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Biology B
Final Exam Review
Explain the purpose of DNA
replication and the steps involved.
Where in the cell does it occur?

Purpose:
Ensure that the resulting replicated cells each have
a complete and exact copy of the original cells
genome (genes)
 So that the daughter cells function like the parent
cells


Where it occurs:

Nucleus
Steps for DNA
Replication
1. Double helix unwinds
2. Strands separate
3. Free floating DNA
nucleotides are bonded
to the parent strands by
DNA Polymerase
(enzyme)
Describe the functions of the 3 types of RNA. Be
able to identify them in a diagram. Where in the cell
are they located and where are they synthesized?

mRNA (messenger):


rRNA (ribosomal)



Copies information from DNA in
the nucleus
Makes up the ribosome
Made in the nucleolus
tRNA (transfer):

Transfers amino acids in the
cytoplasm to the ribosome
Compare/contrast DNA vs. RNA (where in the
cell each type is found; the subunits and
molecules that make up each subunit).
DNA
Location
Number of strands
Nucleotide
Nucleus
RNA
mRNA: Nucleus
and Cytoplasm
rRNA: Ribosome
tRNA: Cytoplasm
2
1
Phosphate group
Deoxyribose sugar
A, T, G, C
Phosphate group
Ribose sugar
A, U, G, C
Which nitrogen bases are found in
DNA? In RNA?

RNA:

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
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Adenine
Uracil
Guanine
Cytosine
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DNA:
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Adenine
Thymine
Guanine
Cytosine
Which nitrogen bases form
complimentary pairs in DNA? In
RNA?

DNA


A=T
G=C

RNA


A=U
G=C
What is the purpose of transcription? Describe the
steps involved and where in the cell it takes place.
Be able to label a diagram of the process.

Purpose:


Copy information from DNA in the form of mRNA so that it
can be brought to the ribosome to build the protein
Steps:
1. Specific sequence of DNA unwinds and separates
2. RNA polymerase (enzyme) adds complementary RNA
nucleotides to one strand of DNA
3. When complete, mRNA breaks away from the DNA and
leaves the nucleus
4. The DNA winds back up
What is the purpose of translation? Describe the
steps involved and where in the cell it takes place.
Be able to label a diagram of the process.

Purpose:


Translate the mRNA sequence at the ribosome to build the
protein
Steps:
1. mRNA leaves the nucleus for the ribosome.
2. Once there, the ribosome exposes the codon on mRNA
3. tRNA with the amino acid that is coded for by the codon,
transfers the amino acid to the ribosome
a.
Codon matches with the anticodon
4. tRNA continues adding amino acids until ribosome
reaches stop codon – Makes a polypeptide (Protein)
GCU = Ala
Tyrosine = UAU, UAC
Know how to
use a mRNA
codon chart.
What does
GCU on
mRNA code
for? What is
the codon for
tyrosine?
What is a gene?

Sequence of
DNA that codes
for a specific
protein
What makes proteins different from
one another?
What determines which specific
protein is to be produced?

Differences in proteins:


Sequence of amino acids
Determines differences:

Sequence of nitrogen bases in DNA
What are mutations? What kinds of
effect can mutations have on an
organism?

Mutation:

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Changes in one or more nitrogen bases on DNA or
RNA
Effect:
Change the sequence of amino acids coded for by
the DNA/mRNA
 Create a defective protein
 Result in an adaptation
 No effect

What are mutagens? Give 3 examples.

Mutagen:


Something that can cause a mutation (change in
the DNA or RNA sequence)
Examples:
X-ray
 UV light
 Chemicals
 Radioactive substances

What causes one cell to have a different
function than another cell?

All cells in a single organism have the same
DNA/genes

Differentiation of cells results from
activation of different genes

Some genes are “turned off”
GENETIC TECHNOLOGY (13.2)
What is recombinant DNA?

