DEFINITIONS Flashcards
1
Q
Homeostasis
A
Regulation of the internal environment to maintain a constant state.
2
Q
Alternative splicing
A
A process in which primary transcripts from the same gene can be spliced in different ways to yield different mRNAs and therefore different protein products.
3
Q
Amino acid
A
Building blocks of proteins.
4
Q
Anticodon
A
The sequence of three nucleotides in a tRNA molecule that base pairs with the corresponding codon in an mRNA molecule.
5
Q
ATP synthase
A
An enzyme that couples the movement of protons through the enzyme with the synthesis of ATP.
6
Q
Autotroph
A
An organism that is able to synthesize its own food using energy from sunlight or inorganic chemicals.
7
Q
Base
A
A nitrogen-containing compound that makes up part of a nucleotide.
8
Q
Beta sheet
A
One of the two principal types of secondary structure found in proteins.
9
Q
Calvin cycle
A
The process in which carbon dioxide is reduced to synthesize carbohydrates with ATP and NADPH as the energy sources.
10
Q
Carbohydrate
A
An organic molecule containing C, H, and O atoms that provides a source of energy for metabolism and that forms the starting point for the synthesis of all other organic molecules.
11
Q
Carboxyl end
A
The end of a polypeptide chain that has a free carboxyl group.
12
Q
Carboxyl group
A
A carbon atom with a double bond to oxygen and a single bond to a hydroxyl group.
13
Q
Cell
A
The simplest self-reproducing entity that can exist as an independent unit of life.
14
Q
Central dogma
A
DNA -> RNA -> protein
The idea that information flows from nucleic acids to proteins.
15
Q
Chemoreceptor
A
A receptor that responds to molecules that bind to specific protein receptors on the cell membrane of the sensory receptor.
16
Q
Chemotroph
A
An organism that derives its energy directly from organic molecules such as glucose.
- type of metabolism (fungi, bacteria…)
17
Q
Citric acid cycle
A
The third stage of cellular respiration in which acetyl-CoA is broken down and carbon dioxide is released.
18
Q
Cohesion
A
Attraction between molecules, surface tension.
19
Q
Complementary
A
Describes the relationship of purine and pyridine bases where base A only binds with T (or U) and G only pairs with C.
20
Q
Complementary DNA
A
A DNA molecule produced by reverse transcriptase from an RNA template.
21
Q
Covalent bond
A
A chemical bond formed by a shared pair of electrons holding two different atoms together.
22
Q
Cytoplasm
A
The contents of the cell other than the nucleus.
23
Q
Cytoskeleton
A
Helps eukaryotic cells maintain their shape.
24
Q
Daughter strand
A
The strand synthesized from a parental template in DNA replication.
25
Deoxyribonucleic acid
DNA - the information archive in all organisms.
26
Deoxyribose
The sugar in DNA
27
Depolarization
An increase in membrane potential from a negative resting potential.
28
DNA polymerase
An enzyme that is a critical component of a large protein complex that carries out DNA replication.
29
DNA replication
The process of duplicating a DNA molecule during which the parental stands separate and new partner strands are made.
30
Double bond
A covalent bond in which covalently joined atoms share two pairs of electrons.
31
Double helix
The structure formed by two strands of complementary nucleotides that coil around each other.
32
Duplication
A region of chromosome that is present twice instead of once.
33
Electrochemical gradient
A gradient that combines the charge gradient and the chemical gradient of protons and other ions.
34
Electron
A negatively charged particle that move around the atomic nucleus.
35
Endoplasmic reticulum
ER - An organelle composed of a network of membranes that is involved in the synthesis of proteins and lipids.
36
Eukaryote
An organism whose cells have a true nucleus.
37
Exon
A sequence that is left intact in mRNA after RNA splicing.
38
Golgi apparatus
The organelle that modifies proteins and lipids produced by the endoplasmic reticulum and acts as sorting station as they move to their final destination.
39
Heterotroph
An organism that obtains its carbon from organic molecules synthesized by other organisms.
40
Hydophillic
Water loving - class of molecules with which water can undergo hydrogen bonding.
