Exam 1 Flashcards
(176 cards)
1
Q
Functions of neurons and nervous tissue
A
Initiate, integrate, conduct electrical signals
2
Q
What is the most common connective tissue
A
loose connective tissue
3
Q
What tissue makes up bones, tendons, and ligaments?
A
dense connective tissue
4
Q
What are the functions of extracellular matrix
A
Scaffold for cellular attachments
Cell signaling
Collagen fibers/Elastin fibers
5
Q
Homeostasis
A
fluctuation of processes within a predictable and often narrow range
6
Q
Dynamic constancy
A
variation over a short period of time, but stable over a long period of time
7
Q
Steady state
A
a variable is not changing, but energy is required to maintain constancy
8
Q
Equilibrium
A
a variable is not changing, but no energy is required to maintain constancy
9
Q
Set point
A
the “value” of the variable at steady state or equilibrium
10
Q
What would the effect on a pathway be if negative feedback was removed?
A
Too much (an overload) of the product would be produced
11
Q
Feedforward
A
changes in regulated variables are anticipated and compensated for before the change actually occurs
12
Q
Give an example of feedforward inhibition.
A
body temperature regulation
13
Q
What are the components of homeostatic control mechanisms in reflexes? (figure 1.8 & 1.9)
A
Stimulus Receptor Afferent pathway Integrating center Efferent pathway Effector Response
14
Q
Hormone-secreting gland cell pathway
A
Produces hormones that flow through blood vessels and targets cells in one or more distant places in the body
15
Q
Neuron pathway
A
Produces an electrical signal that goes through a neurotransmitter to a neuron or effector in close proximity to site of neurotransmitter release
16
Q
A local cell that produces a paracrine substance
A
targets cells in close proximity to site of neurotransmitter release
17
Q
A local cell that produces an autocrine substance
A
autocrine substance acts on the same cell that secreted the substance
18
Q
Can a neuron, endocrine gland cell, and other cell type release the same chemical messenger?
A
yes
19
Q
Can a certain messenger have multiple functions?
A
yes; a particular messenger may function as a neurotransmitter, a hormone, or a paracrine or autocrine substance
20
Q
Gap junctions
A
physical linkages connecting the cytosol between two cells, which allow molecules to move from one cell to an adjacent cell without entering the extracellular fluid.
21
Q
juxtacrine signaling
A
the chemical messenger not actually being released from the cell producing it, but rather is located in the plasma membrane of that cell. When the cell encounters another cell type capable of responding to the message, the two cells link up via the membrane-bound messenger.
22
Q
Adaptation
A
a characteristic that favors survival in specific environments.
23
Q
Acclimatization
A
improved functioning of an existing homeostatic system; sometimes due to prolonged exposure to an environmental change
24
Q
What is the most common process related to homeostasis?
A
circadian rhythm
25
Circadian rhythm
Cycles approximately once every 24 hours. Waking and sleeping, body temperature, hormone concentrations in the blood, the excretion of ions into the urine, and many other functions undergo circadian variation.
26
What atoms make up 99.3% of total atoms in the body?
hydrogen, oxygen, carbon, and nitrogen
27
atomic number
number of protons in an element
28
atomic mass
The atomic mass scale indicates an atom’s mass relative to the mass of other atoms.
29
gram atomic mass
amount of the element, in grams, equal to the numerical value of its atomic mass
30
How many atoms does one gram of atomic mass contain?
6×10^23 atoms - Avogadro’s number
31
electrolytes
ionic forms of mineral elements
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electronegativity
The measure of an atom’s ability to attract electrons in a covalent bond
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Polar covalent bonds
electrons are shared un-equally
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Non-polar covalent bonds
electrons are shared equally
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Molecules with polar covalent bonds are...
soluble in water
36
Molecules with non-polar covalent bonds are...
insoluble in water
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ionic bond
The strong attraction between two oppositely charged ions
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Hydrogen bonds
- occur when two polar molecules are in close proximity.
- attraction between hydrogen atom of one molecule and oxygen or nitrogen atom of another molecule
- very weak—4% strength of polar covalent bond
- in large number, hydrogen bond have implications pertaining to molecular structure
39
Two commonly encountered groups of atoms that undergo ionization in molecules are the...
carboxyl group (—COOH) and the amino group ("—" NH_2 )
40
Free radicals
- contain a single (unpaired) electron in an orbital of their outer shell
- are unstable and highly reactive
- may remove an electron from another atom to fill their outer shell
- the atom that lost its electron becomes another free radical
- formed by the actions of certain enzymes in some cells, such as types of white blood cells that destroy pathogens
- can be produced in the body following exposure to radiation or toxin ingestion.
- can do considerable harm to the cells of the body.
