DNA Flashcards
the main functions of dna (5)
- carrying genetic instructions (codes)
- maintaining structure and regulation
- protein synthesis
- passing on hereditary material
- replication
the importance of dna replicationin living organisms (6)
- in cell division to produce new cells and tissues
- to maintain chromosome number and ensure that the same genes are in every cell
- to help with growth through protein synthesis
- to regenerate damaged or ageing tissues through mitosis
- for production of spores and vegetative growth in asexual reproduction
- to produce gametes through meiosis in sexual reproduction
the cell cycle
in the cell cycle cells grow and increase in size (interphase) and then divide to form daughter cells (mitosis)
the cell cycle: first gap phase (g1)
cell performs its normal metabolic functions and grows until its appropriate surface area to volume ration is reached
the cell cycle: second gap phase (s)
the dna content of the nucleus duplicates into two sets
the cell cycle: second gap phase (g2)
the cell produces microtubules to separate the chromosomes during mitosis
the cell cycle: mitosis
the chromosomes separate into two sets
the cell cycle: cytokinesis
splits the cytoplasm into two daughter cells that now enter the g1 phase of growth - the start of the cycle
dna replication: unwind and unzip
- an enzyme called helicase breaks weak h bonds between base pairs, separating the two strands of the dna molecule of the parent cell
dna replication: template forms
- each strand acts as a template for the formation of a new complementary strand of dna, forming two sets of dna
dna replication: nucleotides pair up
- free nucleotides in the nucleus pair up with the bases on the exposed single dna strands. an enzyme called dna polymerase matches the bases on the template with the free nucleotides through complementary nitrogenous base pairing
dna replication: bases pair up
pyrimidine bases (thymine & cytosine) pair with purine bases (adenine & guanine)
dna replication: helix forms
there are now two identical molecules of dna, both of which are double-stranded. each one twists to form a helix
uses of dna replication in biotechnology (5)
- cloning cells in tissue culture
- gene splicing to produce resistance to certain diseases, and to manufacture antibiotics, insulin, growth hormones and gmos
- dna profiling and forensics
- paternity and maternity testing
- genetic counselling of parents to infomr them about inheritable disorders and conditions
the technique of dna profiling (5)
1 smaple dna is extracted and put into a test tube
2 the dna is cut into fragments using a restriction enzyme
3 the enzyme cuts every person’s dna differently, as long as it is dna from a region of sequences unique to an individual. electrophoresis is used to show the differences in size
4 the dna is mixed with a fluorescent substance to show the bands under ultraviolet light
5 the band can be compared with a known dna sample
