Chapter 3- Meiosis

Question 1

Meiosis

Answer 1

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

Question 2

Meiosis I

Answer 2

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

Question 3

Meiosis II

Answer 3

Equational division
Sister chromatids separate
Chromosome number remains constant

Question 4

Mechanisms to Increase Genetic Diversity

Answer 4

Crossing Over
Independent Assortment

Question 5

Alpha Thalassemia

Answer 5

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

Question 6

Spermatogenesis

Answer 6

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

Question 7

Oogenesis

Answer 7

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

Question 8

Stages of Embryonic Development

Answer 8

Fertilization
Cleavage
Gastrulation
Neurulation
Neural Crest Development
Organogenesis

Question 9

Fertilization

Answer 9

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

Question 10

Cleavage

Answer 10

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

Question 11

Gastrulation

Answer 11

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

Question 12

Neurulation

Answer 12

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

Question 13

Organogenesis

Answer 13

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

Question 14

Morphogenesis

Answer 14

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

Question 15

Processes of morphogenesis

Answer 15

Axis specification, pattern formation, an dorganogenesis

Question 16

Paracrine Developmental Mediators

Answer 16

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

Question 17

Transcription Factors mediating development

Answer 17

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

Question 18

Sonic Hedgehog (Shh)

Answer 18

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

Question 19

Homeobox (HOX) Genes

Answer 19

Conserved transcription factors that regulate body segmentation
Differential combinations create segments

Question 20

Pattern formationi

Answer 20

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

Question 21

Limb formation

Answer 21

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

Question 22

Congenital Abnormalities

Answer 22

Birth defects in structure or function from intrauterine life

Question 23

Dysmorphology

Answer 23

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

Question 24

Syndromic Abnormality Pattern

Answer 24

Causative agent causes defects in parallel

Question 25

Brachio-oto-renal dysplasia

Answer 25

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

Question 26

Sequential Abnormality Pattern

Answer 26

Defects in single organ cause further symptoms

Question 27

Robin Sequence

Answer 27

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

Question 28

Malformations

Answer 28

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

Question 29

Deformation

Answer 29

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

Question 30

Disruptions

Answer 30

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

Question 31

Teratogens

Answer 31

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

Question 32

Factors influencing teratogenicity

Answer 32

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

Question 33

Hirschsprung Disease (HSCR)

Answer 33

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

Question 34

Gorlin Syndrome

Answer 34

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

Question 35

Hutchinson-Fuilford Progeria Syndrome (Progeria)

Answer 35

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

Question 36

Traits associated with longevity

Answer 36

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