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Human Genetics > Exam One > Flashcards

Exam One Flashcards

1
Q

Human Genome

A

23 Chromosome pairs

  • 22 pairs of autosomes
  • 1 pair of sex chromosomes.
  • Humans are Diploid 2N
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2
Q

Chromosome Structure

A
  • p arm: short arm
  • q arm: long arm
  • centromere and telemores
  • microtubules are important for positioning
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3
Q

Centromere

A
  • metacentric= center
  • submetacentric= slightly off to one side
  • acrocentric=
  • telocentric= at the tip
  • MSAT
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4
Q

Eukaryotic Cells

A
  • Histone: proteins that associate with one another. The DNA wraps around the histone.
  • Nucleosome: DNA wrapped around histone protein
  • Chromatin: DNA complexed with histone proteins .
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5
Q

The Central Dogma

A

DNA–>[transcription]–> RNA–>[translation]–>protein

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6
Q

Genes

A

inherited DNA sequences that control biochemical and physiological traits of an organism by directing synthesis of proteins.

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7
Q

Genome

A

the ENTIRE COLLECTION of all genetic material (both genes and nonprotein coding DNA) in the cells of an organism: entire genetic blueprint.

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8
Q

Cell Division Goals

A

Mitosis: make two GENETICALLY IDENTICAL
Meiosis: make HAPLOID gametes. Germ cells specialized for reproduction. Have only one copy of the gene.

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9
Q

Cell Cycle

A 
Interphase (cell growth)
-G1: committed to dividing
-S :DNA replication 
-G2: cell prepares for mitosis
Mitosis
-Prophase
-Metaphase
-Anaphase
-Telophase
Cytokinesis
*Checkpoints are important to make sure things are happening properly.
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10
Q

Interphase

A
  • nuclear envelope/ membrane is present
  • relaxed chromatin
  • no dyads
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11
Q

Prophase

A
  • chromosome condense
  • sister chromatids
  • spindle fiber (microtubule) formation
  • nuclear membrane disintegrates
  • spindle fibers attach
  • become visible as dyads
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12
Q

Metaphase

A
  • chromosome align on metaphase plate (equatorial plate)

- aligned at the center so that the sister chromatids will go to different poles

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13
Q

Anaphase

A
  • sister chromatids separate and move toward opposite poles.
  • when they separate you then can refer to them as chromosomes.
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14
Q

Telophase

A
  • chromosomes arrive at poles
  • nuclear membrane reforms
  • chromatin begins to relax
  • cleavage furrow forms
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15
Q

Mitosis (Function)

A
  • used for division of somatic cells

- development and replacement

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16
Q

Cell Division and Cell Death

A

balance between:

  • mitosis(cell division): produces two somatic cells from one
  • apoptosis(PCD): precise genetically-programmed sequence…eliminating different cells
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17
Q

Programmed Cell Death (proper development)

A
  • formation of fetal fingers and toes
  • menstruation
  • synapse formation in the brain
  • sunburn
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18
Q

Programmed Cell Death (organism integrity)

A
  • Cells infected with viruses (done by themselves or immune system)
  • Cells with DNA damage (problems with genome)
  • Cancer cells (radiation & chemicals induce apoptosis in some type of cancer cells)
  • Cells of the immune system: defects in apoptosis are associated with autoimmune diseases.
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19
Q

Apoptosis

A

highly choreographed processes

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20
Q

Somatic cells (body)

A

two copies of the genome and perform body functions

DIPLOID 2N

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21
Q

Germ cells (sperm & egg)

A

one copy of the genome and are specialized for reproduction

HAPLOID N

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22
Q

Zygote

A

cell differentiates into a female or male

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23
Q

Stem Cells

A
  • present throughout life and provide for growth and repair
  • self renewal
  • ability to differentiate into multiple cell types
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24
Q

Stem Cells (in Healthcare)

A

-discovery and development of drugs
-observing the earliest sign of disease
-treatment of disease via implants and transplants
ex/
Chord Blood Banking
Bone Marrow Transplants

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25
Q

Sources of human stem cells

A
  • embryonic stem cells
  • induced pluripotent stem (tips) cells
  • adult stem cells
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26
Q

Genetic Significance of Meiosis

A
  • conservation of chromosome number
  • variability in gametes due to independent alignments
  • new combinations of hereditary traits due to recombination
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27
Q

Meiosis 1

A
  • 2 standard divisions
  • PAIRING OF HOMOLOGOUS CHROMOSOMES
  • sister chromatids remain attached all thru MI
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28
Q

Meiosis 1 Prophase

A
  • Chromosomes condense
  • Dyads visible
  • CROSSING OVER between homologous chromosome
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29
Q

Crossing Over

A

-produces genetic variation

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30
Q

Meiosis 1 Metaphase 1

A
  • Homologous pairs line along the metaphase plate

- maternally derived faces one pole, paternally derived faces another

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31
Q

Random Distribution/ Independent Alignment

A

-produces genetic variation

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32
Q

Meiosis 1 Anaphase 1

A
  • homologous pairs separate and move toward opposite poles

- sister chromatids remain attached to the centromere.

