Chapter 2: Cells Flashcards
membrane proteins
- peripheral =loosely attached to one side surface (generally hydrophilic, held in place by H-bonding and electrostatic interaction, disrupt/detach by chaning cxn and pH)
- integral=embeds inside membrane (hydrophobic; use detergent to destroy membrane and expose proteins)
- transmembrane = all the way through, both sides (type of integral)
phospholipid membrane permeability
- small, uncharged, nonpolar molecules (polar can only if small and uncharged) and hydrophobic molecules can freely pass across the membrane
- everything else (ions and large polar molecules) requires a protein transporter (large, polar and charged molecules)
- impermeable=”resistant to”
channel proteins
provide passageway through membrane for hydrophilic (water-soluble) substances (polar and charged)
recognition proteins
such as major-histocompatibility complex in macrophage to distinguish between self and foreign; they are glycoproteins due to oligosaccharides attached
ion channels
- passage of ions across membrane.
2. gated channels in nerve and muscle cells respond to stimuli (can be voltage gated, ligand-gated, mechanically gated)
porins
- allow passage of certain ions and small polar molecules
- aquaporins increase rate of H2O passing (kidneys and plant root cells.
- these tend not to be specific, they are just large, if you can fit you’d go through
carrier proteins
- bind to specific molecules, changes shape, molecule is passed through
- for example, glucose into cell (type of transport protein)
- seem to be specific to movement across membrane
transport proteins
- can use ATP (not all transport use ATP)=active transport
- Na+/K+ pump to maintain gradients
- facilitated diffusion
adhesion proteins
attach to neighboring cells, provide anchors for internal filaments and tubules (stability)
receptor proteins
binding site for hormones and other trigger molecules
cholesterol
- adds rigidity to membrane of animal cells under normal conditions (at low temps it maintains fluidity)
- sterols provide similar function in plant cells
glycocalyx
- a carb coat that covers that outer face of cell wall of some bacteria and some animal cells.
- consists of glycolipids (attached to plasma membrane) and glycoproteins (such as recognition proteins)
- may provide adhesive capabilities, barrier to infection, or markers for cell-cell recognition.
nucleus
- chromatin=general packaging structure of DNA around proteins in eukaryotes, the tightness of the packaging varies depending on cell stage
- chromosomes=tightly condensed chromatin when the cell is ready to divide
- histones= serve to organize DNA which coil around in into a bundled nucleosome (8 histones)
- nucleolus=inside the nucleus, the maker of ribsomes (rRNA) ***[rRNA is synthesize in nucleolus + ribosomal proteins imported from cytoplasm= ribosomal subunits form; these subunits are exported to the cytoplasm for final assembly into complete ribosome.
- Nucleus bound by double layer nuclear envelope w/ nuclear pores for transport (mRNA, ribosome subunits, dNTPS, proteins) in /out.
- no cytoplasm in nucleus, instead nucleoplasm.
nuclear lamina
dense fibrillar network inside nucleus of eukaryotic cells (intermediate filament and membrane associated proteins). Provides mechanical support; also helps regulate DNA replication, cell division, and chromatin organization.
nucleoid
irregular shaped region within the cell of prokaryote that contains all/most generic material
cytoplasm
- THIS IS AN AREA, NOT A STRUCTURE!
- metabolic activity and transport occur here.
- cyclosis is streaming movement within cell
- doesn’t include nucleus, but does include cytosol, organelles, everything suspended w/n cytosol but nucleus
cytosol
cytosol doesn’t include the stuff suspended within the gel-like substance, it is JUST the gel-like stuff. THINK JELLO vs VEGGIE STEW
ribosome
- 60S + 40S =80S, eukaryotes
- prokaryote (50S+30S=70S); 3.the two subunits produced inside the nucleolus moved into the cytoplasm where they assembled into a single 80S ribsome (larger S value = heavier molecule) …. made of rRNA+protein,
- function to make proteins
Endoplasmic Reticulum
- Rough ER: creates glycoproteins by attaching polysaccharides to polypeptides as they are assembled by ribosomes [in eukaryotes RER is continuous with the outer nuclear membrane]
- Smooth ER: synthesizes lipids and hormones for export … in liver cells, SER functions to breakdown toxins, drugs, and toxic by-products from cellular rxn
- Smooth and striated muscle have SER called sarcoplasmic reticulums that store and release ions such as Ca2+
lysosomes
- vesicles produced from golgi contain digestive enzymes (low pH for fxn)
- break down nutrients/bacteria/cell debris
- any enzyme that escape from lysosomes remains inactive in the neutral pH of cytosol
- functions in apoptosis (releases contents into cell)