Genetics
BIO.B.2
Protein Synthesis
RNA
 Made up of
1.Phosphate
2.Ribose (a sugar)
3.Four bases
 RNA bases are:
◦ Adenine
◦ Guanine
◦ Cytosine
◦ Uracil (instead of thymine)
 Single stranded
 Forms part of ribosomes
 Two types of RNA:
◦tRNA (transfer)
◦mRNA (messenger)
TRANSCRIPTION
USING DNA TO MAKE mRNA
 RNA
polymerase (an
enzyme) unzips DNA by
breaking the Hydrogen
bonds between the bases.
 Only
one strand of DNA is
transcribed.
 Complementary RNA
nucleotides are added to the
DNA strand.
DNA RNA
A – U
G – C
T – A
C – G
 The
start codon is the signal for
the place to start transcription.
 Transcription stops at the stop
codons.
 The
sequence of bases along
DNA that is transcribed is a
gene.
 The RNA that is made is mRNA.
DNALC animation
mRNA PROCESSING
After
mRNA is made,
enzymes may cut out
pieces of the strand.
The sections that are
removed are called
introns.
The
sections that
remain are called
exons and are put
together.
The finished/mature
mRNA strand then
leaves the nucleus and
is ready for translation.
The Importance of Proteins
 Each
gene controls the
making of a protein.
 A gene is section of DNA
that gives instructions for
a specific protein to be
made
 20
amino acids make up
all proteins
 Proteins are required for
almost every reaction that
occurs in your body!
CODONS
 Codon
- three bases in a
row that determine the
amino acid that is used
to make a protein.
mRNA Codon Chart
 Some
codons do not
represent amino acids, but
instead act as stop signals
(the end of a protein).
 Note, one amino acid may
have more than one codon.
TRANSLATION
FROM mRNA TO PROTEIN
 Begins
when a ribosome
attaches to a mRNA strand.
 mRNA is used to make a
specific protein (or
polypeptide).
 The
organelle where
proteins are made.
 They are made up of 2
subunits with 2 binding
sites.
RIBOSOMES
 tRNA
(transfer RNA) is a
strand of nucleotides that has an
amino acid attached to it.
 tRNA carries the appropriate
amino acid to the
mRNA/ribosome complex.
 If mRNA is UGG then the tRNA
is ACC.
tRNA
 Translation
begins with
the start codon.
 Each amino acid that is
brought in to the
ribosome is attached to
the growing amino acid
chain (or protein)
 The bond between amino
acids is called a peptide
bond.
About
15 amino acids
are added per second.
 Translation
stops when a
stop codon is reached.
 There are no tRNA’s for
the stop codons.
 The protein is released to
do its job.


Sometimes the finished protein goes into
the rough ER. The rough ER transports it to
various places including the plasma
membrane, Golgi apparatus, and cytoplasm.
The Golgi processes and packages proteins.
Fro example, some proteins have sugars
attached to them. The remodeled proteins
leave the Golgi in vesicles (sacs) to go to
other parts of the cell or to leave the cell.
Where does the protein go?
BIOTECHNOLOGY
The future is here!
◦ Mutation - changes in the DNA
sequence that affect genetic
information
◦ Types of mutations:
 Gene mutations - changes within a
single gene
 Chromosomal mutations changes within a whole chromosome
(affects multiple genes)
MUTATIONS
Gene Mutations
 Point
Mutation - a change
in a single nucleotide
(example: changing an A to
a C)
 Frame-shift Mutation - an
insertion or deletion of a
nucleotide that causes a
different reading of codons
from the point of the change
to the end of the gene
 Normal
AAT TAA TAG GAT TTT AAA
 Mutation
AAT TAG TAG GAT TTT AAA
Point Mutations
The G was used
instead of an A.
 Usually
occurs as a result of
an insertion or deletion
 Normal
TAC GCA TGG ATT
 Insertion
TAT CGC ATG GAT T
Frame-Shift Mutations
T was inserted after the A.
 THE
FAT CAT ATE THE RAT
 THE
FAT C AT A TE T HE R AT
DELETION of H
 TEF ATC ATA TET HER AT
 not make sense, frameshift Just
like this mutated sentence does
mutations make nonsense proteins
that cannot do their jobs correctly.
Example using words:
Deletion – when part or all of a
chromosome is lost
 Duplication – when part of a chromosome
is mistakenly repeated
 Inversion – when part of a chromosome
becomes oriented in reverse of its normal
direction
 Translocation – when one part of a
chromosome breaks off and attaches to
another nonhomologous (not the partner)
chromosome

Chromosomal Mutations
Deletion
Duplication
Inversion
Chromosomal
Mutations
Translocation
When do mutations occur?
During DNA replication, mistakes can be
made when DNA polymerase adds
complementary nucleotides.
 If this mutation or mistake happens very
early on in a baby’s development, the
mutation can affect the entire baby. The rest
of the cells will have that same mutation.
 Remember, we all start off as one cell that
must make many news cells through mitosis.
Every time your cells divide, DNA has to copy
itself and mistakes can be made.

