Test One Flashcards
What is the name of the combination of DNA, histones and other proteins that make up the chromosome?
Chromatin
What is the extended form of chromatin called?
euchromatin
What is the condensed form of chromatin called?
heterochromatin
What can be compared to “beads on a string”?
Euchromatin
What organelle divides and heads to the poles in mitosis?
Centrosomes
What does the centrosome consist of?
2 centrioles
What is the name of the microtubules that spread from the centrosomes?
Mitotic spindle fibers
What is the name of the connection site of the chromosome?
Centromere
What are the three types of tubules present in a dividing cell?
- Kinetochore (break chromosomes), 2. polar (support breaking chromosomes) and 3. aster (found near centrosomes)
What two subunits make up microtubules?
- Alpha tubulin and 2. Beta tubulin
What is the growth and the shrinking called of microtubules?
- Polymerization and 2. Depolymerization
What is the name of the proteins that move along the microtubule tracks?
Motor proteins
What energy do motor proteins use?
ATP
What is responsible for spindle formation, chromosome alignment and separation, and avoiding aneuploidy in the cells?
Motor proteins
What three phases make up interphase?
G1, S and G2
What shrinks and disappears during prophase?
Nucleolus
What marks the beginning of prometaphase?
The breakdown of the nuclear envelope
What are the four most common sites of metastisis?
- Lungs, 2. Liver, 3. Bones and 4. Lymph nodes
What is the term that describes chromosomes that can undergo crossing over?
Bivalent Chromosomes
What position allows crossing over?
Synapsis
What is it called when genetic material starts being transferred from strand to strand?
Chiasma
What cells make the germ line?
Primordial germ cells
What type of tumor can form from primordial germ cells?
Teratoma
What are immature male and female gametes called respectively?
Spermatogonia and oogonia
What are mature male and female gametes called respectively?
Spermatozoa and definitive oocyte
What prevents more than one sperm from fertilizing the egg?
The zona pellucida
When a zygote undergoes cleavage to divide into smaller cells, what are these smaller cells called?
Blastomeres
How many cells must be present for the young zygote to be termed a Morula?
32
What is it called when Down syndrome occurs due to a translocation of chromosome 21 onto 14?
Robertsonian translocation
What is Mosaicism?
When the extra chromosome 21 is lost throughout cleavage in some cells resulting in variations of Down’s syndromes
What is penetrance?
How much a genotype associates with its respective phenotype
What are the folds called in Down’s patients?
Epicanthal folds
What is it called when maxillary and mandibular teeth have a size discrepancy that will not allow proper occlusion?
Bolton Discrepancy
What is it called when there are 8 blastomeres and the outside ones become convex will the inners concave?
Compaction
What is PGD
Preimplant Genetic Diagnosis
What are the outer cells called in a developing embryo?
Trophoblasts
What are the inner cells called in a developing embryo?
Embryoblasts
What is the name of the water-filled cavity in the morula and how does it get there?
Blastocyst, Na/atpase pumps oriented basally
What are the two sides of the blastocyst called?
Embryonic versus abembryonic
What is it called when, at five days, the embryo gets rid of the outside covering of the trophocytes?
Zona hatching
When cells proliferate where they make contact with the endometrium of the uterus and congeal into a large mass of cytoplasm and nuclei, what is this called?
Syncytium
When does the embryo form the bilaminar disc?
Week two
What are the two layers of the bilaminar disc?
- Epiblast (primary ectoderm) and 2. Hypoblast (primary endoderm)
When does the amniotic fluid appear?
Day 8
When do syncitotrophoblasts almost completely cover the embryo?
Day 9
What is the name of the area not initially covered with syncitotrophoblasts called?
Coagulation plug
What do hypoblasts form at day nine?
The extraembryonic endoderm
Once the blastocyst cavity is lined with hypoblasts, what is it called?
Heuser’s membrane
As Heuser’s membrane forms, what else forms?
Extra embryonic mesoderm
Once Heuser’s membrane forms, what is the cavity known as?
Primary yolk sack
When do cytotrophoblastic lacunae make contact with maternal capillaries to take up blood flow?
Days 11-13
What are the two names given to the extra outer cavity formed between days 12 and 13?
