Presenting:
DNA and RNA
1
DNA stands for Deoxyribonucleic acid
1. It belongs to the class of biochemical
molecules known as nucleic acids.
2. It is made up of atoms of :
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorous
2
Importance of DNA
1. It carries genetic information from one generation
to the next.
2. DNA sequences create genes which then
determine inherited traits.
3. DNA can be easily copied during the creation of
new cells.
3
Where is DNA located?
Chromosome
DNA
double
helix
Histones
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Regents Practice Question #1
The diagram below represents levels of organization within a cell
of a multi-cellular organism.
The level represented by X is composed of
(1) four types of base subunits
(2) folded chains of glucose molecules
(3) twenty different kinds of amino acids
(4) complex, energy-rich inorganic molecules
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Regents Practice Question #1(Answer)
The diagram below represents levels of organization within a cell
of a multi-cellular organism.
The level represented by X is composed of
(1) four types of base subunits
(2) folded chains of glucose molecules
(3) twenty different kinds of amino acids
(4) complex, energy-rich inorganic molecules
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Regents Practice Question # 2
Which model best represents the relationship between a
cell, a nucleus, a gene, and a chromosome?
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Regents Practice Question # 2 (Answer)
Which model best represents the relationship between a
cell, a nucleus, a gene, and a chromosome?
Correct Answer
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Regents Practice Question # 3
Which diagram represents the relative sizes of the
structures listed below?
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Regents Practice Question # 3 (Answer)
Which diagram represents the relative sizes of the
structures listed below?
Correct
Answer
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Structure of DNA
1. DNA is a long molecule made up of units called
nucleotides.
2. Each nucleotide is made up of three basic
parts:
•
•
•
5-carbon sugar (deoxyribose)
phosphate group
nitrogenous base
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N
U
C
L
E
O
T
I
D
E
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There are 4 kinds of Nitrogenous bases
Adenine
phosphate
Guanine
Cytosine
5 carbon sugar
Thymine
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DNA is a double helix in which two strands
are wound around each other.
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
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Complimentary Base Pairing
1. The two DNA strands are held together at the
nitrogenous bases by weak hydrogen bonds. The
bases will always pair up in the following way:
•Adenine bonds to Thymine A-T
•Cytosine bonds to Guanine C-G
2. Francis
Crick and James Watson published the
structure of the DNA molecule in 1953.
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Check for Understanding of DNA Structure
1. What is the name of the
sugar?
2. What is the symbol used to
represent the sugar?
3. Name the 4 nitrogenous
bases.
4. Name the complimentary
base pairs.
5. What type of bonds hold the
bases together?
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Check for Understanding of DNA Structure (Answers)
1.What is the name of the sugar? deoxyribose
1. What is the symbol used to represent the sugar?
3. Name the 4 nitrogenous bases.
adenine, thymine cytosine, guanine
4. Name the complimentary base pairs.
adenine – thymine
cytosine - guanine
5. What type of bonds hold the bases together?
hydrogen bonds
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When will DNA replication occur?
•DNA replication is the process of copying a DNA
molecule
•DNA must replicate during cell division so that the
genetic information can be passed to the daughter
cells.
•In order to direct cell functions DNA must
replicate itself and send the information out of the
nucleus because the DNA is not permitted to leave
the nucleus.
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DNA Replication 1. The DNA separates into 2
strands. It unzips itself with
Process
the help of an enzyme
called DNA polymerase.
2. Each parent (old) strand
serves as a template
(model) for making a new
DNA strand complimentary
to itself.
3. Replication results in 2
daughter strands each
consisting of an old DNA
strand and a new DNA
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strand.
Your Turn! DNA Replication
Following base pairing rules, create a new DNA molecule
A T
A T
A T
T A
T A
T A
CG
C G
GC
G C
Parent New
DNA Polymerase
Unzips the DNA
+
C G
G C
New
Parent
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Regents Practice Question # 4
Several structures are labeled in the diagram of
a puppy shown below.
Every cell in each of these structures contains
(1) equal amounts of ATP
(2) identical genetic information
(3) proteins that are all identical
(4) organelles for the synthesis of glucose
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Regents Practice Question # 4 (Answer)
Several structures are labeled in the diagram of
a puppy shown below.
Every cell in each of these structures contains
(1) equal amounts of ATP
(2) identical genetic information
(3) proteins that are all identical
(4) organelles for the synthesis of glucose
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Regents Review Question # 5
Mustard gas removes guanine (G) from DNA.
For developing embryos, exposure to mustard
gas can cause serious deformities because
guanine
(1) stores the building blocks of proteins
(2) supports the structure of ribosomes
(3) produces energy for genetic transfer
(4) is part of the genetic code
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Regents Review Question # 5 (Answer)
Mustard gas removes guanine (G) from DNA.
