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Flashcards in Pedigree Mendelian Genome Trouble Deck (39):
0

Outsider rules for autosomal dominant and recessive

Dominant: unknown parents are assumed to be heterozygous
Recessive: unknown parents are assumed to be homozygous normal

1

Which pedigree type can skip generations?

Autosomal recessive

2

Are males and females equally affected for autosomal recessive disorders? X-linked recessive?

Autosomal recessive: yes
Xlinked recessive: females more likely to be carriers than displayers of phenotype

3

What cell cycle stage does the Mendel's two laws take place in?

Meiosis for both

4

What is Mendel's first law of segregation state?

At meiosis, alleles separate from eachother so that each gamete receives 1 copy of each allele

5

What does Mendel's second law state?

Segregation of each set of alleles in meiosis is independent of segregation of other alleles

6

2 principal factors that determine the inheritance patterns seen in single gene disorders

1. Quality of phenotype
2. Location of gene locus

7

Penetrance

Probability that a gene will have phenotypic expression at all.

"All or nothing"

Gene is expressed or it isn't.

8

What is a threat to Penetrance?

Age dependent mechanism.

Likelihood manifesting trait dep on age

9

5 threats to expressivity

PMSES

1. Phenocopies
2. Modifier genes
3. Stochastic effects
4. Environmental factors
5. Sex influenced/ limitations

10

Allelic heterogeneity

Different Mutations of same gene/locus can similar phenotype

11

Pleiotropy

1 gene mutation/defect can cause multiple phenotypes

12

What two factors produce phenotype?

Genotype and environment

13

SNP error frequency

1 SNP every 1000 bp = each individual ~ 3 mil bp different

14

Is random variation in genome beneficial/harmful?

Almost always harmful

16

Minisatellite (indel)

Type of variation in genome

VNTR (variable # tandem repeats)
Randomly repeated 10-100 bp
Imp for fingerprinting

17

Copy number variation (CNV)

Type of variation in genome

Variation in segments of genome from 200bp-2Mbp
Can range from 1 additional copy to many (Ie: A-B-C-C-D)
Primary type of structural variation

17

Categories of genomic DNA sequencing and frequencies

1. Single copy sequences (50%)
2. Repetitive DNA (40-50%)
3. Genes (introns, exons, flanking seq) (20-25%)
4. Translated/protein coding seq (1.5%)

18

Microsatellite (indel)

Type of variation in genome

STRP (short tandem repeat polymorphisms)
Di, tri, tetra nucleotide repeats
5x10^4 per genome

19

Types of repetitive DNA that exist in hu genome

1. Tandem repeats
2. Dispersed repetitive elements

20

Types of Dispersed repetitive elements

1. Alu family
- ie: short interspersed repetitive elements (SINES)
2. L1 family

21

Tandem repeats

aka "Satellite DNA"
Spread throughout the genome
Found on heterochromatic regions on ch 1, 9, 16, y

Ie: alpha satellites

22

Describe estimated number of genes

25,000-30,000

23

Retrotransposition

These repeats may cause insertional inactivation of genes and may facilitate aberrant recombination events btwn diff copies of dispersed repeats, leading to disease

Ie: nonallelic homologous recombination (NAHR)

24

List diff types of hu genes

1. Protein coding
2. RNA coding
3. Pseudogenes

25

1q21.1 duplication and deletions result in what?

Dup: macrocephaly, autism
Del: microcephaly, schizophrenia

26

DUF1220

a protein domain that cause evolutionary advantage (inc in brain size) -> inc 1q21.1instability -> inc in DUF1220

27

Prior to meiosis, cells complete how many rounds of replication?

One (s phase)

28

After initiation of meiosis, cells then undergo how many rounds of chromosome segregation?

2 successive rounds

29

Synapsis

Homologous ch. align along their lengths and pair at corresponding DNA seq.

30

Bivalents

Pair of homologous chromosomes (during Synapsis)

31

Synaptonemal complex does what?

Promotes inter homolog intxn

32

Chiasmata

Physical links btwn homologs during reciprocal recombination

33

Random segregation of homologous ch gives rise to how many diff possible combinations?

8x10^6
or
2^23 (2 homologs of each 23 ch)

34

Nondisjunction

Pairs of ch fail to segregate properly

35

Nondisjunction events are related to what two factors?

Position and numbers of Chiasmata

36

What happens if recombination occurs too close to centromere? Too far?

1. Cause Spindle attachments, segregation during meiosis 1 -> crossing over less effective -> inc risk of ND
2. Homologs become entangled -> reduced/absent recombination and inc risk of ND

37

What happens to gametes when ND occurs in meiosis I? Meiosis II?

l. All gametes abnormal
II. Half gametes normal, half abnormal

38

Triploidy

Extra ch in all 23 pairs ( ie, 69, XXX)