Domain III - Genetics
 Deoxyribonucleic
acid
 Made up of nucleotides
 Sugar
– deoxyribose
 A phosphate group
 One of four nitrogen bases
Adenine (A)
 Guanine (G)
 Cytosine (C)
 Thymine (T)

 Is
in the shape of a double helix
 The
two strands are
held together by
hydrogen bonds
between the
nucleotides
Adenine pairs with
thymine
 Guanine pairs with
cytosine

 The
order of the
bases is the genetic
code
 DNA
makes an exact copy of itself
 Takes place in the nucleus
An enzyme ‘unzips’ the DNA
2. Free nucleotides pair up with the
exposed nucleotides
3. This continues until two identical
copies of the DNA molecule are made
1.
 The
two copies each contain one
side from the ‘original’ DNA and one
‘new’ side
 Ribonucleic
acid
 3 differences (from DNA):
 Sugar
is ribose instead of deoxyribose
 Uracil instead of thymine
 Single helix instead of a double helix
3
types of RNA:
 Messenger
RNA (mRNA)
 Transfer RNA (tRNA)
 Ribosomal RNA (rRNA)
 The
process of
making RNA from
DNA
 Occurs in the
nucleus
 Only one side of
the DNA strand is
used to make the
RNA
 The
process of converting the
information on the mRNA into a protein
 The mRNA carries the message from
the nucleus to the ribosomes, where
the proteins are made
 The tRNA molecules bring the amino
acids to the ribosomes
The 3 base codon on the mRNA corresponds
to a 3 base anticodon on the tRNA
 Each codon carries the code for a specific
amino acid

 Which
of the following shows how
information is transformed to make
a protein?
DNA → RNA → protein
b. gene → chromosome → protein
c. cell respiration → ATP → protein
d. ATP → amino acid → protein
a.
 Information
on mRNA is used to
make a sequence of amino acids
into a protein by which of the
following processes?
replication
b. translation
c. transcription
d. transference
a.
 ‘Father
of Genetics’
 Studied inheritance in pea plants
 Concluded that each organism has
two genes for each trait – one from
mom, one from dad
 Genes come in different forms
called alleles
 Dominant
– the trait that is expressed
 Recessive – the trait that is hidden
 Law
of Dominance – the dominant
allele will prevent the recessive allele
from being expressed
 Law of Segregation – gene pairs
separate when gametes are formed, so
each gamete has only one allele of
each pair
 Law of Independent Assortment –
different pairs of genes separate
independently of each other when
gametes are formed
 Homozygous
– two identical alleles (TT or
tt)
 Heterozygous – two different alleles (Tt)
 Monohybrid – genetic cross involving one
trait
 Dihybrid – genetic cross involving two traits
 Genotype – the genetic makeup of the
organism (Tt)
 Phenotype – the physical appearance of
the trait (tall)
 Pea
plants have seeds that are
either round or wrinkled. In this
cross, what will be the phenotypic
ratio of the offspring?
50% RR and 50% Rr
b. 25% RR, 50% Rr, and
25% rr
c. 50% round seeds and
50% wrinkled seeds
d. 100% round seeds
a.
 Interphase
G1 phase – cell
growth
 S phase – DNA
replication
 G2 phase –
preparation for
mitosis

M
phase
Mitosis
 Cytokinesis – division
of the cytoplasm

 Division
of the nucleus
 Two identical daughter cells are
produced
 The chromosome number remains
the same
 Purpose:
 Growth
and tissue repair
 Asexual reproduction
 Prophase
– the duplicated chromosomes
become visible and spindle fibers form
across the cell; the nuclear envelope starts
to break up
 Metaphase – the chromosomes attach to
the spindle and line up randomly in the
middle of the cell
 Anaphase – the chromosomes are pulled to
opposite ends of the cell
 Telophase – a nuclear membrane forms
around the chromosomes at each end of
the cell; spindle fibers disappear;
chromosomes become less visible
 Why
is it important for the cells of
multicellular organisms to undergo
mitosis?
a.
b.
c.
d.
Mitosis allows for reproduction with male
and female gametes.
Mitosis increases variation within an
organism.
Mitosis produces cells that are different
from the original dividing cell.
Mitosis produces identical cells to the
original dividing cell.
 The
production of gametes (sex cells
– sperm and eggs)
 The chromosome number is cut in
half, producing haploid gametes
 Diploid

