Chap 3: cells Flashcards
What is cell theory
Cell is the smallest structural and functional living unit
- all living things are composed of unicellular or multicellular
- cell is basic unit of life
- cells arise from preexisting cells
Epithelial, Fibroblasts and erthrocytes cells
cells that connect body parts, form linings or transport gases
skeletal muscle and smooth muscle cells
Cells that move organs and body parts
fat cell
cells that stores nutrients
macrophage
cells that fight disease
nerve cell
cell that gathers information and controls body functions
sperm
cell of reproduction
nerve cells consist of what
cell body, nucleolus, dendrites, axon, nucleus, axon hillock
muscle cells consist of what
nuclei, perimysium, straitions, skeletal muscle fiber
what are the 3 basic parts of human cells?
plasma membrane: flexible outer boundary, selectively permeable
cytoplasm: intercellular fluid containing organelles
nucleus: control center
cell membrane and its parts
75% phospholipids (lipid bilayer)
- phosphate heads: polar and hydrophilic
- fatty acid tails: nonpolar and hydrophobic
5% glycolipids
- lipids with polar sugar groups on outer membrane surface
20% cholesterol
- increases membrane stability and fluidity
what are the 2 types of membrane proteins
integral proteins
- firmly inserted into membrane and most are transmembrane
- functions as transport proteins (channels + carriers), enzymes/receptors
peripheral proteins
- loosely attached to integral proteins
- functions as enzymes, motor proteins, cell to cell links. provide support on intercellular surface and form part of glycocalyx
what are the 6 functions of membrane proteins
- transport channels
- receptors for signal transduction
- attachment to cytoskeleton and extra cellular matrix (maintain cell shape)
- enzymatic activity
- intracellular joining: CAM - cell adhesion molecule
- cell to cell recognition - identification tag
what are the 3 membrane junctions
- tight junction: impermeable
- prevents fluid and most molecules from moving between cells - desmosome - rivets that anchor cells together (velcro)
- gap junction: communicating, small pores b/w cells that allow small molecules to pass
what are the 2 types of membrane transport
plasma membranes are selectively permeable
- passive transport: no energy required, substance moves down concentration gradient
- active transport: energy required, substance moves against concentration gradient (ATP)
what determines passive permeability
- lipid solubility of substance
- channels of appropriate size
- carrier proteins
- concentration gradient
- charge of substance
what are the 3 passive processes
- simple diffusion
- facilitated diffusion
- carrier mediated
- channel mediated - osmosis
what is simple diffusion
no polar lipid soluble and HYDROPHOBIC diffuses directly through phospholipid bilayer (O2/CO2/lipid soluble vitamins)
what is facilitated diffusion
utilizes carrier proteins or channel proteins that exhibits specificity, saturable (rate determined by number of carriers/channels), can be regulated in terms of quantity and activity
what are carrier proteins and channel proteins?
carrier proteins: binding of substrate causes shape change in carrier
channel proteins: aqueous channel formed by transmembrane proteins, leakage channels, gated channels
what is osmosis?
movement of solvent across a selectively permeable membrane
water diffuses through plasma membranes through lipid bilayer or through water channels (aquaporins)
what happens when membrane is permeable to both solute and water
volume remains unchanged and solute moves from left to right (low to greater osmolarity)
what happens when membrane is permeable to water but impermeable to solute
both solutions have identical similarity but volume of solution is greater in the right because water is free to move
what is tonicity and it’s 3 types?
tonicity: ability of solution to cause a cell to shrink/swell
- isotonic: solution with same solute concentration as that of cytosol (ideal)
- hypertonic: solution having GREATER SOLUTE concentration than cytosol (lose water via osmosis and shrink - more solute)
- hypotonic: a solution having LESSER SOLUTE concentration than that of the cytosol (gain of water via osmosis and lyse - low solute)
what are the 2 active processes?
Uses ATP to move solutes
- Active transport
- Vesicular transport
what is active transport and its two types
requires carrier proteins (solute pumps)
moves solutes AGAINST conc gradient
2 types:
- primary: energy via hydrolysis of ATP causes shape change so that solutes are pumped across - sodium potassium pump
- secondary: depends on ion gradient created by primary active transport and energy stored in gradients used indirectly to drive transport of other solutes (polar/charged solutes)
what is vesicular transport and its 3 types
transport of LARGE particles, macromolecules, and fluids across plasma membrane
endocytosis: transport into cell
- phagocytosis, pinocytosis, receptor mediated endocytosis
exocytosis: transport out of cell
transcytosis: transport into/across, then out
what is phagocytosis
ENDOCYTOSIS
engulfs a large particular forming pseudopods around it and encloses it within a membrane sac known as phagosome. phagosome combined with lysosome. indigested contents remain in vesicle or ejected by exocytosis
ex. white blood cell phagocytosis
what is pinocytosis and which of the 3 vesicular transport is it?
ENDOCYTOSIS
cell gulps drops of extracellular fluid containing solutes into tiny vesicles. no receptors, so process is NONSPECIFIC. most vesicles are protein coated (nutrient absorption in small intestine)
ex. absorption by intestinal cells
what is receptor mediated endocytosis
claritin coated pits provided for main route for endocytosis and transcytosis
uptake enzyme, hormones, lipoproteins, iron, and insulin
macromolecules
ex. hormone/chrolesterol uptake
what is membrane potential
separation of oppositely charged particles across a membrane creates a membrane potential (voltage)
- resting membrane potential (RMP): voltage measured in resting state in all cells
- 50-100 mV
- results from diffusion and active transport of ions (K+)
what 4 establishes RMP?
