Genetics

Question 1

Genotype

Answer 1

All of the alleles of an organism

Homozygous or heterozygous

Question 2

Phenotype

Answer 2

measurable trait an organism has (the trait exhibited)

Question 3

Chromosome

Answer 3

structure composed of genes located in nucleus of a cell (humans have 46)

Question 4

Locus

Answer 4

specific location of a gene on a chromosome

Question 5

Allele

Answer 5

Different versions of a gene (humans have 2 on each autosomal gene, one from each parent)

Question 6

Mutation

Answer 6

a change in some part of the DNA code

Spontaneous or induced

Question 7

Mitosis

Answer 7

Division of somatic cells

One exact copy of each chromosome made and distributed into 2 daughter cells

Question 8

Meiosis

Answer 8

Process which gamete cells are produced (egg/sperm)
Only occurs in germ cells of gonads
2 consecutive divisions>4 sperm cells, 1 egg

Question 9

Sex chromosomes vs Autosomes

Answer 9

Humans have 22 autosomes, 1 allosome (sex pair-determines gender, X and Y)
autosomes are any chromosome that isn’t a sex chromosome

Question 10

Autosomal vs X-linked

Answer 10

Autosomal affect males and females equally, x-linked are more common in males

Question 11

Translocation

Answer 11

rupture of a chromosome resulting in pieces restocking in wrong combinations

Question 12

Deletion

Answer 12

genetic material removed from chromosome

Question 13

Insertion

Answer 13

genetic material added to a chromosome

Question 14

Penetrance

Answer 14

probability that people in a population who have a particular gene combination will show the condition

Question 15

Expression

Answer 15

components of the phenotype that are exhibited in a person

Question 16

Genetic Marker

Answer 16

Sequence of DNA with a known location on a chromosome

Question 17

Dominant vs Recessive

Answer 17

Phenotype of dominant seen in heterosexual and homo

Phenotype of recessive only seen when homozygous recessive

Question 18

Autosomal Recessive

Answer 18

25% chance of infection, 50% chance of carrying gene
2 copies of allele required to express phenotype
males and females equally affected

Question 19

X-linked

Answer 19

5% of disorders
males more likely to develop mutant phenotype, females are recessive
no male to male, but all daughters of affected male are carriers

Question 20

Trisomy 21

Answer 20

Down syndrome
most common chromosomal abnormality in live births/non-lethal
Michael translucency
intellectual disability, characteristic facial appearance, cardiac/hearing/visual/GI problems

Question 21

Trisomy 18

Answer 21

Edward’s Syndrome
2nd most common
kidney/heart defects, delayed development, club foot, low ears, small jaw, clenched hand
many die before birth or in first month
Intra-uterine growth restriction is hallmark of pregnancy
Increased risk with maternal age

Question 22

Trisomy 13

Answer 22

Patau syndrome
severe intellectual disability, cleft lip/palate, seizures, small jaw, polydactyly, heart/brain defects
many die within first days/weeks

Question 23

Cri-du-Chat Syndrome

Answer 23

deletion of part of short arm of chromosome 5
Partial monosomy
cat-like cry (larynx development), wide set eyes, low ears, intellectual disability

Question 24

Klinefelter’s Syndrome

Answer 24

Only affects males
extra X chromosome
accounts for many first trimester losses
hypogonadism, infertility, gynecomastia, reduced hair

Question 25

Turner Syndrome

Answer 25

Only affects females
Monosomy (only one x, 45 chromosomes)
Gonadal dysgenesis, short, broad chest, webbed neck, infertility, amenorrhea, CV abnormalities

Question 26

Huntington’s Disease

Answer 26

Neurodegenerative disorder
uncontrolled movements/chorea, emotional problems, loss of thinking ability, changes in personality, adult onset
HD gene on chromosome 4 (CAG), dominant
Microscopic protein deposits in neurons
Autosomal dominant

Question 27

Alzheimer’s

Answer 27

Neurodegenerative
most common form of dementia (65%), usually late onset (after 60 years)
Loss of acetylcholine
Familial-early onset (<5%)
Sporadic-late onset (more common), APOE chromosome 19
Autosomal dominant

