DNA + Reproduction

Question 1

Describe how the developing embryo is supplied with nutrients

Answer 1

Placenta develops by an umbilical cord
Supplies nutrients such as glucose, amino acids, salts oxygen from mother’s blood
Via diffusion from high to low concentration

Question 2

Describe role of placenta in the development of an embryo

Answer 2

Diffusion of nutrients such as glucose, amino acids
Allows embryo to respire and make proteins via protein synthesis
Remove CO2 and urea

Question 3

Describe the function of the amniotic fluid surrounding the fetus

Answer 3

Protects foetus
Shock absorber and cushions foetus

Question 4

Describe the process of meiosis

Only used to produce gametes
Used for sexual reproduction
Halves number of chromosomes - produces haploid cells in humans

Answer 4

Parent cell grows
DNA replicates forms 2 copies of each chromosome
Homologous pairs of chromosomes join together
And exchange sections of DNA
Homologous pairs of chromosomes are pulled apart
Cell divides
Chromatids separate
Cell divides again

Question 5

Describe the process of mitosis

Occurs throughout human body and plants
Used for asexual reproduction (cloning)
Same chromosome number - produces diploid cells in humans

Answer 5

Cell grows
DNA replicates forms 2 copies of each chromosome
Chromosomes line up attach
Chromatids are pulled apart to opposite ends of the cell
Cytoplasm and cell membrane divide form two identical cells

Question 6

Describe the stages by which a bacterium can be genetically modified to produce
large amounts of a named human protein

Answer 6

Locate insulin gene on chromosome
Cut gene from rest of chromosome using DNA restriction enzyme
Remove plasmid from bacterium (E.coli) and cut open with SAME restriction enzyme
Produces sticky ends
DNA ligase enzyme forms bonds between nucleotides make single piece of DNA
Plasmid = recombinant DNA
Plasmid carrying human DNA is referred to as a vector