Title: DNA / RNA
1DNA / RNA
2DNA
- Deoxyribonucleic acid (DNA) is a nucleic acid
that contains the blueprint for making the
proteins the cell needs. - DNA contains genes.
- Genes are specific messages instructing the cell
on how to construct a protein.
3DNA
- DNA is the chemical used to pass genetic
information on to the next generation of
organisms. - DNA controls the synthesis of proteins, which
helps determine the characteristics of the
organism and regulate the cells metabolism.
4DNA
- DNA contains the genetic instructions used in the
development of all known living organisms and
some viruses. - DNA molecules are used for long term storage of
information. - DNA carries the instructions necessary to create
RNA and proteins therefore, it is often compared
to a blueprint.
5DNA Structure
- DNA is a nucleic acid.
- Nucleic acids are large polymers of nucleotides.
6DNA Structure
- DNA consists of two long polymers of simple units
known as nucleotides. - These two strands run in opposite directions to
each other and are therefore known as
anti-parallel. - The strands have backbones made of sugars with
phosphate groups attached.
7DNA Structure
- Attached to each sugar is one of four types of
molecules called bases. - Information is encoded in the sequence of these
four bases along the backbone. - The information is read using the genetic code.
8DNA Structure
- The genetic code specifies the sequence of amino
acids within proteins. - The code is read by copying stretches of DNA into
RNA (A process known as transcription).
9DNA Structure
- A nucleotide consists of a sugar molecule, a
phosphate group, and a nitrogenous base. - There are four different nitrogenous bases in DNA
10DNA Structure
- Adenine (A), guanine (G), cytosine (C), and
thymine (T). - The DNA nucleotides can combine into a long
linear DNA molecule that can pair with another
linear DNA molecule.
11DNA Structure
- The two paired strands of DNA form a double helix
with sugars and phosphates on the outside and the
nitrogenous bases on the inside. - The nucleotides form hydrogen bonds with one
another, which helps to stabilize the helical
structure.
12DNA Structure
- Adenine pairs with Thymine (A-T).
- Guanine pairs with Cytosine (G-C).
13(No Transcript)
14Nitrogenous Bases
- The nucleotide bases are nitrogenous bases that
are involved in pairing in DNA and RNA. This is
known as base pairing. - In genetics they are simply called bases.
- Adenine, Guanine, Cytosine, and Thymine are DNA
bases. - Adenine, Guanine, Cytosine, and Uracil are RNA
bases.
15Adenine
16Guanine
17Thymine
18Cytosine
19Uracil
20Chromosomes
- Within cells, DNA is organized into structures
called chromosomes.
21Chromosomes
- The chromosomes are duplicated before the cell
divides, a process known as DNA replication. - Within the chromosomes, chromatin proteins such
as histones compact and organize DNA. The
chromatins help determine which parts of the DNA
are transcribed.
22Eukaryotes Vs. Prokaryotes
- Eukaryotic organisms (animals, plants, fungi, and
protists) store their DNA inside the cell
nucleus. - Prokaryotic organisms (bacteria and archae) have
no nucleus therefore, the DNA is found in the
cytoplasm.
23DNA Replication
- When a cell grows and divides, two new cells
result. - DNA replication is the process by which a cell
makes another copy of its DNA. - Base pairing rules and many enzymes make
replication possible.
24DNA Replication
- DNA replication is the process of copying a
double-stranded DNA molecule to form two
double-stranded molecules.
25DNA Replication
- Each DNA strand holds the same genetic
information therefore, both strands can serve as
a template for the reproduction of the
complementary strand. - The template strand is conserved in its entirety
and the new strand is assembled from nucleotides.
This is known as semiconservative replication.
26DNA Replication
- The resulting double-stranded DNA molecules are
identical. - DNA replication must happen before cell division
can occur.
27DNA Replication
- Helicases are enzymes that bind to the DNA and
separate the two strands of DNA. - DNA polymerase incorporates DNA nucleotides into
the new DNA strand. The nucleotides enter
according to the base pairing rules.
