Chapter 6

Question 1

What are Congenital Disorders?

Answer 1

Present at birth; may be genetic or environmental or both

Question 2

What are Congenital Malformations?

Answer 2

Structural defects caused by errors in fetal development

Question 3

Who is Gregor Mendel?

Answer 3

Father of genetics; discovered patterns of inheritance in pea plants

Question 4

How are chromosomes characterized?

Answer 4

By total size, length of arms, and banding pattern

Question 5

What are Chromatids?

Answer 5

Two identical linear chromosome units that separate during meiosis

Question 6

What is a Centromere?

Answer 6

The point where two chromatids are joined

Question 7

What does Diploid mean?

Answer 7

Cells with 23 pairs (46 total) chromosomes

Question 8

How many chromosome pairs do humans have?

Answer 8

23 pairs: 22 autosomes, 1 pair sex chromosomes

Question 9

What is the difference between a Phenotype and a Genotype?

Answer 9

Phenotype = observable traits; Genotype = genetic makeup

Question 10

What is the purpose of Meiosis?

Answer 10

To produce haploid germ cells with 23 chromosomes each

Question 11

What are Genetic Traits?

Answer 11

Traits encoded by genes at specific loci on chromosomes

Question 12

What are the three Patterns of Inheritance?

Answer 12

Codominant, Monogenic, Polygenic

Question 13

What is a Mutation?

Answer 13

Permanent change in DNA structure

Question 14

What causes mutations?

Answer 14

Radiation, chemicals, viruses

Question 15

Name the two basic types of Mutation.

Answer 15

Point mutation and Frameshift mutation

Question 16

How do single and double-stranded DNA breaks differ in repair?

Answer 16

Single-stranded breaks can be repaired easily; double-stranded may lead to permanent loss

Question 17

What is a genetic disorder?

Answer 17

A condition caused by abnormalities in genes or chromosomes

Question 18

What are the four groups of Genetic Disorders?

Answer 18

Chromosomal abnormalities, Mendelian single-gene, Non-Mendelian, Multifactorial/polygenic

Question 19

What do Chromosomal Abnormalities result from?

Answer 19

Aberrant number or structure of chromosomes

Question 20

What is Aneuploidy?

Answer 20

Abnormal number of chromosomes

Question 21

What is the main process that causes Aneuploidy?

Answer 21

Nondisjunction during meiosis

Question 22

What is Monosomy?

Answer 22

Deficiency of one chromosome

Question 23

What is Polysomy?

Answer 23

Excess of one or more chromosomes

Question 24

List risk factors for aberrant chromosome number.

Answer 24

Advanced maternal age, parental genetic issues, crossing over errors

Question 25

What causes Abnormal Chromosome Structure?

Answer 25

Breakage and rearrangement during meiosis or mitosis

Question 26

What meiosis event can lead to abnormal structure?

Answer 26

Crossing over errors

Question 27

What mitosis event can lead to abnormal structure?

Answer 27

Chromosome breakage and faulty repair

Question 28

List the four types of rearrangements in chromosomes.

Answer 28

Translocation, Inversion, Deletion, Duplication

Question 29

What is Translocation?

Answer 29

Exchange of DNA between nonhomologous chromosomes

Question 30

Describe Inversion.

Answer 30

Chromosome segment removed and reinserted upside-down

Question 31

Describe Deletion.

Answer 31

Loss of a chromosome segment

Question 32

Describe Duplication.

Answer 32

Extra copies of chromosome segments

Question 33

Describe Trisomy 21 (Down Syndrome).

Answer 33

Extra 21st chromosome; causes intellectual disability, heart defects

Question 34

Describe Trisomy 18 (Edwards Syndrome).

Answer 34

Severe retardation; most die shortly after birth

Question 35

Describe Trisomy 13 (Patau Syndrome).

Answer 35

Severe anomalies; most die shortly after birth

Question 36

Name three extremely rare trisomies.

Answer 36

Trisomies 8, 9, and 22

Question 37

What is Cri du Chat Syndrome?

Answer 37

Deletion of chromosome 5p; cat-like cry, round face, heart issues

Question 38

What is the most common sex chromosome abnormality?

Answer 38

Klinefelter Syndrome

Question 39

Describe Klinefelter Syndrome.

Answer 39

XXY or more; male with feminization, tall, low testosterone

Question 40

Describe Turner Syndrome.

Answer 40

Monosomy X; female with short stature, webbed neck, no ovaries

Question 41

What are Mendelian Single-Gene Disorders?

Answer 41

Disorders from mutations in a single gene

Question 42

What is a Pedigree?

Answer 42

Diagram tracing inheritance across generations

Question 43

Features of Autosomal Dominant Disorders?

Answer 43

One mutated copy sufficient, equal male/female, vertical inheritance

Question 44

Features of Marfan Syndrome?

Answer 44

Tall, thin, long limbs, aortic rupture risk

Question 45

Features of Huntington Disease?

Answer 45

Neurodegeneration, late onset, involuntary movements

Question 46

Features of Autosomal Recessive Disorders?

Answer 46

Both copies must be mutated, consanguinity often involved

Question 47

What is Albinism?

Answer 47

Lack of melanin due to enzyme deficiency

Question 48

What is Phenylketonuria?

Answer 48

Cannot metabolize phenylalanine; tested at birth

Question 49

What is Cystic Fibrosis?

Answer 49

Thick secretions from chloride transport defect

Question 50

Features of Sex-Linked (X-linked) Disorders?

Answer 50

Mostly males affected, daughters of affected fathers are carriers

Question 51

Name two X-linked disorders.

Answer 51

Hemophilia A, Duchenne muscular dystrophy

Question 52

What is Genomic Imprinting?

Answer 52

Genes marked differently by parent of origin

Question 53

What are examples of imprinting disorders?

Answer 53

Angelman (maternal), Prader-Willi (paternal)

Question 54

What are polygenic/multifactorial disorders?

Answer 54

Result from interaction of multiple genes and environment

Question 55

What are examples of multifactorial disorders?

Answer 55

Hypertension, cancer, diabetes

Question 56

What are examples of multifactorial traits?

Answer 56

Height, weight, intelligence

Question 57

When is fetal development most vulnerable?

Answer 57

Between 3rd and 9th weeks of gestation

Question 58

What are teratogenic agents?

Answer 58

Environmental agents causing birth defects

Question 59

What does TORCH stand for?

Answer 59

Toxoplasmosis, Other (e.g. syphilis), Rubella, CMV, Herpes

Question 60

What are risk factors for further genetic evaluation?

Answer 60

Maternal age ≥35, previous chromosomal disorder, family history, metabolic disorders

Question 61

What is gene therapy?

Answer 61

Replacing defective genes with functional ones using rDNA technology