Name:______________________________________________________________Date:__________________________
Test #4 Study Guide: DNA- Mutations
A. Review material from previous tests
B. Nucleic Acids
a. Made up of nucleotides (monomers)- which contain a phosphate group,
a sugar, and a nitrogenous base
b. DNA- genetic material of the cell (nucleus)
c. RNA- leaves the nucleus, goes to cytoplasm (ribosomes)
to make proteins
C. DNA = Deoxyribonucleic Acid
a. Double Helix
b. Does not leave the nucleus
c. Deoxyribose- sugar
d. Nitrogen Bases: Adenine, Thymine, Cytosine, Guanine
e. Strands are complementary and held together by H bonds
(weak bonds that can “unzip”)
i. A = T
G=C
f. Can replicate itself (DNA Polymerase)- identical copy
g. Can transcribe itself (RNA Polymerase) – codes for mRNA
h. Genetic Code = Sequence of Nitrogenous Bases
D. RNA = Ribonucleic Acid
a. Single stranded
b. Made in the nucleolus, but can leave nucleus to go to cytoplasm
c. Ribose – sugar
d. Nitrogen Bases: Adenine, Uracil, Guanine, Cytosine
i. A = U
G=C
e. 3 types:
i. mRNA (messenger)-carries the code (recipe) from nucleus to ribosome
ii. rRNA (ribosomal)- makes up the ribosomes (oven)
iii. tRNA (transfer)- carries amino acids to ribosomes to incorporate into proteins (ingredients)
Some important vocabulary and concepts to know (Please make sure you know how to demonstrate these processes as
well):
Replication: DNA makes an identical copy of itself, mainly when a cell is going to divide, or repair itself.
Occurs in the Nucleus
Transcription: DNA codes for mRNA, to bring the code to the ribosome
Translation: mRNA is read at the ribosome (in codons),
complementary based to anticodons on tRNA,
and proteins are made
Codon: 3 base sequence on the mRNA that codes for a
specific amino acid
Anticodon: 3 base sequence on the tRNA that complements the
codon to help construct the polypeptide chain at
the ribosome
Name:______________________________________________________________Date:__________________________
Test #4 Study Guide: DNA- Mutations
E. Mutations
a. Any change in a DNA molecule (errors that occur during replication or transcription)
b. Can be random!!! (no known cause)
c. Can be caused by external factors such as
i. Radiation (x-rays, uv light, cosmic rays, gamma radiation)
ii. Carcinogens (cancer causing chemicals)
iii. Pollutants (pesticides, dioxin, DDT)
d. Are much more serious when they occur in SEX cells because they can be passed on to the next
generation!!!
F. Types of Mutations:
a. Chromosomal mutations- when a chromosome becomes altered either by breaking off a piece, inverting
the nucleotides on the chromosome, or having an extra/missing chromosome
i. Deletion- loss of all or part of a chromosome
ii. Duplication- a segment of chromosome is repeated
iii. Inversion- genes on the chromosome are in the wrong order
iv. Translocation- piece of chromosome breaks off and attaches to a nonhomologous chromosome
v. Extra chromosome (trisomy)- instead of a pair of homologous chromosomes, one inherits three
1. Very serious because they affect many genes on the chromosome. Can be studied using a
karyotype (picture of a person’s chromosomes)
2. Examples:
a. Down Syndrome (Trisomy 21)- child is born with three chromosome #21.
Characterized by mental retardation, abnormal facial features, often accompanied
by heart malformations
b. Turner’s Syndrome (X_ females)- females with only one x. females are sterile
b. Gene Mutations- changes in the individual base sequences in a DNA molecule. May involve as little as a
change in one nucleotide (point mutations, which can be silent, missense, or nonsense) or a shift in a
sequence of nucleotides (frameshift mutation) which is more serious because every single codon will be
affected
i. Substitution- one base is substituted for another (point)
ii. Insertion- extra base is inserted into DNA (frameshift)
iii. Deletion- one base is deleted from DNA (Frameshift)
1. Examples:
a. Sickle Cell anemia- one wrong base on DNA causes the wrong hemoglobin
protein to be made (blood cells are misshaped)
b. Cystic fibrosis- one wrong base on DNA causes excess mucus production that
clogs lungs, breathing passages, and digestive tract
c. Albinism- don’t make pigment
d. PKU- Phenylketonuria- people can’t break down phenylalanine, it accumulates in
the brain and causes them to become retarded. If caught at birth, can be treated
with diets that avoid phenylalanine
e. Dwarfism- abnormal growth
f. Huntington’s Disease- manifests itself in middle age (40+), typified by a rapid
deterioration of the central nervous system
g. Tay-Sach’s disease- fatal disorder of the Central Nervous System. Death usually
occurs before age 3. Prevalant in Eastern European Jewish Population.
Name:______________________________________________________________Date:__________________________
Test #4 Study Guide: DNA- Mutations
Practice Questions:
What do we call the process shown
Describe the relationship between
Describe the mutations occurring in
below? Why is it used? Describe
the pictures below.Which
the three structures shown below.
what you know about this person
chromosome is normal?
based on the picture.
1.
2.
3.
4.
Identify and compare/contrast the
two structures shown below.
Identify each of the molecules below.
Identify the processes occurring at
each arrow below. Identify where
each process occurs.
Label each of the lettered structures below. Describe (in detail the process
occurring in this picture.
What are the two main aspects of
DNA’s structure that allows it to be
replicated and to be transcribed?
What enzyme controls DNA
replication? What enzyme controls
DNA transcription to mRNA? Be able
to replicate and transcribe the original
DNA template below.
New DNA
strand
Original
DNA
template
A
T
C
C
C
G
T
C
A
A
T
T
G
T
A
C
G
G
T
mRNA
strand