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DNA
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Organic Compounds
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Any compound that contains BOTH
Carbon (C) and (H)
– Methane CH4
– Glucose C6H12O6
Organic Compounds for
Metabolism
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Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates and Lipids

Carbohydrates
– Provide Energy
– Contain C, H, O in a 1:2:1 ratio
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

C6H12O6
C5H10O5
Lipids
– Store Energy
– Contain C, H, O; but have less Oxygen than
Carbohydrates
Proteins and Nucleic Acids

Proteins
– Important for body-building material (muscles)
– Made from Amino Acids
– Contain C, H, O, and N

Nucleic Acids
– Helps to store cellular information
– Includes DNA and RNA
– Contain C, H, O, N, and P
DNA
The Blue Print of Life

DeoxyriboNucleic Acid

Contains the genetic information
used for our growth and
development
Credit for structure is given to
Watson and Crick.

What DNA is Composed Of
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Double stranded
DNA is made up of Nucleotides
Each nucleotide has:
– A 5-carbon sugar: Deoxyribose
– A phosphate
– A nitrogen base
The Nitrogen Bases

The four Bases of DNA are:
– Adenine (A)
– Thymine (T)
– Cytosine (C)
– Guanine (G)

The base pairing are:
– Adenine with Thymine
– Cytosine with Guanine
Purines and Pyrimidines

Purines: 1 ring
– Adenine (A)
– Guanine (G)

Pyrimidines: 2 rings
– Thymine (T)
– Cytosine (C)

Purines can only pair with Pyrimidines
Structure of DNA

Structure
– Two strands twisted
together (helix)
– Sides of Ladder

Alternating Phosphate
and Sugar
– Rungs of Ladder

Pair of nucleotide bases
Replication



Replication is the process of
duplicating DNA
Two identical copies of DNA result
The process occurs:
– in the nucleus
– During the s-phase of the cell cycle
Replication Process
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
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DNA Helicase unzips the double
helix
Free-floating nucleotides from within
the nucleus “repair” each side
Two new and identical structures
result
– Complimentary (original strand)
– Template (newly formed strand)
Replication Practice
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Where does replication take place?
During what phase of the cell cycle?
Practice:
– Template:
ATTGCAGGCCTTAGTCAC
– Replicate:
More Practice

AGTTCAGCGGTATTAGCTAGCAACCGT
RNA
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RiboNucleic Acid
RNA is made of nucleotides
Single stranded
Each nucleotide has
– 5-carbon sugar; Ribose
– Phosphate group
– Nitrogen Base
The RNA Bases

The four bases of RNA are:
– Adenine
– Uracil
– Cytosine
– Guanine

The base pairs are
– Adenine and Uracil
– Cytosine and Guanine
Comparing DNA and RNA
DNA
RNA
2 strands
1 strand
Deoxyribose sugar
Ribose Sugar
Adenine - Thymine
Cytosine - Guanine
Adenine - Uracil
Cytosine - Guanine
Made by Replication
Made by Transcription
Types of RNA

Three Types:
– mRNA: (messenger) Takes code from
DNA in nucleus to ribosome
– tRNA: (transfer) Brings amino acids to
the ribosome to build proteins
– rRNA: (ribosomal) Makes up
ribosomes
Transcription



RNA polymerase
unzips the DNA
structure
Free-floating RNA
nucleotides repair
ONE SIDE of the
structure
The new mRNA strand
leaves the nucleus to
go to a ribosome in the
cytoplasm
Transcription Practice
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DNA strand:
ATACTGTCAGTATGGCCAT
RNA strand:
Practice problem:
TATTACGACCCGTACTAGAATG
Reverse Transcription
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DNA strand:
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RNA strand:
UAGGCUACUGAUCCAAUG
Proteins
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There are 20 different amino acids
that join together to make proteins
The amino acids are joined by
peptide bonds
AA + AA + AA + AA = Protein
Codons
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Codons are groups of three nitrogen
bases
They signal for specific amino acids
– CUC (Leucine)
– ACC (Threonine)

