Test 2 Flashcards
(130 cards)
1
Q
What are the four types of macromolecules
A
- Carbohydrates
- Lipids
- Proteins
- Nucleic acid
2
Q
Characteristics of carbohydrates (monosaccharides)
A
- 1 carbon, 1 H2O
- 2 different isomers: OH below ( alpha) and above (beta) plane of the ring
- Can either be right (D-) or left (L-) handed
3
Q
How are disaccharides assembled?
A
From two monosaccharides linked by a dehydration synthesis reaction (glycosidic bond)- either alpha or beta depending on orientation of OH)
4
Q
what are polysaccharides
A
longer chains formed by the end-to-end linking of monosaccharides. (types of macromolecule assembled by covalent linkage)
- dehydration synthesis that assembles them is an example of polymerization (identical or nearly so monomers join like links in a chain to form a larger molecule (polymer)
5
Q
Most common polysaccharides and their function
A
- starch, glycogen: energy store
- cellulose: structure/support
6
Q
Are polysaccharides always linear?
A
No, they may have branches and side chains
7
Q
Characteristics of lipids
A
- water-insoluble and non polar (C-H)
-three categories: fats, phospholipids, steroids - backbone: isoprene or fatty acids
8
Q
Isoprene is the structural unit for which categories of lipids
A
steroids and a number of phospholipids
9
Q
what gives the fatty acid its acidic properties and what happens when their length increases
A
- the carboxyl group (COOH)
- less water soluble and more solid
10
Q
what are the primary lipids of the celle membrane (ER, Golgi, vesicle)
A
Phospholipids
11
Q
Characteristics of phospholipids
A
- glycerol forms backbone of the molecule (in most) but only to of the binding sites are linked to fatty acids
- third site is linked to a polar phosphate group, which also binds to another unit
- contains: 2 hydrophobic fatty acids at one end, attached to a hydrophilic polar group
12
Q
What happens to a phospholipid when it’s fatty acid chain is unsaturated (double bond instead of another H)
A
bend in the chain
13
Q
what is the difference between a structural isomer and an enantiomer
A
structural isomer: same chemical formula but atoms arranged in different ways (different functional groups)
enantiomers: same functional groups, different molecular structure. mirror images that can’t be superimposed
14
Q
How is a triglyceride formed
A
Glycerol + fatty acids = triglyceride (look at picture)
15
Q
Characteristics of steroids
A
- framework of four carbon rings that are derived from isoprene
- small differences in their side groups help differentiate one steroid from another
16
Q
What is the most abundant steroid and its characteristics
A
the sterols.
- it has a single polar OH group linked to one end of the ring framework and a complex non polar hydrocarbon chain
- dula solubility and tend to assume positions that satisfy these properties (go between phospholipids)
- ex: cholesterol: important component of the plasma membrane (phytocerols in plants)
17
Q
What is the role of cholesterol in the plasma membrane
A
regulates membrane fluidity and stability, acting as a buffer that prevents the membrane from becoming too rigid or too fluid at different temperatures (integral or peripheral)
18
Q
Function and example of structural proteins
A
F: Support
E: alpha and beta tubular
19
Q
Function and example of enzymatic proteins
A
F: Increase the rate of biological reactions
E: DNA & RNA polymerase
20
Q
Function and example membrane transport proteins
A
F: Speed up movement of substances across biological membranes
E: Ion transporters, glucose transporters, aquaporins
21
Q
Function and example of hormones
A
F: Carry regulatory signals between cells
E: Insulin, parathyroid
22
Q
Function and example of antibodies
A
F: defend against invading molecules and organisms
E: antibodies
23
Q
Function and example of motile proteins
A
F: produce cellular movement
E: myosin, dynein, flagella, cilia
24
Q
Function and example of regulatory proteins
A
F: Promote or inhibit the activity of cellular molecules
E: Cyclins (cellular checkpoints), protein kinases
25
Function and example of receptor proteins
F: bind molecules at cell surface or within cell
E: hormone receptors
26
How do amino acids form proteins
linked by dehydration synthesis (peptide bond) reaction between the NH2 group and CO (double bond) group
27
4 types of proteins
- uncharged polar
- negatively charged polar (acidic)
- positively charged polar (basic)
- non polar
28
What is the primary structure of proteins
Sequence of amino acids:
- determined by the nucleotide sequence of the coding region of the protein's corresponding gene
29
What is the secondary structure in proteins
hydrogen bonds between atoms of the backbone
30
How do the chemical properties of amino acids influence the function of proteins
Polarity and charge: influence how they interact with each other and fold
31
How do the size and shape of amino acids influence the function of proteins
Bulky Amino Acids: Amino acids with large side chains, such as tryptophan or phenylalanine, can affect the protein's overall shape and the way it folds.
