Cell Structure & Function
This organelle is continuous with the nuclear envelope and synthesizes secreted and membrane proteins.
What is the rough ER?
When in development do PGCs migrate to the gonad?
week 4-5
Which organelle contains its own circular DNA, maternally inherited?
Mitochondria
What does “gating” mean in ion channels, and give the three triggers.
Opening/closing conformational change; triggered by voltage, ligand, or stretch.
What are the three types of muscle tissue, and how are they distinguished histologically?
Skeletal muscle
Striated, long cylindrical fibers
Multiple nuclei at periphery
Voluntary
Cardiac muscle
Striated, branched fibers
Single central nucleus
Intercalated discs
Involuntary
Smooth muscle
Non-striated, spindle-shaped cells
Single central nucleus
Involuntary
This organelle stores calcium in muscle cells.
What is the sarcoplasmic reticulum?
What is the chromosome number and ploidy of a cell in anaphase of meiosis 1?
n, 2c
Lagging strand is made in short fragments. Name them, and the enzymes that remove primers and seal gaps.
Okazaki fragments; RNase H & DNA pol δ; DNA ligase.
Which pufferfish neurotoxin blocks voltage-gated Na⁺ channels?
Tetrodotoxin (TTX).
What is the functional unit of skeletal muscle, and its boundaries? What is the difference between the I band and A band?
Sarcomere, bounded by Z-lines.
I band: light, only actin
A band: dark, actin and myosin
What sugar coat surrounds many cell membranes and aids in cell recognition?
What is the glycocalyx?
During meiosis I, homologous chromosomes pair up and exchange genetic material at these sites.
What are chiasmata?
Define “degenerate but unambiguous” in the genetic code.
Many codons per amino acid (degenerate), but each codon = only one amino acid (unambiguous).
What type of collagen is found in basal vs reticular lamina?
Basal = type IV; Reticular = type III and VII
Fill in the blanks: The__________ nerve branches into the _______________ nerve, which innervates the ___________ and _____________ of the carotid artery, functioning in modulating __________.
Deficiency of this vitamin prevents hydroxylation of proline and lysine in collagen synthesis.
What is vitamin C?
Cell with how many chromosomes result from nondisjunction in meiosis I?
Gametes with 24 or 22 chromosomes.
Which specific DNA repetitive sequence is 6bp, and what kind of DNA is it categorized as?
telomeric, mini satellite DNA
Compare Na⁺ vs K⁺ voltage-gated channel gating (activation/inactivation gates)
Na⁺: 1 activation + 1 inactivation gate; K⁺: 1 activation gate only.
What is the innervation and action of rhomboid muscles?
Dorsal scapular nerve (C4–C5); retract scapula & rotate to depress glenoid.
Which molecular tag is added to proteins destined for lysosomes?
mannose-6-phosphate
Describe seven characteristics common to most epithelium
Polarity, connected to lamina propria, basement membrane, nourished by diffusion due to lack of blood vessels, have intercellular adhesion methods, highly regenerative, contain keratin intermediate filaments.
A child has an autosomal dominant disease. The parents are phenotypically normal. What is the likely etiology of the disease?
gonadal mosaicism
What is wallerian degeneration? Where does it occur? And where can it be fixed?
When there is neuronal damage, distal to the injury the cell undergoes Wallerian degeneration. The endoneurium sends signals that the BBB is damaged which causes cytokine signaling, bringing in macrophages. The Schwann cells dedifferentiate, assisting in phagocyte activity and forming a big ball of cells surrounding the axon, reforming the connection. This allows at times for axonal regeneration. (ONLY PNS)
In the CNS, macrophages cannot bridge the BBB, preventing neuronal regeneration. Form scars rather than regeneration.
What is the innervation and actions of the pectoralis major?
medial pectoral nerve and the lateral pectoral nerve. arm adduction, medial rotation, and flexion and extension of the humerus.