Download DNA Base Pairing and Replication

Replication,
Transcription and
Translation
Biology
Powerpoint #2 – Chapter 12
Mr. Velekei
Vocabulary
10)
11)
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DNA Polymerase
DNA Replication
Semi-Conservative
Warm Up: Base Pairing
1.
A C C T GA
2.
G C
T
G
A
AG
3. Describe what a double helix would
look like untwisted:

Ladder, with bases for steps
4. What is the DNA
‘backbone’ made of?
Phosphorous
and Sugar

DNA Replication
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
1. What is DNA replication?
Making a copy of DNA
 DNA replication is when DNA
polymerase (an enzyme) opens
the DNA molecule and matches
complimentary bases to each
base.

Mitosis with Replication
2
2
2
Makes 2 Identical Cells
Mitosis without Replication
1
2
Makes 2 Different cells with
half as much DNA
1
3. Why is DNA replication important for
cells and multicellular organisms?
Replication allows cells to divide
Forming cells that are genetically
identical to the original
DNA Replication
New strand
Original
strand
DNA
polymerase
Growth
DNA
polymerase
Growth
Replication
fork
Replication
fork
New strand
Original
strand
Nitrogenous
bases
4. When does DNA Replication occur?
After the cell grows
big enough to divide,
during interphase, the
“S” phase
5. What is a chromosome?
A chromosome is DNA that is
twisted up very tightly around
histones
6. What is DNA Polymerase?

Principal enzyme in DNA replication;
adds nucleotides to growing strand
of DNA and proofreads new strand
of DNA
7. Draw a picture of a Chromosome
before and after DNA replication
8. Drawings of the 3 steps of DNA
Replication
DNA
Polymerase
9. Explain why DNA replication is considered
‘semi-conservative?

In the new DNA created, one
strand is from the original,
and one is a new one.
Semi = part of
Conserve = save
Transcription
Biology
Powerpoint #2 – Chapter 12
Mr. Velekei
Vocabulary
13)
14)
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16)
17)
Exon
Intron
RNA Polymerase
Transcription
Uracil
RNA
Where is DNA stored?
Nucleus
______________________
 What organelle makes proteins?
Ribosomes
______________________
 Where are proteins made?
Cytoplasm
______________________

What problem might this pose?

DNA can not take directions for making
proteins to the ribosomes.
How does RNA solve this problem?

RNA is a disposable copy of DNA
that can leave the nucleus
B. RNA’s structure is very similar to the structure of
DNA except for 3 major differences:
1.
RNA has ribose sugar instead
of deoxyribose
2. RNA is single-stranded
3. RNA has uracil (U) instead of
thymine (T)
DNA: AGTCCTTTAGT
RNA: AGUCCUUUAGU
There are three main types of RNA:
1. Ribosomal RNA (rRNA)
2. Transfer RNA
(tRNA)
3. Messenger RNA (mRNA)
III. Transcription
A.
Transcription: Producing RNA by copying part of
the DNA’s nucleotide sequence
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA
polymerase
DNA
RNA
B.
Describe the process of transcription using drawings.
1. RNA Polymerase rips
open the DNA double
helix
2. RNA polymerase grabs
bases and lines them up
with the original DNA
strand
3. Half of the DNA is
copied into a strand of
mRNA, then the DNA
strand closes,
hydrogen bonds
reform
C. How does RNA polymerase know
where to start?
Starts when it finds
a “promoter”
(specific base
sequence)
Found near the
beginning of a
gene sequence
D. Describe the process of RNA editing



RNA editing is a process that occurs in
the nucleus.
It removes introns “intervening
sequences” and leaves mRNA with only
the exons “expressed sequences.”
After editing a cap and tail are attached
and the mRNA is ready to enter into the
cytoplasm.
Translation
Biology
Powerpoint #2 – Chapter 12
Mr. Velekei
Vocabulary
18)
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Anticodon
‘AUG’
Codon
Polypeptide
‘Stop’ Codon
Translation
IV. Translation
A.
B.

Proteins are long chains of amino acids.
Codon: 3 consecutive nucleotides that
“code” for a specific amino acid.
What is the universal “start” codon:


AUG
What are the three “stop” codons?
 UGA, UAA, UAG
The Genetic Code
The Genetic Code
C. Use the genetic code below to translate
the following mRNA sequences:
mRNA:
AUGUAACGGGCAUUUUAA
1.
mRNA:
UCCAUGGAAGUGAUUCCAUAA
2.
mRNA:
CCAUGUGUCCCCAAUGAAAA
3.
C. Use the genetic code below to translate
the following mRNA sequences:
mRNA:
AUGUAUCGGGCAUUUUAA
1.
Methionine (START), Tyrosine, Arginine, Alanine, Phenylalanine, STOP.
mRNA:
UCCAUGGAAGUGAUUCCAUAA
2.
Serine, Methionine, Glutamic Acid, Valine, Isoleucine, Proline, STOP
mRNA:
CCAUGUGUCCCCAAUGAAAA
3.
Methionine, Cysteine, Proline, Glutamine, STOP, Lysine
D. Translation:
The decoding of
RNA into a
polypeptide
chain (protein)
The Central Dogma of
Biology is:
DNA  RNA  protein
E.
Where does the first step
take place? Nucleus
Where does the second
step take place?
Cytoplasm
F. What is the job of tRNA during translation? Bringing
amino acids to the ribosomes and match them up
with the correct base on mRNA.
What is an anticodon? The three bases on a tRNA that
match with the mRNA codons.
G. What is the role of the
ribosome during
translation? It is the site of
protein assembly
H.
1) mRNA is transcribed in the nucleus then
travels to the cytoplasm
2) Ribosome grabs mRNA. tRNA brings amino acids
to the ribosome
3) tRNA matches with complimentary mRNA.
Ribosome makes peptide bond between amino
acids, and breaks the bond between tRNA and
amino acid.
4) Peptide chain continues to grow until ribosome
reaches a stop codon
Protein is complete.