Chapter 2 - Cell Structure & Function Flashcards
What is the type of bond forming nucleotide polymers?
phosphodiester
What is the type of bond forming protein polymers?
Peptide
What is the type of bond forming lipid polymers?
n/a
What is the type of bond forming carbohydrate polymers?
Glycosidic linkage
What is glycosylation?
process of adding carbohydrate groups for recognition.
What is the function of proteins?
perform most of the cellular tasks, provide structure, and regulate cellular processes
What is the function of phospholipids?
serve as structural component of membranes
what is the function of cholesterol?
precursor for steroid hormones and membrane component
what is the function of acylglycerol?
provides long-term energy storage (can have up to 3 fatty acid tails of differing lengths)
what is the function of waxes?
establishes a protective barrier. ex. ear wax.
steroids?
4 ringed carbon structures that function as chemical messengers for endocrine system and are important structural components in membrane.
What is the best carbohydrate for energy storage?
glycogen
What is the central dogma of genetics?
info stored in DNA determines which RNA coding is produced and which protein sequences are generated.
Steps of enzymatic activity?
- substrate enters active site of enzyme
- enzyme binds to substrate and the enzyme’s shape changes slightly (induced fit)
- enzyme/products complex forms
- products leave the active site of enzyme
What are the 7 protein classes?
structural, enzymatic, regulatory, motile, transport, storage, and defensive.
function of structural proteins
provides cell or tissue strength
ex. collagen in connective tissue
function of enzymatic proteins
catalyzes specific reactions
ex. amylase hydrolyzes starch into shorter carbohydrate chains
function of regulatory proteins
chemical messengers
ex. insulin regulating blood glucose by signaling to other cells to increase glucose uptake
function of motile proteins
aids cell movement
ex. actin and myosin initiate muscle contraction
function of transport proteins
moves substances within/between cells
ex. GLUT1 permits glucose to cross the plasma membrane
function of storage proteins
stores nutrients
ex. ovalbumin provides amino acids to developing chick embyryo
function of defensive proteins
protects against disease
ex. antibodies tag pathogens for clearance by the immune system
What happens in the mitochondria?
the E.T.C. drives ATP synthase inside mitochondria. Oxidative phosphorylation
What happens in ribosomes?
made up of rRNA/proteins; conducts translational processes, large and small subunits assembling around mRNA transcription, and peptide bond formation is catalyzed.
What happens in smooth ER?
lipid synthesis, metabolizes carbohydrates, stores calcium for rapid signaling events, and houses detoxifying enzymes to clear drugs and toxins.
What happens in nucleolus?
rRNA is made and ribosome assembly
What happens in golgi apparatus?
sorting organelle, package into vesicles, cis cisterna; POST OFFICE OF CELL
What happens in centrioles?
microtubules are organized to form pathways for protiin trafficking during interphase and the mitotic spindle during mitotic phase.
Phospholipid bilayer
glycerol backbone w/ 2 fatty acid tails and phosphate head. amphipathic arrangement
What is the function of the cholesterol within membrane?
regulates membrane fluidity
Oxidative Phosphorylation
occurs during aerobic respiration when ATP is synthesized by the phosphorylation of ADP
Functions of transmembrane proteins:
molecular transport, cell adhesion, cell-cell recognition, signal transduction, and enzymatic activity
Peripheral Proteins:
located at edge of membrane by reversibly interacting with phospholipid’s polar group or permanently embedding into bilayer using a GPI anchor.
Fluid Mosaic Model
-plasma membrane is 2D fluid
-phospholipids, membrane proteins, and cholesterols are constantly moving to maintain the bilayer
-can freely rotate clockwise/counter and move laterally from side or front to back (CANNOT DO TRANSVERSE MIGRATION)
Factors determining membrane fluidity:
temp, saturation, and cholesterol
How does temperature affect membrane fluidity?
if temp increases, then kinetic energy increases, and the movement of the bilayer increases. ex. stick of butter.
How does saturation of phospholipid’s fatty acid tails affect membrane fluidity?
- saturated acid = single bond = straight structure = pack in tightly = less movement
- unsaturated acid = at least 1 double bond = “kinked” structure = more fluidity
How do cholesterols affect the membrane fluidity?
AT STANDARD TEMPS: increased cholesterol = DECREASED membrane fluidity
AT LOW TEMPS: cholesterol can serve as a spacer
Lipid rafts
What is a lipid raft?
contain specialized collection of membrane proteins for signaling pathway. Cholesterol levels re increased for more rigidity.
Brownian Motion
Molecules move randomly in this process
Active transport
against gradient; if ATP is needed = primary active transport
Permeable
small, non-polar solutes
ex. oxygen, CO2, steroid hormones
Impermeable
large, polar solutes
ex. carbohydrates, proteins, charged ions
Passive transport
Simple diffusion (high to low), osmosis (water, iso, hyper, hypo), and facilitated diffusion (transport proteins)
Proteins used in passive transport
Channel Protein: serves as a pore to permit a flow of solutes across membrane (no binding site)
Carrier Protein: has binding sites to chaperone a fixed # of solutes across membrane.
Types of Carrier Proteins
Voltage-gated, Ligand-gated (EC and IC), mechanosensitive
What kind of protein is the sodium-potassium pump?
Carrier Protein that does active transport. 3 Na+ out and 2 K+ in
What kind of protein is the proton pump?
Channel protein that does active transport
Sickle Cell Disease
caused by single point mutation that changes glutamic acid for valine within the beta globulin subunit of hemoglobin. Causes protein misfolding
Lysosomal Degradation
breaks down all four biomolecules using hydrolytic enzymes and acidic environment
Proteasomal Degradation
breaks down proteins only using proteolysis within the proteasome complex
SNARE proteins
direct the release of vesicles from the cell until a signal is given. Secretory vesicles have V-SNARES that associate w/ t-SNARES on target membrane
Autocrine signaling
cell signals back to itself
Paracrine signaling
occurs between 2 cells in close proximity (tissues)
Types of local signaling
direct contact and gap junctions (quickest response)
Long distance signaling
endocrine: signal is received by a distant cel in the body (hormones)
Metatropic Receptor Signaling
Steps:
1. Ligand binds transmembrane receptor
2. Receptor undergoes conformational change
3. A signaling cascade of effector molecules and second messengers are activated
4. Transcription factors are activated
5. Gene expression is induced
Nuclear Receptor Signaling
Allows ligand to ENTER cell.
- Hormone enters by simple diffusion
- Binds to nuclear receptor
-Receptor-hormone complex binds to Hormone Response Element and acts as transcription factor in nucleus
- protein is made
Ionotropic Receptor Signaling
just goes through channel protein
2 apoptosis pathways
- Extrinsic apoptotic pathway
- Intrinsic apoptotic pathway