41
Examples of biologically important free radicals
- superoxide anion, O_2∙–
- hydroxyl radical, OH∙
- nitric oxide, NO∙
42
How much of total body weight is made up of water?
60%
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Hydrolysis
involves the breaking of a chemical bond with the additions of elements of water ("—" H and "—" OH) to the products formed
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How does water move in osmosis?
low to high concentrations
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hydrophilic
"water loving"
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hydrophobic
"water fearing"
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Amphipathic molecules
a special class of molecules that have a polar or ionized region at one site and a nonpolar region at another site.
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Solute concentration
the amount of solute present in a unit volume of solution.
49
Formula for molarity:
M=mol/liter
50
Acid
releases protons (hydrogen ions) in solution
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Base
accepts protons (hydrogen ions) in solution
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formula for pH
pH = -log[H+}
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What is the homeostatic range for pH in the extracellular fluid in the body?
7.35-7.45
54
Carbohydrates
Disaccharides and Polysaccharides
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What are the subunits of carbohydrates
Monosaccharides
56
Subclasses of lipids
Triglycerides
Phospholipids
Steroids
Fatty acids
57
Subunits of triglycerides
Fatty Acids, Glycerol
58
Subunits of phospholipids
Fatty Acids, Glycerol, Phosphate
59
Proteins
Polypeptides
60
Subunits of proteins
amino acids
61
Nucleic acids
DNA & RNA
62
Subunits of nucleic acids
nucleotides
63
What organic molecule makes up the largest percentage of body weight?
proteins (17%)
64
Glycogen
exists in the body as a reservoir of available energy that is stored in the chemical bonds within individual glucose monomers.
65
Hydrolysis of glycogen
leads to the release of the glucose monomers into the blood, thereby preventing blood glucose from decreasing to dangerously low levels.
66
Glucose
often called “blood sugar” because it is the major monosaccharide found in the blood.
67
What atoms are lipids prominently composed of?
hydrogen and carbon atoms
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What is the physiological importance of lipids
energy source, cell membranes, cell signaling
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Fatty acid
chain of carbon and hydrogen atoms with an acidic carboxyl group at one end.
70
saturated fatty acid
carbons are linked by single covalent bonds
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unsaturated fatty acid
contain one or more double bonds between carbon atoms
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monounsaturated
one double bond is present
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polyunsaturated
more than one double bond present
74
Triglycerides
glycerol (a three-carbon sugar-alcohol) bonds to three fatty acids
75
What constitutes for the majority of the lipids in the body
triglycerides
76
Where are triglycerides synthesized
the liver
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Where are triglycerides stored and what is their function?
adipose tissue where they serve as an energy reserve
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Phospholipids
glycerol bound to two fatty acids and a phosphate.
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Phosphate
polar, hydrophilic region
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Fatty acid
non-polar, hydrophobic region
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Are phospholipids hydrophylic or hydrophobic?
BOTH! They are amphipathic
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What does the amphipathic structure of phospholipids allow them to form?
Lipid bilayers of cellular membranes
83
Steroids
structure: Four interconnected rings of carbon atoms form the skeleton of every steroid.
NOT WATER SOLUBLE
84
Examples of steroids
- cholesterol cortisol from the adrenal glands
| - female (estrogen) and male (testosterone) sex hormones secreted by the gonads.
85
Proteins account for about how much of the organic material in the body?
50%
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What are proteins composed of
carbon, hydrogen, oxygen, nitrogen, and small amounts of other elements, notably sulfur
87
Structure of amino acids
- terminal carbon atom
- amino ("—" NH_2 )
- carboxyl (—COOH)
- hydrogen atom
- amino acid side chain or R-group (amino acid side chain)
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How are essential amino acids obtained?
diet
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Primary structure of proteins
the number of amino acids in the chain, and the specific sequence of different amino acids.
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What is a polypeptide?
analogous to a linear string of beads, each bead representing one amino acid.
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Secondary structure of proteins due to hydrogen bonds
- alpha helix (coil)
| - beta pleated sheet
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What role do beta pleated sheets and alpha helices play in proteins?
they tend to impart upon a protein the ability to anchor itself into a lipid bilayer.
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Tertiary structure of proteins due to side chains
- Folding
| - Functional protein
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What are the 5 main structures that determine tertiary structure of proteins?
- hydrogen bonds between side groups of amino acids or with surrounding water molecules;
- ionic interactions between ionized regions along the chain;
- interactions between nonpolar (hydrophobic) regions;
- covalent disulfide bonds linking the sulfur-containing side chains of two cysteine amino acids; and
- van der Waals forces.
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Quaternary structure of proteins
polymerization of tertiary structures
| ex- hemoglobin
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Nucleic acid functions
storage, expression, and transmission of genetic information.
