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Human Genetics and Disease > Chapter 3- Meiosis > Flashcards

Chapter 3- Meiosis Flashcards

1
Q

Meiosis

A

Cell division in two stages that produces haploid gametes in germline cells
Maintains chromosome number within species

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2
Q

Meiosis I

A

Reduction division
Homologous chromosomes separate
Chromosome number reduces from 46 to 23
Crossing over occurs

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3
Q

Meiosis II

A

Equational division
Sister chromatids separate
Chromosome number remains constant

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4
Q

Mechanisms to Increase Genetic Diversity

A

Crossing Over
Independent Assortment

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5
Q

Alpha Thalassemia

A

Misalignment of alpha globin genes can lead to duplication-deletion events
Missing 1+ copies of alpha globin gene leads to globin imbalance and buildup of beta chains

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6
Q

Spermatogenesis

A

Spermatogonium- Primary Spermatocyte- Secondary Spermatocyte- Sptermatid- Spermatozoa
Continuous division and maturation after puberty
I spermatogonium produces 4 sperm

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7
Q

Oogenesis

A

Oogonium- Primary oocyte- Secondary oocyte- Ovum
Produce polar bodies during each meiotic division
Begins during utero, Meiosis I finishes during ovulation, Meiosis II completed during fertilization

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8
Q

Stages of Embryonic Development

A

Fertilization
Cleavage
Gastrulation
Neurulation
Neural Crest Development
Organogenesis

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9
Q

Fertilization

A

Matured sperm meets oocyte in fallopian tube
Sperm DNA enters oocyte
Meiosis II finishes and induces polarity relative to entry site

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10
Q

Cleavage

A

Frequent Mitotic divisions to increase cell number
~4 days- 16 cells, morula
Blastocyst- Hollow mass of 100 cells
Trophoblast- Outer layer, becomes chorion and amnio
Inner cell mass becomes embryo
Implantation occurs around day 7

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11
Q

Gastrulation

A

Invagination and migration to form 3 primary germ layers
Ectoderm- Skin and nervous system
Mesoderm- Muscle
Endoderm- Tracts
Days 14-28

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12
Q

Neurulation

A

Initiation of organogeneis at weeks 3-4
Ectoderm divides into neural tube and crest
Neural tube folds and pinches off to become CNS
Adjacent neural crest migrate to become pigment and distal neurons and smooth muscle

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13
Q

Organogenesis

A

Transformation of germ layers into distinct organs
All organs present by week 8- Fetus

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14
Q

Morphogenesis

A

Process by which order is created in an organism
Mediated by cell growth, migration, interaction and death
Mediated by growth factors and hormones

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15
Q

Processes of morphogenesis

A

Axis specification, pattern formation, an dorganogenesis

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16
Q

Paracrine Developmental Mediators

A

Extracellular Growth Factors
Fibroblast growth factor (FGF) Family
Hedgehog Family

17
Q

Transcription Factors mediating development

A

Regulate gene expression and differentiation
HOX, PAX, and T-BOX Families

18
Q

Sonic Hedgehog (Shh)

A

Transcription regulating protein with axis specification
Shh binds to patched, removes smothened inhibition
Activates GLI Transcription factors

19
Q

Homeobox (HOX) Genes

A

Conserved transcription factors that regulate body segmentation
Differential combinations create segments

20
Q

Pattern formationi

A

Axis specification-
Dorsal/ventral
Anterior/posterior
Right/left

21
Q

Limb formation

A

Mesoderm cells divide and protrude forming limb bud
Apical Ectodermal Ridge (AER) cells on end regulate proximal/distal growth
Zone of Polarizing Activity (ZPA) found under AER releases Shh to regulate anterior-posterior development

22
Q

Congenital Abnormalities

A

Birth defects in structure or function from intrauterine life

23
Q

Dysmorphology

A

Study of congenital birth defects that alter form of newborn
Determine maternal health, environmental, and genetic contributions

24
Q

Syndromic Abnormality Pattern

A

Causative agent causes defects in parallel

25
Q

Brachio-oto-renal dysplasia

A

Error in conserved ear and kidney genes causes ear, neck, and kidney abnormalities

26
Q

Sequential Abnormality Pattern

A

Defects in single organ cause further symptoms

27
Q

Robin Sequence

A

U-shaped cleft palate and small mandible
Mandibular restriction cause posterior tongue alignment, disrupts palate shelves, creates cleft palate

28
Q

Malformations

A

Intrinsic error in embryonic tissue formation
Genetic, maternal diabetes or medication, or infection as potential causes

29
Q

Deformation

A

Abnormal form or position of body region
Caused by extrinsic factors impinging on fetal development thru 35-38 weeks
Malformed uterus, crowding, or decreases in amniotic fluid

30
Q

Disruptions

A

Extrinsic factors destroy fetal tissue
Vascular insufficiency, trauma, or teratogens

31
Q

Teratogens

A

Chemical or other agents that cause birth defects
Thalidomide, cocaine, cigarettes, alcohol, viruses, nutrient excess

32
Q

Factors influencing teratogenicity

A

Timing, dosage, and duration
Ability to cross placenta
Maternal and fetal genetic susceptibility
Mechanism of action

33
Q

Hirschsprung Disease (HSCR)

A

Congenital megacolon caused by neural crest failure to innervate internal anal sphincter
Bowel becomes dilated via obstruction
Mortality due to ruptured colon

34
Q

Gorlin Syndrome

A

Mutation in patch 1 in Shh pathway
Patch 1 acts as tumor suppressant
Increased risk of cancer and de novo mutations

35
Q

Hutchinson-Fuilford Progeria Syndrome (Progeria)

A

Disorder of accelerated aging
Mutations in LMNA Gene- Encodes lamin A
Abnormal Lamin A- Progerin- Unstable nuclear envelope
Increased DNA damage- Growth failure
Baldness, cranial defects
Loss of body fat, dry scaly skin, stiff joints
Cardiovascular issues and insulin resistance

36
Q

Traits associated with longevity

A

Insulin resistance
Control of cell cycle
Lipid metabolism
Immune and stress responses
Antioxidant enzyme expression
Nutrient metabolism

Human Genetics and Disease (10 decks)

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