Normal body cells
 Haploid

(2n) – 2 of each chromosome
(n) – 1 of each chromosome
Sex cells
 There
are two divisions
 Meiosis
I
Prophase I – crossing over can occur
 Metaphase I
 Anaphase I
 Telophase I

 Meiosis
II
Prophase II
 Metaphase II
 Anaphase II
 Telophase II

 Changes
in the nucleotide sequence
of a DNA molecule
 Substitution – a single nucleotide is
substituted for another one (A
instead of G)
 Insertion – a nucleotide is added
 Deletion – a nucleotide is removed
 A mutation can be harmful, neutral,
or beneficial depending on how it
affects the protein that is produced
 What
is a source of genetic
variation?
mutation
b. adaptation
c. replication
d. transcription
a.
 Recombinant
genes

DNA – inserting foreign
Human insulin is mass produced by bacteria
that have had the human insulin gene
inserted
 Creates
genetically modified organisms
Cotton plants have been modified to resist
worm attacks
 Bacteria have been modified to clean up oil
spills, manufacture alcohol, and process
minerals

 Which
of the following is the
correct base-pairing rule for DNA?
A-U; C-G
b. A-G; T-C
c. A-T; G-C
d. A-C; T-G
a.
A
mutagenic factor that can alter
DNA by the loss of a chromosome
segment is known as
translocation
b. crossing over
c. deletion
d. nondisjunction
a.
 In
Mendel’s experiments with a
single trait, the trait that
disappeared in the first generation
and reappeared in the next
generation is called the
homozygous trait
b. dominant trait
c. recessive trait
d. heterozygous trait
a.
 Which
of the
following
correctly shows
the shape of a
DNA molecule?
 Changes
to an organism’s DNA can
cause unexpected traits to be
expressed in its offspring. DNA in
an individual’s gametes will most
likely be altered before being
passed to offspring if exposed to
x-rays
b. loud sounds
c. magnetic fields
d. extreme temperatures
a.
 Agricultural
companies have
developed the ability to control the
genetic characteristics of their crops.
Genetic engineering techniques have
been used to produce all of the
following effects except
a.
b.
c.
d.
grow salt-tolerant crop plants
decrease harvesting time
make crop plants resistant to disease
decrease soil nitrogen levels
 In
fruit flies, the gray body color
(G) is dominant to the ebony body
color (g). What is the genotypic
ratio of the offspring of a
heterozygous gray female and an
ebony male?
25% Gg, 75% gg
b. 50% Gg, 50% gg
c. 75% gray, 25% ebony
d. 100% gray
a.
 The
process of meiosis produces
gametes. How does this process
increase reproductive variability?
Different combinations of alleles are
produced.
b. Each allele from the parent cell forms
a separate gamete.
c. Each pair of genes undergoes crossingover with different genes.
d. The two genes are passed on to a
daughter cell, resulting in new traits.
a.
 DNA
and RNA are nucleic acids. A
characteristic of RNA is that it
remains in the chromosomes in the
nucleus
b. is involved in translating information
in DNA into proteins
c. undergoes crossing-over during meiosis
d. is replicated during the process of
mitosis
a.
 ATG
is a DNA triplet that codes for
an amino acid. Which mRNA codon
will pair with the ATG triplet
ATG
b. GTU
c. TAC
d. UAC
a.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
A
B
D
D
A
C
C
C
D
A
D
B
A
B
D
 http://www.doe.k12.ga.us/ci_testin
g.aspx?PageReq=CI_TESTING_EOCT&
SubPageReq=GUIDES
 Google image search
 Campbell, Neil A. and Reece Jane B
(2001). "6". Biology. Benjamin
Cummings.
 Miller, Kenneth R. and Levine Joseph
S. (2002). Biology. Prentice Hall.