99 Questions
DNA wraps around histone proteins — positively charged called what?
lysine, arginine
Single-stranded Binding (SSB) Proteins bind to what is created by helicase?
Binds ssDNA
Describe the composition and structure of a DNA molecule
wrapped lysine, arginine chromatin
what are Heterochromatin?
is tightly packed and inactive
DNA backbones run in opposite directions called?
antiparallel
What is the complementary sequence of the DNA strand 5'-ATCGGTA-3'?
3'-TACCGAT-5'
what is the initiation step in DNA replication?
when the DNA molecule is unzipped, it allows the creation of two new DNA strands based on the information in the original DNA.
what nucleotide sequence does the initiation step occur?
origins of replication (Ori) -A-Tbasepairs
what is the elongation step in DNA replication?
where the actual copying of the DNA strands occurs.
what is the termination step in DNA replication?
the final step of DNA replication
Topoisomerase
Remove supercoils in DNA double helix by cleaving one or both DNA strands
Topoisomerase I
Cuts one strand, rotates it around the intact strand, and reseals the nick
Topoisomerase II
Binds tightly to DNA to make a transient break in both strands
The site of replication is called the
replication fork
DNA pol III synthesizes DNA only
5′ →3′ direction
Leading strand synthesizes in
5′ → 3′ direction
Lagging strand synthesized discontinuously (Okazaki fragments)
5′ → 3′ direction.
DNA Polymerase requires a
primer
What is the primary function of the enzyme Helicase in DNA replication
Unwinding and unzipping the double-stranded DNA.
Which role does DNA Polymerase primarily perform during DNA replication?
C) Building a new DNA strand by adding nucleotides.
What is the primary function of Primase in DNA replication?
Creating short RNA primers on the DNA.
Which task is most closely associated with Ligase in DNA replication?
Sealing the gaps in the sugar-phosphate backbone.
What is the primary role of Single-Strand Binding Proteins in DNA replication?
Holding the unzipped DNA strands apart.
What is the primary function of Topoisomerase in DNA replication?
Unwinding and relieving tension in the DNA ahead of the replication fork.
What is the primary characteristic of leading strand synthesis in DNA replication?
D) It is synthesized continuously in the same direction as the replication fork.
What sets lagging strand synthesis apart from leading strand synthesis in DNA replication? A) It involves the creation of Okazaki fragments. B) It is synthesized continuously in the 3' to 5' direction. C) It requires only one RNA primer. D) It proceeds in the same direction as the replication fork.
A) It involves the creation of Okazaki fragments.
What is the role of primase in leading strand synthesis?
B) It creates RNA primers on the leading strand.
How is the lagging strand primed for DNA synthesis in DNA replication? A) It doesn't require priming. B) Primase creates a single RNA primer for the entire lagging strand. C) Primase creates multiple RNA primers along the lagging strand. D) DNA polymerase III initiates replication without primers.
C) Primase creates multiple RNA primers along the lagging strand.
What is the key characteristic of DNA synthesis on the leading strand in terms of continuity?
D) It is synthesized continuously.
How are the gaps between Okazaki fragments on the lagging strand sealed in DNA replication? A) DNA helicase seals the gaps. B) DNA polymerase III seals the gaps. C) DNA ligase seals the gaps. D) DNA primase seals the gaps.
C) DNA ligase seals the gaps.
What is the primary function of telomeres in human cells?
B) Protecting the ends of chromosomes from degradation.
Why do telomeres naturally shorten with each cell division? A) To increase the risk of cancer. B) To promote cell division. C) To prevent DNA loss from the ends of chromosomes. D) To enhance DNA replication efficiency.
C) To prevent DNA loss from the ends of chromosomes.
hat is the primary function of telomerase in cells? A) Repairing DNA damage. B) Promoting uncontrolled cell division. C) Adding repetitive DNA sequences to telomeres. D) Preventing cellular aging.
C) Adding repetitive DNA sequences to telomeres.
How does telomere shortening contribute to cellular aging? A) It enhances cell division. B) It prevents DNA damage. C) It limits the number of cell divisions a cell can undergo. D) It activates telomerase.
C) It limits the number of cell divisions a cell can undergo.
In what context is telomerase often overexpressed or reactivated in cells?
D) In some cancer cells.
