Chapter 1: Introduction to cells
Cells:small, membrane in closed units filled with a concentrated aqueous solution of chemicals
and endowed with the ability to create copy of them.
Cells: fundamental units of life
Main question: what life is and how it works?
Unity and diversity of cells
Cells vary in appearance and function.
Size: in micrometers.
Paramecium: single celled, moves by beating cilia.
Branched nerve cell, receives thousands of signals
Human white blood cells: approach and engulf red blood cells
Living cells have a similar basic chemistry
Cells are living things in the sense that they can grow reproduce and convert energy
from one form to another.
In all living things, genetic instructions-genes- are stored in DNA molecules.
Written in same chemical code
Constructed out of same chemical building blocks
Interpreted by same chemical machinery
Duplicated in the same way
DNA polymer chain is made out of 4
DNA instructions are transcribed into set of
polymers called RNA.
Serves as mRNA: messages carried by this
polymer chain are translated into protein.
Protein: structural support, catalysts and
Made from same set of 20 amino acids but
different sequences giving diff 3-D shape or
conformation. Pages: 1-38
Contain genetic info in the form of DNA or RNA
Have no ability to reproduce on its own
Copied by parasitizing the reproductive machinery of the host cell.
Inert and inactive outside their host cells
All cells evolved from the same ancestor
DNA replication 2 daughter cells
Copying is not always perfect, may cause mutations
Mutations can create offspring that are changed for worse, better or neutral
Survivor genes : genes of next generations
Sexual reproduction: 2 cells fuse, DNA mixed and then new combination is presented
in next generation
Evolution: the process by which, living species become gradually modified and adapted to
their environment in more and more sophisticated ways.
Genes provide the instruction for cellular form, function and complex behavior.
Cell’s genome: the entire set of genetic info in its DNA.
It’s a genetic program that instructs cell how to function.
Diff types of cells: fat, skin, bone
^ All contain identical copies of DNA.
They vary in terms of their use of the genetic instruction.
Diff cells express diff genes
Cells under microscope
Light microscope (17 century) vs electron microscope(1930s)
Electron microscope transmits beam of electron instead of light
The invention on light microscope led to the discovery of cells
1. The cell is the smallest unit of life
2. All living things are made up of cells
3. New cells arise only from pre-existing cells
Cells, organelles and even molecules can be seen under light microscope
Cells separated by extracellular matrix: dense material made of protein fibers
embedded in polysaccharide gel.
Cell components differ in terms of refractive index.
General cell anatomy
5 nm thick enclosing membrane surrounding cell
Internal membranes : membrane surrounding organelles
Plasma membrane: external membrane Pages: 1-38
Types of microscopes
1. Light microscope: magnifies up to 1000 times and resolves as small as
2. Transmission electron microscope: electron microscope used to look at thin section
3. Scanning electron microscope: scatters electrons off the surface of the sample and
used to look at surface details of sample and other structures
The prokaryotic cell
Presence or absence of nucleus used as a fundamental classification of living things.
Prokaryotes: organism whose cells don’t have a nucleus.
The terms Bacterium and prokaryotes are interchangeable
Archaea are related to bacteria
Diff shapes and sizes of bacteria
Prokaryotes are the most diverse of cells
Most are single celled
Diverse in terms of chemistry
Aerobic (using oxygen) vs anaerobic prokaryotes
species that live
Bacteria in soil or make
archaea live in harsh
The eukaryotic cell
Organisms whose cells have nucleus.
Plants, animals and fungi are formed from eukaryotic cells.
Table: structure and function Pages: 1-38
Structure Diagram Function and description
Nucleus Stores info of cell
Most prominent organelle
Contains most of the DNA of
Enclosed within 2 membrane
that form nuclear envelope
In light microscope giant DNA
molecules become visible as
RNA synthesized in nucleus
Mitochondria Generate energy to power the
Present in all eukaryotic cells
Contain their own DNA
Reproduce by dividing into 2
Thought to evolve from engulfed
bacteria in ancestral eukaryotic
Intestinal parasite giardia lack
Chloroplast Found in plant and algae cells,
capture energy from sunlight.
Contain internal sacks which
Photosynthesis sugar +
Chloroplast contain their own
The sugar is then used by
mitochondria to produce energy
Thought to evolve from