Lecture 6-10 Flashcards
Name the 4 lipids.
1) fatty acids
2) triacylglycerols
3) phospholipids
4) steroids
How can fatty acids vary?
- chain length
- presence, number, position of double bonds
- isomers
Compare saturated and unsaturated fatty acids.
- saturated: single bonds causing the molecule to be fairly straight and packed together
- unsaturated: cis double bonds present that put a bend in the molecule (polyunsaturated fatty acids have multiple double bonds)
What is the structure of fatty acids?
has a carboxyl and methyl end
What is the structure of triacylglycerols and its bonding?
- three fatty acids attached to a glycerol backbone
- ester linkages are formed between glycerol and fatty acid from dehydration reaction
Identify the differences between plant and animal lipids. Name the exceptions.
plants:
-rich in unsaturated fatty acids and are liquid at room temperature
-coconut oil
animals:
-rich in saturated fatty acids and solid at room temperature
-duck fat
What are the characteristics of trans fats?
- produced by hydrogenation of vegetable oils
- unsaturated fats with trans double bonds
- solid at room temperature
What is the structure of phospholipids?
- two fatty acids
- a phosphate group with a charged molecule attached
- glycerol backbone
How are phospholipids oriented in a two layered bilayer?
- hydrophilic head interact with themselves and water, facing the outside
- hydrophobic tails interact with themselves and face the inside of the bilayer
What is the structure of steroids?
-carbon skeleton with 4 rings
What is cholesterol and what is its role?
- steroid
- maintains structure and fluidity
- component of cell membranes
- precursor of sex hormones
All cells must be able to…
1) keep internal environment different from external
2) expel wastes
3) make proteins with ribosomes
4) divide and replicate (reproduction)
Explain the fluid mosaic model.
- phospholipid bilayer where hydrophobic tails are on the inside and hydrophilic heads are facing the outside
- proteins embedded in bilayer and are unequally distributed (proven by freeze fracturing)
- glycoproteins are on the outside of the bilayer
Where are the integral, peripheral, and transmembrane proteins located?
integral: within the bilayer
peripheral: attached to the surface
transmembrane: span the whole bilayer
Identify the 6 functions of membrane proteins.
1) transport of solutes and molecules
2) enzymatic activity in metabolic reactions
3) signal transduction
4) cell to cell recognition
5) intercellular joining
6) attachment to cytoskeleton and extracellular matrix
How do you explain the movement of phospholipids in the fluid mosaic model?
- mostly move laterally in bilayer
- flip flop rarely
What is the role of cholesterol in membrane fluidity?
- stabilizes membrane fluidity
- reduces movement and prevents packing
Explain the permeability of the plasma membrane.
- permeable to small non polar molecules
- not permeable to large charged molecules
Explain the importance of cell size.
- volume must be large enough to contain all material necessary for functions of life
- volume must be small enough so the surface area can maximize its capabilities to control inputs and outputs
Which are the first eukaryotes to evolve?
Protists- unicellular eukaryotes
What are the differences between prokaryotes and eukaryotes?
- eukaryotes are larger
- prokaryotes have no membrane bound organelles
- genetic information is free in a nucleoid in prokaryotes; in a nucleus in eukaryotes
- prokaryotes don’t have mitochondria or chloroplasts
What are the similarities between prokaryotes and eukaryotes?
have extracellular structures (outside of plasma membrane)
List the order in which organisms evolved.
1) prokaryotes
2) atmospheric oxygen
3) single-celled eukaryotes
4) multicellular eukaryotes
5) animals
6) colonization of land
7) phanerozoic eon
What happened before the oxygen revolution in the Earth’s history?
earliest prokaryotes generated ATP without oxygen, used other molecules instead, due to low levels of oxygen in the atmosphere
How did oxygen accumulate during the oxygen revolution?
early prokaryotes had specialized cell membranes for photosynthesis where oxygen was a byproduct
Where are free and bound ribosomes located in prokaryotes and eukaryotes?
prokaryotes: in the cytosol
eukaryotes: free ribosomes in the cytosol
bound ribosomes are attached to the endoplasmic reticulum
What is the function of the free and bound ribosomes?
carry out protein synthesis
free: make cytosolic proteins
bound: make proteins that are inserted into membranes
What is the structure of ribosomes?
composed of protein and rRNA (ribosomal RNA) that are made in the nucleus
How are membranes within the cell continuous or connected?
vesicles
Name the 5 components of the eukaryotic endomembrane system.
1) nuclear envelope
2) endoplasmic reticulum
3) golgi apparatus
4) vesicles and vacuoles
5) lysosomes
What is the key difference between the smooth and rough ER of the endoplasmic reticulum?
smooth ER: lacks ribosomes
rough ER: with ribosomes
Identify the functions of the smooth endoplasmic reticulum.
1) synthesizes lipids
2) metabolizes carbohydrates
3) detoxifies poison
4) stores calcium
Identify the functions of the rough endoplasmic reticulum.
1) modifies proteins
2) distributes transport vesicles
3) produces membranes
How does the golgi apparatus have directionality?
cis face: receiving side of the golgi apparatus
trans face: shipping side of the golgi apparatus
Identify the functions of the golgi apparatus.
1) modifies products of the ER
2) manufactures macromolecules
3) encloses materials in transport vesicles (some go to the plasma membrane and some rejoin the golgi for further modification
Identify the functions of vacuoles.
- storage
- transport
- digestion
Compare contractile vacuoles, central vacuoles, and food vacuoles.
contractile vacuoles: pump excess water out of cells in freshwater protists
central vacuoles: hold organic compounds and water in plant cells
food vacuoles: formed by phagocytosis
What are the functions of lysosomes?
