CELL BIO MIDTERM

Which of the following bonds are found between the nitrogenous bases in DNA

Hydrogen

The folding of a protein into a globular form comprises which level of organization?

Primary

Secondary

Tertiary

Quaternary

Tertiary

Which type of molecule mainly imparts fluidity to the plasma membrane?

Carbohydrates

Lipids

Proteins

Nucleic acid

Lipids

Which of the following we the building block of proteins

Amino acids

Nuclei’s acids

Fatty acids

Nitrogenous bases

Amino acids

Which of the following is comprised of 9 triplet configuration of micro tubules?

Cilia

Arctic

Basal bodies

Centrioles

Basal bodies and centrioles

How does simple diffusion differ from vacillated diffusion

It is slower

It is faster

It is much slower

What is the sight of lipid synthesis

Smooth ER

Protein synthesis for export

Rough ER

Simple diffusion

The passive transport mechanism by which oxygen moves directly across the lipid bilayer of the plasma membrane.

perichondrium

where immature chondrocytes are located

receptors located in the epidermis

free nerve endings and merkel cells

what kind of tissue forms the fetal skeleton

hyaline cartilage

ribosomes

cellular organelles with 2 subunits

microfilaments

cytoskeletal component that lies directly beneath the plasma membrane

which are most similar in structure?

cilia and basal bodies

basal bodies and centrioles

cilia and centrioles

cilia and microvilli

microvilli and basal bodies

basal bodies and centrioles (9 microtubule triplets)

T/F Corneal epithelium continues to undergo mitosis throughout life

TRUE

T/F RPE continues to undergo mitosis throughout life

FALSE

T/F Bowman’s membrane can regenerate itself when damaged

FALSE

adding a 5’-7-methyl cap to the primary RNA transcript during nuclear processing…

protects against degradation

which type of tissue forms the main part of the exocrine gland duct system

stratified cuboid

which tissue maximally suited for diffusion of gasses through it

simple squamous epithelium

adhering junctions (zonula adherens)

junctions associated with actin filaments that provide mechanical stability, facilitating cell adhesion and maintaining tissue integrity. (junctions associated with actin)

thickness of peripheral cornea

0.71 mm

Golgi apparatus

The membrane-bound organelle that serves as the site for post-translational modifications of proteins, such as glycosylation.

Peripheral membrane protein

A protein that does not penetrate the lipid bilayer and can be localized to either the internal or external surface of the plasma membrane.

Sodium-potassium pump

A primary active transport protein that uses energy from ATP hydrolysis to transport sodium and potassium ions across the cell membrane against their concentration gradients.

Covalent bond

The most stable chemical bond, formed by the sharing of pairs of electrons between atoms.

Cilia

Microtubule-based cell surface projections characterized by a $9+2$ doublet configuration.

Smooth endoplasmic reticulum (Smooth ER)

The intracellular membranous organelle that serves as the primary site of lipid biosynthesis.

5' cap (5'7' cap)

A modified guanine nucleotide added to the 5' end of a newly synthesized RNA transcript during processing to protect it from degradation.

RNA splicing

The nuclear process of removing non-coding intron sequences from a precursor mRNA transcript occurs in the nucleus.

Nucleolus

The specialized, non-membrane-bound nuclear subcompartment where ribosomal RNA (rRNA) is synthesized and assembled.

RNA polymerase II

The enzyme that synthesizes messenger RNA (mRNA) by reading the template DNA strand in the 3' to 5' direction.

RNA polymerase I

The RNA polymerase specialized in synthesizing ribosomal RNA (rRNA).

RNA polymerase III

The RNA polymerase specialized in synthesizing transfer RNA (tRNA).

Beta-pleated sheet

A secondary level of protein organization formed by hydrogen bonding along the polypeptide backbone.

Cyclins

Regulatory cell cycle proteins that accumulate during specific interphase stages (such as G1, S, and G2) to drive progression toward cell division.

Crystalline lens

The transparent, biconvex intraocular structure responsible for the optical accommodation of the eye.

Limbus

The anatomical border or transition zone between the opaque sclera and the transparent cornea.

Choroid

The vascular, pigmented posterior component of the uveal tract.

Iris

The pigmented contractile diaphragm of the uvea located immediately anterior to the crystalline lens.

Glands of Zeis

Sebaceous oil glands associated with eyelash follicles that secrete the outermost lipid layer of the tear film.

Retinal pigment epithelium (RPE)

The monolayer of melanin-containing simple cuboidal epithelium supporting the photoreceptors of the retina.

Meibomian gland

A modified sebaceous gland located within the tarsal plate of the eyelid that produces an oily secretion via holocrine secretion. (oil gland and exocrine gland)

Claudin

The essential transmembrane protein component of tight junctions (zonulae occludentes).

Connexins

Transmembrane protein subunits that hexamerize into connexons to form intercellular gap junctions.

Hemidesmosomes

Specialized cell junctions found at the basal surface of epithelial cells that anchor intermediate filaments to the underlying basement membrane.

Desmosomes

Intercellular anchoring junctions that link intermediate filaments of adjacent cells together.

Fornix

The loose, flexible transitional fold between the bulbar conjunctiva and the palpebral conjunctiva.

Corneal epithelium

The outermost protective non-keratinized stratified squamous epithelium covering the cornea.

Pacinian corpuscle

An encapsulated mechanoreceptor situated deepest in the dermis that detects deep pressure and high-frequency vibration.

Meissner’s corpuscles

Encapsulated sensory touch receptors located in the dermal papillae that mediate fine touch perception.

