Chapter 01

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Transcript Chapter 01

Chapter 01
A Singular Theme
• Basic structures and mechanisms that
sustain life are common to all living
creatures
• All forms of life are connected to one
another and to their predecessors
Homologous Patterns
• Common
patterns in
bones are signs
of biological
unity
Cells
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Basic structural unit of all living things
Gather fuel and building materials
Produce usable energy
Grow and duplicate
Cells
• Every living thing is a cell or is made of
cells
• All cells contain nearly the same
molecules and undergo similar
interactions
Size and Speed
• The smaller an object is, the faster it
can move
• Life depends on frequent and vigorous
collisions of molecules
Relative Sizes
Relative Sizes
Atoms
• Elemental units of
which everything is
made
• Atomic Diameters:
one to a few
hundred millionths
of an inch
Molecules
• Atoms bonded together
• CO2: source of life’s carbon atoms
• O2: crucial to energy generation in most
life forms
• H2O: aids chemical events inside cells
Molecules
Simple Molecules
• Sugars,
nucleotides,
amino acids
• Food and/or
building materials
Chain Molecules
• Long strings of simple molecules
linked together
• Protein: amino acid chain
• DNA and RNA: nucleotide chains
Molecular Structures
• Chain molecules
fit together in
complex
architectural
arrangements
• Form cell’s
infrastructure
Cell
• Nucleus: contains most of DNA
• Cytoplasm: surrounds nucleus; site of
most active cell processes
Animal Cell
Microscopy
• Mid 1600s: first evidence of existence
of things smaller than the unaided eye
could see
• Robert Hooke: viewed a cork slice with
a magnifying lens; named denselypacked empty chambers “cells”
Measurement Units
• Meter: standard metric system unit of
length
• Centimeter = 1 x 10-2 meter
• Millimeter = 1 x 10-3 meter
• Micrometer = 1 x 10-6 meter
• Nanometer = 1 x 10-9 meter
Light Microscope
• Magnifies and focuses image formed
when light passes through an object
• Can’t distinguish objects smaller or
closer together than the shortest
wavelength of visible light (200 nm)
Transmission Electron Microscope
Scanning Electron Microscope
• Use beam of electrons controlled by
electric or magnetic fields
• Possible to see details of cell surfaces
and rough shapes of large molecular
structures
Scanning
Electron
Micrograph
• The
mitochondrion
(M) is about the
same size as a
common
bacterium (E.
coli)
Electron Micrograph
• View of the nucleus
(N), Golgi bodies
(G), and vesicles (V)
X-ray Diffraction
• Used to study structural details of
individual proteins
• Technique contributed to discovery of
DNA double helix structure and
structure of hemoglobin
X-ray Diffraction
• Protein molecules isolated and crystallized so
they stack regularly in a three-dimensional lattice
• Beam of x-rays focused on protein crystal –
regularly repeating atoms in crystal structure
deflect x-rays at certain angles
• X-rays produce pattern of exposure spots on
photographic film placed behind protein sample
X-ray Diffraction
• X-ray diffraction pattern of DNA captured
by Rosalind Franklin
• The X is an indicator of a helical molecular
shape
Scientific Process
• Observe an interesting event or
phenomenon
• Identify a particular aspect of it that can
be stated as a problem
• Produce an hypothesis that explains the
event
• Test the hypothesis by experiment
Scientific Method
• Conclusions scientists arrive at after
testing many hypotheses are
statements that have probability of
reflecting reality; they are never
certainties
• An idea becomes substance only if it fits
into a dynamic accumulating body of
knowledge
Ultracentrifuge
• Used to separate and compare sizes of
cell components
• A rotor spins tubes containing materials
from broken cells at speeds of up to
80,000 rpm
• Cell components separate out
according to size
The Way Life Works
Central Characters
• DNA: information
The Way Life Works
Central Characters
• Protein: machinery
Your Itinerary
Patterns
Energy and
Information
Machinery and
Feedback
Community and
Evolution