For developing embryos, exposure to mustard
gas can cause serious deformities because
guanine
(1) stores the building blocks of proteins
(2) supports the structure of ribosomes
(3) produces energy for genetic transfer
(4) is part of the genetic code
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Importance of Protein
1. Protein is found everywhere in
your body.
2. Every single cell, tissue, muscle
and bone contains protein.
Protein is essential for providing
bone and muscle strength,
endurance and immunity.
3. It is estimated that the human
body may contain over two
million proteins.
Sickle Cell Disease
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Protein Synthesis
1. Genes control the production of proteins which occurs
on the ribosomes.
2. Each gene directs the production of a specific protein
or special proteins such as hormones and enzymes.
3. The DNA can’t leave the nucleus but it needs to send
instructions to the ribosome so proteins can be made.
4. The DNA sends a messenger out to the ribosome that
carries the instructions for making the proteins.
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What is RNA ?
1. RNA is the messenger that carries the
instructions to the ribosome so proteins
can be made.
2. It is very similar to a DNA molecule but
yet different enough that it can cross
the nuclear membrane without being
recognized as DNA.
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Structure of RNA
1. The sugar in the nucleotide is ribose.
2. It is single-stranded.
3. It has uracil for a nitrogenous base instead of
thymine.
4. Complimentary base pairs are:
Cytosine – Guanine
C-G
Adenine – Uracil
A-U
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Making a Protein starts with Transcription
Transcription is the name given to the process where a DNA
molecule makes the messenger RNA molecule in the nucleus.
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
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Translation happens when mRNA arrives at the ribosome
1. During translation, the cell uses information from mRNA to
produce proteins that are built from amino acids.
2. Two other types of RNA are involved:
•
•
Transfer RNA ( tRNA) brings amino acids to the ribosome
Ribosomal RNA (rRNA) makes up the ribosome
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Translation from RNA into Protein
Nucleus
Transcription of
Messenger RNA
Phenylalanine
tRNA
Methionine
Lysine
mRNA
Translation by Transfer RNA
Ribosome
mRNA
Start codon
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The Genetic Code
1. Codons are located on the mRNA
2. A codon consists of three nitrogenous bases that code for a
single amino acid that is to be added to the growing protein
chain.
3.There are just 22 different amino acids that exist.
.
Example of codons:
AUG is the start codon that gets the process going
UUC codes for Phenylalanine
AAA codes for Lysine
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Regents Practice Question # 6
The diagram below shows some of the steps
in protein synthesis. The section of DNA
being used to make the strand of mRNA is
known as a
(1) carbohydrate
(2) ribosome
(3) gene
(4) chromosome
37
Regents Practice Question # 6 (Answer)
The diagram below shows some of the steps
in protein synthesis. The section of DNA
being used to make the strand of mRNA is
known as a
(1) carbohydrate
(2) ribosome
(3) gene
(4) chromosome
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What are Mutations?
1. Mutations are changes in the genetic
material of the cell. (DNA)
2. Mutations can be good, bad or neutral.
3. There are 3 different types of
mutations:
•substitutions
•insertions
•deletions
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Substitutions
Substitutions occur when one
nitrogenous base is substituted in place
of another one.
Result:
1.Most likely there will be no
change in the protein made.
2.This mutation only affects one
amino acid in the long
sequence of a protein.
3. It is the least harmful.
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Example of a Substitution:
THECATSAWTHEDOG
THE CAT SAW THE DOG
THE BAT SAW THE DOG
THE CAT SAW THE HOG
THE CAT SAT THE DOG
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Sickle Cell Anemia is a result of a
Substitution Mutation
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Insertions
Insertions occur when one extra
nitrogenous base is added into the DNA
Result:
sequence.
1. BAD
2. All the nitrogenous bases after
the insertion will be regrouped
into different codons.
3. The protein made will be
nonfunctional.
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Example of an insertion:
THECATSAWTHEDOG
THECCATSAWTHEDOG
The letter C was inserted
THE CCA TSA WTH EDO G
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Deletions
Deletions occur when one nitrogenous
base is missing from the sequence.
Result:
1. BAD
2. All the nitrogenous bases
after the deletion will be
regrouped into different
codons.
3. The protein made will be
nonfunctional.
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Example of a Deletion
THECATSAWTHEDOG
THCATSAWTHEDOG
The letter E was missing
THC ATS AWT HED OG
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Regents Practice Question # 7
The diagram below shows a normal gene sequence and three
mutated sequences of a segment of DNA. Which row in the chart
below correctly identifies the cause of each type of mutation?
49
Regents Practice Question # 7
The diagram below shows a normal gene sequence and three
mutated sequences of a segment of DNA. Which row in the chart
below correctly identifies the cause of each type of mutation?
