1. Genetic Abnormalities

2. Mutation: any mistake or change in DNA sequence

3. Point mutation: change in one nitrogen base in DNA; Ex: albinism

4. Silent: results in same aa (or one that does not negatively impact protein)
Nonsense: premature STOP (sickle cell)
Missense: codes for different aa

6. Frameshift Mutation

7. Frameshift THE FAT CAT ATE THE RAT
Insert “H” in “THE” (at the beginning)
THH EFA TCA TAT ETH ERA…
Delete “H” from “THE” (at the beginning)
TEF ATA ATA TET HER T…

8. Insertion vs. Deletion

9. Crossing Over Occurs naturally during Meiosis I
Two homologous chromosomes overlap
Some genes cross over and switch places

10. Crossing Over
Chromosomal crossover (or crossing over) is the exchange of genetic material between homologous chromosomes that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs during prophase I of meiosis during a process called synapsis.

11. Crossing Over

12. Describe common mutation types.
Chromosomal mutation: part of a chromosome is lost, added, or moved to another chromosome; usually not passed on because zygote dies
Crossing over: occurs when chromosomes exchange genes. (This is supposed to happen, but mistakes can occur.)

13. Chromosomal Mutations

14. Nondisjunction
Nondisjunction: occurs when a chromosome pair fails to separate properly during meiosis
Results in gamete with abnormal number of total chromosomes

15. Types of nondisjunction
Monosomy: when gamete has one less chromosome than it should; if it joins with another gamete the zygote would have only 45 chromosomes
Ex: Turner syndrome
Missing a sex chromosome

16. Types of nondisjunction
Trisomy: when gamete has one more chromosome than it should; if it joins with another gamete, the zygote would have 47 chromosomes
Ex: Down’s syndrome, extra #21

17. Nondisjunction

19. Trisomy

20. Trisomy

21. Monosomy

22. Karyotype vs . Pedigree
Karyotype: a photo of an individual’s chromosomes
Pedigree: a family tree (usually tracing the occurrence of a particular trait or disease)

23. Karyotype A picture of an organism’s chromosomes
Can be used to determine if there are genetic abnormalities

24. Karyotyping: pictures of chromosomes are matched up according to size

25. Pedigree symbols

26. Pedigree

27. Pedigree chart

28. Pedigree
Generations
Individuals

29. Sex Linked Trait Pedigree

30. Describe methods of detection
Ultrasound: sound waves are used to generate an image of the unborn child. Used to detect abnormalities of limbs, organs, etc.
Also called sonogram

31. Amniocentesis: fluid surrounding the fetus is drawn out by needle, fetal cells are collected and grown in a lab. Chromosomes can be then karyotyped

32. Chorion villi sampling: a sample of the chorion (membrane surrounding fetus) is taken, chemical tests and karyotyping are performed

33. Quiz 1 A ___ mutation occurs when part of a chromosome is lost.
a. chromosomal b. crossing over c.point
In ___ a gamete has one less chromosome than it should .
a. disomy b. monosomy c. trisomy
___ occurs when chromosomes overlap and genes change places.
a. chromosomal b. crossing over c. point
In ___ a needle withdraws a small amount of fluid from around the fetus for testing.
a. amniocentesis b. chorion villi sampling c. ultrasound
In ___ pictures of chromosomes are cut out and matched up in pairs.
a. DNA fingerprint b. karyotyping c. ultrasound

34. Interpret testcrosses
Testcross: way of determining genotype
Cross individual of unknown genotype with homozygous recessive
If all offspring resemble “unknown” then it is homozygous dominant
If some offspring resemble homozygous recessive parent, unknown is a hybrid
Testcrosses are used in breeding plants and animals if a certain offspring is needed

35. Interpret pedigrees Pedigrees: graphic representation of family tree
Symbols identify sex, if they are carriers, if they have a certain trait, etc.
May be used if testcross cannot be made