Transcript Nerve activates contraction

Chapter 3
Cells and Tissues
Cells and Tissues
 Cells are the building blocks of all living
things
 Tissues are groups of cells that are
similar in structure and function
Anatomy of the Cell
 Life – It’s all about the cell!
 Cells are not all the same but all cells share general
structures and some functions
 Metabolism
 Reproduction
 Irritability
 Mobility
 Ability to Grow
 Cells are organized into three main regions
 Nucleus
 Cytoplasm
 Plasma membrane
Figure 3.1a
The Nucleus
 Control center
of the cell
 Contains genetic
material (DNA)
 Three regions
 Nuclear
membrane
 Nucleolus
 Chromatin
Figure 3.1b
Nuclear Membrane
 Barrier of nucleus
 Contain nuclear pores
that allow for exchange
of material with the rest
of the cell
Nucleolus
 Site of ribosome
production
 Ribosomes then
migrate to the
cytoplasm
through nuclear
pores
Chromatin
 Composed of DNA and
protein
 Scattered throughout the
nucleus
 Chromatin condenses to
form chromosomes when
the cell divides
Plasma Membrane
 Barrier for cell contents
 Double phospholipid
layer
 Hydrophilic heads
 Hydrophobic tails
 Other materials in
plasma membrane
 Protein
 Cholesterol
 Glycoproteins
Plasma Membrane
Figure 3.2
Plasma Membrane Specializations
 Microvilli
 Finger-like
projections that
increase surface
area for absorption
Figure 3.3
Cytoplasm
 Material outside the nucleus and inside
the plasma membrane
 Cytosol
 Fluid that suspends other elements
 Organelles
 Little organs
 Metabolic machinery of the cell
Cytoplasmic Organelles
Figure 3.4
Cytoplasmic Organelles
 Ribosomes
 Site of protein synthesis
 Found at two locations
 Free in the cytoplasm
 Attached to rough
endoplasmic reticulum
Cytoplasmic Organelles
 Endoplasmic reticulum (ER)
 Assembles materials for inside and outside the cell
 Two types
 Rough ER (with ribosomes)
 Smooth ER (without ribosomes)
Cytoplasmic Organelles
 Rough Endoplasmic Reticulum
 Assembles proteins made by the ribosomes to be
exported out of the cell
 Usually found close to the nucleus
 Smooth Endoplasmic Reticulum
 No ribosomes on the surface
 Makes lipids for cell membrane
 Detoxification of drugs
Cytoplasmic Organelles
 Golgi apparatus
 Modify, sort and package proteins
from the rough ER to be secreted
out of the cell or stored in the cell
 “Customization shop” – the
finishing touches
Cytoplasmic Organelles
Figure 3.5
Cytoplasmic Organelles
 Lysosomes
 Filled with enzymes
 Digestion or breakdown of lipids,
carbohydrates, and proteins into small
molecules that the cell can use
 “The cleaners”
 Peroxisomes
 Membranous sacs of oxidase enzymes
 Detoxify harmful substances
 Break down free radicals
(highly reactive chemicals)
Cytoplasmic Organelles
 Mitochondria
 “Powerhouses” of the cell
 Convert energy stored in food to chemical
compounds the cell can use (ATP)
Cytoplasmic Organelles
 Cytoskeleton
 Bones and muscles of the cell
 Network of protein structures that extend
throughout the cytoplasm
 Provides the cell with an internal framework
Cellular Projections
 Not found in all cells
 Used for movement
 Cilia moves materials
across the cell surface
 Flagellum propels the
cell
Cell Diversity
Figure 3.7; 1, 2
Cell Diversity
Figure 3.7; 3
Cell Diversity
Figure 3.7; 4, 5
Cell Diversity
Figure 3.7; 6, 7