28DNA Replication
- In prokaryotic cells, this replication process
starts at only one place along the DNA molecule
(origin of replication). - In eukaryotic cells, the replication starts at
the same time along several different places of
the DNA molecule.
29DNA Replication
- Two new identical, double-stranded DNA molecules
are formed. - The new strands of DNA form on each side of the
old DNA strands.
30DNA Replication
- The exposed nitrogenous bases of the original DNA
serve as the pattern on which the new DNA is
formed. - Two double helices are formed with identical
nucleotide sequences. - A portion of the DNA polymerase molecule edits
the newly created DNA molecule and makes
corrections if needed.
31DNA Replication
32Repair of Genetic Information
- If an error or damage occurs to the DNA helix on
one strand, the pairing arrangement of
nitrogenous bases on the other undamaged strand
can be read. - This information is used to repair the damaged
strand.
33DNA Code
- DNA stores information.
- The order of the nitrogenous bases is the genetic
information that codes for proteins. - The nucleotides are read in sets of three.
- Each sequence of three nucleotides is a codeword
for a single amino acid. - The information to code one protein can be
thousands of nucleotides long.
34RNA Structure And Function
- Ribonucleic Acid (RNA) is important in protein
production. - RNAs nucleotides contain a ribose sugar whereas
DNAs nucleotides contain a deoxyribose sugar. - Ribose has an OH group and deoxyribose has an H
group on the second carbon atom.
35RNA Structure And Function
- RNA contains the nitrogenous bases Uracil (U),
guanine (G), cytosine (C), and adenine (A). - DNA is found in the cells nucleus, while RNA is
made in the nucleus and then moves out into the
cytoplasm of the cell.
36RNA Structure And Function
- DNA directs protein synthesis by using RNA.
- RNA is made by enzymes that read the protein
coding information in DNA. - RNA nucleotides pair with DNA nucleotides.
- RNA contains Uracil instead of Thymine so adenine
in DNA pairs with Uracil in RNA.
37Nucleic Acid Base Pairing Rules
DNA pairs with DNA DNA pairs with RNA RNA pairs with RNA
A pairs with T A pairs with U A pairs with U
T pairs with A T pairs with A U pairs with A
G pairs with C G pairs with C G pairs with C
C pairs with G C pairs with G C pairs with G
38Transcription
- Transcription is the process of using DNA as a
template to synthesize RNA. - The RNA polymerase enzyme reads the sequence of
DNA nucleotides and follows the base pairing
rules between DNA and RNA to build the new RNA
molecule.
39Transcription
- The two strands of the double stranded DNA
molecule are separated to expose the nitrogenous
bases. - The DNAs nitrogenous bases are read and paired
with the RNA nucleotides. - Only one strand of the DNA molecule is read (the
coding strand). The other strand is referred to
as the non-coding strand.
40Transcription
- Promoter sequences are specific sequences of DNA
nucleotides that RNA polymerase uses to find a
protein-coding region of DNA and to find out
which strand of DNA is the coding strand.
41Transcription
- Termination sequences are DNA nucleotide
sequences that indicate when RNA polymerase
should finish making an RNA molecule.
423 Types of RNA
- Messenger RNA (mRNA) carries the blueprint for
making the necessary protein. - Transfer RNA (tRNA) reads mRNA and brings in
the necessary amino acids. - Ribosomal RNA (rRNA) reads the mRNA and brings
in the necessary amino acids.
43Translation
- Translation is the process of using information
in RNA to direct protein synthesis. - mRNA is read in sets of three nucleotides called
codons.
44Translation
- A codon is a set of three nucleotides that codes
for a specific amino acid. - The ribosome is made up of proteins and ribosomal
RNA (rRNA). - The ribsome holds the mRNA in place and reads
its codons.