41
Hydrophobic
Water fearing - class of molecules poorly able to undergo hydrogen bonding with water.
42
Hyrophobic effect
The exclusion of non polar molecules by polar molecules which drives biological processes such as the formation of cell membranes and the folding of proteins.
43
Initiation factor
A protein that binds to mRNA to initiate translation.
44
Inhibitor
A synthesized compound that decreases the activity of an enzyme.
45
Ion
An electrically charged atom or molecule.
46
Intron
A nucleotide sequence that is excised from the primary transcript and degraded during RNA splicing.
47
Isomers
Molecules that have the same chemical formula but different structures.
48
Isotopes
Atoms of the same element that have different numbers of neutrons.
49
Kinetic energy
The energy of motion.
50
Lariat
A loop and tail of RNA formed after RNA splicing.
51
Lipid
A hydrocarbon molecule that is soluble in non-polar solvents but not in water.
Lipids store energy, act as signaling molecules, and are a component of cell membranes.
52
Lysosome
A vesicle derived from the Golgi apparatus that contains enzymes that break down macromolecules such as proteins, nucleic acids, lipids, and complex carbohydrates.
53
Messenger RNA
mRNA - combines with a ribosome to direct protein synthesis.
| Carries the genetic "message" from the DNA to the ribosome.
54
Metabolism
The chemical reactions occurring within cells that convert one molecule to another and transfer energy in living organisms.
55
Mitochondria
Specialized organelles that are the site of respiration in eukaryotic cells, oxidizing chemical compounds such as sugars to carbon dioxide and transferring their chemical energy to ATP.
56
Mitochondrial matrix
The space enclosed by the inner membrane of the mitochondria.
57
Molecule
A substance made up of two or more atoms.
58
Nonpolar
Describes compounds that do not have regions of positive and negative charge.
59
Nonpolar covalent bond
A covalent bond between atoms that have the same electronegativity.
60
Nuclear envelope
The cell structure composed of two membranes, inner and outer, that defines the boundary of the nucleus.
61
Nucleic acid
A polymer of nucleotides that encodes and transmits genetic information.
62
Nucleoid
In prokaryotes, a cell structure with multiple loops formed from supercoils of DNA.
63
Nucleoside
Sugar + base
64
Nucleotide
Sugar + base + phosphate
65
Nucleus (of an atom)
The central part of an atom containing protons and neutrons.
66
Nucleus (of a cell)
The compartment of the cell that houses the DNA in chromosomes.
67
Osmosis
The net movement of a solvent, such as water, across a selectively permeable membrane toward the side of a higher solute concentration.
68
Oxidative phosphorylation
A set of metabolic reactions that occur by passing electrons along an electron transport chain to the final electron acceptor, oxygen, pumping protons across a membrane, and using the proton electrochemical gradient to drive synthesis of ATP.
69
Oxygenic
Producing oxygen.
70
Peptide bond
A covalent bond that links the carbon atom in the carboxyl group of one amino acid to the nitrogen atom in the amino group of another amino acid.
71
Peptidyl site
One of the three binding sites for tRNA on the large subunit of a ribosome.
72
Phenotype
The expressed physical, behavioral, and biochemical traits of an individual. (height, weight, eye color...)
73
Phosphatase
An enzyme that removes a phosphate group from another molecule.
74
Phosphate group
A chemical group consisting of a phosphorus atom bonded to four oxygen atoms.
75
Phospholipid
Type of lipid and a major component of the cell membrane.
76
Pituitary gland
An endocrine gland located at the base of the vertebrate brain that produces a number of different hormones and controls many of the other organs in the endocrine system.
77
Polar
A molecule that has regions of positive and negative charge.
78
Polar covalent bond
Bonds that do not share electrons equally.
79
Polypeptide
A polymer of amino acids connected by peptide bonds.
80
Potential energy
Stored energy that is released by a change in an object's structure or position.
81
Prokaryote
An organism whose cell or cells do not have a membrane bound nucleus. (bacteria)
82
Proteins
The key structural and functional molecules that do the work of the cell, providing structural support and catalyzing chemical reactions. (protein is a synonym for polypeptide)
83
Purine
In nucleic acids, either of the bases adenine and guanine, which have a double-ring structure.
