ExamBlock4 Flashcards
1
Q
Nucleic acids
A
Class of biomolecules found in all living organisms, stores genetic information and protein synthesis
2
Q
Nucleic acids are made up of
A
monomers called nucleotides
3
Q
Nucleotides are made up of
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5 carbon sugar, Phosphate group, and a nitrogenous bases
4
Q
Nitrogenous bases
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A,C,T,G
5
Q
Nucleotides are linked together by
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dehydration synthesis, or polymerization reactions between the sugar of one nucleotide and the phosphate group of another nucleotide (Sugar-phosphate backbone formed)
6
Q
What bonds are between C/G and A/T?
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Hydrogen bonds
7
Q
RNA
A
Single stranded, does not typically form helix, has uracil instead of thymine
8
Q
DNA function
A
Stores information needed to construct a protein
9
Q
RNA function
A
Regulates expression of information during protein synthesis
10
Q
ATP composed of
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Nitrogenous base adenine, 3 phosphate groups, and sugar ribose (just like RNA)
11
Q
Each time a cell divides, it must
A
replicate its DNA
12
Q
Semiconservative replication
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Each newly formed molecule of DNA has one strand conserved from the parent molecule and one newly synthesize strand
13
Q
Replication begins at
A
numerous origins of replication
14
Q
Enzymes invovled in the process of DNA Replication
A
Helicases, primases, DNA Polymerase
15
Q
Helicase
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Unwinds the DNA double helix
16
Q
Primate
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Initiate replication (Places RNA primer along each strand
17
Q
DNA Polymerase
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Adds nucleotides to the unwound parent molecule
18
Q
DNA strands have ______ polarities while replication
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opposite
19
Q
DNA has
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2 antiparallel strands
20
Q
Leading strand of DNA
A
Nucleotides added in a smooth continuous process
21
Q
Lagging strand of DNA
A
Discontinuous mode of replication because DNA polymerase can only work by starting from the replication form and progressing outward (DNA Polymerase can only be added to an existing 3’ nucleotide)
22
Q
Primase has the ability to synthesize a short
A
primer made of a few nucleotides of RNA
23
Q
Okazaki fragments
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Short stretches of DNA in the lagging strand
24
Q
Ligase
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Seals the Okazaki fragments into a continuous strand of DNA
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Mismatch repair
Occurs when DNA polymerase and other proofreading enzymes remove incorrectly paired nucleotides
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Mutation
Permanent change in an organism's DNA
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If a mutation occurs in a reproductive cell, the mutation
can be passed to future generations
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Excision repair
Involves the removal of damaged nucleotides from a DNA molecule
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Polymerase Chain Reaction (PCR)
Laboratory technique to amplify the DNA
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Proteins are made up of long chains
of amino acids
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Primary protein structure
Order of amino acids in a polypeptide chain
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Secondary protein structure
Pleated sheet or helix that approaching chains can form due to bonding between the r groups of amino acids
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Tertiary structure
Overall shape of a protein formed when the secondary structure folds in on itself
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Quaternary structure
Interactions between multiple proteins (large protein complex)
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Central dogma of molecular biology
DNA is transcribed into messenger RNA, and messenger RNA is translated into proteins. In other words, DNA codes for the synthesis of proteins
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Transcription
Occurs in the nucleus of eukaryotic cells
Two strands of DNA separate, or open up sufficiently enough so that RNA can be produced
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RNA Polymerase
Separates the DNA strands in transcription and joins the RNA nucleotides along the exposed DNA template strand
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Promoter
Starting point of transcription: sequence of DNA bases that signals the beginning of RNA synthesis
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RNA Polymerase II
Adds nucleotides to the 3' end of the elongating RNA molecule
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Terminator sequence
Signals the end of RNA synthesis
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ribosomal RNA
combines with proteins to form ribosomes
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transfer RNA molecules
transport amino acids to the growing polypeptide chain. Each tRNA molecule has an amino acid attachment site for a particular amino acid and an anticodon
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Transcription and translation takes place in three stages
initiation, elongation, and termination
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Initiation of translation
mRNA binds to the small subunit of a ribosome
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Three attachment site of a ribosome
E site is the exit site, P site is the peptidyl-tRNA binding site, A site is the t-rna binding site (asomethign)
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Elongation of translation
polypeptide grows by addition of amino acids according to the sequence of bases in the mRNA molecule.
