Chapter 7 Cell Structure and Function. The discovery of cells was dependent on the invention of the...
-
Upload
sandra-hicks -
Category
Documents
-
view
223 -
download
0
Transcript of Chapter 7 Cell Structure and Function. The discovery of cells was dependent on the invention of the...
Chapter 7Cell Structure and Function
The discovery of cells was
dependent on the invention of the
microscope
The Cell Theory1. All organisms (bacteria, protists, fungi, plants,
animals) are made of cells.
2. Cells are the basic unit of structure and function of living things.
3. All cells come from preexisting cells.
Important Scientists
• Hooke discovered and named cells
Early Microscopes = Light Microscopes, where light reflects off an object. Usually cannot see
most organelles with these.
Van Leeuwenhoek’s Microscope
Original Copy
An old German Microscope
Stains add contrast. Some can identify chemical types
Acid-secreting cells of Rattlesnake Venom
Glands
From:Zoologischer Anzeiger - A Journal of Comparative ZoologyVolume 245, Issues 3–4, 24 November 2006, Pages 147–159
Bioweapons synthesis and storage: The venom gland of front-fanged snakes ☆
Stephen P. Mackessy, , Louise M. BaxterSchool of Biological Sciences, University of Northern Colorado, 501 20th St., CB 92, Greeley, CO 80639-0017, USA
Fluorescent Stains
Microscopes are almost always needed to see a cell.
Size: 1-100 micrometers (= µm)
Old terminology: micron
1 m
0.1 m
1 cm
1 mm
100 µm
10 µm
1 µm
100 nm
10 nm
1 nm
Atoms
Small molecules
Lipids
Proteins
Ribosomes
Viruses
Smallest bacteria
Mitochondrion
Nucleus
Most bacteria
Most plant and animal cells
Frog egg
Chicken egg
Length of some nerve and muscle cells
Human height
Una
ided
eye
Lig
ht m
icro
scop
e
Ele
ctro
n m
icro
scop
e
Electron Microscopes Today(Note Problem: Cells are not alive)
SEM = Scanning TEM = Transmission
See surface Thin Section; see through
See 3-D See 2-D
Important Scientists
• Schleiden determined that all plants are made of cells.
• Schwann determined that all animals are made of cells.
Important Scientists Van Leeuwenhoek
discovered that microorganisms live in a huge variety of sources (pond water, rivers, his mouth).
Virchow claimed that all cells come from preexisting cells.
The Two Cell Types
Prokaryotes and Eukaryotes
Prokaryotes = Bacteria and Blue-Green Algae
CHARACTERISTICS• Simple• Coffee bean size• No membrane-bound
organelles but do have ribosomes (rRNA)
• Have DNA, but not in a nucleus
Organelle = “little organ”
Bacteria Types
Cocci (round) Bacillus (rod) Spirillum (spiral)
What good are bacteria?
• Autotrophs– Produce oxygen
• Fix nitrogen– So plants can take it in. We need nitrogen to make
DNA & proteins
• Recycle nutrients• Form antibiotics• Help in digestions and formation of vitamins• Production of cheese and yogurt
Eukaryotes
Characteristics
– More complex
– Larger compared to prokaryotes
– Cell membrane; plants and fungi ALSO have cell walls
– Membrane bound organelles
– DNA in nucleus
Eukaryotes
Organelles are important in keeping non-compatible reactions apart, yet allowing them to happen at the same time = DIVISION OF LABOR
The Basic Animal Cell =
Nucleus + Cytoplasm (Cytoplasm =
organelles + cytosol)
Controls what goes in and out.
A phospholipid bilayer.
Embedded proteins involved in transport.
Carbohydrate side chains involved in cell-to-cell recognition.
Plasma Membrane
Endocytosis and ExocytosisHow larger particles get into and out of a cell
Is this green particle inside the cell?
NUCLEUS
Nuclear envelopeNucleolus
Chromatin
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Ribosomes
Central vacuole
Microfilaments
Intermediate filaments
Microtubules
CYTO-SKELETON
Chloroplast
PlasmodesmataWall of adjacent cell
Cell wall
Plasma membrane
Peroxisome
Mitochondrion
Golgiapparatus
Basic Plant and fungi cells also have cell walls forsupport andprotection Walls are typically made of cellulose (plants) or chitin (fungi).
TYPICALPLANT CELL
NucleusContains chromosomes which are
DNA wrapped around protein spools. • Recall that DNA has the code that tells the cell
what proteins (enzymes) to make.• Uncoiled chromosomes are called chromatin
Also contains nucleoli = areas where rRNA and tRNA are made.
Surrounded by a nuclear envelope that has pores in it.
VacuolesFound in plant cells; store water,
digestive enzymes, salts, pigments, etc.
For support.
VesiclesFound in all cells. Store digestive
enzymes or
other chemicals,
transport chemicals,
LysosomesContain enzymes to break
down food brought in by endocytosis; can also break down own molecules and organelles for recycling.
CytoskeletonA network of
protein fibers that help the cell keep its shape and helps things move around (like a freeway). Some help the cell move.
CiliaShort flagella, often arranged
in rows, that help the cell
move. Typically hundreds.
Primary CiliaSome are chemosensitive, some pressure sensitive. Function in cell signaling, cellular development, and responsible for many diseases.
RibosomesThe site of protein synthesis
Endoplasmic ReticulumA system of tubes
Rough ER:
Lipid components of the cell membrane are made here.
Proteins destined for export, or to become part of the cell membrane, or digestive enzymes are modified here.
Smooth ER:
Lipid components of the cell membrane are also made here.
Involved in the detoxification of drugs.
Golgi ApparatusWhere proteins
from the ER are further refined and packaged for either storage in the cell or final transport out of the cell.
MitochondriaBreak down food to produce
ATP. This process is called cellular respiration
Chloroplasts“Solar Power Plants.” They capture light energy and convert it to chemical energy (sugar). This process is called photosynthesis.
NOTE: Both have their own DNA