- k+ ions and proteins anions mostly inside cell while Na+ mostly outside
- some k+ continually diffuses down concentration gradient out of cell through K+ leakage channels, membrane very permeable to k+
- MEMBRANE INTERIOR BECOMES NEGATIVE bc of large anions trapped inside cell
- electrochemical gradient begins to attract K+ back into cell
what maintains RMP?
Active transport
5. Na+-K+ pump continuously ejects Na+ from cell and carries K+ back in (3 Na out for every 2 K in)
6. steady state maintained because rate of active transport equal to and depends on rate of na+ diffusion into cell
what are the two cell environment interactions
- cell adhesion molecules (CAMs): anchor cells to extracellular matrix or to each other, assist in movement of cells, stimulate synthesis/degradation of junctions, transmit signals to other cells
- membrane receptors (integral proteins):
- contact signaling: touching/recognition of cells
- chemical signaling: interaction between receptors and ligands (neurotransmitters/hormones) to alter activity of cell proteins
what are the 6 steps of chemical signaling?
- ligand (1st messenger) binds to receptor
- activated receptor binds to G protein and activates it
- activated G protein activates/inactivates the effector proteins (enzyme) by causing its shape to change
- activated effector enzymes catalyze reactions that produce second messenger
- second messenger activate other enzymes/ion channels
- kinase enzymes transfer phosphate groups from ATP to specific proteins and activates series of other enzymes that trigger various cell responses
cytoplasm
located in plasma membrane and nucleus
1. cytosol: properties of colloid
- water with solutes (protein, salts, sugars)
2. cytoplasmic organelles
- metabolic machinery of cells
3. inclusions (chemical substances)
- granules of glycogen, lipid droplets, vacuoles, and crystals
what are the membranous cytoplasmic organelles?
mitochondria, peroxisomes, lysosomes, ER, golgi
what are nonmembranous cytoplasmic organelles
cytoskeleton, centriole, ribosome
what is the mitochondria
double membrane, provide most of cells ATP via aerobic cellular respiration, contain their own DNA and RNA (reproduce themselves), site of ATP synthesis
ribosomes
granules containing protein and rRNA
site of protein synthesis
free ribosomes synthesize soluble proteins
membrane bound ribosomes (rough ER) synthesize proteins to be incorporated into membranes/exported from cell
ER and it’s two types
interconnected tubes
continuous with nuclear membrane
rough and smooth
rough: studded with ribosomes, manufactured all secreted proteins, synthesize membrane integral proteins and phospholipid
smooth: synthesis of phospholipids, cholesterol, steroid and storage of glycerides, glycogen, and calcium
golgi apparatus and what are the 3 things that leave here?
stacked and flattened membranous sacs
transport vessels from ER fuse with receiving end of golgi apparatus
3 types of packaged products leave golgi
- plasma membrane renewal
- secretions to be discharged from cell
- enzymes for cytosol contained in lysosomes
lysosomes
membranous bags containing digestive enzymes
digest ingested bacteria, virus, toxins
degrade nonfunctional organelles
break down and release glycogen, bone to release calcium, destroy cells in injured tissues (autolysis)
tay sach disease
genetic disease where lysosome lack enzymes, lipids over accumulate in NN cells
peroxisomes
membranous sacs containing powerful oxidases
detoxify harmful/toxic substances
numerous in liver and kidney
catabolizes fats
smaller than lysosomes
cytoskeleton and 3 types of
throughout cytosol for strength and flexibility
1. microfilaments: cell mobility, actin strands
2. intermediate filaments: tensile strength
3. microtubules: hollow tubes, moves chromosomes during cell division
motor molecules
can attach to receptors on vesicles and walk the organelles along the microtubules of cytoskeleton OR
attached to one element of cytoskeleton can cause it to slide over another as in muscle contraction or cilia movement
centrosome
near nucleus
generates microtubules, organizes mitotic spindle, contained paired centrioles (small tube formed by microtubules)
what are the 2 types of cellular extensions
- cilia and flagella - movement
- whiplike, motile extensions on certains cells
- contain microtubules and motor molecules
- cilia move substances across cell surfaces
- longer flagella propel whole cells - microvilli
- finger like on plasma membrane
- increase SA for absorption
- core of actin for stiffening
- seen in absorption of digestive tract
nucleus control center
genetic library with blueprints for all cellular proteins
responds to signals and dictates kinds and amounts of proteins to be synthesized
uninucleate
red blood cells are anucleate (short life span)
skeletal muscle cells, bone destruction cells, and some liver cells are multinucleate - due to large cytoplasm area to be regulated
nucleoli
dark staining spherical bodies within nucleus
involved in rRNA synthesis and ribosome subunit assembly
packaging site for ribosome
chromatin
threadlike strands of DNA
arranged in fundamental units called nucleosomes
condense into bar like bodies called chromosomes when the cell starts to divide
inclusions
stored glycogen granules, crystals, pigments