Question 28

Breast and Ovarian Cancer Syndrome

Answer 28

BRCA1 and 2

early onset of breast cancer (<50), FH of breast and ovarian cancer, increased bilateral/development of both cancers

Question 29

Colorectal Cancer

Answer 29

Results from genetic and environmental factors
can happen sporadically or from familial inheritance
Diet, exercise, smoking &obesity strong risk factors

Question 30

Familial adenomatous polyposis (FAP)

Answer 30

<1% of colorectal cancers
develops in 20’s, risk of colorectal cancer near 100% usually before 50 years
polyp>cancer development 10+ years
Mutation in adenomatous polyposis coli gene (APC)
Colectomy recommended before 20 years
Autosomal dominant

Question 31

Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

Answer 31

AKA Lynch Syndrome
2-3% of colorectal cancers
rapid transition from adenoma>cancer, occurs in 30’s and 40’s
can occur with or without polyps
50% chance of cancer in women, 70% in men
associated with other cancers (uterus, ovaries, stomach, urinary tract, bowel, bile ducts)
HNPCC gene mutation
Autosomal dominant

Question 32

Chronic Myelogenous Leukemia

Answer 32

excess WBC in bone marrow
more common in men 55years
caused by chromosome 22
Hallmark symptoms-fever, night sweats, fatigue; infections, anemia, bleeding
slow progression
Bone marrow aspiration for diagnosis

Question 33

Hemophilia

Answer 33

Bleeding disorder on F8 (more common, Hemo A) or F9 (Christmas disease, Hemo B)
bleeding into muscles/tissues
X-linked recessive

Question 34

Sickle Cell

Answer 34

Atypical hemoglobin molecules, crescent shaped RBC, premature breakdown of RBC, anemia, SOB, fatigue, renal failure
Mutation of HBB gene
common in Greece, Africa, turkey, Italy…
Most common bleeding disorder in US
Autosomal recessive

Question 35

Cystic Fibrosis

Answer 35

Disruption in water and chloride transport/water balance
causes thick, sticky mucous obstructing airways and pancreatic ducts
difficulty breathing, lung infections, poor growth rate, Meconium ileus (newborn intestinal obstruction)
Mutation in CFTR gene
Sweat chloride test for diagnosis
Autosomal recessive

Question 36

Marfan Syndrome

Answer 36

Mutation of FBN1
Defect in connective tissue (bone, ligaments, muscles, blood vessels, heart valves)
Tall, long arms, thin, long face, scoliosis, hyper flexible, chest deformities
aortic aneurysms/dissection and dislocated lens of eye common
Autosomal dominant

Question 37

Neurofibromatosis Type I

Answer 37

AKA Recklinghausen disease
most common type of mutation NF1 (tumor suppressor)
subcutaneous tumors, cafe-au-lait spots, freckles in axilla/groin
Autosomal dominant

Question 38

Polycystic Kidney Disease

Answer 38

clusters of fluid-filled sacs in kidneys, kidney failure, inability to filter blood properly
hypertension, back pain, hematuria, UTI, kidney stones, aortic/brain aneurysm
recessive rare but lethal
Dominant: PKD1 and PKD2 genes (90%), late onset
Recessive: PKDH1 gene, early onset, lethal

Question 39

Bigest cause of birth defects?

Answer 39

Unknown

Question 40

“inborn errors of metabolism”

Answer 40

autosomal recessive errors present at birth
inherited defect of one or more enzymes
Baby tested at 24-36 hours and 5-10days

Question 41

Aneuploidy

Answer 41

Abnormal number of chromosomes

Question 42

Balanced Translocation

Answer 42

Rupture of chromosome resulting in pieces restocking in wrong combinations

Question 43

Inversion

Answer 43

A chromosome piece is lifted out, flipped around and reinserted

Question 44

Teratology

Answer 44

Study of abnormal development

Question 45

Teratogens

Answer 45

Anything capable of disrupting embryonic or fatal development and producing malformations
Eg: alcohol, tobacco, excess vitamin A
Critical period 3-16weeks

Question 46

Pedigrees

Answer 46

Make-square
Female-circle
Has condition-shaded
Carrier-half shaded