453 Phases of Translation
- Initiation
- Elongation
- Termination
46Initiation
- The small ribosomal subunit binds to the mRNA and
moves along until it reaches an AUG codon to
signal the beginning of translation. - Transfer RNA (tRNA) carries amino acids to the
mRNA complex.
47Initiation
- The anticodon portion of the tRNA interacts with
the mRNA to match the correct amino acid to the
codon in the mRNA nucleotide sequence. - The tRNA that binds to the AUG codon that signals
the beginning of translation carries the amino
acid methionine therefore, every protein begins
with this amino acid.
48Elongation
- The ribosome functions as an assembly line.
- New amino acids are carried by tRNA to the
corresponding mRNA segment. - The anticodon on tRNA matches with the codon on
mRNA. - The amino acid is then attached to the end of the
chain and the protein becomes elongated.
49Termination
- The ribosome will continue to add new amino acids
until a stop signal is reached on the mRNA
molecule. - The stop codon can be either UAA, UAG, or UGA.
50Termination
- When these codons are encountered, a release
factor enters the ribosome. The ribosomal
subunits release mRNA. - The mRNA can then either be reused or broken down
to stop protein production.
51Translation
52Nearly Universal Genetic Code
- The code for making protein from DNA is the same
for nearly all cells. - Bacteria, protists, plants, fungi, and animals
all use DNA to store their genetic information. - They all transcribe information in DNA to RNA.
- They all translate the RNA to synthesize protein
using a ribosome.
53Nearly Universal Genetic Code
- Almost all use the same three nucleotide codons
to code for the same amino acid. - In eukaryotic cells, transcription always occurs
in the nucleu, and translation always occurs in
the cytoplasm.
54Nearly Universal Genetic Code
- These similarities make it possible to use
bacteria to synthesize human proteins (i.e.
insulin). - Some viruses use RNA to store their genetic
information (retroviruses). HIV is an example of
this. Retroviruses use RNA to make DNA, which is
then used to make proteins.
55Gene Expression
- Gene expression occurs when a cell transcribes
and translates a gene. - Cells control which genes are used to make
proteins. - The different cell types in the human body are
due to which proteins the cell is producing.
56Controlling Protein Quantity
- An enzymes activity can be regulated by
controlling how much of that enzyme is made. - The cell controls how much mRNA is available for
translation, which in turn determines the
quantity of the protein produced.
57Controlling Protein Quantity
- Enhancer and silencer sequences affect the
ability of RNA polymerase to transcribe a
specific protein. - Enhancer sequences increase protein synthesis by
increasing transcription. - Silencer sequences decrease protein production by
decreasing transcription.
58RNA Degradation
- Cells regulate gene expression by limiting the
length of time that mRNA is available for
translation. - Enzymes in the cell break down mRNA.
59Mutations
- A mutation is any change in the DNA sequence of
an organism. - Errors during DNA replication can cause mutation.
- External factors can cause mutation
60Mutations
- Radiation, carcinogens, drugs, viruses.
- Not all mutations cause a change in the organism.
- If the mutation occurs away from the
protein-coding sequence of the DNA, it is
unlikely to be harmful to the organism.
61Silent Mutation
- A silent mutation is a change that does not
change the amino acids used to build a protein.
62Nonsense Mutation
- A nonsense mutation causes a ribosome to stop
protein synthesis by introducing a stop codon too
early. - This prevents the formation of functional
proteins.
63Missense Mutation
- A missense mutation causes the wrong amino acid
to be used in making a protein. - This will change the shape of the protein and
affect its active sites. - This can cause an abnormally functioning protein.
64Insertions And Deletions
- Some mutations involve larger spans of DNA than a
change in a single nucleotide. - An insertion mutation adds one or more
nucleotides to the normals DNA sequence.
65Insertions And Deletions
- This can add amino acids to the protein and
change its function. - A deletion mutation removes one or more
nucleotides. - This can delete amino acids from the protein and
change its function.