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Human Genetics and Disease > Chapter 13- Chromosomes > Flashcards

Chapter 13- Chromosomes Flashcards

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Biology 101 flashcards
1
Q

Cytogenetics

A

Study of chromosomes and their abnormalities

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2
Q

Karyotype

A

Displays chromosomes by their size and structure
Used for clinical diagnosis

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3
Q

Telomeres

A

DNA Repeats on chromosome ends
Protects ends of DNA information
Shorten every cell division in absence of telomerase

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4
Q

Centromere

A

Site of spindle fiber attachment
Specialized heterochromatin with DNA and proteins

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5
Q

Telocentric chromosomes

A

Centromere at the tip of chromosomes

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6
Q

Acrocentric chromosomes

A

Centromere close to the end

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7
Q

Submetacentric chromosomes

A

Centromere off-center

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8
Q

Metacentric chromosomes

A

Centromere in the center

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9
Q

Amniocentesis

A

Collecting fetal cells from the amniotic fluid at 16-20 weeks to test for chromosomal and biochemical defects
Recommended for older women or history of chromosomal abnormalities

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10
Q

Chorionic Villi Sampling (CVS)

A

Collect chorionic villi (placental projections) trans-vaginally
Earlier results but less accurate and higher chance of miscarriage

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11
Q

Euploidy

A

Correct chromosome number

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12
Q

Polyploidy

A

Cells with entire extra sets of chromosomes
Triploid- 69 chromosomes
Tetraploid- 92 chromosomes

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13
Q

Aneuploidy

A

Gain or loss of individual chromosomes

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14
Q

Non-disjunction

A

Failure of paired homologs to separate properly during segregation
Occurs in meiosis I or II
Causes aneuploidy

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15
Q

Monosomy

A

2n-1 condition, loss of one chromosome
Lethal very early in embryogenesis

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16
Q

Trisomy

A

2n+1 condition, gain of one chromosome
Varying lethality depending on chromosome repeated

17
Q

Trisomy 21- Down Syndrome

A

95% due to nondisjunction in meiosis I from ovum
Distinctive facial and physical problems
Predisposition for leukemia, alzheimer’s, and heart defects
Varying developmental disability

18
Q

Trisomy 18- Edward’s Syndrome

A

Survival less than 4 months
Most common in stillbirths
Associated with advanced maternal age

19
Q

Trisomy 13- Patau Syndrome

A

95% miscarry
Death within 3 months
Many growth, developmental, and anatomical defects

20
Q

XO- Turner Syndrome

A

Female phenotype
99% die in utero
Loss of one X chromosome from ovum or sperm
Short, infertile, many medical problems
Failure to develop secondary sex characteristics
Only viable monosomy in humans

21
Q

XXX- Triple X Syndrome

A

Little phenotypical change from normal females
Majority never diagnosed

22
Q

XXY- Klinefelter Syndrome

A

Many X with at least 1 Y chromosomes
Male phenotype
Tall, large limbs
Hypogonadism, sterile
Gynecomastia

23
Q

XYY- Jacob’s Syndrome

A

Male phenotype
96% normal development
Great height
Acne
Speech and reading disabilities

24
Q

Translocation of Chromosomes

A

Transfer a piece of chromosome to non-homologous chromosome
Balanced

25
Q

Robertsonian Translocation

A

Breakage of acrocentric chromosomes and fusion of two distinct long arms into hybrid chromosome
No clinical significance for carrier
Produce unbalanced gametes

26
Q

Reciprocal Translocation

A

Breakage of two non-homologous chromosomes with exchange of fragments
Balanced
Normal phenotype with risk for unbalanced gametes

27
Q

Burkitt Lymphoma

A

Translocation of pronto oncogeme c-myc into immunoglobulin heavy chain
Leads to tumor development

28
Q

Chromosomal Deletions

A

Missing genetic segments
Arise de novo from chromosome breaks
Hemizygous expression- Only copy remaining will always be expressed

29
Q

Chromosomal Duplications

A

Part of chromosome is copied, leading to extra genetic material
Occurs during meiosis due to unequal crossing over
Tandem or dispersed repeats

30
Q

Chromosomal Inversions

A

Chromosome segment with flipped orientation
May lead to health problems or reduced fertility
Balanced- Both copies flip
Unbalanced- Only one copy flips- Causes issues in crossing over

31
Q

Isochromosomes

A

Chromosome with two identical arms
2p arms- Short
2q arms- Long

32
Q

Tetrasomy 18

A

Isochromosomes of chromosome 18 lead to low birth weight and developmental abnormalities

33
Q

Ring Chromosomes

A

Chromosome ends break and fuse to one another, forming ring
Arise with telomere loss
Occur with or without disrupting genetic material

34
Q

Uniparental Disomy

A

One parent contributes both copies of a chromosome
Loss during trisomy zygote
Non-disjunction in both parents on same chromosome

35
Q

Robertsonian Down Syndrome

A

5% of cases
Robertsonian translocation of chromosomes 21 and 14
Offspring has chance to inherit hybrid chromosome or normal copies from carrier
Cause trisomy 21

36
Q

Cru du Chat Syndrome

A

De novo deletion on chromosome 5
Delete CTNND2 and HTERT gene
Defects in telomerase and nerve cell development
High pitched cry, intellectual and developmental impairment, low birth weight

Human Genetics and Disease (10 decks)

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