A mutation is a change in a gene

A mutation can only be inherited in it

occurs in a sex cell

Effects of mutations can be:

› Positive

› Negative

› Neutral

Deletion – loss of a

piece of a chromosome

Inversion – piece of

a chromosome breaks off, flips

around, and

reattaches

Translocation – a

piece of one chromosome breaks

off and reattaches

to a nonhomologous

chromosome

Nondisjunction – chromosome fails to

separate from its homologue during

meiosis

Point Mutation – one nucleotide is

changed in the DNA sequence

› Substitution

› Deletion

› Insertion

Substitution – one

nucleotide replacesanother

Deletion – one or

more nucleotides are deleted

Insertion – one or

more nucleotides are added to a

gene

Deletion and insertion mutations can

both result in frameshift mutations, where

all amino acids downstream change

Genetic screening – examination of a

person’s genetic makeup

› Karyotypes, tests for proteins, DNA tests

More than 200 genetic disorders can

now be detected in the fetus

Amniocentesis –

removal of amniotic fluid from around the

fetus between the

14th and 16th week of

pregnancy

Chorionic villisampling - A sample from the zygote

between the 8th and

10th week of

pregnancy

Genetic counseling – the process of

informing a person or couple about their

genetic makeup

› Informs individuals about problems that might affect their offspring

› Predicts the likelihood that a couple will

produce an affected child

Treat the symptoms

Prevent symptoms

Gene therapy – technique that places a

healthy copy of a gene into the cells of

a person whose copy of the gene is

defective