Small Amino Acids: Glycine, for instance, is small and flexible, which can provide the protein with the ability to bend or make tight turns.
32
How do the interaction capabilities of amino acids influence the function of proteins
-hydrogen bonding: crucial for maintaining secondary and tertiary structures
-ionic interactions: Charged amino acids can form salt bridges, stabilizing protein structure and influencing function.
33
How do post-translational mods of amino acids influence the function of proteins
Amino acids can be modified after protein synthesis, affecting protein function: Phosphorylation: Often occurs on serine, threonine, and tyrosine, and can regulate protein activity and signaling pathways.
34
How do the roles in active sites of amino acids influence the function of proteins
Specific amino acids are critical for the function of enzymes, often forming part of the active site where substrate binding and catalysis occur.
35
What are the three possible secondary structures for proteins
Regular: Alpha helix
Regular: beta sheet
Less regular: random coil
36
describe the alpha helix
coil shape formed when hydrogen bonds form between every N-H group of the backbone and the C=O group of the amino acid four residues earlier
hydrophobic
37
describe the beta sheet
hydrogen bonds between atoms of each strand.
some what hydrophilic
when several are assembled together, resembles a beta barrel
38
describe the random coil
imparts flexibility to certain regions of the protein.
U-turns that look different
39
what are the four major interactions between R groups that contribute to tertiary structure
- Ionic bonds
- hydrogen bonds
- hydrophobic interactions
- disulfide bridges
40
what is a quaternary structure, give 2 examples.
2 or more polypeptides coming together to form a functional protein
ex: collagen (triple helix structure)
hemoglobin: tetramer of polypeptides
41
Analyze the consequence of amino acid substitutions on the structure and function of a protein (secondary structure)
- Secondary Structure Disruption: Substitutions that involve amino acids crucial for maintaining alpha helices or beta sheets can disrupt these secondary structures.
42
Analyze the consequence of amino acid substitutions on the structure and function of a protein (tertiary structure)
Changes in amino acids that participate in critical interactions can lead to misfolding or instability in the protein's three-dimensional shape.
43
Analyze the consequence of amino acid substitutions on the structure and function of a protein (quaternary structure)
If the substitution affects an interface between subunits in a multi-subunit protein, it can destabilize the entire complex or prevent proper assembly.
44
what are the four nitrogenous bases in nucleic acids
- adenine
-cytosine
- guanine
- thymine
45
what is the difference between nitrogenous bases as purines and pyrimidines
pyrimidines: 1 ring
purines: 2 rings
46
how many stabilizing hydrogen bonds do an adenine-thymine pair form
2
47
how many stabilizing hydrogen bonds do a cytosine-guanine pair form
3
48
what are the components of a nucleoside
- nitrogenous base
- 5 carbon sugar
- glycosidic bond between nitrogenous base and first carbon
49
Explain how the protein:lipid ratio varies in different membranes of the cell (in general)
- fluid mosaic model refers to the fact that most membranes contain an assortment of protein types
- proteins move more slowly in the fluid environment of the membrane (they are bigger)
- small number of membrane proteins anchor cytoskeleton filaments to the membrane and not move
50
What is the lipid:protein ratio in the plasma membrane vs the mitochondrial membrane
- Plasma: 51:49 (no organelles)
Mitochondrial: 24:76 (enzymes involved with cell. respiration)
51
what are the four major categories of membrane proteins
1. transport
2. Enzymatic activity
3. Signal transduction
4. attachement/recognition
52
Explain the function of transport membrane proteins (and example)
- Provide a hydrophilic channel that allows movement of a specific molecule. ex: GLUT proteins
- change its shape and shuttle a specific molecule from one side of the membrane to another (ex: sodium potassium pump)
53
Explain the function of enzymatic activity membrane proteins (and example)
- catalyzing rxns
- signal transduction
-metabolic pathways
- regulation of cellular activity
- maintenance of homeostasis
- detoxification
ex:enzymes associated with the respiratory and photosynthetic electron transport chains
54
Explain the function of signal transduction membrane proteins (and example)
Membranes often contain receptor proteins on their outer surface that bind to specific chemicals such as hormones. On binding, these receptors trigger changes on the inside surface of the membrane that lead to transaction of the signal through the cell.
ex: insulin increases the cell's permeability to glucose
55
Explain the function of attachment/recognition membrane proteins (and example)
Proteins exposed to both the internal and external membrane surfaces act as attachment points for a range of cytoskeleton elements, as well as components involved in cell-cell recognition
ex: glycoprotein
56
How to identify transmembrane proteins
Presence of stretches of amino acids that are primarily non polar : these regions of the protein interact with the hydrophobic regions of the membrane. Usually 17-20 a.a are needed to span the membrane once.
