BIOL121: 05/21-22/2026 (Mendel)

nucleotides

deoxyribose sugar

phosphate

4 nitrogen bases (A pairs with T, G pairs with C)

purines

adenine (A)

guanine (G)

pyrimidines

cytosine (C)

thymine (T)

RNA

single stranded linear molecule outside nucleus

ribose sugar, THYMINE replaced with URACIL

mRNA, tRNA, rRNA

ATP

directly powers chemical reactions in cells

adenine containing RNA nucleotide + 2 phosphate groups

AMP → ADP → ATP

3 basic parts of cell

PLASMA MEMBRANE = flexible outer boundary

CYTOPLASM = intracellular fluid containing organelles

NUCLEUS = DNA containing control center

nucleolus

ribosome subunit assembly

chromatin

tighly coiled chromosomes in EARLY PROPHASE

ribsosome

protein synthesis

some free in cytoplasm

rough ER

hold proteins and move back to nucleus

smooth ER

fat storage everywhere else

calcium storage (muscle)

centriole

attach to chromosomes to pull

flagella, microvilli, cilia

extracellular materials

INTERSTITIAL FLUID = cells submersed in fluid

BLOOD PLASMA = fluid of blood

CEREBROSPINAL FLUID = fluid surrounding nervous system organs

CELLULAR SECRETIONS = saliva, mucus

EXTRACELLULAR MATRIX = substance acting as glue to hold cells together

cell function

cell metabolism and energy use

synthesis of molecules

communication = electrical and chemical

reproduction and inheritance = specialized to gametes for exchange

plasma membrane

ICF, ECF, INTERSTITIAL FLUID (ECF surround cell)

surface sugars form GLYCOCALYX

6 essential sugars, communication factor

membrane lipids

75% PHOSPHOLIPIDS (lipid bilayer) = polar hydrophilic head, nopnpolar hydrophobic tail

5% GLYCOLIPIDS = lipids with polar sugar groups on outer membrane

20% CHOLESTEROL = increase membrane stability and fluidity

intergral membrane proteins

allow cell communication with environment

½ mass of plasma membrane

transmembrane proteins (span entire membrane)

transport proteins, enzymes, receptors

peripheral membrane protein

loosely attached to integral protein

filaments on intracellular surface for plasma membrane support

enzymes, motor proteins (shape change during cell division and muscle contraction), cell-to-cell connections, support, part of GLYCOCALYX

glycocalyx

consists of sugars (carbohydrates) sticking out of cell surface

GLYCOLIPIDS, GLYCOPROTEINS

specific cell-to-cell recognition

allows immune system to recognize “self vs nonself”

gap junctions

transmembrane proteins form tunnels allowing small molecules to pass cell-to-cell

spread ions, simple sugars, other small molecules

electrical signals passed quickly (cardiac and smooth muscle)

passive transport

movement of molecules DOWN concentration gradient

no cellular energy required ATP

plasma membrane stops diffusion (selective permeability)

simple diffusion

hydrophobic substances diffuse directly through phospholipid bilayer

O2, CO2, fat soluble vitamins

osmosis

water follows sugar → salt → proteins

low to high concentration movement of water

diffuse through lipid bilayer and water channels (AQUAPORINS)

OSMOLARITY = measure of total concentration of solute particles

OSMOTIC PRESSURE = sucks water in

HYDROSTATIC PRESSURE = pushes water out

channel mediated facilitated diffusion

channels with aqueous filled cores formed by transmembrane proteins

ions or water (aquaporins) transported DOWN gradient

LEAKAGE CHANNEL = always open

GATED CHANNEL = controlled by chemical or electrical signal (Ca doors must be electrically opened)

isotonic solutions

0.9%

cell retains normal size and shape (EQUILIBRIUM)

hypertonic solution

2.0%

cell lose water by osmosis and shrink (CRENATE)

hypotonic solution

0.3%

cells take water in by osmosis until bloated and burst (LYSE/HEMOLYSIS)

intravenous solution

ISOTONIC = blood volume needs increased quickly

HYPERTONIC = swollen patients to pull water back to blood

HYPOTONIC = should not be given → dangerous lysing RBC WBC

primary active transport

direct energy from ATP hydrolysis

Ca, H, Na - K pumps (nerves and muscles)