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Nucleotides
monomeric subunits of nucleic acids, which contain a phosphate group, a five-carbon sugar, and a nitrogenous base
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Purine bases:
- adenine (A) and guanine (G)
| - double ring
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Pyrimidine bases
- cytosine (C) and thymine (T)
| - single ring
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What does the adenine base pair with
thymine
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What base does guanine pair with
cytosine
102
Deoxyribonucleic Acid (DNA)
Double helix and hydrogen bonds between the bases
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How does Ribonucleic Acid (RNA) differ from DNA
- Single chain of nucleotides
- Sugar in each nucleotide is ribose rather than deoxyribose
- Pyrimidine base thymine in DNA is replaced by the pyrimidine base uracil (U).
* Uracil pairs with adenine
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Cytoplasm
everything outside of the nucleus
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Cytosol
fluid component of the cytoplasm
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ICF (intracellular fluid)
Cytosol + Fluid in the nucleus
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Functions of Plasma Membranes
- Regulate the passage of substances into and out of cells and between cell organelles and cytosol.
- Detect chemical messengers arriving at the cell surface.
- Link adjacent cells together by membrane junctions.
- Anchor cells to the extracellular matrix
108
Membrane
double layer of lipid molecules containing embedded proteins.
109
Major membrane lipids
Phospholipids and cholesterol
110
What is the function of the cholesterol in the plsama membrane
Cholesterol have a coordinated function in maintaining an intermediate fluidity of the plasma membrane. This contrasts with intracellular membranes which contain very little cholesterol.
111
Integral membrane proteins
- closely associated with the membrane lipids
- cannot be extracted from the membrane without disrupting the lipid bilayer
- amphipathic
- most integral proteins span the entire membrane and are referred to as transmembrane proteins.
112
Functions of transmembrane proteins
- form channels through which ions or water can cross the membrane,
- whereas others are associated with the transmission of chemical signals across the membrane
- the anchoring of extracellular and intracellular protein filaments to the plasma membrane.
113
Peripheral membrane proteins
- are not amphipathic
- do not associate with the nonpolar regions of the lipids in the interior of the membrane.
- located at the membrane surface where they are bound to the polar regions of the integral membrane proteins.
114
Types of membrane junctions
- desmosomes
- tight junctions
- gap junctions
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Integrins
transmembrane proteins that bind to specific proteins in the extracellular matrix and link them to membrane proteins on adjacent cells.
116
Desmosomes
hold cells together but allow for stretching (skin)
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Cadherins
proteins that extend from the cell into the extracellular space, where they link up and bind with cadherins from an adjacent cell.
118
How are desmosomes characterized?
They are characterized by accumulations of protein known as “dense plaques” along the cytoplasmic surface of the plasma membrane.
119
Tight junctions
form a barrier (epithelium of gut or bladder)
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Where are desmosomes limited to?
disk-shaped are of the membrane
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Where does the tight junction occur?
the tight junction occurs in a band around the entire circumference of the cell
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Gap Junctions
form protein channels linking the cytosols of two adjacent cells (myocardium, transmission of electrical activity)
123
Can proteins pass through channels in gap junctions?
No, gap junctions are channels for small molecules such as ions
124
What process turns DNA into RNA?
Transcription
125
What process turns RNA into PROTEIN
Translation
126
How many different ways can the four bases of DNA be arranged?
64
127
What triplets are stop signals?
- UAA
- UAG
- UGA
128
What happens in transcription?
- RNA polymerase binds to the promoter region of a gene and separates the two strands of the DNA double helix in the region of the gene to be transcribed.
- Free ribonucleotide triphosphates base-pair with the deoxynucleotides in the template strand of DNA.
- The ribonucleotides paired with this strand of DNA are linked by RNA polymerase to form a primary RNA transcript containing a sequence of bases complementary to the template strand of the DNA base sequence.
- RNA splicing removes the intron-derived regions, which contain noncoding sequences, in the primary RNA transcript and splices together the exon-derived regions, which code for specific amino acids, producing a molecule of mature mRNA.
129
Translation
- The mRNA passes from the nucleus to the cytoplasm, where one end of the mRNA binds to the small subunit of a ribosome.
- Free amino acids are linked to their corresponding tRNAs by aminoacyl-tRNA synthetase.
- The three-base anticodon in an amino acid–tRNA complex pairs with its corresponding codon in the region of the mRNA bound to the ribosome.
- The amino acid on the tRNA is linked by a peptide bond to the end of the growing polypeptide chain.
- The tRNA that has been freed of its amino acid is released from the ribosome.
- The ribosome moves one codon step along mRNA.
- The previous four steps are repeated until a termination sequence is reached, and the completed protein is released from the ribosome.
- In some cases, the protein undergoes posttranslational processing in which various chemical groups are attached to specific side chains and/or the protein is split into several smaller peptide chains.
