BIOLOGY 11 3.5 DNA

Deletion

a piece of chromosome is deleted

Duplication

 a section of a chromosome appears two or more times in a row

Inversion

a section of a chromosome is inverted

Translocation

a part of one chromosome becomes attached to a different chromosome

Example of Deletion

Cri du Chat:

Caused by a deletion in Chromosome 5;

Kids cry with high pitched - catlike voices

Also has low birth weight, wide spaced eyes, recessed chin and cognitive delays

Example of Duplication

Charcot Marie Tooth Caused by duplication on chromosome 17

Causes muscle weakness and loss of some sensation in lower legs, feet and hands.

Comes with a high foot arch

Example of inversion

FG syndrome

Caused by inversion of the X chromosome. Occurs in almost only all males. Comes with intellectual disabilities, delayed motor development and lower muscle tone.

Example of Translocation

Most Leukemia cases are caused by a translocation between chromosome 9 and 22. Results in an abnormal gene and involves using drugs to stop increased production of white blood cells.

Non - Disjunction

 when Chromosomes do not divide correctly in meiosis 

• Results in gametes with incorrect number of chromosomes

Non - Disjunction in Meiosis 1

When nondisjunction occurs during Anaphase I, no normal gametes will be created

Non - disjunction in Meiosis 2

When nondisjunction occurs during Anaphase II, half of the gametes will have the correct chromosome number

Eupolidy

Correct number of sister chromatids

Monosomy

one too little sister chromatids

Polysomy

One too many Sister chromatids

Down Syndrome

Trisomy 21

1. Intellectual disabilities

2. Short stature

3. Flatteneded face

4. Almond shaped eyes

Edward Syndrome

TRISOMY 18

Sevre intellectual, physical and facial abnormalities; extreme muscle tone

1. Life expectancy about 10 weeks

Patau Syndrome

TRISOMY 13

1. Severe Defects including small, non - functioning eyes

2. Survives only a few weeks after birth

Klinefelter Syndrome

XXY (extra X chromosome)

1. Sterile Male (unable to reproduce)

2. Breast swelling, some feminine body characteristics

Turner Syndrome

XO (missing an x chromosome)

• Sterile Female (cant produce eggs)

• Underdeveloped Female characteristics

• Short stature; webbed neck

Jacobs Syndrome

XYY (extra Y chromosome)

• Some individuals might be taller than average

• Typically no unusual symptoms

Triple X

XXX (extra x chromosome)

• Tall and thing

• Menstrual irregularity

Carrier Screening

• Can be done before or during pregnancy

• Tells you whether you carry a gene for certain genetic disorders that you might pass onto your child 

• Both parents can get tested

Serum Screening

• Only during pregnancy: 1st, 2nd, - trimester screening or BOTH

• Blood test: measures levels of certain proteins in your blood 

Cell Free DNA Screening (noninvasive)

• Tests for DNA from your pregnancy which can can be found in your blood 

• This shows possible chances of genetic disorders 

• Can be done any time after 9 or 10 weeks of pregnancy

Chorionic Villus Sampling (CVS):

• Can be done earlier in pregnancy than Amniocentesis

• Small risk of misscarriage (higher for CVS than Amnio.)

• Sample of placenta tissue

Amniocentesis:

• Small risk of misscarriage 

• Sample of amniotic fluid