57
What is the difference between passive and active transport
P: the movement of molecules across a membrane without the need to expend chemical energy (ATP)
A: energy dependent transport that moves molecules against a concentration gradient
58
what are the two types of passive transport
1. simple diffusion (mvt of molecules from high to low concentration areas)
2. facilitated diffusion (diffusion carried out by either carrier or channel proteins)
59
what is the driving force of diffusion
entropy (molecules bouncing off of each other)
60
what does the rate of passive transport depend on
the concentration gradient that exists across the membrane
61
What does the rate of simple diffusion depend on
1. molecular size
2. lipid solubility
62
What are channel proteins
they form hydrophilic pathways in the membrane through which molecules like ions and water can pass
63
what are carrier proteins
they bind to a specific solute, such as a sugar molecule or an amino acid and transport it across the lipid bilayer
64
can a carrier protein transporting glucose transport fructose?
No, most transport proteins have a very high degree of substrate specificity
65
what are aquaporins
made of non polar alpha helixes to keep the protein embedded in the cell membrane, positively charged polar amino acids draw water into the channel (doesn't allow for the transport of ions)
66
Explain gated channels
can switch between open, closed and intermediate states. Critical to the mvt of most ions
ex: voltage gated ion channels are used in nerve conduction and the control of muscle contraction
67
how many solute can be transferred by carrier proteins at once
1
68
how do carrier proteins work
they undergo shape changes that progressively move the solute binding site from one side of the membrane to the other, thereby transporting the solute (very selective)
69
what is osmosis
the passive diffusion of water across a semi-permeable membrane
-simple diffusion or facilitated (aquaporins).
Solution of lower to higher concentration
70
what are the three states of osmosis
-hypotonic (cells swell)
-hypertonic (cells shrivel up)
-isotonic (no net movement of water)
71
what happens to hypotonic plant cells
the cell pushes up against the cell wall, resulting in what is called turgor pressure
72
What is the difference between primary and secondary active transport
P: the same protein that transports the molecules also hydrolyzes ATP to directly power the transport. (Pumps)
S: the transport is indirectly driven by ATP
73
Primary active transport systems
- Na+, K+, Ca2+(pushes calcium from cytoplasm to cell exterior and into lumen of ER), H+ pumps
*Ions moving against the concentration gradient
74
Explain sodium - potassium pumps
pushes out 3 Na+ ions and pushes in 1 K+ ion in the same pumping cycle.
as result: positive charge accumulates in excess outside the membrane and the inside become negatively charged (eletrical potential difference/voltage)
75
result of difference in charge and ion concentration on each side of the membrane
electrochemical gradiant which stores energy that is used for other transport mechanisms
76
what is associated to the nerve impulse transmission
the electrochemical gradient across the membrane involved with the movement of ions
77
what is the energy source of secondary active transport pumps
the concentration gradient of an ion established by a primary pump
78
what is the driving force for most secondary active transport in animal cells
the high outside / low side Na+ gradient set by the sodium potassium pump
79
what is the transfer of the solute across the membrane always coupled with in secondary active transport
the transfer of the ion supplying the driving force
80
what is the difference between support and antiport
s: cotransported solute moves through the membrane channel in the same direction as the driving ion (cotransport) ex: glucose and amino acids
a: opposite direction (exchange diffusion) ex: red blood cells for coupled movement of chloride ions and bicarbonate ions through a membrane channel
81
what are the largest molecules transported through cellular membranes by passive and active transport
about the size of amino acids or monosaccharides
82
how to import/export larger molecules
endocytosis and exocytosis
83
what happens to endo and exo cytosis if a cell's ability to make ATP is inhibited
it stops
84
what happens in bulk phase endocytosis (pinocytosis)
- extracellular water is taken in + any molecules in that solution.
