Transcript Unit 4 Cellular Biology Cell Structure PPT

CHAPTER 7
CELL STRUCTURE AND
FUNCTION
“You are a metropolis of 50 trillion citizens. Each of the cells in
your body can be considered a sentient being in its own right.
They all act together as a community, performing an ongoing
act of prodigious collaboration.”
Dr. Bruce Lipton
Biologist
CHAPTER 7: CELL STRUCTURE AND FUNCTION
Section 1.
Section 2.
Section 3.
Section 4.
Discovery of Cells
Cell Structure
Cell Boundaries
Diversity of Cellular Life
CELL = THE BASIC UNIT OF LIFE
Go to
Section:
Cell Size
10 fold decrease
Micrometer:
µm = 10-3 mm
10-6 m
0.001 mm
Nanometer:
nm = 10-3 µm
10-9 m
0.000001 mm
0.000000001 m
PERIMICIUM
Anton Von LEEUWENHOEK
Early 1600’s
Discovered living “cells”
“Simple” Microscope
Blood cells and
Bacteria from teeth
ROBERT HOOKE
1665
Termed the word “Cell”
1830’s
Matthias Schleiden = plants
“Botanist”
Theodor Schwann = Animals
“Zoologist”
Rudolf Virchow (1855)
= “cells come from
other cells”
CELL THEORY
1.
All organisms are composed of cells.
2.
Cells are the basic units of structure and function
in living things.
3.
New cells are produced from existing cells.
Electron
Microscopes
1940’s
2 million x
TEM
“Transmission”
SEM
“Scanning”
Rabbit Trachea (cilia)
Bacteria
1-10 microns
Control of Cell Size
(1 micron = 0.001 mm)
Streptococcus
Eukaryotic
10 -100 microns
Blood Cell
As a cell increases in size, its
volume increases faster
than its surface area.
Smaller objects have a
greater ratio of surface
area to volume.
Larger organisms have
“more” cells not “larger”
cells
High surface to volume ratio facilitates
the exchange of materials in/out of cells
PROKARYOTIC CELLS
“Bacteria”
“No True Nucleus”
Organism is a single cell (unicellular)
= a cell that lacks internal structures
surrounded by membranes
EUKARYOTIC CELLS
“True Nucleus”
Protists, Fungi,
Plants, Animals
Organism can be unicellular or multicellular
= cells containing internal,
membrane bound structures
Escherichia coli
Advantages of being multicellular?
Eukaryotic Cells
Animal Cell
Cytoplasm = entire region
between the nucleus
and plasma membrane
Cytosol = semifluid
substance within the
cytoplasm
Plant Cell
Plasma Membrane (Cell Membrane)
= a selective barrier controlling the transport of material in/out of the cell
Nucleus
Nuclear Envelope = double lipid bilayer
enclosing the nucleus (outer and inner)
Nuclear Pores = openings within the
envelope
Chromatin = protein/DNA complex
Nucleolus = synthesis of ribosomes
Ribosome
= synthesize proteins (protein synthesis)
Composed of ribosomal RNA (rRNA) and two sub units (proteins)
Free ribosomes = suspended in the cytosol
Proteins function in the cytosol
Bound ribosomes = attached to endoplasmic reticulum
Proteins are transported around/in/out of cell
Free and Bound are structurally
identical and can alternate
between the two roles (cell adjusts)
Endomembrane System
Membranes that are related either through direct physical continuity or by the transfer of membrane segments as tiny vesicles (sacs made of
membrane)
-Nuclear envelope
-Endoplasmic Reticulum
-Golgi Apparatus
-Lysosomes
-Vacuoules (various kinds)
-Plasma Membrane
Endoplasmic Reticulum (ER)
endoplasmic = “within the cytoplasm”
reticulum = “little net”
Cisternae = network of membranous tubules and sacs
ER membrane is continuous with the Nuclear Envelope
Smooth ER = lacks ribosomes on surface
metabolic processes (synthesis of lipids, metabolism of
carbohydrates, and detoxification of drugs and poisons)
synthesize sex hormones
Rough ER = contains ribosomes on the surface
-provide surface area for ribosomes
-helps package and sort proteins
-forms transport vesicles
Golgi Apparatus
= modifies, stores, targets, and ships products from the ER
especially extensive in cells specialized for secretion
Transport vesicles  “Cis” face  “Trans” face  Transport vesicle
cis/ trans =
opposite polarity
“budding”
Proteins can be modified along the passage (by enzymes)
The Golgi can also manufacture certain macromolecules itself
Lysosomes
= a membrane-bounded sac of hydrolytic enzymes that the cell uses to digest macromolecules
internal pH = ~5 (if burst, enzymes are relatively inactive)
Lysosome formation and function
The lysosome and enzymes are
produced by the ER  Golgi  Lysosome
Phagocytosis = feeding by engulfing
smaller organisms or food particles
Lysosome digests the food  products become cellular nutrients
Autophagy = recycling of organic material (worn out organelles)
Apoptosis = Programmed destruction of own cells (tadpole tails, human webbed fingers)
Vacuoles
Food Vacuole = formed from phagocytosis
Contractile Vacuole = pump excess water out of the cell (protists)
Central Vacuole
-Plant Cells
-Endomembrane System
-Hold reserves of organic compounds
-Pigments for color (flower petals)
-Poisonous/unpalatable compounds (protection)
-Absorb water (growth)
Paramecium
Osmoregulation
Mitochondria
Energy transformation
= site of cellular respiration (ATP synthesis from organic compounds)
Contain ribosomes and own DNA
Grow and reproduce on their own
Mobile
2 membranes (both phospholipid bilyers)
Number of
mitochondria
is correlated
with the cell’s
level of
metabolic activity
Inner membrane has folds (cristae)
Chloroplast
Energy transformation
Photosynthetic production of sugar
“Plastid”
Amyloplasts (store starch/ amylose)
Chromoplasts (have pigments that give fruits and flowers orange/yellow colors)
-Own DNA
-Grow and reproduce on own
-Mobile
-Chlorophyll – pigment
-2 membranes
Cytoskeleton
= a network of fibers (protein) extending throughout the cytoplasm
Gives mechanical support to the cell and maintains its shape
Especially important to animal cells (no cell wall)
Provides anchorage for many organelles
Can be disassembled and reassembled in a different part of the
cell (changing cells shape)
Microtubules
Cellular functions arise from cellular order
A cell is a living unit greater than the sum of its parts
Macrophage –
defends against bacteria
Crawls and reaches with pseudopodia
Engulfs bacteria
Digests by lysosome (produced by
endomembrane system)
Ribosomes synthesize the enzymes
DNA genetic programming
Process requires ATP
Mitochondria
• YouTube - 3D sperm fertilization project
Egeria densa
Homo sapiens
Paramecium
Volvex
“colonial”
Daphnia
“animal”
Actinophrys
Amoeba
Spirogyra
“algae”
Euglena
DO NOT SEEK TO FOLLOW IN THE
FOOTSTEPS OF THE MEN OF OLD;
SEEK WHAT THEY SOUGHT.
- BASHO