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Termination of translation
Elongation continues until a mRNA stop codon reaches the A-site of the ribosome
48
Proteins that are intended to leave the cell contain
signal sequences that facilitate their sorting within the cell
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Newly synthesized proteins produced in the rough ER have
a unique signal sequence that directs them to this organelle
50
Gene regulation
When genetically identical cells differentiate into different cell and tissue types
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Point mutation
A change in a single nucleotide (sickle-cell anemia)
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Frameshift mutations
throw off the reading frame of the genetic message, often result in a completely nonfunctional protein, significantly more damaging than point mutations
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Missense mutation
Results in an amino acid substitution
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Silent mutation
Has no effect on the protein sequence
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Insertion or deletion mutation
Results in a shift in the reading frame
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Nonsense mutation
Substitutes a stop codon for an amino acid
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Adenosine triphosphate (ATP) is the molecule that supplies most
energy for cellular work and is the end product of cellular respiration
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Cellular respiration
which is a metabolic pathway comprised of a series of steps that convert the chemical energy in glucose into the energy contained in ATP.
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Metabolism
all of the chemical reactions that occur in an organism
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Photoautotrophs
Plants convert energy from sunlight into chemical energyC
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Chemoheterotrophs
Eat starch and break it down via a series of catabolic reactions to obtain the stored chemical energy
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Energy
that which can or does move matter. the capacity for doing work
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Kinetic energy
refers to energy that is associated with moving matter
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Potential energy
refers to energy that is stored
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free energy
energy available (or required) to do work in a system
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change in free energy (ΔG) is endergonic if
energy enters the system,
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change in free energy (-ΔG) is exergonic (energy-releasing) if
it leaves the system
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ATP
5-carbon sugar (ribose) attached to a nitrogenous base (adenine; recall our discussion of the nucleotides DNA and RNA) and a group of three phosphates.
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use of an exergonic (energy-releasing) process to drive an endergonic (energy-requiring) process is called
energy coupling
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reduction
gain of electrons
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oxidation
loss of electrons
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Affinity for electrons
electronegativity
73
The more electronegative a molecule is, the more likely it will become
reduced by the addition of electrons in a chemical reaction
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Equation for cellular respiration
C6 H12 O6 + 6 O2 --> 6 CO2 + 6 H2 O + energy
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NAD+ is free to pick up electrons, whereas NADH
has two more electrons and an additional proton.
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A molecule of NAD+ or NADH consists of
two nucleotides (adenine, found in RNA and DNA, and nicotinamide) joined together
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NAD+ functions as an
oxidizing agent (electron acceptor) during cellular respiration, picking up electrons from the catabolic products of glucose (along with hydrogen atoms).
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Stages of cellular respiration
Glycolysis
The Krebs, or Citric Acid cycle
Electron Transport and Oxidative Phosphorylation
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Where does glycolysis occur
cytosol
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Stages 2 and 3 of cellular respiration occur in
mitochondria
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Glycolysis
involves the initial breakdown of glucose to pyruvate (or pyruvic acid), water, and reduced electron carriers (in this case NADH).
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Glycolysis is initiated by the
addition of a phosphate (P), from ATP, to a molecule of glucose; this destabilizes the glucose molecule, and the bonds are then easily broken to release energy.
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substrate-level phosphorylation
can only occur in the presence of a specific kinase enzyme
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It takes two molecules of ATP to break down
one molecule of glucose to pyruvate.
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One of the products of the initial breakdown of glucose is
pyruvate
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Glycolysis generates ATP without using
oxygen as an electron acceptor
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process by which glucose is partially broken down and NAD+ is regenerated is
fermentation
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Alcohol fermentation
pyruvate gives off carbon dioxide and is converted to ethyl alcohol (ethanol) in a two-step process
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lactic acid fermentation
pyruvate is converted to lactate (lactic acid). This figure shows both types of fermentation.
90
In eukaryotes, pyruvate is transported across the
mitochondrial membrane and then converted to acetyl CoA (with the production of NADH and carbon dioxide).
91
Krebs Cycle
electrons are removed from acetyl CoA and these electrons reduce more NAD+, along with another electron carrier, FAD .
92
In the next phase of cellular respiration, the high-energy electrons within NADH and FADH2 will be passed to a
a set of membrane-bound enzymes in the mitochondrion, collectively referred to as the Electron Transport Chain (ETC
93
The movement of protons across the inner mitochondrial membrane (by the electron transport chain) creates a
charge differential (voltage) that will be used to synthesize ATP.
94
When oxygen acts as the terminal electron acceptor
there is a maximal amount of free energy released; hence, more protons can be transported, which means that a greater charge buildup occurs across the inner mitochondria membrane
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As electrons move from one member of the electron transport chain to the next, protons are transported from one side of the membrane to the other, resulting in a
buildup of protons in the intermembrane space
96
mitochondrial matrix
he part of the mitochondrion enclosed within the inner membrane, which houses the enzymes and substrates for the Krebs cycle
97
chemiosmosis
ADP is phosphorylated to make ATP
98
ATP Synthase
Chemiosmosis is accomplished in the presence of the protein complex
99
oxidative phosphorylation
The generation of ATP from chemiosmosis at the end of the Electron Transport Chain is referred to as
100
