacteria) - cells without nuclei
- eukarya (everything else) - cells with "true" nuclei
- A third cell type - characteristic of another domain of life was
discovered by Carl Woese at the University of
Illinois in 1977, resulting in three major cell types.
Prokaryotic Cells
- Pro = before, karyon = kernal (what nuclei looked like to those who
first saw them through a microscope)
- Cells WITHOUT ORGANIZED NUCLEI bounded by a nuclear membrane OR ANY
OTHER MEMBRANE-BOUND ORGANELLES
- Eubacteria (True bacteria) (Text pg. 50, fig. 4.6)
and cyanobacteria (blue-green algae)
- No membrane bound organelles within the bacterial cell
- Nucleoid - the main genetic content of the cell
- Plasmids are small circular pieces of DNA that are
separate from the DNA of the nucleoid.
- Test your knowledge of prokaryote structure.
Eukaryotic Cells
- Eu = true, karyon = kernel (nucleus)
- Cells WITH ORGANIZED NUCLEI bounded by a nuclear membrane AND OTHER
MEMBRANE BOUND ORGANELLES.
- Plants and animals HAVE EUKARYOTIC CELLS
- Fungi, algae, and most other types of organisms, except bacteria and
archaea
- All have a cell (plasma) membrane
- Some have cell walls
Membrane Structure and Function
- Membranes are selectively permeable structures that regulate
the movement of molecules in and out of the cell (bacteria, archaea, and
eukaryotes) and in and out of compartments within the eukaryote
cell.
- The basic structure is a phospholipid bilayer (see here too). Phospholipid molecules
align to form membranes because part of the molecule is hydrophilic (the
phosphate end) and part is hydrophobic (the fatty acid chain). (Text pg
67, fig 5.2)
- The Phospholipid bilayer is a constantly moving, fluid structure.
Proteins and other materials imbedded in it are free to move about.
- Proteins embedded within the membrane perform many
tasks: (Text pg 68, fig. 5.3)
- Receptor proteins: receive and transmit chemical messages so that
cells can respond to changes in their environment.
- Cells respond to hormones produced in your body when hormone
molecules bind to specific receptor proteins in your cell membranes.
(Insulin, growth hormone, sex hormones, thyroid hormones, etc.)
- Antihistimines block the receptor proteins that
normally bind histimines produced when you have an allergic reaction to
something in your environment.
- Cell surface proteins: Important for recognition of self (in
animals). Your blood type and tissue type are determined by the proteins
on the surface of your cells. This is especially important to consider
when getting a transfusion or a tissue or organ transplant.
- Transport proteins: move substances across the membrane
How do materials cross membranes?
- Membrane transport proteins (Text pg 71 fig.
5.9)
- PASSIVE TRANSPORT (no energy needed):
- Diffusion: Movement of molecules from high to low concentrations.
(eg oxygen, carbon dioxide).
- Osmosis: Movement of water from low to high solute (salt)
concentrations.
- Facilitated transport: Movement across the membrane via a protein
channel
- ACTIVE TRANSPORT (need to expend energy):
- Pumping of ions or molecules across the membrane and from low to
high concentrations using the energy from ATP (produced by respiration)
and carrier proteins
- Exocytosis (Text pg. 73 fig. 5.12)
- Endocytosis (Text pg. 74 fig. 5.13)
- Ricin - a
deadly ribosome toxin enters the cell by endocytosis
|