 If
a one of your skin cells divides
right now and a mutation occurs,
this is probably not a problem.
 However, if the mutation causes
certain genes to change, the
new, mutated skin cell can
become a cancer cell.
 Mutagen
– any agent that
causes DNA to mutate
◦UV light
◦Radiation
◦Smoking
◦Many different chemicals
 Mutations
gone wild Cats
Cause of mutations
Gene Regulation
Only some of your genes are being
expressed (used to make protein) at any
given time.
 Your body needs mechanisms to “turn on”
or “turn off” genes.
 Chemicals can act as blocks or starters.
 Some cancers are caused by genes being
turned on that should not have been! For
example, these genes can be turned on
by smoking, which mutates DNA.

Genetic Engineering
Manipulating DNA
Electrophoresis
DNA is cut by restriction enzymes to
make fragments.
◦ Restriction enzymes cut DNA at
specific sequences.
 Electrophoresis is a technique that
separates DNA fragments (using
electricity) in a jello-like slab based on
the size of the fragments.
 Smaller fragments are able to travel
longer distances more quickly.
 DNA has a negative charge so the
fragments will flow toward the positive
electrode (opposites attract).

DNA plus
Powe
restriction
enzyme
Mixture
of DNA
fragments
r
source
Ge
l
 If
you were to compare two
samples of the same DNA
using the same restriction
enzymes, the banding
pattern would be the same.
 Different people make
different banding patterns.
And why would we do this?

DNA Fingerprinting
◦ Paternity Tests
 Children have a banding that is a
combination of their mom’s and dad’s
banding.
◦ Crime solving
 Identify the person who committed a
crime (no two people have the same
DNA)
◦ Medical diagnosis
 Determine if you have the gene that
causes a disease or disorder.
GMOs
 Genetically
modified
organism (GMO) – an
organism with DNA that has
been altered through
genetic engineering
 Transgenic - a GMO that
has been altered with DNA
from another species
Transgenic Bacteria
 Bacteria
have had many
different genes put into them
◦Some examples of human
genes that are put into bacteria
Insulin gene
Human growth hormone gene
Clotting factors gene
Transgenic Animals

Used to study genes and improve the food
supply
◦ Mice with human-like immune
system genes.
◦ Livestock with extra copies of
growth hormone genes.
◦ Sheep and pigs that produce
human proteins in their milk.
Transgenic Plants
 Used
for food supply and
medical supplies
◦Rice with Vitamin A (betacarotene) gene
◦Genes for herbicide and
pesticide resistance in plants
 Producing
genetically identical
organisms from one original cell.
 We have successfully cloned
pigs, cows, mice, sheep, and
monkeys.
 The first animal cloned was a
sheep named Dolly in 1997.
Cloning
Donor
A donor cell is taken from
a sheep’s udder.
Nucleus
These two cells are
fused using an electric
shock.
An egg cell is taken from an
adult female sheep.
Fused Cell
Egg Cell
The nucleus of the
egg cell is removed.
The fused cell
begins dividing
normally.
Foster
Cloned Lamb
Mother
Embryo
The embryo develops
normally into a lamb—
Dolly
The embryo is placed
in the uterus of a foster
mother.
GENETICS
Genetics – the study of heredity or
passing on of genes
 Gene – a sections of DNA that codes for a
protein to be made
 Allele – the form that a gene takes (ex.
dominant or recessive)
 Homozygous – having the same alleles
for a trait






Heterozygous – having different alleles
for a trait
Dominant trait – an allele that is fully
expressed in heterozygotes; represented
by a capital letter
Recessive trait – an allele that is not
observed in heterozygotes; represented by
a lower case letter
Genotype – the combination of alleles
(letters) that an organism has
Phenotype – the physical trait or visible
characteristic determined by the genes
Single Trait Crosses:
Pedigree:
Incomplete Dominance Crosses:
Codominance Crosses:
Multiple alleles crosses:
Blood Types
BLOOD
TYPES
TYPE A
TYPE B
TYPE AB
TYPE O
GENOTYPES
ANTIGENS
(MARKERS)
ANTI-BODIES
(FIGHTERS)
RECEIVE
FROM?
DONATE TO?
Blood Type Crosses:
Sex-linked Crosses: