Cell Biology, Integumentary System, Osmosis, Genetics, and Organelles

Vocabulary flashcards generated from lecture material covering cell cycle phases, mitosis vs meiosis, integumentary system layers/cells/glands/disorders, osmosis and transport, genetics, and cell organelles.

G1 Phase

The initial growth stage of the cell cycle where the cell grows larger and performs normal metabolic tasks.

S Phase

The stage of the cell cycle in which the cell replicates its DNA so each chromosome consists of two sister chromatids.

G2 Phase

The stage of the cell cycle where the cell makes final proteins and prepares for division.

M Phase

The phase of the cell cycle in which the nucleus divides via mitosis and the cytoplasm splits via cytokinesis.

Mitosis

Body cell division occurring in somatic cells that involves one round of division to produce two genetically identical diploid ($2n$) daughter cells.

Meiosis

Sex cell division occurring in germ cells that involves two successive rounds of division (Meiosis I and Meiosis II) with crossing over in Prophase I, producing four genetically diverse haploid ($n$) gametes.

PMAT

The acronym for the four phases of mitosis: Prophase, Metaphase, Anaphase, and Telophase.

Tetrad

A structure consisting of two pairs of sister chromatids aligned together during Prophase I of meiosis.

Mitosis vs. Meiosis Process Comparison

Visual breakdown comparing chromosome duplication, alignment, separation, and end results between mitosis and meiosis.

Mitosis vs. Meiosis Feature Summary Table

Summary table outlining differences in location, function, replication rounds, division rounds, final cell counts, genetic makeup, and chromosome counts.

Melanin

A brown/black pigment produced by melanocytes in the stratum basale and taken up by keratinocytes to absorb UV radiation.

Hemoglobin

A skin pigment derived from blood that imparts a red/pink hue, appearing more prominent where blood vessels are closer to the surface.

Carotene

A yellow/orange skin pigment found in the stratum corneum, obtained from egg yolk and orange/yellow vegetables and fruits.

Dermal Papillae / Epidermal Ridges

Interlocking structures between the epidermis and dermis that prevent epidermal slippage, increase sensitivity, and create fingerprints.

Papillary Layer

The top $20\%$ layer of the dermis composed of loose (areolar) connective tissue.

Reticular Layer

The bottom $80\%$ layer of the dermis composed of dense irregular connective tissue.

Tactile Corpuscles

Light touch sensory receptors located within the dermal papillae.

Lamellar Corpuscles

Deep pressure sensory receptors located in the reticular layer of the dermis.

Eccrine (Merocrine) Glands

Sweat glands that produce a watery secretion directly to the surface of the skin to cool the body.

Apocrine Glands

Sweat glands with ducts leading to hair follicles that develop during puberty and produce a thicker, milky secretion containing fatty acids that cause body odor when digested by bacteria.

Sebaceous Glands

Glands that secrete an oily substance through ducts opening into hair follicles.

Ceruminous Glands

Glands producing cerumen (earwax) that waterproof and protect the ear canal.

Downy Hair

Fine hair type present on a fetus.

Vellus Hair

Fine, pale hair present on children (except eyebrows, lashes, scalp) that makes up two-thirds of female hair and one-tenth of male hair.

Terminal Hair

Longer, coarser, pigmented hair that mostly appears after puberty on the legs, armpits, pubic area, and male face.

Hypodermis

Also known as subcutaneous fat or adipose tissue; a layer beneath the dermis containing loose CT, nerves, and blood vessels that functions in cushioning, insulation, and energy storage.

First-Degree Burn

A burn involving only the epidermis that heals quickly, such as a sunburn.

Second-Degree Burn

A burn involving both the epidermis and dermis, typically resulting from scalds and presenting with blisters.

Third-Degree Burn

A severe burn extending through the epidermis, dermis, and hypodermis (often caused by fire) that requires a skin graft and results in scarring because the skin cannot regenerate.

Basal Cell Carcinoma

The most common and least lethal skin cancer, originating in the stratum basale and rarely metastasizing.