Which of the following DNA repair processes primarily deals with bulky lesions caused by external factors like UV radiation?
B) Nucleotide Excision Repair (NER)
How do Base Excision Repair (BER) and Direct Reversal Repair differ?
B) BER replaces individual damaged bases, while Direct Reversal Repair directly reverses. specific types of damage.
How do Double-Strand Break Repair (DSBR) and Translesion Synthesis (TLS) differ in their mechanisms?
C) DSBR can occur through Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR), while TLS introduces mutations during replication.
What is a common feature among all DNA repair processes?
B) They recognize distortions or lesions in the DNA structure.
Which DNA repair process has the highest potential for introducing mutations during DNA replication?
D) Translesion Synthesis (TLS)
What characterizes spontaneous mutations in DNA? A) They result from exposure to mutagenic chemicals. B) They occur naturally without external influence. C) They are caused by radiation. D) They are always harmful to the organism.
B) They occur naturally without external influence.
Which of the following is an example of an external factor that can induce DNA mutations?
B) Exposure to ultraviolet (UV) radiation.
What is a point mutation?
C) A mutation involving changes in a single DNA base pair.
What happens in a frameshift mutation? A) The mutation involves the substitution of one amino acid for another. B) The mutation introduces a premature stop codon. C) The reading frame of the genetic code is shifted due to insertion or deletion of base pairs. D) The DNA is reversed.
C) The reading frame of the genetic code is shifted due to insertion or deletion of base pairs.
How do missense mutations differ from nonsense mutations?
C) Missense mutations change a single DNA base, affecting one amino acid.
Which type of mutation involves the expansion of repeated DNA sequences within a gene? A) Silent mutations. B) Expanding repeat mutations. C) Frameshift mutations. D) Nonsense mutations.
B) Expanding repeat mutations.
Which molecule is responsible for recognizing and binding to DNA mismatches in the Mismatch Repair (MMR) process?
A) MutS
What is the role of XPF and XPG in Nucleotide Excision Repair (NER)?
A) Recognizing bulky DNA lesions
Which enzyme in Base Excision Repair (BER) cleaves the phosphodiester backbone at the site of the missing base?
B) AP Endonuclease (APE1)
What protein forms a filament on the damaged DNA strand and facilitates strand invasion during Homologous Recombination (HR)?
A) RAD51
Which enzyme directly removes alkyl groups, such as O6-methylguanine, from DNA in the Direct Reversal Repair process?
C) O6-Methylguanine-DNA Methyltransferase (MGMT)
What is the primary role of specialized DNA polymerases (e.g., Pol η, Pol κ, Pol ζ) in Translesion Synthesis (TLS)?
C) Bypassing damaged DNA sites during replication
What is the primary role of specialized DNA polymerases (e.g., Pol η, Pol κ, Pol ζ) in Translesion Synthesis (TLS)? A) Recognizing bulky DNA lesions B) Repairing double-strand breaks C) Bypassing damaged DNA sites during replication D) Sealing gaps in the DNA strand
C) Bypassing damaged DNA sites during replication
Which DNA repair process is specifically designed to correct point mutations like base-pair mismatches during DNA replication? A) Nucleotide Excision Repair (NER) B) Base Excision Repair (BER) C) Mismatch Repair (MMR) D) Homologous Recombination (HR)
C) Mismatch Repair (MMR)
Which DNA repair process is specialized in repairing bulky DNA lesions caused by factors like UV radiation and chemical compounds?
D) Nucleotide Excision Repair (NER)
What is the primary DNA repair process responsible for removing and replacing individual damaged or modified DNA bases?
C) Base Excision Repair (BER)
Which DNA repair mechanisms address breaks that affect both DNA strands, with options for fast but error-prone repair and accurate repair using homologous sequences? A) Mismatch Repair (MMR) B) Base Excision Repair (BER) C) Double-Strand Break Repair (DSBR) D) Direct Reversal Repair
C) Double-Strand Break Repair (DSBR)
What DNA repair process directly removes specific chemical modifications like alkyl groups from DNA? A) Mismatch Repair (MMR) B) Homologous Recombination (HR) C) Direct Reversal Repair D) Translesion Synthesis (TLS)
C) Direct Reversal Repair
Which DNA repair process allows DNA replication to proceed past damaged sites, even if it may introduce mutations? A) Nucleotide Excision Repair (NER) B) Base Excision Repair (BER) C) Translesion Synthesis (TLS) D) Homologous Recombination (HR)
C) Translesion Synthesis (TLS)
Which lobe of the cerebral cortex is responsible for auditory perception, semantics, and memory?