DNA from two
different sources that
has been combined

Example:

Plasmid DNA
What can be produced agriculturally
from recombinant DNA?
1.
2.
3.
4.
Glowing tobacco plants
Plants resistant to insects
Bigger produce, animals
Drought resistant plants
How is genetic engineering
(biotechnology) used to produce
biomedical products such as insulin?
1. Gene of interest is cut out of the DNA of an organism
– Ex. insulin
2. Gene from one organism can be inserted into a plasmid
(vector) – Recombinant DNA
3. Plasmid is then inserted into a bacteria
4. Bacteria will use the foreign gene to make insulin
EVOLUTION (14.1, 15.1,
15.2)
What does the geological
time scale show? Be able to
analyze and determine the
chronological order of
organisms.

Geological time scale
shows the major
events in Earth’s
history in
chronological order
What explains the disappearance of
fossils from one era/period/rock
layer to the next?

Extinction – if the
fossil no longer
appears in rock layers
following where it was
found, then there is a
good chance that it
became extinct
How do fossils form? How can you determine the
age of a fossil? (2 ways)

How Formed?
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Sediment
1.
2.
3.
4.
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Organism dies
Buried under layers of
sediments
Soft tissue decomposes,
bones/hard parts are left
behind
Pressure fossilizes the
bone
Ice
Amber
Trace
Mold
Cast

Age of a Fossil:
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Relative Dating

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Where in the rock layers
the fossils reside
Absolute (radiometric
dating)

Measuring the amount of
radio active isotopes is
still present

What observations did Charles Darwin make
in regards to various species found on the
Galapagos Islands?

Each species had adaptations specific for the
island that they live
What are the principles of
Darwin’s theory of evolution?
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Organisms overproduce
Variation exist among populations
Organisms compete for resources
Variations are inherited
Those with the better adaptations
survive and pass on genes
Natural Selection

Define natural selection according to Darwin.

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How do genetics, variation, and environment
play a role in natural selection?

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Natural selection acts on the genes – organisms that
survive pass on their genes to offspring
What does his theory of evolution suggest? How
does natural selection relate to evolution?
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Organisms with the more favorable variations
(differences) have an increased chance of survival and
reproduction
Organisms best fit for the environment pass on their
genes
What does natural selection specifically act on?
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Variations and genes
Define speciation. Describe the processes that
allow new species to be formed. How do you
know when a new species has formed?
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Speciation:
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Process:
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The development/evolution of a new species
Geographic isolation
Reproductive isolation
Mutation
How Know:
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Species can no longer interbreed (cannot
produce viable offspring)
What is the difference between
geographic isolation and
reproductive isolation?
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Geographic isolation:
Species are separated by a barrier (Ex:
mountain, large river)
 Do not interbreed

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Reproductive isolation:
Species are different because of reproductive
structures or behaviors (mating seasons, calls)
 Do not interbreed
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Geographic Isolation
Reproductive Isolation
How can organisms become
“resistant” to things like pesticides,
antibiotics, etc?
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When a pesticide or antibiotics is used,
it will generally kill most organisms off

A select few will survive
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Survivors have resistance in their genes
The survivors will reproduce and a
majority of the population will be
“resistant”
How can scientists determine whether
two different species came from a
common/related ancestor?
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Homologous structures: same structure,
different function
Embryological similarity: similar
structures as an embryo
Molecular homology: DNA and gene
similarity (biochemistry)
Homologous Structures
Embryology
Define genetic drift. What is a gene pool? Describe
what happens to a gene pool (benefits and
consequences) when genetic drift occurs. How can
lethal alleles be maintained in a gene pool?

Genetic Drift – When a random mutation (or alelle) is
found within a population that isolated itself from the
general population – change in allele frequency

Gene Pool – collection of all of the alleles in the
population

When genetic drift occurs:
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Specific traits become more prevalent within the population
Can be dominant or recessive

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Ex. Tay Sachs, Polydactyly
Lethal Alleles are maintained (kept in the population)
because individuals can be carriers for the bad allele (Ex.
Tay sachs, cystic fibrosis, sickle cell)
What causes evolution to occur more
quickly in a population?