Extraembryonic coelom/chorionic cavity
What happens with the yolk sack on day 12?
The primary yolk sac is ejected and the definitive yolk sac forms
When does the primitive streak appear?
Week 3
What three things constitute the primitive streak?
Primitive pit, groove and node
What is it called when the epiblasts begin to proliferate on day 16?
Gastrulation
What replaces hypoblasts?
Definitive endoderm
Which two directions do the embryonic mesoderm cells migrate?
Laterally and cranially
What do laterally-migrating mesoderm cells form?
Somites
When is the notochordal process formed?
Day 17
What is the thickening called along the primitive streak in the endoderm cells?
Prechordal plate
What does the prechordal plate eventually form?
The mouth
What are the three layers of the trilaminar disc?
- Ectoderm, 2. Mesoderm and 3. Definitive endoderm
What are the names of the two depressions formed in the third week?
- buccopharyngeal membrane and 2. cloacal membrane
When does the primitive streak disappear and what does it leave behind?
Day 26, caudal eminence
When has the embryo divided into somatomeres?
Day 21
Which direction does the notochord travel as it develops?
Caudal to cranial
Which portion of the neural plate lengthens the quickest?
The caudal end
What are the two layers that form as the neuronal tube closes?
- Roof plate and 2. overlying surface ectoderm
What forms the interface between the two layers of neruonal cells?
Neural crest cells
What day do neural crest cells migrate?
Day 24
What transformation do neural crests cells undergo?
Epithelial to mesenchymal
What is the fourth layer?
Neural crest cells
What week does folding come into play?
Week 4
What causes folding?
Differential growth
What two important structures form cranial (?) to the oropharyngeal membrane?
- Cardiogenic area and 2. Septum transversum
What does the septum transversum separate?
Abdominal and thoracic cavities
What causes the locations of the cardiogenic area and the oropharyngeal membrane to switch places?
Forward growth of the neural plate - it causes translocation
When does the closure of neural arches occur?
Week 11
What is an outpocketing of brain called?
Encephalocele
What type of spina bifida is the most severe?
Myelomeningocele
What does somatic mesoderm develop into in pharyngeal arches?
The artery and the muscle
What do neural crest mesenchymal cells develop into in pharyngeal arches?
Bone, cartilage and connective tissue
The incus and the alisphenoid are both associated with which arch?
Arch one, maxillary process
The meckle’s cartilage and the malleus are both associated with which arch?
Arch one, mandibular process
What does the artery in the first arch turn into?
The maxillary artery
What does the second arch cartilage give rise to?
Stapes, styloid process, syloid hyoid ligament and the lesser horn and upper rim of the hyoid bone
What does the second arch artery turn into?
Stapedial artery
What muscles does the second arch somatic mesoderm give rise to?
Muscles of facial expression
Should a lateral cervical cyst form and not dissolve, what is the result?
Cervical cyst
What do neural crest cells from arch three form?
Lower rim of hyoid bone and greater horn of hyoid
What muscle develops from arch three?
Stylopharygeus
What arteries form form arch three?
Common carotid and internal carotid
What three arteries form from arch four?
Arch of aorta, right subclavian and original pulmonary
Where are the muscles associated that develop from arch four?
Pharynx
What two arteries form from arch six?
Ductus arterious and definitive pulmonary
What muscles arise from the arch six?
Laryngeal constrictors
What is the difference in inervation of arch four versus arch six?
Both are CN X, but four is superior laryngeal branch while six is recurrent laryngeal branch
What does the first pharyngeal cleft develop into?
External auditory canal
What do pharyngeal clefts 2, 3 and 4 develop into?
Nothing - they are obliterated
What does the first pharyngeal pouch develop into?
Eustacian tube - middle ear canal
What does the second pharyngeal pouch develop into?
Palatine tonsil
What does the third pharyngeal pouch develop into?
Ventral/inferior - thymus, dorsal/superior - inferior parathyroid
What does the fourth pharyngeal pouch develop into?
Dorsal - superior parathyroid, ventral - ultimobranchial body
What does the ultimobranchial body do?
Induces neural crest cells to become parafollicular cells of the thyroid
Where does the thyroid start forming?
At the end of the foramen cecum
