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Chapters 12-20
Ch 12 - DNA
Scientists  Griffith
- transformation
= process in which one bacteria takes the
characteristics of another (takes in genes)
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Avery
- added enzymes to destroy organic
compounds, but not DNA  trans.
- added DNA-destroying enzymes  no
trans.
Therefore, DNA is the transforming factor
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Hershey and Chase
- bacteria, viruses, radioactive P & S
- observed which material was injected (DNA)
- Genetic material = DNA
Structure
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DNA = deoxyribonucleic acid
Made of repeating nucleotides (subunit)
Nucleotide = sugar (deoxyribose), phosphate,
base
4 bases – adenine, guanine, cytosine,
thymine
A & G = larger purines
C & T = smaller pyrimidines

Chargaff (1949) – studies 
A always same % as T
C always same % as G
- so, _______________
= Chargaff’s Rules
Franklin – (1952) – X-ray diffraction
- showed DNA as a tightly coiled spring = helix
 Watson & Crick (1953) – used Franklin’s and
Chargaff’s info to determine structure
 Double helix held together by weak Hydrogen
bonds
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DNA Replication
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DNA separates into 2 strands – each serving
as template for new strands
Point at which DNA splits = Replication Fork
Enzyme (helicase) breaks H bonds and
untwists DNA
Enzyme (DNA Polymerase) moves
complementary nucleotides in place to bond
properly
Chapter 13 - RNA
RNA
 = ribonucleic acid
 3 structural differences b/t DNA & RNA
DNA
Sugar = deoxyribose
Base = thymine
Double helix
RNA
Sugar = ribose
Base = uracil
Single stranded
Gene Expression
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Step 1 = Transcription
= DNA acts as template to make RNA
Enzyme - RNA polymerase
- reads DNA, binds at promoter
- separates DNA strands
- reads one side of DNA (template strand)
- adds complementary RNA nucleotides
Transcription
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So, transcription from DNA to RNA:
template of DNA: A C G T A T G A T
RNA:
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Where?
Because?
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Genetic Code
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= relationship b/t nucleotides in DNA & amino
acids
Every 3 base letters of mRNA stands for an
amino acid = codon
START codon = AUG
STOP codons = UAA, UAG, UGA
Codon Table #2
Translation
Molecular Biology Dogma
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DNA  RNA  Protein
Mutations
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= heritable changes in a gene; lead to
evolution
Can be :
- neutral
- harmful – ex. Cancer, sickle cell
- helpful – resistance to poisons, HIV
Gene Mutations
Chromosomal Mutations
Chapter 14
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Pairs 1-22 = autosomal
chromosomes
(autosomes)
23rd pair = sex
chromosomes
(determine gender)
- Male (XY); Female
(XX)
Pedigree

Chart that shows inheritance of a trait over
several generations
INHERITANCE PATTERNS
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Complete Dominance
Codominance
Incomplete dominance
Multiple Alleles
Polygenic
Environmental Conditions
X-linked traits
Sex influenced traits
MULTIPLE ALLELES TRAIT
= trait controlled by genes
that have more than 2
alleles
- Any combo of 2 alleles
produces different
phenotypes
- Ex. Blood types
Genotype
Phenotype
IAIA or IAIi
Type A
IBIB or IBIi
Type B
IAIB
Type AB
IiIi
Type O
Ch 16 - Evolution
Darwin  Evolution = genetic change in a species
over time
 Natural Selection = the process by which
organisms with variations most suited to
their local environment survive and leave
more offspring.
1 The Struggle for Existence
Organisms produce more
offspring than can survive.
Grasshoppers can lay over
200 eggs at a time. Only a small
fraction of these offspring survive to
reproduce.
2 Variation and Adaptation
There is variation in nature,
and certain heritable variations—
called adaptations—increase an
individual’s chance of surviving and
reproducing. In this population of
grasshoppers, heritable variation
includes yellow and green body color.
Green coloration is an adaptation:
Green grasshoppers blend
into their environment and so are
less visible to predators.
3 Survival of the Fittest
Because their green color
serves to camouflage them from
predators, green grasshoppers have a
higher fitness than yellow
grasshoppers. This means that green
grasshoppers survive and reproduce
more often than do yellow
grasshoppers in this environment.
4 Natural Selection
Green grasshoppers become more
common than yellow grasshoppers in
this population over time because:
(1) more grasshoppers are born than
can survive, (2) individuals vary in
color and color is a heritable trait,
and (3) green individuals have a
higher fitness in their current
environment.
Lamarck –
- similar species descended from a common
ancestor
- to explain changes, said acquired traits
were passed on to offspring
Acquired traits = traits that arose during
lifetime, not determined by genes
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Artificial selection
= process in which nature provides the
variations, and humans select those they find
useful.
Evidence for Evolution
Fossils
 Homologous structures
= Structures shared by related species and
that come from a common ancestor
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Analogous structures
= Body parts that share common function,
but not structure
ex. Bird wing and bee wing
 Vestigial structures
= inherited from ancestors but has none or
little function
 Embryological development
- similar in vertebrates
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Genetics
- DNA sequences shows organism’s history
- closely related organisms will have similar
DNA sequences & similar amino acid
sequences
 All living things follow same genetic code
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Ch 18 Classification
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Systematics = science of naming and
grouping organisms
Aristotle – B.C. – 1st to group living things
- 2 kingdoms – Plant or Animal
Carolus Linnaeus – 1730s – Swedish botanist
 Binomial nomenclature – 2 part scientific
name
 Scientific name = Genus species or Genus
species
 Ex. Homo sapien or H. sapien
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Ex. Carnegiea gigantia
giant Segauro cactus
Ex. Permyscus californicus
common California mouse
Ex. Nymphea odorata
fragrant water lily
Name – location, characteristics, scientist
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Developed hierarchy :
- Kingdom – broadest
- Phylum
- Class
- Order
- Family
- Genus
- Species – most specific
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Cladogram – diagram that links organisms by
showing how evolutionary lines branched off
from common ancestors
Based on a derived character = trait that
arose in the most recent common ancestor
and was passed on
Six Kingdoms
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Animalia
Plantae
Fungi
Protista
Archaebacteria
Eubacteria
Three Domains
Domain – based on rRNA sequences
 3 Domains
- Archae (K. Archaebacteria)
- Bacteria (K. Eubacteria)
- Eukarya (K. A, P, F, P)
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Ch 20 – Prokaryotes & Viruses
Bacteria
 Domain Archae
- Kingdom Archaebacteria
- walls lack peptidoglycan
- DNA more similar to eukaryotes
- live in extreme environments
Domain Bacteria
- Kingdom Eubacteria
- walls with peptidoglycan
- larger domain
- found everywhere
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Eubacteria
- grouped by 2 things
1. shape: - bacillus – rod
- coccus – spherical
- spirallus – spiral, corkscrew
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2. Response to Gram Stain:
- Gram positive – purple, retains stain; thicker
layer of peptidoglycan
- Gram negative – pink, doesn’t retain stain;
thinner layer of peptidoglycan; unaffected by
many antibiotics
Viruses
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Size - ~20nm – 250nm
Some char. of life, not all:
- no nucleus, cytoplasm, organelles, or
membrane
- no cellular functions
- need a host cell to reproduce
Structure
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Made of : 1. Nucleic Acid (DNA or RNA)
2. Protein coat around it (capsid)
Some also have:
- lipid envelope outside capsid
*helps it infect cell
- glycoprotein – used to attach to host cell
Viral Replication