Cell functions Flashcards
Chapter 6
Enzymes
Functional proteins. Chemical catalysts reducingactivation energy needed fro a reaction. Regulate metabolic pathways - specific to one substance - inhibited or activated by various physical and chemical agents
Cellular respiration review
1 glucose (C6H12C6) — glycolysis in cytosol
—>
2 pyruvic acid + oxygen — citric acid cycle and ETC in mitochondrion
—>
CO2 + H2O + 36 or 38 ATP
Anabolism
Protein synthesis - begins with genetic master code in cell’s DNA - influences all cell structures and functions
Cell reproduction
Mitosis: Cell reproduce by splitting themselves into two smaller daughter cells - each cell must contain sufficient cytoplasm (including mitochondria and other organelles) as well as complete set of genetic information
Allosteric effector
Alters enzyme function by changing its shape - may inhibit or activate enzymes by altering shape of active site - includes antibiotic drugs, changes in pH, changes in temperature, and cofactors
Glycolysis without oxygen
Pyruvate acid molecules will follow the anaerobic pathway to form lactic acid - as oxygen becomes available, lactate converts back to pyruvate or even glucose
Glycolysis
Glucose break down to form 2 Peruvian acid molecules - occurs in cytosol, outside of any organelle - anaerobic reaction - produces 2 ATP
Sodium-potassium pump
- 3 Na+ in cytosol bind to pump proteins, which triggers ATP ydrolysis
- shape of protein changes and 3 Na+ are deported into ECF
- 2 K+ then bind, trigger ATP hydrolysis, protein changes shape and 2K+ desposited into cell, protein shape now ready for 3Na+
Active transport
Requires expenditure of metabolic energy by the cell. Transport by pumps and vesicles. Moves up concentration gradient
Exocytosis
Processs by which large molecules (proteins) can leave the cell when they are too large to move out throug the cell membrane. Also provides a way to add new plasma membrane
Meiosis
Cell division that occurs only in primitive sex cells during the process of becoming mature sex cells with 23 chromosomes
Isotonic solution
Cell stays the same size because there is no net movement of H2O into or out of the cell
End product inhibition
When a chemical product at the end of a metabolic pathway binds to the allosteric site of one or more enzymes along the pathway that produce it in order to inhibit synthesis of more product (negative feedback)
Coenzyme
Organic non protein molecule that is a nonprotein cofactors.
Diffusion
Movement of solute down concentrartion or electrical gradient. Stops when reaches equilibrium
Osmosis
Movement of water through a semi-permeable membrane down concentration gradient. Particle movement is limited, so water moves. Aquaporins allow movement through phospholipid membranes
Passive transport
Does not require energy expenditure or activity from membrane. Stuff moves down a concentration or electrical gradient
- diffusion - osmosis - osmotic pressure - channel mediated passive - carrier mediated transport
Hypotonic solution
Causes the cell to swell as H2O moves into it. Cell may burst (lyse)
Carrier mediated transport
Facilitated diffusion of solute through a membrane by a carrier. Open on one side, solute enters and binds, it closes and opens the other side. Can be reversible.
Transport by pumps
Driven by energy from hydrolysis of ATP and energy stored in an ionic concentration gradient - utilizes carrier proteins - most prevelant is sodium-potassium pump.
Metabolic pathways
Chemical reactions that occur in a sequence of reactions, requires enzymes
Hypertonic solution
Causes cell to shrink as H2O moves out. Cell may be permanently damaged and die.
Receptor-mediated endocytosis
Receptors in plasma membrane bind to specific molecules in ECF, which triggers endocytosis
Cell metabolism
Set of chemical reactions of a cell
Phagcytosis
Cell engulfs large solid particles (whole bacteria, viruses, worn out cells) and the vesicles fuse with lysosomes that break down unwanted material - undigested materials are secreted by exocytosis or reside within the cell in a residual body
Citric acid cycle
Pyruvate acid from glucose is converted to acetyl coenzyme A (CoA) - occurs in the mitochondria of the cell (where enzymes are located) - produces CO2 + energy in the form of energized electrons
Transport by vesicles
Substances dont actually go through the plasma membrane
Genetic code
Dictates structures of each protein produced by the cell
Pinocytosis
Cell drinking. ECF enters cell. Cell ingests fluid and solutes and then removes material from plasma membrane (receptors and channels). Cell can regulate membrane this way.
Channel mediated transport
Facilitated diffusion of solute through a membrane channel. Gated channels open/close by various triggering mechanisms. Protein tunnels. Solute specific.
Cell growth
Depends on using genetic info in DNA to make the structural and functional proteins needed for cell survival - Newly formed cell synthesize new molecules and organelles, including an extran set of DNA molecules in anticipation of reproduction
Active site
Chemically fits the substrate on the enzyme. Thats where the magic happens
Endocytosis
Traps extracellular material and brings it into the cell. Cytoskeleton forms vesicle. 3 types: receptor-mediated endocytosis, phagcytosis, and pinocytosis
Equilibrium
Equal concentration. Not a static state without movement but a balanced state stat in which the number of molecules crossing the membrane is equal in both directions.
Catabolism
Protein breakdown
Osmotic pressure:
Water pressure that results from osmosis. Osmotic pressure is higher in the solution with higher concentration and this drives the water out.
Catalysts
Participate in chemical reactions but are not themselves changed by a reaction
Cellular respiration
Glucose —> CO2 + H2O + energy
Glycolysis + citric acid cycle + electron transport chain
Electron transport chain
Energized e- are carried to specialized molecules embedded in the inner mitochondrial membrane - e- are shuttled along a chain of specialized molecules and cause protons to be pumped into intermembrane space - protons (H+) cross back through the inner mitochndrial membrane into inner chamber by way of reverse pump carriers - ATP synthase carriers convert the energy of passive proton flow into chemical energy which is transferred to ATP molecules - produces 34 ATP (along with citric acid cycle)
Glycolysis with oxygen
Pyruvate acid molecules will follow the aerobic pathway and enter the citric acid cycle
Kinases
Active enzymes, which are naturally inactive because they are synthesized as inactive proenzymes
Transcription
Gene code in DNA is copied to messenger RNA (mRNA) in the cell nuclus - mRNA separates from the DNA strand and carries a “message” of gene code sequence to a ribosome in the cytoplasm - cell translates genetic code - tRNA transfers amino acids from cytoplasm to the ribosome - as amino acids are brought into place, peptide bonds join them to produce an entire protein (process of translation)
Dynamic equilibrium
Condition of continual, constant diffusion
