Cellular Level of Organization Vocabulary Flashcards

Vocabulary flashcards covering cellular structure, cell theory, membrane lipids, membrane proteins, transport mechanisms, and organelle functions based on lecture notes.

Cell Theory

The principle stating that all organisms are composed of cells and cell products, cells are the simplest structure, organism structure and function are due to cellular activities, cells come only from preexisting cells, and cells of all species exhibit biochemical similarities.

Phospholipid Bilayer

A cell membrane structure consisting of two adjacent sheets of phospholipids arranged tail to tail, where hydrophobic tails associate in the interior and polar heads contact fluid inside and outside the cell

amphipathic

Molecules arranged in bilayer

Cholesterol

A lipid molecule comprising $20\%$ of membrane lipids that holds phospholipids still and can stiffen the cell membrane.

Glycolipids

Phospholipids with short carbohydrate chains on the extracellular face, accounting for $5\%$ of membrane lipids. Phospholipids with short carbohydrates chains on extracellular face. Contributes to glycocalyx- carbohydrates coating on surface of membrane proteins

Integral Proteins

Membrane proteins whose hydrophobic regions penetrate into or all the way through the lipid bilayer; some drift in the membrane while others are anchored to the cytoskeleton.

Peripheral Proteins

Membrane proteins that adhere to one face (inside or outside) of the membrane without penetrating the phospholipid layer, usually tethered to the cytoskeleton.

Receptors

Membrane proteins that bind chemical signals.

Second Messenger Systems

Systems within membrane proteins that communicate inside the cell upon receiving a chemical message.

Channel Proteins

Membrane proteins that allow hydrophilic solutes and water to pass through the membrane; they may be continuously open or gated.

Ligand-gated Channels

Gated channel proteins that open or close in response to chemical messengers. Crucial to nerve and muscle function

Voltage-gated Channels

Gated channel proteins that respond to physical stress or voltage changes on a cell, crucial for nerve and muscle function.

Carriers

Membrane proteins that bind specific solutes and transfer them across the cell membrane.

Pumps

Carrier proteins that consume ATP to transport solutes across the cell membrane against concentration gradients.

Cell Identity Markers

Glycoproteins on the cell membrane that act as identification tags.

Cell Adhesion Molecules

Proteins that mechanically link a cell to extracellular material or to other cells.

Glycocalyx

A fuzzy carbohydrate coat external to the plasma membrane involved in protection, immunity, defense against cancer, transplant compatibility, cell adhesion, fertilization, and embryonic development.

Microvilli

Cell surface projections that increase surface area by $15$ to $40\times$, highly developed in absorptive cells as a brush border, and sometimes containing actin filaments that tug toward the cell center to milk absorbed contents.

Simple Diffusion

The unassisted passage of small, non-polar substances such as oxygen and carbon dioxide across the lipid bilayer down their concentration gradient.

Facilitated Diffusion

The movement of substances across the plasma membrane down their concentration gradient with the assistance of channel proteins or carrier proteins. Channel proteins are less selective than carrier proteins, and usually mildly discriminate between their cargo based on size and charge

Osmosis

The diffusion of water through a semipermeable membrane down its concentration gradient.

Tonicity

The ability of a surrounding solution (bath) to affect fluid volume and pressure in a cell. Dependent on the concentration of non-permeating solutes!!!!!

Hypotonic Solution

A solution with a lower concentration of non-permeating solutes (such as distilled water) that causes a cell to absorb water and swell.

Hypertonic Solution

A solution with a higher concentration of non-permeating solutes that causes a cell to lose water and shrivel (crenate).

Isotonic Solution

A solution that causes no change in cell volume, such as normal saline ($0.9\%\,\text{NaCl}$).

Sodium-Potassium Pump

(Active transport) Found in many membranes. An active transport pump powered by ATP that extrudes $3$ sodium ions and imports $2$ potassium ions into the cell per cycle. Moves them in opposite directions

Endocytosis

A form of active transport in which a cell envelopes extracellular materials using its cell membrane.

Phagocytosis

A relatively nonselective form of endocytosis in which a cell engulfs a large particle.

Pinocytosis

A form of endocytosis in which a cell takes in small particles suspended in fluid.

Receptor-mediated Endocytosis

A selective form of endocytosis where the cell envelopes material in response to external receptors binding a specific ligand.

Exocytosis

A active process where material packaged in an intracellular vesicle is exported when the vesicle membrane fuses with the cell membrane, releasing its contents into the extracellular space.

Pancreatic Acinar Cells

Cells that produce and secrete digestive enzymes via exocytosis, containing tiny black granules are secretory vesicles filled with enzymes that will be EXPORTED FROM THE CELLS VIA EXOCYTOSIS- digestive enzymes

Membranous Organelles

Internal cell structures enclosed by membranes, including the nucleus, mitochondria, lysosomes, peroxisomes, endoplasmic reticulum, and Golgi complex.

Non-membranous Organelles

Internal cell structures that lack membranes, including ribosomes, centrosomes, centrioles, and basal bodies.

Rough ER

A network of thin membranous sacs studded with ribosomes that serve as primary sites of protein synthesis.

Smooth ER

A network of membranous sacs that synthesizes phospholipids and steroid hormones, regulates cellular $\text{Ca}^{++}$ concentration, metabolizes carbohydrates, and breaks down toxins.

Golgi Apparatus

An organelle resembling a stack of pancakes that manipulates, organizes, modifies, packages, and tags products from the rough ER, and produces LYSOSOMES.

phospholipid structure

consists of polar phosphate, “head” which is hydrophilic and a non polar lipid “tail”, which is hydrophobic. Unsaturated fatty acids result in kinks in hydrophobic tails.

Mitochondria

Energy-conversion factories of the cell. Composed of two separate lipid bilayer membranes. Along the inner membrane are various molecules that work together to produce ATP

Peroxisome

membrane bound organelles that contain an abundance of enzymes for DETOXIFYING harmful substances and lipid metabolism

What is cytoskeleton and what are the 3 components?

Microtubules, microfilaments, intermediate filaments

Cytoskeleton plays an important role in maintaining cell shape and structure, promoting cellular movement and aiding cell divisionicM

Microvilli

Extension of membrane- 15-40x more surface area

It is best developed in cells specialized in absorption. May appear as a fringe brush boarder.

Some contain actin filaments that are tugged towards center of cell

Cilia

Hairlike processes- 7-10m long

They extend from the surface of eukaryotic cells. Helps with balance in inner ear, light detection in retina, “Antenna” for monitoring nearby conditions

Motile cilia

Respiratory tract, uterine tubes, ventricles of brain, ducts of testes

50-100 on each cell

beat in waves sweeping material across a surface

power strokes followed by recovery strokes

nucleus

largest organelle

control center of the cell. contains genetic material that determines the entire structure and function of cell

multinucleate muscle

different from cardiac and smooth muscle cells because they have nuclei. Long and stringy, form when smaller cells merge together during development. all nuclei from those original small cells stick around in the big muscle cell, making it multinucleated.

Deoxyribonucleic acid

(DNA) long thread like molecule

average human DNA 2in. 46 chromosomes in human cells

Hydrogen molecules are involved in holding the two strands of DNA double helix together

What does a nucleotide consist of?

Sugar, phosphate group, nitrogenous base!!!!!!!

DNA Macrostructure

DNA strands wrap around histones, forming chromatin, which condenses into chromosomes during cell division

DNA Molecular Structure

Double helix and two complementary strands

Strands are linked together by hydrogen bonds between nitrogenous base pairs

Sides- backbone, alternating phosphate groups and deoxyribose sugar.

Pairing rule

Adenine pairs with Thymine

Cytosine pairs with Guanine

What is the law of complementary base pairing?

One strand determines the base sequence of the other

What are two types of nitrogenous bases in nucleic acids

Purines (double ring) pyrimidines (single ring)

Purines

Adenine and guanine

Pyrimidines

Cytosine thymine and uracil

genetic code

holds all the genetic information necessary to build a cells PROTEIN

what are 3 important RNAs for protein synthesis

Messenger, ribosomal, and transfer RNA

Splicing RNA

in the nucleus, a structure called a spliceosome cuts out introns (encoding regions) within a pre-mRNA transcript and reconnects the exons

What is translation

The process of translating from RNA to protein. mRNA is read by a complex including ribosomes and tRNAs, which bring amino acids to build a polypeptide chain

What is a codon

3 base sequence of mRNA that directly encodes an amino acids

Describe the process from DNA to protein

Transcription in the nucleus produces mRNA, which is sent to the cytoplasm for translation. The mRNA transcript is decoded into a protein with the help of ribosomes and tRNAs.

What are two major phases of the cell cycle

Mitosis (cell division) and interphase (cell growth and normal functions) Interphases is subdivided into G1, S, and G2 phases

What is the purpose of cell division?

To oversea the separation of identical genetic material into two new nuclei, followed by the division of the cytoplasm.

Control of the Cell Cycle

Cells proceed through the cell cycle under the control of molecules like CYCLINS and CYCLIN-DEPENDENT kinases. These molecules determine if a cell Is ready to move to the next stage.

What is Hematopoiesis

The process of differentiation of multipoint cells into blood and immune cells. These stem cells give rise to many different cell types, including immune cells and red blood cells.

What are Transcription Factors

Proteins that affect the binding of RNA polymerase to a particular gene on the DNA molecule, regulating gene expression

What is the significance of STEM cells

Their capacity to differentiate into specialized cells makes them valuable for therapeutic applications to replace damaged cells.

What is a Totipotent Stem cells

A stem cell with the capacity to differentiate into specialized cells, potentially useful in therapies