Flashcards in Kuehn - Development and Meiosis Deck (57):
What is a zygote?
fertilized egg, after nuclear fusion
What period of time do the pre-embryonic stages consist of?
first two weeks of development
What are the three different stages of development?
Pre-embryonic, embryo, and fetus
List the 4 pre-embryonic stages
zygote, 2-8 cell stages, morula, and blastocyst
What is an embryo
developing organism from 2-8 weeks
What is a fetus
developing organism from week 9 to birth
What are two additional terms associated with development
Conceptus and Trimester
What does CONCEPTUS mean
embryo or fetus including all surrounding membranes derived from zygote
What is a TRIMESTER
1/3 of the human gestational period (not related to developmental stages)
List the 9 basic processes of development
growth, differential growth, selective cell death, cell differentiation, migration, epithelial folding, cavitation and cannalization
What is growth and what three things increase in this process?
an increase in overall cell size; cell number, cell size, and extracellular matrix
What pathology is associated with GROWTH
hyperplasia (number) and hypertrophy (size)
What is differential growth?
one side or part of a structure grows faster than another
What is is differential growth mechanism for?
it is the major mechanism that allows organs to reach their ultimate shape
What is induction
a chemical signal causing a change in cells resulting in migration, differentiation, or other change
What two things can this chemical signal (induction) be?
a surface signaling molecule or chemical released into extracellular matrix
What is an example of double indcution?
lens of eye
optic vesicle → lens → optic cup
Cells programmed (by specific genes) to die to allow structure to develop is know as which process?
selective cell death
Provide two examples of selective cell death
hands (cells btwn fingers die) and the brain (many cells die in fetal life)
What is cell differentiation?
Cells change from undifferentiated (nonspecialized) to differentiated (specialized) types
What is metaplasia
a pathologic de-differentiation and re-differentiation
What is physical movement of cells from one location to another called?
What type of movement does migration usually involve
amoeboid and chemotaxis towards or away from specific developmental factors
What is important in cases of nerve axons related to migration
it can involve only a part of the cell
What is epithelial folding and when does it take place?
When the edges of some types of undifferentiatiated, flat epithelia can fold over on themselves; Upon appropriate induction
What 2 things does epithelial folding form and provide an example for each?
Form a tube (e.g., neural tube)
Form a ball (e.g., eye, lens of eye, or otic cyst)
What contracts in the terminal web of the epithelial cells during folding?
actin filaments contract
What are cavitations and cannalizations?
opening of spaces in originally solid tissues as the cells move to a peripheral location
What do cavitations and cannalizations create?
the blastocyst cavity, celom, and lumen of the gut cavity
Name the different classes and developmental factors commonly used during development
Morphogens, notch, transcription factors, and receptor tyrosine kinases,
What are morphogens
Diffusable molecules, released locally; react with cells to govern pattern of development
List the 5 morphogens
Retinoic acid, transforming growth factor β, bone morphogenic proteins, hedgehogs, and WNT
What does retinoic acid (vitamin A) do?
it fine tunes interactions of other developmental factors
What does transforming growth factor β do?
it promotes cell growth and differentiation
What pathway does transforming growth factor β use?
uses SMAD pathway
What are bone morphogenic proteins?
pivotal developmental signaling molecules
Why are bone morphogenic proteins important?
they are critical for anything derived from mesoderm (ie. muscles, etc)
What is a hedgehog series (ie. SHH)?
a critical developmental gene requiring cholesterol to become active
Why is WNT important?
it is critical in pattern development and axis patterning. Critical for early development!
What does WNT use?
it uses β-catenin to activate gene sequences
What are transcription factors?
a large class of intracellular/integral proteins that regulate expression of target genes
How do transcription factors regulate expression?
they either activate or repress
what is a HISTONE transcription factor?
proteins that bind to and organize DNA
What is a Hox/Homeobox transcription factor?
proteins found in all animal species and invertebrates, that regulate segmental separation and development
What are Paired Box (Pax) genes transcription factors?
with paired domains, are factors which can either activate or repress specific genes
What are Basic Helix-Loop-Helix (bHLH) transcription factors?
factors which help regulate fate determination and differentiation
What do Basic Helix-Loop-Helix (bHLH) have?
have a charged DNA binding region and hydrophobic parts for protein-protein interactions
Name two Basic Helix-Loop-Helix (bHLH) transcription factors?
Myogenin and Neurogenin
What are receptor tyrosine kinases?
cell surface receptors including growth factors transfer high energy phosphates
What do receptor tyrosine kinases regulate (5)?
cell migration, proliferation, survival, apoptosis, and new growth, etc. (also used in normal cell function)
What growth factors do receptor tyrosine kinases include?
insulin, epidermal growth factors, nerve growth factors, etc
What are the 3 domains of the receptor tyrosine kinases?
extra-cellular ligand binding domain, trans-membrane domain, intra-cellular kinase domain
In what type of cells does meiosis occur?
In germinal (sex) cells only
What are the 9 basic steps of Meiosis?
Interphase1, Prophase (1,2), Metaphase (1,2) Anaphase (1,2), and Telophase (1,2)
What are 3 main points regarding Mitosis?
same number of chromosomes at start and end, ends with 2 diploid cells, and happens in all cells
What are 3 main points regarding Meiosis?
Only occurs in gametes, Meiosis 1 is known as "reduction division", and final 4 cells are haploids