84
Pyrimidine
In nucleic acids, any of the bases thymine, cytosine, and uracil, which have a single-ring structure.
85
R group
A chemical group attached to the central carbon atom of an amino acid, whose structure and composition determine the identity of the amino acid.
86
Receptor
A molecule on cell membranes that detects critical features of the environment. Receptors detecting signals that easily cross the cell membrane are sometimes found in the cytoplasm.
87
Receptor activation
The "turning on" of a receptor, which often occurs when a signaling molecule binds to a receptor on a responding cell.
88
Receptor protein
The molecule on the responding cell that binds to the signaling molecule.
89
Release factor
A protein that causes a finished polypeptide chain to be freed from the ribosome.
90
Replication
The process of copying DNA so genetic information can be passed from cell to cell.
91
Repressor
A protein that, when bound with a sequence in DNA, can inhibit transcription.
92
Responding cell
The cell that receives information from the signaling molecule.
93
Restriction enzyme
Any one of a class of enzymes that recognizes specific nucleotide sequences in double-stranded DNA and cleaves DNA at or near those sites.
94
Restriction site
A recognition sequence in DNA cutting which is typically four or six base pairs long.
95
Ribonucleic acid
RNA - a molecule chemically related to DNA that is synthesized by proteins from a DNA template.
96
Ribose
The sugar in RNA.
97
Ribosome
A complex structure of RNA and protein bound to the face of the rough endoplasmic reticulum in the cytoplasm, on which proteins are synthesized.
98
Ribulose bisphosphate carboxylase oxygenase
Rubisco - the enzyme that catalyzes the carboxylation reaction in the Calvin cycle.
99
Ribulose 1,5-bisphosphate
RuBP - the 5-carbon sugar to which carbon dioxide is added by the enzyme rubisco.
100
RNA editing
The process in which some RNA molecules become a substrate for enzymes that modify particular bases in the RNA, thereby changing its sequence and sometimes what it codes for.
101
RNA polymerase
The enzyme that carries out polymerization of ribonucleoside triphosphate from a DNA template to produce an RNA transcript.
102
RNA splicing
The process of intron removal from the primary transcript.
103
Secondary active transport
Active transport that uses the energy of an electrochemical gradient to drive the movement of molecules.
104
Sensory receptor cell
A sensory neuron with specialized membranes in which receptor proteins are embedded.
105
Sigma factor
A protein that associates with RNA polymerase that facilitates its binding to specific promoters.
106
Signal sequence
An amino acid sequence that directs a protein to its proper cellular compartment.
107
Smooth endoplasmic reticulum
The portion of the endoplasmic reticulum that lacks ribosomes.
108
Solute
A dissolved molecule such as the electrolytes, amino acids, and sugars often found in a solvent such as water.
109
Stroma
The region of the chloroplast where the Calvin cycle takes place.
110
Substrate
A molecule acted upon by an enzyme.
111
Supercoil
When a circular molecule of DNA coils upon itself.
112
T cell receptor
A protein receptor on a T cell that recognizes and binds to an antigen.
113
Telomerase
An enzyme containing an RNA template from which complementary telomere repeats are synthesized.
114
Telomere
A repeating sequence at the end of a eukaryotic chromosome.
115
Template strand
In DNA replication, the parental strand whose sequence is used to synthesize the complementary daughter strand.
116
Termination
In protein translation, the time at which the addition of amino acids stops and the completed polypeptide chain is released from the ribosome.
In cell communication, the stopping of a signal.
117
Terminator
A DNA sequence at which transcription stops and the transcript is released.
118
Thymine
A pyrimidine base.
119
Transcription
The synthesis of RNA from a DNA template.
120
Transfer RNA
tRNA - noncoding RNA that carries individual amino acids for use in translation.
121
Translation
Synthesis of a polypeptide chain corresponding to the coding sequence present in a molecule of messenger RNA.
122
Unsaturated
Describes fatty acids that contain carbon-carbon double bonds.
123
Valence electrons
The electrons farthest from the nucleus which are at the highest energy level.
124
Saturated
Describes fatty acids that do not contain double bonds.
