BIO 325 Study Guide - Fall 2018, Comprehensive Midterm Notes - Reading Company, Embryo, Gene
12 Oct 2018
School
Department
Course
Professor
BIO 325
MIDTERM EXAM
STUDY GUIDE
Fall 2018
BIO 325: Animal Development
Lecture 1 Reading
Chapter 1) Making New Bodies
Mechanisms of Developmental Organization (Pages 1-3)
● Embryo: a developing organism between fertilization and birth
● Development: slow process of progressive change
● Zygote: fertilized egg
● The study of animal development is called embryology, after that phase of an organism that
exists between fertilization and birth
● Most organisms never stop
● Fertilization, cleavage, gastrulation, organogenesis, metamorphosis, regeneration, and
senescence
● Differentiation: cellular diversity
● Morphogenesis: creation of ordered form- coordinating cell growth, cell migration and cell
death
● The sperm and egg are highly specialized cells, and only they can transmit the instructions for
making an organism from one generation to the next
● Stem cells- that are able to form new structures even in adults
● The development of many organisms is influenced by cues from the environment that
surrounds the embryo or larva
○ Sex of turtles depends on the temperature the embryo experiences while in the egg
Chapter 24) Development in Health and Disease
Birth Defects, Endocrine Disruptors, and Cancer (Pages 735-743)
● Only 20-50% of human cleavage-stage embryos successfully implant in the uterus
● Of the embryos that do implant successfully, studies show that only about 40% survive to term
● ~ 2.5% of babies who do come to term have a recognizable birth defect
● Body has back-up pathways and redundancies that permit a great deal of flexibility
● 3 major pathways to abnormal development:
○ Genetic mechanisms: mutations in genes/changes in the # of chromosomes can alter development
○ Environmental Mechanisms: agents from outside the body cause deleterious phenotypic changes
by inhibiting/enhancing developmental signals
○ Stochastic (random) events: chance plays a role in determining the phenotype and some
developetal aoalies are just ad luk
The Role of Chance
● Developmental outcomes are probabilistic rather than predetermined
● X chromosome inactivation in females
find more resources at oneclass.com
find more resources at oneclass.com
BIO 325: Animal Development
Lecture 1 Reading
● Random fluctuations in both transcription and translation leading to variations in the levels of
proteins produced at any given time
Genetic Errors of Human Development
● Congenital (present at birth)- due to mutations, aneuploidies (improper chromosome #) and
translocations
The Nature of Human Syndromes
● Syndromes- several abnormalities occurring together
○ Caused by either a chromosomal event- several genes added/deleted or pleiotropy- the production
of several effects by a single gene or pair of genes
○ Mosaic Pleiotropy when the effects are produced independently as a result of the gene being
critical in different parts of the body (KIT gene for blood stem cells and pigment stem cells)
■ Can be a result of aneuploidies- errors in the # of particular chromosomes
■ Extra copy of chromosome 21- Trisomy 21- Down Syndrome
○ Relational Pleiotropy when a defective gene in one part of the embryo causes a defect in another
part, even though the gene is not expressed in the second tissue
Genetic and Phenotypic Heterogeneity
● Genetic heterogeneity: the production of similar phenotypes by mutations in different genes-
syndrome = sterility, anemia, and albinism
● Phenotypic heterogeneity: the same mutation can produce a different phenotype in different
individuals- genes are not autonomous agents
Teratogenesis: Environmental Assaults on Animal Development
● Discovery of Thalidomide: a sedative used to help manage pregnancies- could cause limb and
ear abnormalities in the human fetus
● Exogenous agents that cause birth defects are called teratogens- produce their effects during
certain critical timeframes
● Human development divided into an embryonic period (more harm done in this stage)
and fetal period
● Teratogens: drugs, chemicals, viruses, radiation, high body temperature, metabolic conditions
● Alcohol as teratogen: fetal alcohol syndrome (FAS)- small head size, physical abnormalities,
small brain
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Embryo: a developing organism between fertilization and birth. The study of animal development is called embryology, after that phase of an organism that exists between fertilization and birth. Fertilization, cleavage, gastrulation, organogenesis, metamorphosis, regeneration, and senescence. Morphogenesis: creation of ordered form- coordinating cell growth, cell migration and cell death. The sperm and egg are highly specialized cells, and only they can transmit the instructions for making an organism from one generation to the next. Stem cells- that are able to form new structures even in adults. The development of many organisms is influenced by cues from the environment that surrounds the embryo or larva. Sex of turtles depends on the temperature the embryo experiences while in the egg. Birth defects, endocrine disruptors, and cancer (pages 735-743) Only 20-50% of human cleavage-stage embryos successfully implant in the uterus. Of the embryos that do implant successfully, studies show that only about 40% survive to term.
