BIOLOGY

GENETICS INC. DISEASE AND STEM CELLS

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POLYDACTYLISM

-CAUSED BY A DOMINANT GENE / ALLELE

-CAN BE INHERITED FROM ONE PARENT

- P = Polydactylism (DOMINANT)

- p = normal (RECESSIVE)

EG 

MUM = pp (HOMOZYGOUS RECESSIVE)

DAD = Pp (HETEROZYGOUS)

PUNNETT SQUARE HERE:

                                                      50% CHANCE CHILD IS NORMAL

                                                      50% CHANCE CHILD IS POLYDACTILE

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CYSTIC FIBROSIS

-AFFECTS THE LUNGS AND PANCREAS

-ORGANS (INCLUDING REPRODUCTIVE SYSTEM) ARE CLOGGED UP BY A THICK STICKY MUCAS

-CF IS CAUSED BY A RECESSIVE ALLELE FROM BOTH PARENTS

C = DOMINANT       c = RECESSIVE

PUNNETT SQUARE HERE:

PARENTS ARE KNOWN AS CARRIERS

IF BOTH PARENTS ARE HETEROZYGOUS, OFFSPRING DOES NOT HAVE CF

One in 25 carry the CF gene in the UK, but most people are unaware.

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HUNTINGTON'S DISEASE

-CAUSED BY ONE DOMINANT GENE

-CAUSES DEATH AT MIDDLE AGE

H = HUNTINGTONS      h = NO HUNTINGTONS

MUM = hh DAD = Hh

PUNNETT SQUARE HERE:          

                                           50% CHANCE OF INHERITING DISEASE

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SCREENING FOR GENETIC DISEASES PROS/CONS

FOR

  • 'Healthier' humans
  • Would not want children to suffer
  • Could prepare yourself
  • May not want to pass onto offspring
  • Able to live life to the fullest

AGAINST

  • Unethical - embryo's have not given consent
  • Religious beliefs - life starts at conception and is sacred
  • Screening is expensive
  • Would not want to worry that your children had the disease
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CURING GENETIC DISEASES

- NO WAY AT THE MOMENT OF CURING GENETIC DISORDERS BUT THOUGHTS THAT GENETIC ENGINEERING COULD HELP

- TRIED CUTTING OUT FAULTY ALLELES AND REPLACING THEM WITH HEALTHY ONES IN PEOPLE WITH CF BUT SO FAR IT HASN'T CURED ANYONE

- IT IS POSSIBLE TO SCREEN DURING PREGNANCY OR IVF FOR INHERITED GENETIC DISEASES HOWEVER THIS RAISES MANY ETHICAL ISSUES, ESPECIALLY IF AFTER TESTING PEOPLE CHOOSE WHETHER OR NOT TO HAVE A FAMILY

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THE FUTURE OF STEM CELL RESEARCH

  • Some ethical concerns have been removed after the discovery of umbilical cord blood containing stem cells
  • Therapeutic cloning could be very useful but is proving very difficult

     - this involves using cells from an adult to produce a cloned early embryo of themselves.

  • There are hopes that stem cells will change medicine in the future

ADVANTAGES: - can help diseases by growing new organs when needed, help save lives

DISADVANTAGES: - ethical issues, slow progress, unaware of potential problems that could occur, religious issues, expensive to set up labs/equipment

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STEM CELLS

-UNSPECIALISED CELLS

-THAT CAN DIFFERENCIATE INTO MANY DIFFERENT TYPES OF CELL WHEN NEEDED

-FOUND IN EMBRYOS  AND ADULT BONE MARROW AND UMBILICAL CORD BLOOD

-THE EMBRYO FORMS A HOLLOW BALL OF CELLS AND THE INNER CELLS OF THIS BALL ARE THE STEM CELLS

-POSSIBLITY OF GROWING ACTUALY ORGANS IN THE FUTURE

-ADULTS HAVE SOME STEM CELLS REMAINING IN THEIR BONE MARROW, BRAIN, OVARIES ETC

-THEY ARE ONLY NEEDED IF TISSUE IS DAMAGED / INJURED / DISEASED

-SCIENTISTS US THEM TO REPAIR SPINAL CORDS, HEART VALVES, INSULIN PRODUCING CELL (DIABETICS)

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