Medical Genetics I

Front 1

Define: Disorders caused entirely or partly by genetic factors.

Back 1

Genetic disorders

Front 2

What are the three classes of genetic disorders?

Back 2

Chromosomal
Single Gene
Multifactorial disorders

Front 3

Define: Genetic disorders due to gain or loss of segments or entire chromosomes

Back 3

Chromosomal disorders

Front 4

Define: Genetic disorders due to individual mutant genes

Back 4

Single Gene disorders

Front 5

Define: Genetic disorders due to multiple gnese often acting in concert with environmental factors

Back 5

Multifactorial disorders

Front 6

Define: One of the different forms (variants) of a gene within a population.

Back 6

Allele

Front 7

Define: an individual with two identical alleles

Back 7

Homozygote

Front 8

Define: an individual with tow different alleles

Back 8

Heterozygote

Front 9

An individual with only one allel, chromosome or chroomosome segment, instead of the usual two.

Back 9

Hemizygote

Front 10

Define: Allele that is expressed in the heterozygote.

Back 10

Dominant allele (or trait)

Front 11

Define: Allele that is expressed only in homozygotes or hemizygotes.

Back 11

Recessive trait

Front 12

Define: Genetic constitution: the genotypic ratio in the Offspring is 1CC:2Cc:1cc

Back 12

Genotype

Front 13

Define: Observable expression of genes; if c is recessive the phenotypic ratio in the offspring is 3 normal:1 affected

Back 13

Phenotype

Front 14

Define: Heterozygote for a mutant allele: gnerally used for a recessive disorder.

Back 14

Carrier

Front 15

Define: When more than two alleles for a particular gene existing at an appreciable frequency in the population.

Back 15

Polymorphic

Front 16

At what percentage is an allele considered polymorphic?

Back 16

>1%

Front 17

Give an example of a "codominant" gene.

Back 17

ABO blood groups in Humans

Front 18

Define: A measure of the extent of DNA condensation.

Back 18

Packing ratio

Front 19

Define: the study of heredity.

Back 19

Genetics

Front 20

Define: A disease caused by a mutation in the genetic material (DNA).

Back 20

Genetic disease

Front 21

Define: A disease that is present at birth.

Back 21

Congential disease

Front 22

DEfine: The study of heritable changes in gene function that occur without a change in DNA.

Back 22

Epigenetics

Front 23

In the first division during Meiosis (Meiosis I) what is dividing unit?

Back 23

Chromosomes

Front 24

In the second division during Meiosis (Meiosis II) what is the dividing unit?

Back 24

Chromatids

Front 25

Define: Members of the same chromosome pair?

Back 25

Homologous chromosomes

Front 26

Define: A disease that is present at birth.

Back 26

Congential disease

Front 27

DEfine: The study of heritable changes in gene function that occur without a change in DNA.

Back 27

Epigenetics

Front 28

In the first division during Meiosis (Meiosis I) what is dividing unit?

Back 28

Chromosomes

Front 29

In the second division during Meiosis (Meiosis II) what is the dividing unit?

Back 29

Chromatids

Front 30

Define: Members of the same chromosome pair?

Back 30

Homologous chromosomes

Front 31

Define: The number of complete sets of chromosomes present in the cell or organisms.

Back 31

Ploidy

Front 32

Define: Two complete sets of chromosomes.

Back 32

Diploidy

Front 33

Where are sister chromatids linked?

Back 33

Centromere

Front 34

Synapse occurs during Meiosis I or II?

Back 34

Meiosis I

Front 35

Reductional division occurs during Meiosis I or II?

Back 35

Meiosis I

Front 36

Equational division occurs during Meiosis I or II?

Back 36

Meiosis II

Front 37

Define: when the number of chromosomes is reduced by half during Meiosis I.

Back 37

Reductional division

Front 38

Define: when the number of chromosomes remains the same during Meiosis II but a transition from Diploid to haploid occurs.

Back 38

Equational division

Front 39

During Meiosis I what generates diversity and unique allelic combinations?

Back 39

Crossing over or Recombination

Front 40

Define: The structure and number of chromosomes characteristic for each species.

Back 40

Karyotype

Front 41

Define: Chromosome end

Back 41

Telomere

Front 42

Define: Heterochromatin to which the spindle fibers attach during cell division

Back 42

Centromere

Front 43

Define: Having the centromere in the middle

Back 43

Metacentric

Front 44

Define: Having the centromere somewhat distant from teh middle

Back 44

Submetacentric

Front 45

Define: Having the centromere near the telomere.

Back 45

Acrocentric

Front 46

Define: The exact multiple of the number of chromosomes in a normal gamete (or in a cell)

Back 46

Euploid

Front 47

Define: the non euploid situation arising during meitosis or meiosis by a faiulre of chromosome to separate normally.

Back 47

Aneuploidy

Front 48

Define the failure of chromosomes to separate normally

Back 48

Nondisjunction

Front 49

What is the names given to the resultant gametes after disjunctions (Hint: -somic)

Back 49

Trisomic
Monosomic

Front 50

Chromosomal disorder: 47, XXY; associated with tall stature postpubertal testicular failure, and azzospermia (no sperm)

Back 50

Klinefelter syndrome

Front 51

Chromosomal abnormality characterized by tall stature and increased incidence of speech delay.

