Cells
Microscopes and Cells: History
In 1663, __________ coined the term “cells”
10 years later, _________________ observed bacteria and protozoa
In 1833, __________ observed and coined the term “nucleus”
Cell Theory: History
In 1838 (and 1839) German scientists, ________________ & ________________ independently came up with the “Cell Theory”
Cell Theory
All living things are composed of one or more cells.
Cells are organisms' basic units of structure and function.
Cells form by free-cell formation, similar to the formation of crystals (spontaneous generation).

In 1855, German physician Rudolph Virchow discovered that…
How big are cells?
Eukaryotic cells include _______ & _______ cells.
Most eukaryotic cells are between __ and ___ m.
What is the limit of the light microscope?
Why?

What is used to see smaller objects? __________________
Electron Microscopy
___________ Electron Microscopes (TEM) emit light through a thin piece of heavy metal ion stained tissue
________ Electron Microscopes (SEM) reflect light off of a piece of heavy metal ion stained tissue
Prokaryotic Cells (cells without a nucleus) for ex. bacteria
Eukaryotic Cells (cells with a nucleus)
Differences and similarities between Prokaryotes and Eukaryotes
Differences
Prokaryotes lack:
True nucleus
Membrane bound organelles
Prokaryotes are much smaller than eukaryotes (prokaryotes are ~1 – 10 m and eukaryotes are 10 – 100 m )
Similarities
Both have:
DNA
Cytoplasm
Ribosomes
Plasma Membrane

The Plasma Membrane (1)
The Plasma Membrane (in all cells)
It is a semi-permeable barrier that allows for the passage of certain things based upon ______, _______, and _____________.
What are the forms of transport across a cell membrane?
Plasma Membrane’s Microvilli

Microvilli are fingerlike-projections from the cell’s membrane that increase the surface area.
Cell Wall (in plant cells and prokaryotic cells)
Surrounding the , this feature does the following for plant cells and prokaryotes:
Provides Support
Provides Protection
Cytoplasm (in all cells)
The jelly-like fluid that holds all organelles within the cell
Nucleus and nucleolus (in eukaryotic cells)
Ribosomes are made here:
DNA and proteins form
found in the nucleus
Openings in the nuclear membrane
Ribosomes: (in all cells) Function in
Endoplasmic Reticulum (in eukaryotic cells)
There are two types:
ER has ribosomes attached.
Modifies & transports proteins
ER does not have ribosomes on it.
Synthesizes
Breaks down carbohydrates
Detoxifies drugs & poisons
Golgi Apparatus (in eukaryotic cells)
ER products move here in
Vesicles (in eukaryotic cells)
Organelles that transport materials from the ER to the golgi and eventually to the plasma membrane
Mitochondria (in eukaryotic cells)
takes place in this organelle.
It is often called the “ “ of the cell because it creates energy for the cell
Chloroplasts (in plant cells)
An organelle that converts energy from the sun into chemical energy (sugar) The process is called:
The Cytoskeleton (in all cells)
A network of fibers that extend throughout the cytoplasm,
Three types:
Cytoskeleton: Functions
Provides shape and support (skeletal)
Moves the organelles within the cell and helps move flagella/cilia
Centrosome (in eukaryotic cells) and Centrioles (in animal cells only)
Centrosomes make microtubules.
In animal cells, a pair of structures called (made of microtubules) help in cell division.
Cilia and Flagella (in all cells)
Hair-like projections that aide in movement
Cilia are shorter, more numerous and move back & forth
Flagella are longer & move in a snake-like motion.
Lysosomes (in animal cells)
Membrane-bound organelle in animal cells that contains ___________enzymes that help clean-up the cell

Vacuoles (in eukaryotic cells)
Large, central organelle in plants
Stores water and waste products
In animals, it stores food and is small in size compared to plant vacuoles
Plant Cell
Plant Cell
Plant Cells have a few unique organelles:
Vacuoles
Plastids (e.g., chloroplasts)
Cell wall
Vacuoles
Definition: membranous sacs filled with water that serve a variety of functions:
Storage of “food”, water, oil, pigments, toxins, & waste.
Helps to maintain turgor pressure.
Young plant cells often contain many small vacuoles, but as the cells mature, these unite to form a large central vacuole.

Cell Sap
The fluid contained in a vacuole is called the cell sap.
Water soluble pigments called anthocyanins may be present. These pigments impart colors to flowers, fruit, seeds, leaves, stems, and roots.
Calcium oxalate and other salts may be dissolved or present as precipitates. Crystals may serve to protect the plant from herbivores, storage of toxic substances, or act as a reservoir for calcium. About 75% of flowering plants produce calcium oxalate crystals in some or all of their organs.
Anthocyanin and Pigmentation
Plasmolysis
Definition: the contraction of cells within plants due to the loss of water through osmosis.
It is when the cell membrane “shrinks away” from the cell wall and the vacuole collapses.
Occurs when water is drawn out of the cell (high water concentration  low water concentration).
Causes plants to wilt.
Calcium Oxalate Crystals
Plastids
Definition: large organelles that are associated with pigments and other storage products (e.g., starch).
A typical plant cell will usually have 20-40 plastids.
Several Types:
Chloroplasts
Leucoplasts- Amyloplasts (starch)/Elaioplasts (oil)
Chromoplasts
Chloroplasts
Definition: plastids that capture light energy from the sun to make “food”; contain chlorophyll (Elodea)

Leucoplasts
Definition: colorless plastids that store starch or oil
Found in things like tubers (e.g., Irish potatoes), roots, leaves, grains, fruits, and seeds.
Chromoplasts
Definition: plastids that make & store carotenoid pigments
Found in red & yellow peppers, tomatoes, flower petals …
Carotenoid pigments are not water soluble, but it is fat soluble.
β-carotene is broken down in the mucosa of the small intestine by beta-carotene dioxygenase to retinol, a form of vitamin A.
Vitamin A, is a yellow fat-soluble, antioxidant vitamin important in vision, embryo development, and bone growth. Vitamin A is required in the production of rhodopsin, the visual pigment used in dim lights.
VAD leads to night blindness, permanent blindness, and other medical problems.
Cell Wall
Definition: a flexible outer barrier made of cellulose fibrils that surrounds plant cells.
Functions:
Protection & Support
Determines plant shape & size
Maintains turgor pressure
Regulates movement in and out
Cell-cell communication
Cellulose
Cellulose is a polymer of β-D-Glucose, which in contrast to starch, is oriented with -CH2OH groups alternating above and below the plane of the cellulose molecule thus producing long, unbranched chains.


Pectin
Pectin is a polysaccharide that acts as a cementing material in the cell walls of all plant tissues.
The white portion of the rind of lemons and oranges contains approximately 30% pectin.
Pectin is an important ingredient of fruit preserves, jellies, and jams.
Pectin is a complex polysaccharide consisting mainly of esterified D-galacturonic acid resides in an α-(1-4) chain.


Plasmodesmata
Definition: small tubes that connect plant cells to each other, establishing living bridges between cells.
Allow certain molecules to pass directly from one cell to another.
These channels, penetrate the cell wall and are lined with plasma membrane, uniting all connected cells with essentially one continuous cell membrane.