Temporal lobe
Which lobe of the cerebral cortex is the visual processing center?
Occipital lobe
Which division of the nervous system is responsible for responding to and moving about in our environment?
Motor Division
Which level of CNS function controls subconscious body activities such as arterial pressure, respiration, and feeding reflexes?
Lower brain level
Which level of CNS function is essential for thought processes and functions in association with lower centers?
Higher brain or cortical level
Which portion of the nervous system performs specific functions, but it is the cortex that opens the world up for one's mind?
Higher brain or cortical level
Which level of CNS function contains the medulla, pons, mesencephalon, hypothalamus, thalamus, cerebellum, and basal ganglia?
Lower brain level
Which division of the nervous system processes information and creates memory?
Integrative Division
What is the primary function of the enzyme Helicase in DNA replication?
Separating the DNA double helix into two strands
What is the primary function of telomerase in cells?
Adding repetitive DNA sequences to telomeres
What is the main function of the dendrites in stimulating neurons?
Receiving signals from presynaptic neurons
Which neurotransmitter is considered the chief excitatory transmitter in the central nervous system (CNS)?
Glutamate
Which ions are involved in creating an inhibitory post synaptic potential (IPSP)?
Chloride ions (Cl-)
What type of summation occurs when excitatory post synaptic potentials (EPSPs) created by distant synapses overlap?
Spatial summation
What is the role of glutamate in creating an excitatory post synaptic potential (EPSP)?
It opens sodium channels
Which ions permeability are involved in creating an excitatory post synaptic potential (EPSP)?
Sodium ions (Na+)
What is the main function of the axon terminal in a neuron?
Transmitting action potentials
What is the primary function of the soma in a neuron?
Receiving signals from presynaptic neurons
What is the main function of the dendrites in a neuron?
Receiving signals from presynaptic neurons
What is the main function of the axon terminal in a neuron?
Transmitting action potentials
Which ion is responsible for the build-up of calcium in presynaptic terminals during synaptic facilitation?
Calcium ions
Which neurotransmitter is responsible for the majority of synaptic connections in the central nervous system (CNS)?
Glutamate
What is the primary function of neuropeptides in synaptic transmission?
They cause long-term changes in the number of neuron receptors
What pH change can usually induce a diabetic coma?
From 7.4 to 7.0
What environmental change can increase neuronal excitability and potentially initiate a petit mal seizure?
Alkalosis
What is the primary role of telomeres in human cells?
To prevent DNA loss from the ends of chromosomes
What is the primary function of specialized DNA polymerases (e.g., Pol η, Pol κ, Pol ζ) in translesion synthesis (TLS)?
Bypassing damaged DNA sites during replication
What is the primary function of topoisomerase in DNA replication?
To unwind the DNA double helix
What is the complementary sequence of the DNA strand 5'-ATCGGTA-3'?
3'-TAGGCCT-5'
How are the gaps between Okazaki fragments on the lagging strand sealed in DNA replication?
DNA ligase seals the gaps
Which of the following is the chief excitatory transmitter in the central nervous system (CNS)?
Glutamate
What is the main function of telomeres in human cells?
To protect the ends of chromosomes from degradation
Which of the following environmental changes can lead to unconsciousness?
Hypoxia
Which type of neurotransmitter causes long-term changes in the number and sizes of synapses?
Neuropeptides, slowing acting transmitters
What is the primary role of synaptic facilitation?
To enhance responsiveness following repetitive stimulation
Which ions are involved in creating an inhibitory post synaptic potential (IPSP)?
Anions
What is the primary function of the axon terminal in a neuron?
To transmit signals to other neurons
Which DNA repair process is specifically designed to correct base-pair mismatches during DNA replication?
Mismatch Repair (MMR)
Which of the following is an example of an external factor that can induce DNA mutations?
Radiation
What is the primary characteristic of leading strand synthesis in DNA replication?
It is synthesized continuously in the 3' to 5' direction
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