Na+ — K+ PUMP (ANTIPORTER) = pumps 3 Na+ OUT, pump 2 K+ IN

LEAKAGE CHANNEL = leaking Na+ INTO, leaking K+ OUT

secondary active transport

indirect energy from ionic gradient

movement of polar or charged particles across membranes

vesicular transport

fluid filled vesicles with larger particles

fuse with membrane

golgi apparatus, WBC engulfing bacteria

transport → one area or organelle → to another t

transcytosis

move across cell (into, across, out)

endocytosis → exocytosis

HIV virus throughout body

exocytosis

transport out of cell

ejected substance enclosed in SECRETORY VESICLE

hormones, neurotransmitters, mucus, cellular waste

endocytosis

transport into cell

formation of protein coated vesicles

RECEPTORS = very selective process (pathogens can disrupt)

vesicle pulled inside → fuse with lysosome or undergo transcytosis

endocytosis types

PHAGOCYTOSIS = “cell eating/kill” (macrophages, WBC)

PINOCYTOSIS = “cell drinking” absorption by intestinal cells

RECEPTOR-MEDIATED ENDOCYTOSIS = “picky eater” endocytosis and transcytosis of specific molecules

membrane potential

electrical charge difference across plasma membrane

separation of oppositely charged particles (ions)

measured as voltage (V)

resting membrane potential (RMP)

voltage measured in resting state in all cells

-50 to -100 mV in different cells

-70 CELL -90 HEART

K+ leaks out, membrane more permeable (primary influence)

Na+ attracted inside cell (cell is negative)

cytosol

gel-like solution made up of water and soluble molecules

proteins, salts, sugars

inclusions

Non-living substances in the cytoplasm used for storage (or waste)

glycogen granules (skeletal muscle/liver), pigments (skin), lipid droplets, vacuoles, crystals

organelles

NONMEMBRANOUS = ribosomes, cytoskeleton, centrioles (allow compartmentalization)

MEMBRANOUS = mitochondria, ER, golgi, peroxisomes, lysosomes

mitochondria

produce ATP via aerobic (O2 required) cellular respiration

double membranes = inner have many folds studded with enzymes (CRISTAE)

own DNA, RNA, and ribosomes

resemble bacteria = same cell division FISSION

ribosomes

FREE RIBOSOMES = site of synthesis of soluble proteins functioning in cytosol or other organelle

MEMBRANE BOUND RIBOSOMES = attached to ER, site of synthesis of protein to incorporate into membranes, lysosomes or export

ROUGH ER = site of synthesis of many plasma membrane proteins and phospholipids

SMOOTH ER = lipid synthesis, detoxification, calcium storage

golgi apparatus

cistern sacs modify, concentrate, and packages proteins and lipids received from rough ER

“UPS” = transport, modify, tag, sort, package proteins

peroxisomes (gray/purple)

membranous sacs containing detoxifying substances that neutralize toxins

FREE RADICALS = toxic, highly reactive, can ruin cells if not detoxified

breakdown and synthesis of fatty acids

OXIDASE = toxins → H2O2

CATALASE = H2O2 → water

lysosomes (yellow/orange)

digestive enzymes (acid hydrolases) = digest ingested bacteria, viruses and toxins

breakdown and release GLYCOGEN, Ca+ from bone

AUTOLYSIS = cells to digest themselves

centrosome and centrioles

microtubule organizing center (granular matrix and centrioles)

pair of barrel-shaped microtubular organelles lying right angles to each other

radiate from centrosome to rest of cell

centrioles → cilia, flagella, microvilli

cilia

whiplike, motile extensions on surfaces of certain cells

move substances across cell surface one direction (respiratory cell)

flagella

longer extensions propelling whole cell (sperm tail)

microvilli

fingerlike extensions of plasma membrane

increase surface area for absorption

actin microfilament core = stiffening projections

intestinal and kidney tubule

interphase

G1 = grow and increase size

S = genetic material replicate (DNA, RNA, ribosomes)

G2 = final prep for cell division

REPLICATION FORK = point where strands separate

REPLICATION BUBBLE = active area of replication

DNA POLYMERASE = attach to primer and begin adding nucleotides form new strand

DNA HELICASE = unzips and separates strands

prophase

EARLY PROPHASE = CHROMATIN tightly coils and condenses into CHROMOSOMES, CENTROMERE moves to opposite poles

LATE PROPHASE = NUCLEAR ENVELOPE breaks down, disappears, CHROMOSOMES free throughout cell

anaphase

chromosomes pull apart from middle

CYTOKINESIS begins = division of cytoplasm

telophase

NUCLEAR ENVELOPE = reappears

CLEAVAGE FURROW

protein synthesis

code consists of 3 sequential bases (triplet code)

specifies the code for a particular amino acid s

skit (DNA)

DNA (in nucleus) can’t get through nuclear pore

TRANSCRIPTION inside nucleus = DNA info coded in mRNA

communicate to mRNA (GCTA…)

DOES NOT LEAVE NUCLEUS

skit (mRNA)

“scribe”

leave nucleus to ribosome

communicate DNA message (GCTA → CGAU) then return to DNA

TRANSLATIONS = outside of nucleus = mRNA decoded to assemble polypeptides