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33
Q

Meiosis 1 Telophase 1

A
  • chromosomes are at opposite poles
  • cleavage furrow
  • NO NEW DNA SYNTHESIS before meiosis II
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34
Q

Meiosis II

A

products are not genetically identical in the cell due to recombination and random assignment

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35
Q

Meiosis II Prophase II

A

sister chromatids are attached at centromeres

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36
Q

Meiosis II Metaphase II

A

chromosomes (attached sister chromatids) line up INDIVIDUALLY along the metaphase plate

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37
Q

Meiosis II Anaphase II

A

sister chromatids separate for the first & only time in meiosis

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38
Q

Meiosis II Telophase II

A

chromosomes at opposite poles

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39
Q

Spermatogenesis

A

continual process in males; each meiosis produces 4 mature gametes (sperm cells)

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40
Q

Oogenesis

A

-discontinuous
-arrested in prophase I until puberty
-meiosis I after ovulation
meiosis II after fertilization
- one mature gamete (egg)

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41
Q

-omy

A

individual chromosomes

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42
Q

-ploid

A

one or more complete sets of chromosomes

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43
Q

Chromosomal Rearrangements

A
  1. Duplications
  2. Deletions
  3. Inversions
  4. Translocations
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44
Q

aneuploidy

A

individual chromosomes

45
Q

polyploidy

A

entire sets of chromosomes

46
Q

unbalanced gened dosage

A

leads to altered characteristics

can be detrimental if it is a gene that is important in the early developmental stage

47
Q

chromosome inversion

A
  • order of alleles change

- may lead to an alteration in gene function and regulation

48
Q

translocation

A

-movement of genetic material between nonhomologous chromosomes
Types:
1. Reciprocal 2. Nonreciprocal 3. Robertsonian

49
Q

Non-disjunction

A

the failure of homologous chromosomes to properly segregate.

*monosomy & trisomy almost always lethal

50
Q

Non-disjunction of Autosomes

A

Trisomy 13: Patau Syndrome
Trisomy 18: Edward Syndrome
Trisomy 21: Down’s Syndrome

51
Q

Non-disjunction of sex chromosomes

A

imbalance in sex chromosomes is less damaging than imbalance in autosome

52
Q

Klinefelter Syndrome

A

XXY

2n+1

53
Q

Turner’s Syndrome

A

XO

2n-1

54
Q

Random X-inactivation

A

only one X is in an active state; all others are inactive & condensed into Barr Bodies

55
Q

Nondisjunction of Sex Chromosomes

A
  • easy assay is Barr body

- # Barr Bodies= #supernumerary x chromosomes

56
Q

Nondisjunction of Meiosis I

A

All 4 gametes are abnormal

  • [2]Trisomic (2n+1)
  • [2]Monsomic (2n-1)
57
Q

Nondisjunction of Meiosis II

A

2 normal gametes, 2 abnormal gametes

  • [2] Normal diploid (2n)
  • [1] Trisomic (2n+1)
  • [1] Monosomic (2n-1)
58
Q

Uniparental Disomy

A

both homologs from one parent; attempt to correct aneuploidy

59
Q

Problem of having both homologs from one parent

A
  • HOMOZYGOSITY for any detrimental alleles
  • IMPRINTING
  • small number of humans genes expression occurs by parental origin
  • only one parental allele (maternal or paternal) is expressed in some cells
  • the other allele is repressed
60
Q

Mendel’s Principle

A
  • Principle of Segregation

- Principle of Independent Assortment

61
Q

Principle of Segregation

A

each individual possesses 2 alleles that segregate when gametes are formed
(occurs in anaphase; happens if crossing over occurs or not)
[separation of homologous]

62
Q

Phenotype

A

characteristics you can see

  • Dominant
  • Recessive
63
Q

Genotype

A 
genetic makeup
*Homozygous
    Dominant
    Recessive
*Heterozygous
64
Q

Monohybrid Cross

A
  • one characteristic

* both are heterozygous

65
Q

Probability “and”

A

multiplication

66
Q

Probability “or”

A

addition

67
Q

Dihybrid Cross

A

-two characteristics

68
Q

Principle of Independent Assortment

A
  • alleles at different loci segregates independently of one another
  • Phenotypic Ratio 9:3:3:1
69
Q

Simple Mendelian Inheritance

A

-Complete dominance (AA=Aa in phenotype)
-both parents contribute equally
-trait is controlled by one gene
-inheritance is governed by Principles of Segregation & Independent Assortment
[most phenotypes don’t exhibit patterns of simple Mendelian inheritance]

70
Q

Lethal alleles

A
  • cause death usually in development
  • can alter phenotypic ratios
  • can be dominant or recessive
71
Q

Recessive lethal

A

2 copies required for death
ex. cystic fibrosis, sickle cell anemia
(Homozygous recessive is missing or dies)

72
Q

Dominant lethal

A

1 copy required for death
ex/ huntington disease
(Heterozygotes and homozygous dominant are typically very severely affected and often die early in development

