Zoology Module Four

Exam One

Nucleus

contains most of the DNA in eukaryotic cell

Ribosomes

complexes made of ribosomal RNA and protien, use info from DNA to make protiens in two locations

Nuclear envelope

double membrane lipid bilayer surrounding nucleus

Nuclear pores

regulate entry/exit of molecules from the nucleus

Nucleolus

in nucleus, site of ribosomal RNA (rRNA) synthesis

Free ribosomes

protiens built in cytosol

Bound ribosomes

made on the outside of the endoplasmic reticulum or the nuclear envelope

Endomembrane system

regulates protien traffic and does metabolic functions, made of: nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, plasma membrane

Endoplasmic reticulum

over half of membrane in most eukaryotic cells, continous with nuclear envelope, two distinct regions: smooth ER and rough ER

Smooth ER (SER)

lacks ribosomes, sythesizes lipids, detoxifies drugs and poisons, stores calcium ions

Rough ER (RER)

surface studded with ribosomes that secrete glycoprotiens, distributes transport vesicles, membrane factory for cell

Golgi apparatus

flattened membranous sacs (cisternae), shipping and recieving center, modifies products of the ER, makes certain macromolecules

Lysosome

digestive compartments, fuses with food vacule to digest contents, can perfom autophagy

Autophagy

recycles cell’s own organelles and macromolecules

Vacuoles

diverse maintenence compartments, from ER and golgi apparatus

Mitochondria

sites for cellular respiration, powerhouse of the cell, inner membrane creates two compartments: intermembrane space and mitochondrial mix

Endosymbiont theory

ancestor or eukaryotes engulfed oxygen-using nonphotosynthetic prokaryotic cell, evolved into mitochondria

Cristae

outer and inner layer of mitochondria folded into cristae, large surface area for synthesis of ATP

Peroxisomes

oxidation, specialized metabolic compartments, have enzymes that remove hydrogen atoms and transfer them to oxygen, forms hydrogen peroxide

Cytoskeleton

network of fibers extending through cytoplasm, organizes and achors, composed of three types of molecular structures: microtubules, microfilaments, intermediate filaments

Microtubules

thickest of cytoskeleton components, shape cell, guides organelle movement, seperates chromosomes during division

Microfilaments

twisted double chain of actin, support cell shape, form a cortex just inside plasma membrane

Myosin

in microfilaments that function in cellular motility have this protien in addition to actin

Intermediate filaments

more permanant cytoskeleton fixtures, support cell shape and fix organelles in place

Extracellular matrix

made up of glycoprotiens (like collagen, proteoglycans, fibronectin), can regulate cell behavior by communication through integrins, can influence activity of genes in nucleus

Integrins

transmembrane receptors

Cell junctions

three types: tight junctions, desmosomes, gap junctions

Tight junctions

membranes of cells press together, prevents leakage of extracellular fluid

Desmosomes

anchoring junctions, fasten cells together into sheets

Gap junctions

communicating junctions, provide cytoplasmic channels between adjacent cells