Zoology (Cells pt. 1)

Zoology

the study of animals

Zoology

It is one of the broadest fields in all of science because of the immense variety of animals and the complexity of the processes occurring within animals

Anatomy

Study of the structure of entire organisms and their parts.

Cytology

Study of the structure and function of cells.

Comparative Genomics and Bioinformatics

Study of the structure, function, and evolution of the genetic composition of groups of animals using computer based computational methods.

Ecology

Study of the interaction of organisms with their environment.

Embryology

Study of the development if an animal from the fertilized egg to birth or hatching.

Genetics

Study of the mechanisms of transmission of traits from parents to offspring.

Histology

Study of tissues

Molecular Biology

Study of the subcellular details of structure and function.

Parasitology

Study of animals that live in or on other organisms at the expense of the host.

Physiology

Study of the function of organisms and their parts.

Systematics

Study of the classification of, and the evolutionary interrelationships among animal groups.

Entomology

Study of Insects

Herpetology

Study of amphibians and reptiles

Ichthyology

Study of fishes

Mammalogy

Study of Mammals

Ornithology

Study of Birds

Protozoology

Study of Protozoa

Hierarchy of Relatedness

illustrates how the classification system depicts the degree of relatedness.

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Hierarchy of Relatedness

Ecology

the study of the relationships between organisms and their environment.

Cells

·    the functional units of life, in which all of the chemical reactions necessary for the maintenance and reproduction of life take place.

·    They are the smallest independent units of life.

Prokaryotic and Eukaryotic

Two basic types of cells

Prokaryotes

Lacks nuclei and other membrane-bound organelles

Archaea and Eubacteria

These simpler (prokaryotic or prokaryotes; “before nucleus”) cells are classified into two domains

Cell

the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed.

Matthias Scheiden

·    Announced that all plant tissue was composed of cells

Theodor Schwann

·    Described animal cells as being similar to plant cells

Rudolf Virchow

All cells come from preexisting cells

Prokaryotic Cells

·    Lacks a nucleus

·    Bacteria and cyanobacteria

·    1^st type of cell to evolve

·    Genetic material located in region called nucleoid

Eukaryotic Cells

·    DNA bound by a nuclear membrane

·    Contains membranous organelles

·    Animals, Plants, Fungi, Protists

Eukaryotic Cells

·    Larger and more complex than prokaryotic cell

·    All eukaryotes (“true nucleus”) have cells with a membrane-bound nucleus containing DNA.

Plasma Membrane, Cytoplasm, Nucleus

All eukaryotic cells have three basic parts:

Plasma Membrane

is the outer boundary of the cell.

·    It separates the internal metabolic events from the environment and allows them to proceed in organized, controlled ways.

·    Has specific receptors for external molecules that alter the cell’s function.

Cytoplasm

is the portion of the cell outside the nucleus.

Cytosol

Semifluid portion of the cytoplasm

Nucleus

the cell control center.

·    It contains the chromosomes and is separated by its own nuclear envelope.

Nucleoplasm

Semifluid material in the nucleus

Plant and Animal

2 cell types

Plant Cell

·    10-100 micrometers in length

·    Typically rectangular or cubic in shape.

Animal Cell

·    10-30 micrometers in length

·    Typically round or irregular in shape

Cell Modification

are re-acquired by the cell after cell division that helps the cell in different beneficial ways

Apical, Lateral, Basal

Three types of cell modification

Apical Modification

Cell modification found on the apical surface of the cell.

Cilia & Flagella, Villi & Microvilli, Pseudopods, Extra Cellular Matrix

Apical Modification

Cilia

short, hairlike structures that moves in waves.

Flagella

·    long, whiplike structures.

Cilia and Flagella

Formed from microtubules

Villi

finger-like projections that arise from the epithelial layer in some organs.

Microvilli

smaller projections that arise from the cell’s surface.

Villi and Microvilli

·    They help to increase surface area allowing for faster and more efficient adsorption.

Pseudopods

·    Temporary, irregular lobes formed by amoebas and some other eukaryotic cells.

·    Bulge outward to move the cell or engulf prey.

Extra Cellular Matrix

·    Compound secreted by the cell on its apical surface

·    Cell wall is the extracellular structure in plant cells that distinguishes them from animal cells

·    Glycoprotein is the main ingredient

Lateral Modification

Cell modification found on the lateral surface of the cell.

Tight, Gap, Adhering

Types of Lateral Modification

Tight Junction

·    Act as barriers that regulate the movement of water and solutes between epithelial layers

·    Prevent leakage of ECF

Adhering Junction

·    Anchoring junction on the lateral surface of the cell

·    Very similar to the anchoring junction of the basal surface of the cell

·    Fasten cells to one another

Gap Junction

·    Also known as communicating junctions

·    Closable channels that connect the cytoplasm of adjoining animal cells

Presence of connexon that allow direct exchange of chemical between the cytoplasm of two cells

Basal Modification

Cell modification found on the basal surface of the cell.

Desmosomes / Hemidesmosomes

Basal Modification

Desmosomes / Hemidesmosomes

·    Anchoring junction on the basal surface of the cell

·    Rivet-like links between cytoskeleton and extracellular matrix components such as the basal lamina that underline epithelia

·    Primarily composed of keratin, integrins and cadherins

S. Jonathan Singer and Garth Nicolson

developed the fluid-mosaic model of membranes tructure.

Fluid mosaic model

According to this model, a membrane is a double layer (bilayer) of proteins and phospholipids and is fluid rather than solid.

Sea

The phospholipid bilayer forms a fluid this in which specific proteins float like icebergs

Mosaic

refers to the many different kinds of proteins dispersed in the phospholipid bilayer.

Polar, Non-polar

The phospholipids have one _____ end and one _________ end.

Polar Ends

are oriented on one side toward the outside of the cell and into the fluid cytoplasm on the other side

Non polar ends

face each other in the middle of the bilayer.

Tails

Molecules attract each other and are repelled by water, hydrophobic

Heads

 are located over the cell surfaces (outer and inner) and are “water attracting” (they are hydrophilic)

Cholesterol

present in the plasma membrane and organelle membranes of eukaryotic cells.

Cholesterol

·    help make the membrane less permeable to water-soluble substances.

·    In addition, the relatively rigid structure helps stabilize the membrane

Glycoproteins

Carbohydrates + proteins

Glycolipids

Glycoproteins + Lipids

Glycocalyx

Carbohydrates + proteins & lipids

Glycocalyx

Cell coat. This arrangement of distinctively shaped groups of sugar molecules it acts as a molecular “fingerprint” for each cell type