DNA mutations and stem cells

Question 1

describe substitution of bases

Answer 1

replacement of a base by a different base
mis sense = incorrect amino acid inserted
nonsense = stop codon produced early
silent = same amino acid coded for as code is degenerate

Question 2

describe deletion

Answer 2

base is deleted causes frameshift
alters all following triplet codes
incorrect codons means incorrect amino acid sequence
incorrect amino acid sequence = incorrect h ionic and disulphide bonds = incorrect tertiary structure = non functional enzyme
no enzyme substrate complexes form

Question 3

what are the other types of gene mutation

Answer 3

addition- extra base inserted same affect as deletion
duplication- one or more bases repeated leads to frameshift to the right
inversion- group of bases separate and rejoin but in the reverse order
translocation - separate from DNA sequence on one chromosome join to base sequence on another chromosome

Question 4

causes of mutations

Answer 4

mutagenic agents
high energy ionising radiation
chemicals

Question 5

whats a stem cell

Answer 5

undifferentiated cells. can specialise into other types of cell. will replace themselves and keep dividing

Question 6

what are the different types of stem cell

Answer 6

totipotent = found in early embryo can differentiate into any type of cell, zygote is totipotent

pluripotent= found in embryos can differentiate into almost any type of cell e.g embryonic and fetal stem cells

multipotent stem cells = found in adults can differentiate into limited number of specialised cells e.g stem cells in bone marrow into any type of blood cell

unipotent = can only differentiate into one type of cell