Correct
50
. Regents
Practice Question # 8
The shape of a protein is most directly
determined by the
(1) amount of energy available for synthesis
of the protein
(2) kind and sequence of amino acids in the
protein
(3) type and number of DNA molecules in a
cell
(4) mistakes made when the DNA is copied
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Regents Practice Question # 8(Answer)
The shape of a protein is most directly
determined by the
(1) amount of energy available for synthesis
of the protein
(2) kind and sequence of amino acids in the
protein
(3) type and number of DNA molecules in a
cell
(4) mistakes made when the DNA is copied
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Regents Review Question # 9
Which row in the chart below best describes
what happens when some DNA bases are
deleted from genes ?
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Regents Review Question # 9 (Answer)
Which row in the chart below best describes
what happens when some DNA bases are
deleted from gene?
Correct
54
Regents Review Question # 10
Which sequence best represents the
relationship between DNA and the traits of
an organism?
55
Regents Review Question # 10 (Answer)
Which sequence best represents the
relationship between DNA and the traits of
an organism?
Correct
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What causes mutations?
There are two ways in which DNA can
become mutated:
1. Mutations can be inherited.
• Parent to child
2. Mutations can be acquired
• Environmental damage
• Mistakes when DNA is copied
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What are Mutagens?
Mutagens are environmental factors that
cause mutations. They include but are not
limited to:
1.High temperatures
2.Toxic chemicals (pesticides)
3.Radiation ( nuclear and solar)
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Regents Review Question # 11
A chemical known as 5-bromouracil causes a
mutation that results in the mismatching of
molecular bases in DNA. The offspring of
organisms exposed to 5-bromouracil can have
mismatched DNA if the mutation occurs in
(1) the skin cells of the mother
(2) the gametes of either parent
(3) all the body cells of both parents
(4) only the nerve cells of the father
60
Regents Review Question # 11 (Answer)
A chemical known as 5-bromouracil causes a
mutation that results in the mismatching of
molecular bases in DNA. The offspring of
organisms exposed to 5-bromouracil can have
mismatched DNA if the mutation occurs in
(1) the skin cells of the mother
(2) the gametes of either parent
(3) all the body cells of both parents
(4) only the nerve cells of the father
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Regents Review Question # 12
Researchers have found that formaldehyde and
asbestos can alter DNA base sequences. Based
on this research, the use of these chemicals has
been greatly reduced because they
(1) may act as fertilizers, increasing the growth of
algae in ponds
(2) have been replaced by more toxic compounds
(3) are capable of causing mutations in humans
(4) interfere with the production of antibiotics by
white blood cells
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Regents Review Question # 12 (Answer)
Researchers have found that formaldehyde and
asbestos can alter DNA base sequences. Based
on this research, the use of these chemicals has
been greatly reduced because they
(1) may act as fertilizers, increasing the growth of algae
in ponds
(2) have been replaced by more toxic compounds
(3) are capable of causing mutations in humans
(4) interfere with the production of antibiotics by white
blood cells
63
Regents Review Question # 13
A boy inherits genes for tallness, but his growth is
limited as a result of poor nutrition. This is an
example of
(1) an inherited disorder
(2) environmental influence on gene expression
(3) expression of a hidden trait
(4) a characteristic controlled by more than one
pair of genes
64
Regents Review Question # 13 (Answer)
A boy inherits genes for tallness, but his growth is
limited as a result of poor nutrition. This is an example
of
(1) an inherited disorder
(2) environmental influence on gene expression
(3) expression of a hidden trait
(4) a characteristic controlled by more than one pair of
genes
65
Regents Review Question # 14
The sickle-cell trait is an inherited condition resulting
from the presence of abnormal molecules of the protein
hemoglobin in red blood cells. A person with the sicklecell trait may have a child with the same condition
because the child receives from the parent
(1) abnormal red blood cells
(2) abnormal hemoglobin molecules
(3) a code for the production of abnormal hemoglobin
(4) a code for the production of abnormal amino acids
66
Regents Review Question # 14 (Answer)
The sickle-cell trait is an inherited condition resulting
from the presence of abnormal molecules of the protein
hemoglobin in red blood cells. A person with the sicklecell trait may have a child with the same condition
because the child receives from the parent
(1) abnormal red blood cells
(2) abnormal hemoglobin molecules
(3) a code for the production of abnormal hemoglobin
(4) a code for the production of abnormal amino acids
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Regents Review Question # 15
Which situation would most likely produce a gene
mutation in a squirrel?
(1) The squirrel stops using its claws for digging.
(2) The squirrel is exposed to radiation for several days.
(3) Oak trees gradually become less common.
(4) The weather becomes wetter for a short period of
time.
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Regents Review Question # 15 (Answer)
Which situation would most likely produce a gene
mutation in a squirrel?
(1) The squirrel stops using its claws for digging.
(2) The squirrel is exposed to radiation for several days.
(3) Oak trees gradually become less common.
(4) The weather becomes wetter for a short period of
time.
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