Some codons start or stop protein
synthesis
–
–
–
–
AUG (Start)
UAA (Stop)
UAG (Stop)
UGA (Stop)
Facts About Translation
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It is also called Protein Synthesis
It occurs
– At a ribosome
– In the cytoplasm
Translation (Protein Synthesis)
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mRNA breaks into codons and
signals specific amino acids
tRNA brings the amino acid to the
ribosome
Each amino acid bonds to another to
form a protein
Transcription and Translation
Translation Practice
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mRNA:
Amino acid:
Practice
mRNA:
tRNA:
Amino acid:
AUG AGC UGG GGG UAU UAG
Met Ser Leu Gly Tyr Stop
AUG UGU AGC CCU AUU UAA
Central Dogma of Protein
Synthesis
Mutation
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Mutations any changes to either DNA or
RNA.
Causes: copying errors in the DNA during
mitosis and by exposure to ultraviolet
radiation, xrays, radioactivity, or viruses.
Results: genetic disorders, death, or have
no affect.
Most mutations are repaired by enzymes.
Mutations

Chromosome
–
–
–
–
–
Insertion
Deletion
Translocation
Substitution
Nondisjunction
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Gene
– Point
– Frameshift
Insertion

Insertion: the addition of one or
more nucleotide base pairs into a
genetic sequence
– Ex: Normal: AAACCCGGG
Mutated: AAACACCGGG
Deletion


Deletion: part of a
chromosome or a
sequence of DNA
is missing.
Any number of
nucleotides can be
deleted, from a
single base to an
entire piece of
chromosome.
Example
Normal: AAACCCGGG
Mutated: AAACCGGG

Substitution
Substitution: one or
more nucleotides are
substituted by the same
number of different
nucleotides.
 In most cases, only one
nucleotide is changed.
 Example:
Normal: AAACCCGGG
Mutated: AAACACGGG

Gene Mutations

Frame-shift mutation:

causes a change all the
way down a DNA sequence, making each codon a different
sequence. (MORE SERIOUS!)
EX. CAG TTC CTG GAA -> (frameshift)-> CAG TTA CCT
GGA
– Insertion
– Deletion

Point-shift mutation:

a single letter is the only
thing changed in the DNA sequence
EX. GTA CTG CAA-----> (point mutation) -----> GTA GTG CAA
– Substitution
Viruses
Virus

Virus is a tiny non-living particle that
enters and then reproduces inside a
living host cell.
Characteristics of Viruses
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Have either DNA or RNA.
May be single stranded or double
stranded.
Nonliving because cannot:
–
–
–
–
–
–
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make food
take in food
use energy
respond to stimuli
make waste
multiply on their own.
A Bacteriophage is a virus that infects
bacteria.
Virus Shape and Size


Viruses are smaller than
bacteria (measured in
nanometers)
Structure: (2 main Parts)
– Protein Coat
– Inner Genetic Material
(DNA or RNA)
Virus Shapes and Sizes
Lytic Cycle:

Lytic Cycle: Virus
enters cell and uses cell
to reproduce. (Ex. Flu,
Rhinovirus)
– Viral DNA destroys Cell
DNA, takes over cell
functions and destroys
the cell.
– The Virus replicates.
– There are symptoms of
viral infection.
– Active viral infection
takes place.
Lysogenic Cycle

Lysogenic Cycle: Virus enters
cell and becomes part of cells
DNA. May enter lytic cycle if
exposed to stress. (Herpes, cold
sores.)
– Viral DNA merges with Cell DNA
and does not destroy the cell.
– There are no symptoms of viral
infection.
– Passive viral replication takes place.
Lysogenic/Lytic Cycle
Lytic VS Lysogenic Cycle
Ways to Protect
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Vaccinations: weakened or dead
viruses injected into the body to
stimulate immune response.
(Antibodies form against virus)
Proper hygiene/hand washing
Minimize risk by avoiding risky
behavior.
(ex. IV drug use, unprotected sex)
Cancer

Some viruses have been linked to
the formation of tumors.
– HPV linked to cervical cancer
– Hepatitis B and C linked to liver cancer
– Epstein-Barr linked to lymphoma