LAB 2 Cell Biology and Membrane Structure

Comprehensive flashcards covering cell structure, membrane components, organelles, DNA replication, and specialized extensions based on the human biology lecture transcript.

Cells

The smallest living structures and the building blocks of multicellular structures, varying in size, shape, and function.

Plasma (cell) membrane

The structure that surrounds cellular contents and separates the cell from the surrounding fluid.

Nucleus

The organelle that contains the genetic content (DNA) of the organism.

Cytoplasm

The portion of the cell that contains the fluid (cytosol) and organelles.

Organelles

Functional pieces within a cell that keep the cell alive.

Intracellular fluid (ICF)

Also called cytosol, this fluid is found inside the cell and accounts for $\frac{2}{3}$ of the water in the body.

Extracellular fluid (ECF)

Fluid found outside of the cell, accounting for $\frac{1}{3}$ of the water in the body; consists of interstitial fluid and plasma.

Interstitial fluid

A compartment of the extracellular fluid located between cells.

Plasma

A compartment of the extracellular fluid found within blood vessels.

Phospholipid bilayer

The basic structure of the plasma membrane, composed of polar hydrophilic heads and nonpolar hydrophobic tails.

Cholesterols

Stabilizing components of the plasma membrane made from steroids (4 carbon ring structure) embedded between fatty tails.

Integral proteins

Proteins embedded within and extending across the plasma membrane.

Peripheral proteins

Proteins that are not embedded but are attached loosely to the internal or external surfaces of the membrane.

Glycocalyx

A fibrous meshwork of carbohydrates on the external surface of the membrane, including glycoproteins and glycolipids.

Transport Proteins

Membrane proteins such as channels, carriers, and pumps that regulate the movement of substances across the selectively permeable membrane.

Ligands

Specific molecules, such as neurotransmitters or hormones, that bind to cell surface receptors.

Identity markers

Proteins that identify a cell as ‘self’ to prevent the immune system from destroying it.

Nuclear envelope

A double membrane structure separated from the cytoplasm that contains nuclear pores to allow molecular entry and exit.

Nucleolus

A structure within the nucleus responsible for the production of ribosomes.

Histones

Globular proteins around which DNA molecules are wrapped.

Chromatin

Long strands of DNA molecules present when a cell is not dividing.

Chromosomes

Tightly coiled structures of DNA formed during mitosis to prevent tangling during cell division.

DNA helicase

The enzyme responsible for unwinding and breaking the hydrogen bonds between parental DNA strands during replication.

DNA polymerase

The enzyme that assembles new strands of DNA by forming covalent bonds between nucleotides.

Rough Endoplasmic Reticulum

A network of membranous channels with fixed ribosomes that synthesizes, modifies, and stores proteins.

Smooth Endoplasmic Reticulum

Ribosome-free channels responsible for lipid synthesis, glycogen metabolism, and drug/alcohol detoxification.

Golgi Apparatus

Four or five membranous sacs that receive, modify, and store proteins while forming secretory vesicles.

Secretory vesicles

Vesicles made exclusively by the Golgi apparatus for secreting substances out of the cell or to the plasma membrane.

Lysosomes

Sacks of enzymes with an acidic fluid ($pH$ of $5$) that remove damaged organelles or break down molecules from endocytosis.

Peroxisomes

Small sacs that break down specific molecules like fatty acids and amino acids, and synthesize lipids like bile salts.

Mitochondria

The organelle responsible for creating energy ($ATP$) through cellular respiration.

Cristae

Inward folds of the inner mitochondrial membrane containing enzymes for energy-producing reactions.

Ribosomes

Organelles made of two rRNA subunits that function to make proteins; can be free or bound.

Proteasomes

Structures found in the cytoplasm and nucleus that break down proteins tagged with ubiquitin.

Microfilaments

Thin strands made of the protein actin that maintain cell shape, form microvilli, and assist in muscle contraction.

Microtubules

Hollow tubes composed of the protein tubulin that anchor organelles and form centrioles, cilia, and flagella.

Centrosome

A structure composed of two perpendicular centrioles that produces spindle fibers for chromosome movement during cell division.

Cilia

Microtubule-based extensions that move in a wave-like motion to move substances across the cell surface.

Flagella

Microtubule-based extensions, like the tail of a sperm cell, that move the cell through body fluids.

Microvilli

Non-movable extensions made of microfilaments that increase the surface area of the plasma membrane for absorption.