AP Biology: Cells & Organelles

AP Biology: Cells & Organelles figure references from Ch. 7 Campbell & Reece, Biology 6th ed.

Cell Basics & Scientists -all organisms are composed of cells -structure & function: though similar, most have specialized structure for a specialized function (neurons, muscle fibers, etc.) -Robert Hooke- first observed cells in cork -Leeuwenhoek- observed living cells…modern microscope resolution (resolution down to 2x diameter of hydrogen) -Schleiden- made 1st statement of cell theory

Cell Theory -organisms are made up of cells and metabolism and heredity occurs in these cells -cells are the smallest living “thing” -all cells currently arise from other cells

Why aren’t individual cells larger? -communication via diffusion -relationship of surface area to volume ratio & the rate of diffusion fyi: what is the longest cell in a human?...what is the biggest cell in the animal kingdom?

PROKARYOTES pro-“before”, karyon-“kernel or nucleus” -simplest organisms, about 10x’s smaller than eukaryotes, quite diverse (fig 7.4)

Cell Walls -made of peptidoglycan (carbohydrate matrix w/ peptide cross-links) -Gram staining (+ or -) Simple Interior Organization -strength gained via cell wall…how does penicillin work? -no compartmentalization & no membrane bound organelles -membrane may have some characteristics of organelles Flagella (fig 7.23-24) -for motility -note: different mechanism of movement when compared with eukaryotes -can propel a bacterium at 20 cell diameters/sec.!! DNA -single circular, double helix chromosome -plasmids (segments of copied DNA) Ribosomes -protein synthesis -prokaryotic ribosomes are identifiably different from eukaryotic ribosomes Nucleoid- no true nucleus, more of a nuclear area

EUKARYOTES -more complex, larger, compartmentalized, include membrane bound organelles, etc.

Nucleus (fig 7.9) -anchored in the cell by cytoskeleton -nuclear envelope -double layer of phospholipid bilayer -nuclear pores w/ molecular chaperones to regulate what gets in and out -nuclear localization signals = the “secret handshake” to get into the nucleus -fyi: ~100 proteins make up a single channel, the average mammalian nucleus contains ~3500 pores1 -fyi: channels disassemble during cell division and reassemble after1 -nucleus contains genetic material -chemical characteristics of DNA -coiled around histones making a nucleosome…why?

Alan Cotten, Fossil Ridge High, KISD - Cells & Organelles: Campbell & Reece 6th ed. Endoplasmic Reticulum (fig 7.11) -endoplasmic means “within nucleus” -ER is a continuation of the nucleus (phospholipid bilayer) -cisternae (think “cistern”) Smooth ER (SER) -anchors enzymes concerned with synthesizing carbohydrates, lipids, hormones, sex hormones -detoxification via enzymes by hydroxylating (-OH) toxins making them water soluble and ready for excretion -barbiturate use, SER manufacture, & tolerance Rough ER (RER) -embedded w/ ribosomes making it appear “rough”(fig. 7.10) -signal sequences (often sugars)

Ribosomes (fig. 7.10) -made up of rRNA and proteins -function of free ribosomes vs. those embedded in RER -consists of 2 subunits: different size subunits in eukaryotes vs. prokaryotes -read genetic material and translates it into protein (realize that proteins are the “work horses” of the cell) -look to nucleolus for ribosome creation

Golgi Complex / Golgi Apparatus (fig 7.12) -made of phospholipid bilayer (why is this significant?) -function to modify sugars originally placed by ER or add chemicals(creating glycoprotein, glycolipid) and sort for distribution -cisternae (what’s a cistern?)

Lysosomes (fig. 7.13, 7.14) -made of phospholipid bilayer (why again?) -“janitors” of the cell -may come from Golgi -primary vs. secondary lysosomes -need low pH in secondary lysosomes…how?...why? acid hydrolase work in low pH (burst lysosomes = not too distructive!) -why don’t lysosomes digest themselves? -bacteria = no lysosomes -Tay Sacchs

Microbodies -called peroxisomes in animal cells, glyoxysomes in plants -function = detoxification through use of oxidases, resulting in H2O2 hence the name in animals

Alan Cotten, Fossil Ridge High, KISD - Cells & Organelles: Campbell & Reece 6th ed. Mitochondria (fig 7.17) -powerhouse of cells, converting glucose to ATP -structure -double phospholipid bilayer (why double?) -cristae (containing ETC enzymes)…why the folds? -matrix (containing Krebs cycle enzymes) -endosymbiotic theory: have own bacteria-like DNA, bacteria-like ribosomes, bacteria-like inner membrane, bacteria-like replication

Chloroplasts (fig 7.18) -manufacturing food via sun & carbon dioxide photosynthesis -structure -double phospholipid bilayer -grana and stroma -thylakoids: function -endosymbiotic theory here as well for many of the same reasons as mitochondria stated above.

Cytoskeleton (fig 7.27) -supports shape of cell (c/c prok. with euk.) -scaffolding for enzymes, cytoskeleton, etc. (location is key) 3 TYPES OF CYTOSKELETON Microfilaments (actin) -long intertwined filaments, spontaneously form & spontaneously disappear. -functions for cell movement and tension bearing -muscles, blood clots, pseudopod, cleavage furrows, etc. -phalloidin (death mushroom cap) MCB p. 786

Microtubules -made of substance called tubulin -made by centrosomes (contain the organelle centrioles), oddly plants and fungi don’t have centrioles -function to maintain cell shape and movement of materials (mitosis, vesicle trafficking) -short “lifespan” constantly polymerizing & depolymerizing (controlled by GTP) kinesins (towards edge) and dyneins (towards nucleus) -cancer treatments?- Taxol (yew tree)

Intermediate filaments -act as tension bearers as well -examples: keratin, vimentin = more stable than other cytoskeleton types MCB fig 19-37 -intermediate filaments are the ones that anchor organelles

Cilia & Flagella (fig 7.25) -structure (c/c with prok.) -dynein involved in movement

Vacuole -large central vacuole usually found in plants -storage of starch, but also water, waste, etc.

Alan Cotten, Fossil Ridge High, KISD - Cells & Organelles: Campbell & Reece 6th ed. MCB = 1 Mitochondria, chloroplast, Cystoskeleton diagrams from R&J 1996 4th ed.

Alan Cotten, Fossil Ridge High, KISD - Cells & Organelles: Campbell & Reece 6th ed.