Cells: Basic Structures & Functions

Historical Timeline of The Cell and Development of The Cell Theory Early 1600’s 1665 1670 1838 1839 1855 under a microscope and names Hooke observes dead plant cells them “cells” Virchow, german medical doctor, looks at cells dividng under a microscope. Leeuwenhooke first to look at living things through a microscope Schleiden, a botanist, concludes that all plants must be made of cells. Schwann, a zoologist, concludes the same about animals, all must be made of cells. Invention of the microscope

In 1665, Robert Hooke used a microscope to examine a thin slice of cork (dead plant cell walls). What he saw looked like small boxes.

Hooke is responsible for naming cells. Hooke called them “CELLS” because they looked like the small rooms that monks lived in called Cells.

Anton van Leeuwenhoek In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organisms (living things) in pond water. Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth

Cell Theory Nearly a century after Hooke’s findings, several other scientist’s discoveries led to the formation of the cell theory.

Beginning of the Cell Theory In 1838, a German botanist named Matthias Schleiden concluded that all plants were made of cells Schleiden is a cofounder of the cell theory

In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells Schwann also cofounded the cell theory

In 1855, a German medical doctor named Rudolph Virchow observed, under the microscope, cells dividing He reasoned that all cells come from other pre-existing cells by cell division

CELL THEORY IS FORMED All living things are made of cells Cells are the basic unit of structure and function in all living organisms (basic unit of life) Cells come from the reproduction of existing cells (cell division)

Discoveries Since the Cell Theory In 1970, American biologist, Lynn Margulis, provided evidence that some organelles within cells were at one time free living cells themselves Supporting evidence included organelles with their own DNA Chloroplast and Mitochondria

Simple or Complex Cells

Although ALL living things are made of cells, organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize into tissues, etc.

Types of Cells Living organisms are made of either prokaryotic or eukaryotic cells – the two major kinds of cells which can be distinguished by structural organization

Prokaryotes – The first Cells Cells that lack a nucleus or membrane- bound organelles Includes bacteria Simplest type of cell Single, circular chromosome

No nucleus, DNA scattered through center of the cell. Surrounded by cell membrane & cell wall made of (peptidoglycan) Contain ribosomes (no membrane) in their cytoplasm to make proteins Examples of bacteria: E.coli, Streptococcus

Eukaryotes Cells that HAVE a true nucleus and membrane-bound organelles Includes protists, fungi, plants, and animals More complex type of cells

Eukaryotes contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles

Two Main Types of Eukaryotic Cells Animal Cell Plant Cell

Cell Boundaries Cell Wall Outer boundary in bacteria, plant and fungi cells NOT found in animal cells Primary function: provide support and structure

Plasma Membrane Also call the cell membrane Found in ALL cells Primary function: maintain homeostatsis Provides protection from environment Regulates exchange with the environment Selectively permeable Controls what enters and what does not

Plasma Membrane Composed of 3 Biomolecules: Lipids Phospholipids make up the phospholipid bilayer Hydrophillic head and hydrophobic tails Two phospholipids orient themselves tail to tail to form the phospholipid bilayer Cholesterol Found in plasma membrane of animal cells Provides stabilization

Plasma Membrane 2. Carbohydrates 3. Proteins “ID tags” to identify cells 3. Proteins Embedded in the phospholipid bilayer Function: serve as channels and pumps for transport in and out of cell

Plasma Membrane

Plasma Membrane