Squamous Cell Carcinoma

A skin cancer originating in the stratum spinosum that can metastasize to lymph nodes, scalp, lower lip, and back of the hand.

Malignant Melanoma

A rare (<$5\%$ of skin cancers) but aggressive skin cancer originating from melanocytes that is usually fatal if it metastasizes.

Epidermis

The avascular outermost layer of skin composed of keratinized stratified squamous epithelium.

Keratinocytes

Epidermal cells that produce keratin and take about 4 weeks to travel to the surface.

Dendritic Cells

Specialized macrophages in the epidermis that function as immune cells.

Stratum Basale

A single layer of cells at the base of the epidermis undergoing consistent mitosis, containing stem cells and melanocytes.

Stratum Spinosum

An epidermal layer consisting of many cell layers with limited mitosis and a water barrier above which cells die.

Stratum Granulosum

An epidermal layer composed of 2 to 5 layers of keratinocytes containing dark granules of keratin and fat.

Stratum Lucidum

A clear epidermal layer found only in thick skin, such as on the palms and soles.

Stratum Corneum

The outermost, thickest epidermal layer made of around 30 layers of dead, scaly cells that are constantly shed as dander.

Aquaporins

Transmembrane channel proteins that specifically allow the passage of water into and out of cells.

Osmolarity

The total solute concentration of a given solution.

Osmotic Pressure

The hydrostatic pressure needed to stop osmosis, which is directly proportional to solute concentration.

Tonicity

The ability of a surrounding solution to affect cell volume and internal pressure by driving water movement via osmosis.

Hypotonic Solution

A solution with a lower solute concentration than the cell (e.g., pure $H_2O$), causing water to enter the cell and leading to cell bursting (lysis).

Isotonic Solution

A solution with the same solute concentration as the cell (e.g., $0.9\%\,NaCl$), resulting in no net movement of water.

Hypertonic Solution

A solution with a higher solute concentration than the cell (e.g., $10\%\,NaCl$), causing water to leave the cell and leading to cell shriveling (crenation).

Active Transport

Movement of substances across a membrane against their concentration gradient, requiring a carrier protein and energy consumption.

Exocytosis

An active bulk transport mechanism where membrane proteins packaging large particles into vesicles discharge their contents outside the cell.

Endocytosis

An active bulk transport mechanism where large particles or substances are engulfed and brought into the cell.

Gene

A specific segment of DNA that encodes instructions for making RNA or protein.

Allele

Alternative forms of the same gene that code for variations of a given trait.

Homozygous

Possessing two identical alleles for a particular trait (e.g., $bb$ or $BB$).

Heterozygous

Possessing two different alleles for a particular trait (e.g., $Bb$).

Genotype

The specific alleles present in an individual's genetic code for a trait.

Phenotype

The observable physical or functional expression of a trait in an organism.

Co-Dominance

A pattern of inheritance where more than one dominant allele exists and both alleles are fully expressed in the phenotype (e.g., AB blood type).

Sex Linkage

Inheritance of traits carried on the X chromosome, causing the resulting phenotype to appear significantly more often in males.

Nucleus

Organelle housing DNA where gene expression occurs via transcription ($\text{DNA} \rightarrow \text{mRNA}$).

Golgi Complex

Organelle that receives proteins from the ER, then sorts, cuts, packages, and distributes them in vesicles.

Rough Endoplasmic Reticulum

Endoplasmic reticulum studded with ribosomes that performs protein synthesis and manufactures plasma membranes.

Smooth Endoplasmic Reticulum

Endoplasmic reticulum lacking ribosomes that synthesizes steroids, stores $Ca^{2+}$, and detoxifies alcohol and drugs.

Lysosomes

Organelles containing digestive enzymes that act as the cell's recycling center to digest old/foreign material and initiate programmed cell death (apoptosis).

Mitochondria

Powerhouse organelles that synthesize ATP for cellular energy transfer, abundant in highly active cells.

Centrioles

Cell division organelles that attach to the cytoskeleton to help pull the cell apart during division.