DNA Replication Precedes Cell Division chapter 8.2 Flashcards
The 3 ways cell divide
- Binary fission
- Mitosis
- Meiosis
Before the the procession begin what process must first take place
a cell must first duplicate its entire genome ( all of the cell’s genetic material.
—REPLICATION
DNA replication
a cell duplicate its entire genome ( all of the cell’s genetic material before cell division
. The cell copies all of its information letter by letter. ( all of the encoding instruction)
Code
a systematic collection of rules and instructions
Encode
be responsible for producing a substance or form with inherit instructions or code
Why is DNA Replication SEMICONSERVATIVE
Semiconservative refers to the simp lied view of Dna replication
- DNA strands unwind and separate
- Each exposed strand ( parent strand)is a template that attracts and binds with complementary nucleotides, a, t, c, g
- The process ends with two identical double stranded DNA molecules.
Each double strand consist of a parent strand and a daughter strand. they in essence conserved half of the original molecule
?ist the enzymes/ proteins that aid in DNA Replication
1.Helicase
2. Binding proteins
3. Primase
4. DNA Polymerase
5. Ligase
How Bob Prime Dirty Polymer Linoleum
Helicase
Unwinds the double helix and separate strands
Binding Proteins
Stabilize each strand of the unwounded double helix.
Prevent single strands from rejoining
Primase
Add a short RNA primer to each template strand
2. The RNa Primer attracts the DNA Polymerase enzyme
DNA Polymerase
- Adds DNA nucleotides to the RNA primer
- Proofreads by checking and replacing incorrect bases just added
- As the new DNA Strands grow, hydrogen bonds form between complementary bases
- Can only build to an existing strand, therefore Primase puts down a RNA primer to facilitate this)
- Can only build on the 3’ end, NEVER 5’ end
What happens to the RNA primer after Dna nucleotides are matched to it
Enzymes remove the primer and match Dna nucleotides to the newly formed Dna Strand
leading strand
Since DNA Polymerase can only add nucleotides to the 3’ end only one strand is continuous ( leading strand) extend outwards
lagging strand
The opposite Dna strand that gains dna nucleotide on the RNA primer extending inwards (discontinuous)
. Replication occurs in pieces
Okazaki Fragments
On a lagging strand Rna attract DNA bases in pieces. these pieces are known as Okazaki Fragments
The steps of DNA Replication
- HELICASE unwinds double helix
- BINDING PROTEIN prevent single strand from rejoining
- PRIMASE adds short RNA primer to template strand
- direction always 5’-3’
- DNA POLYMERASE : adds DNA nucleotides to the RNA Primer at the start of each DNA to be replicated.
. also proofreads and replaces incorrect bases
- Leading ( continuous) strand synthesis continues in a 5’ to 3’
- Discontinuous synthesis produces Okazaki fragments on the lagging strand
- Enzymes replaces RNA primer with Dna
- Ligase seals sugar-phosphate backbone.
Ligase
Joins Okazaki fragments and seals nicks in the sugar phosphate backbone
How long does it take to copy Dna nucleotides in a human cell’s 46 chromosomes
8 to 10 hours
Mutation
is any change in a cell’s DNA Sequence
Why does require a great deal of energy
because a large organized nucleic acid contains much more potential energy than do many individual nucleotides.
. Energy is required to synthesize nucleotides and to create the covalent bonds that join them toghetherin the new strands of DNA
. Many of the enzymes that participate in DNA replication, including Helicase and Ligase also require energy in the form of ATP to catalyze their reactions
Why does DNA replicate
DNA replicates before a cell divides to give a complete set of genetic instructions to each daughter cell.
What is semiconservative replication
Semiconservative replication means that only one strand of a DNA molecule is newly formed. The other strand is original DNA from the parent cell.
What are the steps of DNA replication
The helicase enzyme unwinds and separates a double-stranded DNA molecule; the primase enzyme forms a short stretch of complementary RNA on each DNA template; starting at the end of the RNA primer, DNA polymerase adds DNA nucleotides that are complementary to the template strand, proofreading and correcting errors as it goes; RNA primers are removed; on the lagging strand, the enzyme ligase joins fragments of DNA.
What is the role of RNA primers in DNA replication
The RNA primer is added to the start of the DNA segment being replicated and acts to attract the DNA polymerase, which can only add nucleotides to an existing strand
What happens if DNA polymerase fails to correct an error?
A mutation occurs