Free nerve endings

Unencapsulated terminal nerve fibers located in the epidermis that detect pain and temperature sensations.

Merkel cell

A light-touch receptor cell residing within the stratum basale of the epidermis.

Krause receptors

Sensory bulboid receptors found deeper in the dermal layer of the skin.

Sclera

The dense regular connective tissue forming the protective outer white layer of the eye, composed predominantly of collagen type I.

Lamina cribosa

The sieve-like, weakest region of the sclera through which retinal ganglion cell axons pass to form the optic nerve.

Stratum lucidum

A translucent waterproofing epidermal layer present only in thick skin and absent in thin skin.

Stratum basale (Stratum germinativum)

The deepest epidermal layer containing dividing stem cells and the cell bodies of melanocytes.

Corneal transparency

An optical property primarily maintained by the uniform diameter and precise, regular spacing of collagen type I fibrils.

Iris stroma

The loose areolar connective tissue vascular layer forming the main body of the iris, typically devoid of adipose tissue.

Hypodermis

The subcutaneous layer deep to the dermis, composed primarily of adipose tissue.

Inner layer of the ciliary epithelium

The non-pigmented epithelial cell layer of the ciliary body responsible for secreting aqueous humour into the posterior chamber.

Posterior bilayer epithelium of the iris

The heavily pigmented two-cell-thick epithelial layer on the back of the iris facing and lining the posterior chamber.

Embryonic nucleus of the lens

The central-most and earliest-formed portion of the lens containing the oldest crystallin proteins and exhibiting the highest refractive index. Densest part of lens

Iris dilator

The pupillary dilator muscle structure composed of contractile myoepithelial cells.

Central corneal thickness

The anatomical measurement across the center of the normal human cornea, approximately equal to $0.52\,\text{mm}$.

Ora serrata

The serrated boundary where the ciliary body's non-pigmented inner epithelium transitions into the neural retina.

Iris crypts

Microscopic pits or openings located on the anterior border layer of the iris.

Iris sphincter

The circular smooth muscle responsible for pupillary constriction, situated within the medial stroma of the iris.

Anterior lens capsule

The elastic basement membrane covering the anterior surface of the lens that continues to thicken with advancing age.

Osteoblasts

Bone cells that synthesize and secrete osteoid (collagen and proteoglycans) and can revert to osteoprogenitor cells.

Osteocytes

Mature bone cells that reside entrapped within the calcified, mineralized extracellular matrix inside lacunae.

Canaliculi

Microscopic fluid-filled canals traversing bone matrix that interconnect the lacunae of neighboring osteocytes in an osteon.

Haversian canal (Central canal)

The central vascular channel around which concentric lamellae are arranged in an osteon.

Fibrocartilage

A dense, durable type of cartilage containing abundant collagen fibers that constructs the intervertebral disks.

Hyaline cartilage

A glassy cartilage containing type II collagen and proteoglycans (lacking elastic fibers) that forms the developing fetal skeleton and calcifies in osteoarthritis.

Elastic cartilage

A flexible cartilage type characterized by high concentrations of elastic fibers within its extracellular matrix.

Corneal endothelium

The single posterior cellular monolayer of the cornea, composed of simple squamous epithelium.

Lacrimal gland

The tear-producing exocrine gland classified morphologically as a compound tubuloacinar (tubulacinar) gland.

Sweat gland (Sudoriferous gland)

A cutaneous exocrine gland morphologically classified as a simple coiled tubular gland.

Holocrine secretion

A mode of glandular secretion where the entire secretory cell ruptures and dies to discharge its oily contents, characteristic of sebaceous and meibomian glands.

Tear film layers

The three-tiered precorneal film structured from superficial to deep as lipid, aqueous (water), and mucin.

Epidermis

The keratinized stratified squamous epithelium providing the outer protective barrier of the skin.

Lysosomes

Membrane-bound acidic organelles containing hydrolytic enzymes specialized for macromolecular degradation.

Rhodopsin

A visual photopigment molecule classified structurally as a 7-transmembrane-domain protein.

Astral spindle fibers

Microtubules of the mitotic apparatus that radiate outward from and surround the centrioles / centrosomes.

Free ribosomes

Cytoplasmic ribosomes that synthesize proteins intended to remain within the cytosol or migrate to mitochondria.

Spindle checkpoint

The mitotic regulatory checkpoint occurring at metaphase that ensures all chromosomes are properly aligned at the metaphase plate and attached to spindles.

Cyclin-dependent kinases (CDKs)

Protein kinases controlling cell cycle transitions that must be phosphorylated and bound to cyclins to achieve catalytic activity.

Vitreous base

The strongest anatomical attachment of the vitreous body, straddling the ora serrata and the pars plana of the ciliary body.

Palpebral conjunctiva

The mucous membrane lining the inner surface of the eyelids, composed of stratified cuboidal or stratified columnar epithelium.

Sarcoplasmic reticulum

where is calcium sequestered in the muscle? also smooth endoplasmic reticulum

T-tubule system

Deep, tubular invaginations of the sarcolemma that penetrate directly into the interior of the muscle fiber

Sarcolemma

The specialized plasma membrane of a muscle cell/fiber (approximately 9 nm thick) Myofibrils attach to the sarcolemma internally

ventral horn

what is the location of somas of motorneurons

T/F mueller cells are a type of schwann cell

False

parafoveal region

Where is the greatest thickness of ganglion cells

perifoveal region

Represents the transition zone where the macula merges into the peripheral retina. rod dominants

T/F Rods are densest about 40 degrees from the fovea

False (20 degrees)