DNA replication Flashcards
what is DNA rep
As part of a cell’s preparation for cell division, the cell copies its entire genetic compliment by duplicating each chromosome. The resulting molecules are identical to the original DNA molecule and also to each other
importance of DNA replication
assists in the inheritance process by transfer of the genetic material from one generation to another.
process of DNA rep
To do this the DNA that runs the full length of each chromosome replicates producing two identical copies of DNA, that now form the two sides of a duplicated chromosome (called sister chromatids). The two chromatids have matching identical copies of the original DNA molecule.
nuclear division process of meiosis
During the first division (Division I) the pairs of homologous (matching) chromosomes separate. During the second division (Division II) the sister chromatids separate.
what is meiosis
Meiosis is a nuclear division process that occurs during sex cell formation in the gonads. The daughter cells produced are haploid (have 1 set of chromosomes).
what is involved in meiosis
it produced genetically different daughter cells. These divisions result in four ‘daughter’ cells (rather than the two daughter cells produced by mitosis). Each of these four daughter cells contains only half as many chromosomes as the original ‘parent cell’ (Daughter cells are haploid)
what is mitosis
is a nuclear division process that produces normal body cells during growth, repair and replacement. The cells produced are diploid (have 2 sets of chromosomes). Mitosis is the name given to the nuclear division process that occurs during growth, repair and replacement of somatic cells.
nuclear division process of mitosis
prophase, metaphase, anaphase, telephase. only occurs once.
what is involved in mitosis
Mitosis results in the production of two ‘daughter’ cells that are genetically identical to each other and to their ‘parent’ cell. Both daughter cells are diploid and have the same number of chromosomes as each other and also the original parent cell.
prophase
nuclear membrane disintegrates, spindle fibres begin to form as centrioles move to poles (parts of centromeres attach to separate spindle fibres)
first step of DNA rep
the ‘unzipping’ of this double helix via H bonds breaking between complimentary base pairs. (Each original side (or strand) of the DNA molecule now serves as a template that directs the production of new complementary strands.
second step of DNA rep
free floating DNA nucleotides in the nucleus attach to specific complimentary bases along both sides of the unzipped original molecule according to the base-pairing rules.(new DNA chains are formed)
3rd step of DNA rep
the double stranded DNA molecules that have been formed rewind / twist up, (each copy of DNA consisting of one ‘old’ strand and one ‘new’ strand).