- No binding by surface receptors
- like taking a big gulp of water
85
what happens in receptor-mediated endocytosis
- molecules to be taken in bound to outer surface of cell by receptor proteins (integral to plasma membrane)
- recep. prot. recognize and bind to only certain molecules (but can be hijacked by viruses)
86
what part of the cell is lost during exocytosis
part of the plasma membrane
87
what happens in exocytosis
- secretory vesicles move through the cytoplasm and contact plasma membrane
- used by neurons during the synapse process
- vesicle membrane fuses with the plasma membrane, releasing the vesicle's contents to the cell exterior
88
what are membrane surface receptors
they recognize and bind signal molecules and they are integral membrane proteins that extend through the entire membrane
89
how do response pathways work
- the signal cell binds to a receptor
- receptor changes shape
- the signal is relayed inside the cell py protein kinases
- the phosphorylation cascade amplifies the signal (email blast)
- it makes it to the nucleus
90
what are kinase proteins
any protein that can phosphorylate another molecule
91
what is signal transduction
cell signalling that causes a cellular response, which leads to gene expression
92
what is the particularity of internal receptors
small internal molecules can directly diffuse through the plasma membrane and interact with internal receptors
93
what are the three types of neurons
- efferent (away from NS)
-afferent (towards NS)
-Interneuron (connect efferent from afferent)
94
what is the myosin sheath
It surrounds the axon, providing insulation, which lead to higher speed and conductivity of the nerve impulse
95
what initiates action potential
a change in membrane potential
96
what is the membrane potential
an electrical gradient across the plasma membrane: more positive charges on the outside than the inside
97
what is the resting membrane potential
- 70 mV
98
what establishes the resting membrane potential
Na+/K+ sodium pumps
99
What maintains the resting membrane potential
-Na+ leak channels that let some sodium ions return inside the axon in potential exceeds -70
-K+ leak channels letting potassium ions return outside
100
what happens if the threshold potential is reached
-depolarization begins (Na+VGIC open) burst of of sodium ions in the axon
- around 30/40 mV, Na+ VGIC slam shut and K+ VGIC open (repolarization begins)
- Hyperpolarization because K+ water channels close slowly (refractory period) ease up on Na+ VGIC doors but keep one there
101
why is there a refractory period
-prevents a rapide refaire of that neuron
- ensures a one way nerve impulse
102
what happens during the synapse
- when action potential reaches the axon terminal, synapse process enables the signal to transfer from a pre to post synaptic neuron
- when reaching axon terminal, depolarization triggers opening of gates ca2+ channels
- inward flow of ca2+ ions forces the exocytosis of neurotransmitter vesicles
-neurotransmitters are expelled into the synaptic cleft, detected by neurotransmitter receptors on dendrites of postsynaptic neuron
103
can the activation of neurotransmitter receptors trigger the initiation of an action potential in the postsynaptic neuron
yes
104
what is the urinary system's filtration unit
the nephron: it filter's blood at bowman's capsule and reabsorbs the essential materials at the tubules
105
how must animals keep their cellular and extracellular fluids
iso-osmotic
106
what are osmoconformers
most marine animals can match the osmotic concentrations of their environment.
107
how many nephrons does a human kidney have
more than a million
108
in mammals, urine is _______-osmotic to body fluids
hyper.
it is a water conserving adaptation
109
what are the three structures that interact to conserve nutrients and water, balance slats and concentrate waste for excretion from the body
- the structural arrangement of the loop of henle: descends into the medulla and returns to the cortex
- differences in permeability: of successive regions of the nephron to water and ions established by specific group of membrane transport proteins in each region
- a gradient in concentration : of molecules and ions in the interstitial fluid of the kidney
110
the farther away an electron is from the nucleus of an atom...
the greater potential energy that electron possesses (as it moves closer to the nucleus, it loses potential energy)
111
higher electronegativity in an atom =
less potential energy
112
Is there more or less electronegativity in carbohydrates than lipids
less, because less oxygen (which has a high electronegativity)
113
What happens when energy is absorbed
the electron is in an excited state, away from the nucleus (third energy)
114
What is thermodynamics
a branch of science that concerns energy and how it changes during chemical and physical transformations
115
what is an isolated system
-the only true one is the universe
-does not exchange energy or matter with its surroundings
-a thermos bottle is close to be an isolated system
116
what is a closed system
- saucepan of water with a lid on a stove
- earth
- exchanges energy with its surroundings
117
what is an open system
- ocean and all living things
-exchanges both energy and matter with its surroundings
118
what is the first law of thermodynamics
Energy can be transformed but not created or destroyed
119
what is the second law of thermodynamics
The entropy of a system and the surroundings will increase-- energy will always become more spread out
120
what is entropy
the measure of disorder in a system
121
What does G mean
free energy
122
what does delta H mean
enthalpy = potential energy
123
what does S mean
entropy = disorder
124
do molecules at higher temperature typically have more or less entropy than lower temperatures
more
125
do endothermic processes have a higher enthalpy than exothermic processes
yes, because the reactants have a higher enthalpy than the products.
more complex molecules have more potential energy
126
are catabolic (breakdown) reactions spontaneous or non spontaneous
spontaneous, their delta G is negative (
127
are anabolic (synthesis) reactions spontaneous or non spontaneous
non spontaneous. their delta G is positive (only exceptions is ice to water)
128
what is a spontaneous reaction also referred to
exergonic process (doesn't require energy inputs, releases energy)
129
Reactions tend to be spontaneous if they are...
exothermic
130
what is a nonspontaneous reaction also referred to
endergonic process