- joins vacuoles to digest macromolecules
- involved in phagocytosis and autophagy
Compare phagocytosis and autophagy.
phagocytosis: cell engulfs and digests material outside the cell
autophagy: cell digests and recycles own organelles and macromolecules within the cell
What are the functions of peroxisomes?
- break down fatty acids
- detoxification
- takes H ions from substrates plus oxygen to produce hydrogen peroxide and water
What is the structure of the mitochondria?
2 membranes folded into cristae:
- smooth outer membrane
- inner membrane (associated with circular DNA)
1) intermembrane
2) mitochondrial matrix
What is the role of the ribosomes in the mitochondrial matix?
make proteins for the mitochondrion
What is the role of cristae in mitochondrion?
increase surface area for the enzymes
How do mitochondria vary?
- cell/tissue type
- response to factors
What is the structure of the chloroplasts?
- inner and outer membranes
- thylakoid membranes
- intermembrane space (between inner and outer)
Explain the endosymbiosis theory.
- mitochondria and chloroplasts arose from endosymbiosis
- prokaryotes respiring with oxygen were taken up by another cell and became mitochondria
- prokaryotes that photosynthesized were taken up by another cell and became chloroplasts
Show the evidence that helps prove the endosymbiosis theory.
- membrane of chloroplasts and mitochondria are similar to some prokaryotes
- circular DNA is similar to prokaryotes
- ribosomes more similar in mitochondria and chloroplasts to those of prokaryotes than to cytosolic ribosomes in eukaryotes
Identify the functions of the cytoskeleton.
- supports cell
- maintains shape
- regulates biochemical activities
- anchors organelles in eukaryotes
Identify the function of the motor proteins, such as dynein.
- produce motility that helps move organelles and vesicles along the cytoskeleton
- bends cilium using ATP
Rank the cytoskeleton fibers from thinnest to thickest.
microfilaments, intermediate filaments, microtubules
Identify the functions and location of the microfilaments.
- resist tension
- maintain shape
- involved in movement processes
- located in cytoplasmic streaming and muscle movement
How do the microfilaments in muscles work?
myosin and actin filaments move past each other to shorten the muscle cell
How do the microfilaments in amoeboid movement work?
actin and myosin polymerize to form pseudopodium
Identify the functions and location of the intermediate filaments.
- in permanent and semi permanent structures of the cells in animals
- involved in fixing shape or position
Identify the functions and location of microtubules.
- polymers of tubulin
- involved in movement of cells or organelles
- components of cilia and flagella that are specialized for beating, that can move liquid or air or past a cell
What is the structure of a motile cilium?
- groups of microtubules covered in extension of the plasma membrane
- anchored by basal body with a ring of 9 groups of 3 microtubules (triplets)
- ring of 9 groups of 2 microtubules (doublets) *9+2 arrangement
Name the extracellular structures.
1) cell wall
2) extracellular matrix
3) capsule
What is the function of a prokaryote’s capsule?
protects against dehydration
What are the functions and structures of cell walls in prokaryotes?
-protects the cell
-maintains its shape
-prevents excessive uptake of water
-gram positive: thick layer of peptidoglycan
gram negative: thin layer of peptidoglycan plus an outer membrane
What are the functions and structures of cell walls in plants?
- cellulose microfibers embedded in a matrix of polysaccharides and protein
1) primary cell wall
2) middle lamella: thin layer of polysaccharides between primary walls of adjacent cells
3) secondary cell wall: between plasma membrane and primary cell wall
4) plasmodesmata: allows the cytoplasm of one cell to be continuous with another and to communicate between them
What is the structure of the animal extracellular matrix?
- fibronectins attached to integrins
- collagens
- proteoglycans
Compare tight junctions, desmosomes, and gap junctions.
tight junctions: form a barrier to prevent leakage by binding cells tightly together
desmosomes: intermediate filaments holding cells together in strong sheets
gap junctions: membrane proteins form pores for cells that need to communicate with others
What is the function of transport proteins?
speed the passive movement of molecules across the plasma membrane
Explain facilitated diffusion.
provide corridors for specific molecules or ions into or out of the cell
channel and carrier proteins
Compare the channel and carrier proteins.
channel proteins: provide hydrophilic corridors
carrier proteins: translocates the solute-binding site across the membrane without changing its shape
Compare isotonic, hypertonic and hypotonic solutions.
isotonic: equal concentrations of solutes across a membrane where there is no net movement of water
hypertonic: solution with more total solutes
hypotonic: solution with less total solutes
What happens to animal cells when it is placed in a hypotonic solution? Hypertonic solution? Isotonic solution?
Hypotonic: cell takes in water and bursts
Hypertonic: cell loses water and shrivels up
Isotonic: nothing happens
What happens to plant cells when it is placed in a hypotonic solution? Hypertonic solution? Isotonic solution?
Hypotonic: turgid, cell wall resists water pressure
Hypertonic: plasmolysis, cell loses water and shrivels up and pulls away from the cell wall
Isotonic: flaccid
Name two storage molecules.
starch and glycogen
What is the role of ATP in active transport?
- ATP hydrolysis releases energy that will be used for active transport
- phosphate group transferred to a transport protein
- protein changes shape which allows movement of solute
- dephosphorylation results in another shape change
- active transport allows cells to maintain concentrations of solutes different from surroundings
What does the sodium potassium pump do for animal cells?
- high concentration of potassium and low concentration of sodium inside the cell
- has binding sites specific for each ion
- change of shape during binding and releasing of ions
- unequal charge exchange, causing a charge difference between the two sides of the membrane
What does the membrane potential and electrochemical gradient do inside a cell?
- used to move charged molecules across the membrane
- more positive inside and more negative outside
- anions move out and cations move in