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Population is small
Isolated
Many Mutations
HUMAN BODY SYSTEMS:
Nervous (36.1, 36.3), Immune (39.1,
39.2), Endocrine (35.3), Skeletal
(34.2), Muscular (34.3), Digestive
(35.1), Respiratory (37.1), Circulatory
(37.2), Urinary (37.3)
What are the major functions of each system?
What are the major organs within each system
and what are their specific functions?
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Nervous System: Processes information, controls every process
Immune System: Build up resistance to disease
Endocrine System: Releases hormones to maintain growth,
metabolism, and homeostasis
Digestive System: Break down nutrients from food
Circulatory System: Distribute blood, oxygen, nutrients
throughout the body
Respiratory System: Exchange oxygen and carbon dioxide in
cells
Skeletal and Muscular System: Support and movement of the
body
Exocrine: Dispose of waste (urine, sweat)
What is the relationship between one system and
each of the other systems? How does each system
work with the other systems? For example, be able
to explain what systems would work together in
order for you to be able to jump or talk? to maintain
homeostasis? to respond to stimuli? breathe?
digest food?

SEE INTERACTION CHART
Describe the function and
structure of a neuron.

Function: Receive
and send
chemical/electrical
signals from outside
environment
Nervous System (36.1, 36.3) and
Endocrine System (35.3)
What are the three types of neurons?
1. Sensory Neuron:
a. Receive signals
2. Interneuron:
a. Brain and spinal
cord
b. Process info
3. Motor neuron:
a. Do response
What is an
impulse?

Path that signals in the nervous system take
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Pathway:

Senses  Sensory neuron  interneuron (brain) 
motor neuron – muscle (movement)
How do drugs affect the transmission of
an impulse?
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Drugs can slow
down response time
They interfere with
the passing of
signals from one
neuron to another
Compete with
neurotransmitters
for receptors on
neurons
Explain how a feedback loop
(negative feedback system) works.
Immune System (39.1, 39.2, 34.1, 18.1, 18.2)
What is the body’s first line of defense? Second
line?


First Line of Defense
 Barriers
 Inflammation
Second Line of Defense
 Cell Mediated Response: T cells 
cytotoxic T cells
 Humoral Response: B cells  antibodies
How does immunity occur? How does the immune
system respond to antigens?
1. Macrophage engulfs a pathogen
2. Activates T helper cell
a. T helper cell activates B cell
i. B cell makes antibodies
ii. Makes memory cells
b. T helper cell activates cytotoxic T cell
i. Cytotoxic T cell destroys infected cells
ii. Makes memory cells
What are pathogens, antibodies, antigens?

Pathogen: Disease causing
substance

Antigen: Foreign substance in the
body

Antibodies: Proteins that the
immune system uses to find and
attach to pathogens and antigens
What is the
function of white
blood cells?

Identify antigens

Break down and
remove antigens

B cells – make
antibodies

T cells – Destroy
infected cells
What are the functions antibodies?

Antibodies are
released by B cells

Bind to antigens

Signal Macrophages
to digest antigen
Compare/contrast viruses vs. bacteria
(characteristics). How does each one “work” once it
infects the body? How do you treat the illnesses that
each one produces? What are some effective
defenses against each one?
Viruses
Bacteria
How infects
Uses a host cell
Produces toxins
Treatment
Run course or
antivirals
Antibiotics
Defenses
Vaccines
Anti-microbials
How does HIV affect the immune system?

Attacks and uses
Helper T cells to
make more HIV
viruses

Helper T cells
activate the immune
system
What is AIDS? What can result from this
disorder?

Acquired Immunodeficiency
Syndrome
 When the number of T cells
drops below a certain
number
 Individual dies from
opportunistic infections
 Infections that are usually
easily defended against
with a healthy immune
system