130
Mutations
- Chemicals or ionizing radiation can cause structural changes to DNA resulting in a change in the nucleotide sequence.
- A change in nucleotide sequence may lead to a change in the structure of a protein.
- Changes in protein structure may impair cell function or may cause cell death.
131
Protein Degradation
- Different proteins degrade at different rates.
- A denatured (unfolded) protein is more readily degraded than a protein with an intact conformation.
- Proteins can be targeted for degradation by the attachment of a small peptide, ubiquitin, to the protein. This peptide directs the protein to a protein complex known as a proteasome, which unfolds the protein and breaks it down into small peptides.
132
Ligand
- molecule (including another protein) or ion that binds to a protein by one of the following forces:
- electrical attractions between oppositely charged ionic or polarized groups on the ligand and the protein, or
- weaker attractions due to hydrophobic forces between nonpolar regions on the two molecules.
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Binding Site
region of a protein to which a ligand binds
134
How many binding sites can a protein have?
It can have multiple
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What does the binding of the ligand do to the protein?
It either activates the protein or inhibits the protein
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Chemical specificity
ability of a protein-binding site to bind specific ligands
137
What does specificity depend on?
conformation
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Affinity
strength of ligand-protein binding
139
What does the affinity of a binding site determine?
how likely it is that a bound ligand will leave the protein surface and return to its unbound state.
140
What is the strength of a bond with high affinity?
strong
141
What is the strength of a bond with low affinity?
weak bond
142
What happens when a protein has a high-affinity binding site for a ligand?
very little of the ligand is required to bind to the protein
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Saturation
the fraction of total binding sites that are occupied at any given time.
144
The percent saturation of a binding site depends upon what two factors?
1) the concentration of unbound ligand in the solution
| 2) the affinity of the binding site for the ligand
145
Allosteric modulation
an allosteric protein has two binding sites
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Functional site (aka active site)
carries out the protein’s physiological function
147
Regulatory site
a modulator molecule binds to the regulatory site and changes the conformation of the functional site
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Covalent modulation
covalent bonding of charged chemical groups to some of the protein’s side chains.
149
Phosphorylation
covalent modulation by adding a phosphate group (negatively charged)
150
Protein kinase
enzyme that mediates phosphorylation
151
Phosphoprotein phosphatase
enzyme that mediates de-phosphorylation
152
Catabolism
the breakdown of organic molecules
153
Anabolism
the synthesis of organic molecules
154
What do chemical reactions do?
break and form chemical bonds.
155
How is breakdown and synthesis of organic molecules achieved?
through chemical reactions
156
Determinants of reaction rates:
Reactant concentration
Activation energy
Temperature
Catalyst
157
What does a greater concentration do to a reaction rate:
the reaction rate incerases
158
what does a greater activation energy do for reaction rate?
slower reaction rate
159
what does a higher temperature do for reaction rate?
increases reaction rate
160
what does the presence of a catalyst do fro a reaction rate?
it increases reaction rate
161
Reversible Reactions
- A+B⇌C+D+Small amount of energy
| - At chemical equilibrium, product concentrations are only slightly higher than reactant concentrations.
162
Irreversible Reactions
- E+F⇌G+H+Large amount of enery
| - At chemical equilibrium, almost all reactant molecules have been converted to product.
163
Law of Mass Action
The direction of a chemical reaction is determined (in part) by the concentrations of reactants and products.
164
Enzymes
protein molecules, so an enzyme can be defined as a protein catalyst.
165
What do enzymes do to activation energy? What do they do to biological reactions?
Enzymes lower the activation energy and make biological reactions proceed at a faster reaction rate.
166
cofactors
Cofactors bind to an enzyme and alter the enzyme’s conformation to facilitate its interaction with a substrate.
167
Enzyme-mediated reactions are regulated by what three major factors?
- substrate concentration
- enzyme concentration
- enzyme activity
168
Metabolic Pathways
- Multienzyme pathways are the basis of cellular metabolism.
| - An example is the transfer of energy released from the breakdown of fuel molecules to ATP.
169
Essential Nutrients:
water, minerals, amino acids, fatty acids
170
Essential mineral elements
- 7 major mineral elements
| - 13 trace elements
170
Essential mineral elements
- 7 major mineral elements
| - 13 trace elements
171
Essential amino acids
```
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
```
172
Essential fatty acids
Linoleic acid
| Linolenic acid
173
Other essential nutrients
Inositol
Choline
Carnitine
174
Water-soluble vitamins
```
B1: thiamine
B2: riboflavin
B6: phridoxine
B12: cobalamine
Niacin Pantothenic acid
Folic acid
Biotin
Lipoic acid
Vitamin C
```
175
Fat-soluble vitamins
Vitamin A
Vitamin D
Vitamin E
Vitamin K