Back 51

XXY syndrome

Front 52

Chromoomal disorder characterized by 45, X; short stature, amenorrhea, infertility and somatic abnormalities

Back 52

Turner Syndrome

Front 53

Chromosomal abnormality characterized by XXX and tall stature

Back 53

Triple XXX syndrome

Front 54

What is the most commo trisomy and its resulting syndrome. characterized by head facial abnormalities, growh retardation,and variable mental retardation.

Back 54

Trisomy 21 or Down Syndrome

Front 55

What causes most cases of Down Syndrome?

Back 55

Maternal non-disjunction at Meiosi I resulting from increasing maternal age.

Front 56

What causes the majority of Turner syndrome cases?

Back 56

Paternal nondisjunction

Front 57

Define this structural abnormatility: Extra copy of part of a chromosome leading to partial trisomy

Back 57

Duplication

Front 58

Define this structural abnormatility: Breakage and rejoining of a chromosome segment in reverse order

Back 58

Inversion

Front 59

Define this structural abnormatility: Breakage and rejoining of a chromosome segemnt in reverse order including the centromere.

Back 59

Pericentric inversion

Front 60

Define this structural abnormatility: Breakage and rejoining of a chromosome segment in reverse order not including the centromere.

Back 60

Paracentric inversion

Front 61

Define this structural abnormatility: Deletion of telomeres and fusion of the broken ends to form aring; very unstable during mitosis and frequenlty lost

Back 61

Rign chromosome

Front 62

Define this structural abnormatility: Segment of one chromosome inserted into a non-homologous chromosome.

Back 62

Insertion

Front 63

Define this structural abnormatility: Chromosome having one arm duplicated and the other arm lost; arises when the centromere divides abnormally and can involve either the short (ISO p) or long (ISO q) arm.

Back 63

Isochromosome

Front 64

Define this structural abnormatility: Exchange of chromosome segments between non-homologous chromosomes; two main types are recirpocal and Robertsonian.

Back 64

Translocation

Front 65

Define this structural abnormatility: Material is simply exchanged between two chromosomes.

Back 65

Reciprocal translocation

Front 66

Define this structural abnormatility: Occurs when there is a a fusion at the centromere between two acrocentric chromosomes with the loss of the short arms and the satellites.

Back 66

Robertsonian translocation

Front 67

What trisomy is characterized by severe facial dismorphism, cardiac malformations, and other internal abnormalities?

Back 67

Trisomy 13 (Patau syndrome)

Front 68

What trisomy is characterized by a distinct appearance, heart abnormalities and other internal abnormalities?

Back 68

Trisomy 18 (Edwards syndrome)

Front 69

What are the two types of structural abnormalities?

Back 69

Balanced and unbalanced chromosome rearrangements.

Front 70

What type of chromosomal rearrangement is characterized by a loss or gain of chromosomal material?

Back 70

Unbalanced chromosome rearrangement.

Front 71

What type of chromosomal rearrangement is charaterized by no loss or gain of chromosomal material?

Back 71

Balanced chromosome rearrangement.

Front 72

Name some causes of chromosome breaks.

Back 72

Exogenous (radiation, certain chemicals)
Endogenous (free radicals)
Programmable (meiosis, Ig rearrangment)

Front 73

What are three ways that the histone octamer can be chemically modified in epigentic modification?

Back 73

Acetylation, methylation, phophorylation

Front 74

Give an example of an epigenetic alteration disease.

Back 74

Rett syndrome

Front 75

What where the four conclusions of Mendel?

Back 75

Each physical trait is controlled by a pair of hereditary determinants
One gene is inherited from each parent
Law of segregation
Law of independent assortment

Front 76

What is the law of segregation?

Back 76

Each gamete receives only one allele of a pair, and alleles segregate equally. That is, if an individual is heterozygous (Cc), half the gametes will receive the C allele, and half will receive the c allele.

Front 77

What is the law of independent assortment?

Back 77

Alleles of one gene segregate independently of alleles of other genes.

Front 78

What are the five components of histones?

Back 78

H1, H2A, H2B, H3 and H4

Front 79

Are histones basic or acidic?

Back 79

Basic, about 25% of the amino acids are lysine or arginine.

Front 80

What is the function of H1?

Back 80

It associates with the linker DNA and serves to stabilize the nucleosome and higher order chromatin structure

Front 81

What are nucleosomes?

Back 81

Repeating units of packaged DNA

Front 82

What is links individual nucleosome?

Back 82

Linker DNA.

Front 83

Which is condensed, metabolically inactive and stains darkly?

Back 83

Heterochromatin

Front 84

What is the normal karyotype for a human?

Back 84

Twenty two pairs of autosomes and one pair of sex chromosomes.

Front 85

What is the most common trisomy?

Back 85

Down syndrome (Trisomy 21)

Front 86

which type of inversion is more severe, Paracentric or pericentric?

Back 86

Paracentric are particularly mitotically unstable because of there is either two or no centromeres.