DNA Replication
SC.912.L.16.3
Describe the basic
process of DNA
replication and how it
relates to the
transmission and
conservation of the
genetic information.
Source: http://genes.atspace.org/1.4.html
What do I need to know?
 the basic process of DNA replication and
how it relates to the transmission and
conservation of genetic information
 that mutations in the DNA sequence may
or may not result in phenotypic change
and how mutations in gametes may result
in phenotypic changes in offspring
 the basic processes of transcription and
translation and how they result in gene
expression
 the basic processes of DNA are universal
in organisms
 that similarities in the genetic codes of
organisms are due to common ancestry
and the process of inheritance
Blame it on.. DNA
Video - Key Vocabulary
 DNA
 RNA
 transcription
 translation
 amino acid
 protein
 cytoplasm
 ribosome
Video:
 nitrogen bases
https://www.youtube.com/watch?v=gqvYOr78THo
 mutation
Structure of DNA

DNA is made of subunits
called nucleotides

DNA nucleotides are
composed of a
phosphate, deoxyribose
sugar, and a nitrogencontaining base

The 4 bases in DNA are:
adenine (A), thymine (T),
guanine (G), and
cytosine (C)
Source:
http://bootstrike.com/Genetics/DNA/im
ages/structure.gif
DNA Replication
Source: http://y12hb.files.wordpress.com/2013/03/semi-conservative.png
Think About This…
 DNA is only found in
the nucleus
 Who we are, how we
look, and the
mechanisms that make
are body function are
all determined by
proteins
 Proteins are only made
in the ribosome.
Source:
http://www.biologycorner.com/resourc
es/DNA-RNA.gif
Why do we need both
DNA and RNA?

DNA holds all the genetic
information

DNA damage = mutation

Safer in the nucleus

RNA acts as messenger
Source:
http://classconnection.s3.amazonaws.com/3
33/flashcards/903333/png/transcription__translation1320698154407.png
Protein Synthesis: The
Central Dogma
DNA vs. RNA
 type of sugar
 bases
 # of strands
Source: http://i.qkme.me/365r3l.jpg
Types of RNA
Type
Function
Messenger RNA
(mRNA)
Carries copies
of the
instructions for
assembling
amino acids
from DNA to the
rest of the cell
1
Ribosomal RNA
(rRNA)
Is a part of
ribosomes
Transfer RNA
(tRNA)
Transfers each
amino acid to
the ribosome to
help assemble
proteins
2
3
2
3
1
Source:
http://crescentok.com/staff/jaskew/isr/anato
my/anatomy1/mrna.gif
Transcription

the making of
messenger RNA (mRNA)
from DNA in the nucleus

DNA unwinds and mRNA
is made complementary
to the DNA
 A=U
 G=C

3 nitrogen bases in
mRNA is called a codon
Source: http://i.qkme.me/365r3l.jpg
Translation
 Involves 20 different
amino acids in the
sequence given by
the three-base
codons built from an
alphabet of four
bases
 the process in the
ribosome builds the
polypeptide chains
that will become
proteins
Source: http://hyperphysics.phyastr.gsu.edu/hbase/organic/translation
.html
Genetic Code
The Language of Proteins
 each 3 nucleotide sequence in
an mRNA strand is called a
codon
 codes for a 1 amino acid
 codes for an amino acid using
specific rules
 there are 64 (43) possible
codes, but only 20 amino acids
 more than 1 triplet may code
for the same amino acid
 note that several codons can
also act as start (AUG) or stop
(UAA) signals
Source:
http://cronodon.com/BioTech/Ribosomes.html
Activity: Transcribe &
Translate a Gene
Mutations
 Mutation: change in
DNA
 if a base is
substituted or
deleted, the triplet(s)
are different
 this sometimes
leads to difference in
the protein
Basic Process of DNA
is Universal
 Mutation: change in
DNA
 if a base is
substituted or
deleted, the triplet(s)
are different
 this sometimes
leads to difference in
the protein
Show What You Know
Genes for medically important proteins can be cloned and inserted into
bacteria, as shown in the diagram below.
Why can bacteria recognize a human gene and then produce a human
protein?
A.
DNA replication in bacteria and humans is the same.
B.
Bacterial cells contain the same organelles as human cells.
C.
The basic components of DNA are the same in humans and bacteria.
D.
Bacterial cells and human cells contain the same kind of
chromosomes.
Show What You Know
A cell is replicating its DNA. Part of the DNA
strand reads ACCGTAC. The new strand built off
this segment reads TGGAATG. What effect might
this have when the DNA replicates in the future?
A. Cells having the new DNA version will look or
operate differently from cells with the original
DNA.
B. Only the sections of DNA without mistakes will
be used in the future so the DNA strand will
shorten.
C. The DNA will be exactly like the original since
only the original strand of DNA is used as a
template.
D. When the new strand is used as a template the
strand built from it will differ from the original
DNA.
Show What You Know
Which of the following
processes produces the
nucleotide sequence UUA
from the sequence AAT?
A. meiosis
B. replication
C. respiration
D. transpiration
Show What You Know
When an extra nitrogenous base is inserted into the
DNA sequence of a gene, the protein product of the
gene is usually nonfunctional. Which of the
following statements best explains why?
A. The inserted base increases the rate of
translation in the corresponding mRNA
sequence.
B. The inserted base causes the DNA sequence to
be transcribed into the RNA in the opposite
direction.
C. The inserted base causes the codons in the
mRNA sequence to be incorrect for the desired
protein.
D. The inserted base signals enzymes to translate
the DNA sequence rather than the RNA
sequence into the protein.
Show What You Know
The diagram to the right represents a
process that occurs in the nucleus of
a eukaryotic cell.
Which of the following statements
describes what is happening in this
process?
A. Molecules of RNA are forming
chromosomes.
B. A molecule of mRNA is directing
the production of tRNA.
C. Molecules of DNA are being
packaged for export to the
ribosomes.
D. A molecule of DNA is being
replicated to make two identical
copies.