2.1.3 dna replication
✅
what is dna replication- Cells divide to produce more cells during growth
or repair of tissues.
The two daughter cells produced by cell division are genetically identical to
the parent cell and to each other.
✅
what happens to cells after dna replication- A cell’s chromosomes are
usually long, thin strands.
Just before the cell divides, the chromosomes become shorter, thicker and
more visible.
Each chromosome duplicates and becomes two strands, each one called a
chromatid. The two chromatids are joined at the centromere.
✅
how does DNA replicate- Helicase enzymes separate the two DNA
strands. The point at which the two
strands are separated is called the replication fork.
Each strand is kept apart by single-stranded binding (SSB) proteins.
DNA polymerase reads the sequence and adds free-floating DNA
nucleotides that have complementary bases to form new strands. DNA
polymerase catalyses the joining of nucleotides with phosphodiester bonds
DNA polymerase reads the parent strand in a 3’ to 5’ direction and builds
the leading strand in a 5’ to 3’ direction, towards the replication form.
This is a continuous process.
In contrast, the lagging strand is built away from the replication fork, but still
in a 5’ to 3’ direction. It grows in a discontinuous fashion – in small sections
called Okazaki fragments
The Okazaki fragments are joined together by DNA ligase
The DNA helix continues to unwind and separate. The leading strand
grows
continuously towards the replication fork. At the same time, the lagging
strand grows discontinuously, away from the fork.
There are multiple replication forks along the entire length of the DNA
molecule which speeds up replication. Replication occurs in both directions
✅
what is dna replication- Cells divide to produce more cells during growth
or repair of tissues.
The two daughter cells produced by cell division are genetically identical to
the parent cell and to each other.
✅
what happens to cells after dna replication- A cell’s chromosomes are
usually long, thin strands.
Just before the cell divides, the chromosomes become shorter, thicker and
more visible.
Each chromosome duplicates and becomes two strands, each one called a
chromatid. The two chromatids are joined at the centromere.
✅
how does DNA replicate- Helicase enzymes separate the two DNA
strands. The point at which the two
strands are separated is called the replication fork.
Each strand is kept apart by single-stranded binding (SSB) proteins.
DNA polymerase reads the sequence and adds free-floating DNA
nucleotides that have complementary bases to form new strands. DNA
polymerase catalyses the joining of nucleotides with phosphodiester bonds
DNA polymerase reads the parent strand in a 3’ to 5’ direction and builds
the leading strand in a 5’ to 3’ direction, towards the replication form.
This is a continuous process.
In contrast, the lagging strand is built away from the replication fork, but still
in a 5’ to 3’ direction. It grows in a discontinuous fashion – in small sections
called Okazaki fragments
The Okazaki fragments are joined together by DNA ligase
The DNA helix continues to unwind and separate. The leading strand
grows
continuously towards the replication fork. At the same time, the lagging
strand grows discontinuously, away from the fork.
There are multiple replication forks along the entire length of the DNA
molecule which speeds up replication. Replication occurs in both directions
