Introduction to CellsMILLER AND LEVINE BIOLOGY 7.1 – 7.2

How do we know cells exist?

In 1665 Robert Hooke used an early microscope to examine a piece of cork (plant material).

At the same time, Anton van Leeuwenhoek used a single lens microscope to examine pond water.

Where did the term cells come from?

Cell Theory

Following the discovery of cells, scientists agreed that both plants and animals are made of cells and are the smallest units of life. This lead to a cornerstone of biology known as “Cell Theory”.

Cell Theory states:All living things are made up of cells.Cells are the basic unit of structure and function of

living things.New cells are produced from existing cells.

How do we study cells?

Light microscopes

How do we study cells?

Electron microscopes

Two major cell categories

ProkaryoticBacteria

EukaryoticAnimal cellsPlant cells

What are the differences?

Prokaryotes

Eukaryotes

- Generally smaller and simpler - Generally larger and

more complex

- DO NOT separate genetic material - DO separate their nucleus genetic material

in the nucleus

Eukaryotic

Prokaryotic

Exocrine secretory epithelial cells Salivary gland mucous cell (polysaccharide-rich secretion) Salivary gland number 1 (glycoprotein enzyme-rich secretion) Von Ebner's gland cell in tongue (washes taste buds) Mammary gland cell (milk secretion) Lacrimal gland cell (tear secretion) Ceruminous gland cell in ear (earwax secretion) Eccrine sweat gland dark cell (glycoprotein secretion) Eccrine sweat gland clear cell (small molecule secretion) Apocrine sweat gland cell (odoriferous secretion, sex-hormone sensitive) Gland of Moll cell in eyelid (specialized sweat gland) Sebaceous gland cell (lipid-rich sebum secretion) Bowman's gland cell in nose (washes olfactory epithelium) Brunner's gland cell in duodenum (enzymes and alkaline mucus) Seminal vesicle cell (secretes seminal fluid components, including fructose for

swimming sperm)

Thyrotropes Gonadotropes Corticotropes Intermediate pituitary cell, secreting melanocyte-stimulating hormone Magnocellular neurosecretory cells secreting oxytocin secreting vasopressin Gut and respiratory tract cell thyroid epithelial cell parafollicular cell Parathyroid gland cells Parathyroid chief cell Oxyphil cell

How are cells organized?

Cell

membrane/

wall Cytoplasm

Nucleus

Within the cell are various organelles which you will read about in chapter 7.2(Pg. 196)