73
Q

Dominant

A
  • interaction between alleles at the same locus

* *heterozygote is same as one parent

74
Q

Incomplete (partial) dominance

A

-interaction between alleles at the same locus
heterozygote is intermediate
ex/ hypercholesterolemia (FH)

75
Q

Codominance

A

Heterozygote exhibits both phenotypes
-full & independent phenotypic expressions of both alleles
Monohybrid genotypic & phenotypic ratio (1:2:1)
ex. blood

76
Q

Incomplete dominance ratios

A

in a monohybrid cross the phenotypic and genotypic ratios mirror each other
(1:2:1)

77
Q

Epistasis

A

one gene hides/ masks the effect of another gene at a different locus
ex/ Bombay Blood (can’t make the H compound)

78
Q

Gene Interaction

A

genes at multiple loci determines a single phenotype

79
Q

Cystic Fibrosis

A

single gene responsible for a variety of traits

  • recessive genetic disease
  • > 10 million are (symptomless) carriers
80
Q

Pleiotropy

A

single gene impacts many characteristics

81
Q

Sex-linked

A

genes on x and y chromosome

82
Q

Sex-influenced

A

genes on autosomes more readily expressed in one sex

ex/ facial hair

83
Q

Sex-limited

A

autosomal genes expressed only in one sex

ex/ females have a uterus

84
Q

Genomic imprinting

A

genes whose expressions is influenced by sex of transmitting parent

85
Q

genes on sex chromosomes

A
  • addition of sex as a phenotype is an extension of simple Mendelian inheritance
  • genes on sex chromosome can affect other traits than sex
86
Q

X & Y pairing meiosis I

A
  • Pseudoautosomal regions (Par 1 (p) & Par 2 (q))

- PAR has the ability to cross over

87
Q

SRY

A
  • turns on/off other genes
  • destroys female structures
  • male structures are stimulated
  • Y-linked traits involve infertility and are not transmitted
88
Q

Genomic Imprinting (epigenetic silencing)

A
  • silencing maintained in somatic cells
  • modification: adding a methyl group to silence
  • X-inactivation turns off the entire chromosomes
  • Imprinting turns off specific genes
  • male& female balance each other {ex/ placenta size}
89
Q

Genomic Imprinting disease

A
  • chromosome 15: neuromuscular defects. mental retardation
  • Prader-Willi syndrome: inherited from father
  • Angelman syndrome: inherited from mother.
90
Q

Phenotypes are often modified by environmental effects

A

ex/ bunnies that are genetically identical , but pigment differs with temperature

91
Q

Multifactoral

A

polygenic and influenced by the environment
(many overlapping phenotypes)
ex/ human height

92
Q

Penetrance

A

PERCENTAGE of individuals with a particular genotype that expresses the expected phenotype
(what we expect to see is what we actually see)

93
Q

Incomplete Penetrance

A

Genotype does not produce expected phenotype

94
Q

Expressivity

A

Degree to which a character is expressed

once you see it then you can talk about how much you actually see it

95
Q

Incomplete Penetrance & Variable Expressivity

A

alteration or suppresion of the effects of a particular gene due to the effects of other genes and environmental factors ex/ human polydactyly; penetrance is 90%

96
Q

Multiple Alleles: the Rule

A
  • individual carries two alleles for each autosomal gene
  • gene can have multiple alleles in the human population
  • different allele combinations can produce variations in the phenotype
97
Q

Investigate characteristics in human

A
  1. Twin studies: examine concordance of a trait between members of a twin pair.
  2. Adoption studies: comparisons of adopted persons with their adoptive parents and their biological parents.
  3. Pedigrees: pictorial representation of a family history.
98
Q

Magnitude of genetic risk

A

determines a family’s decision about future pregnancies

99
Q

Tay-Sachs disease

A

autosomal recessive

100
Q

Pedigree analysis

A
  • specific disease or characteristic
  • initiated by a probing
  • symbols represent individuals in the family
101
Q

Proband

A

doesn’t have to be the first person impacted by the characteristic. They are the ones that seek help

102
Q

Pedigree analysis patterns

A
  1. Dominant or Recessive
  2. Autosomal, sex-linked, or mitochondrial
  3. confirm chosen mode of inheritance works for all individuals
103
Q

Testcross

A

with homozygous recessive

104
Q

features of sex-linked inheritance

A
  • must include sex as a phenotype
  • heterozygote is phenotypically normal carrier
  • Y has no gene (or alleles) for this trait, so HOMOZYGOUS males display recessive X linked trait more frequently
105
Q

Dominant Phenotype

A
  • generally appears in every generation

- affected individuals have at least one affected parent

106
Q

Recessive Phenotype

A
  • can skip generations

- affected individuals can be born from unaffected parents

107
Q

Autosomal

A

approx equal frequency in both sexes

108
Q

Sex-linked

A
  • appears more in one sex
  • Y-linked: fathers to all
  • Sons are hemizygous and inherit X from mom
109
Q

Mitochondrial

A

maternal lineage not paternal

Human Genetics (1 decks)

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