BIOS-251 COMPREHENSIVE EXAM 2026
QUESTIONS WITH ANSWERS GRADED A+
◉ all genetic material in a cell. Answer: genome
◉ what is the sub division of genome. Answer: - chromosome
- plasmid
◉ what is the sub division of chromosomes. Answer: genes (coding
region)
non-coding region
◉ what composes the DNA back bone. Answer: sugar
phosphate
◉ which are the 4 nucleotides in DNA. Answer: Adenine
Thymine
Cytosine
Guanine
,Uracil (only in RNA)
◉ what is the difference between bacterial and Eukaryota chromosomes.
Answer: Most bacteria have only one circular chromosome, whereas
eukaryotes tend to have multiple linear chromosomes
◉ Why is DNA semi-conservative?. Answer: When DNA divides, each
copy receives one half of the original DNA and one half new DNA.
◉ enzyme(s) that uncoiled the DNA. Answer: topoisomerase and gyrase,
and begins at a region called the origin of replication
◉ enzyme that unwinds and begins separating the DNA strands in both
directions. Answer: helicase
◉ enzyme that stabilize the single stranded DNA. Answer: single strand
binding proteins
◉ what is required for the addition of nucleotides in DNA replication?.
Answer: a free 3' hydroxyl group
◉ enzyme that adds an RNA primer to the strand being replicated.
Answer: primase
,◉ enzyme that makes sure the proper nucleotide is bound, and connects
it to the growing DNA strand. Answer: DNA polymerase
◉ DNA lagging strand. Answer: - DNA is synthesized in pieces
- multiple RNA primers are added
- assembled together by the enzymes DNA -polymerase and ligase
◉ 3 main process of DNA replication. Answer: - initiation
- elongation
- termination
◉ Central Dogma. Answer: DNA -> RNA -> Protein
The process by which DNA is used to encode proteins
◉ what some of the characteristics of transcription/RNA. Answer: -
Only specific regions are copies
- RNA strands are produced, which do not bind with the DNA (exist as
single strands)
- No proofreading
, ◉ what are the 5 steps in transcription. Answer: Step 1: RNA
polymerase binds to the promoter (a regulatory region directly upstream
of the gene) and initiates DNA unraveling
Step 2 : RNA polymerase facilitates the assembly of free ribonucleotides
into chains of RNA, using the DNA as a template
Step 3: The RNA polymerase continues along the gene adding to the
RNA chain, which does not permanently pair with the DNA, but exists
as a single strand
Step 4: RNA synthesis continues until the RNA polymerase encounters a
specific region of DNA known as a terminator
Step 5: Once the terminator is reached, the RNA polymerase stalls and a
rho termination protein facilitates the RNA polymerase and RNA strand
to disassociate from the DNA
The DNA is re-wound and the RNA is free to go on to the next step
◉ name for groups of 3 base pairs of the mRNA. Answer: codons
◉ how many codons are non-coding or stop codons?. Answer: 3 are
non-coding or stop codons
only 61 of the 64 encode amino acids
QUESTIONS WITH ANSWERS GRADED A+
◉ all genetic material in a cell. Answer: genome
◉ what is the sub division of genome. Answer: - chromosome
- plasmid
◉ what is the sub division of chromosomes. Answer: genes (coding
region)
non-coding region
◉ what composes the DNA back bone. Answer: sugar
phosphate
◉ which are the 4 nucleotides in DNA. Answer: Adenine
Thymine
Cytosine
Guanine
,Uracil (only in RNA)
◉ what is the difference between bacterial and Eukaryota chromosomes.
Answer: Most bacteria have only one circular chromosome, whereas
eukaryotes tend to have multiple linear chromosomes
◉ Why is DNA semi-conservative?. Answer: When DNA divides, each
copy receives one half of the original DNA and one half new DNA.
◉ enzyme(s) that uncoiled the DNA. Answer: topoisomerase and gyrase,
and begins at a region called the origin of replication
◉ enzyme that unwinds and begins separating the DNA strands in both
directions. Answer: helicase
◉ enzyme that stabilize the single stranded DNA. Answer: single strand
binding proteins
◉ what is required for the addition of nucleotides in DNA replication?.
Answer: a free 3' hydroxyl group
◉ enzyme that adds an RNA primer to the strand being replicated.
Answer: primase
,◉ enzyme that makes sure the proper nucleotide is bound, and connects
it to the growing DNA strand. Answer: DNA polymerase
◉ DNA lagging strand. Answer: - DNA is synthesized in pieces
- multiple RNA primers are added
- assembled together by the enzymes DNA -polymerase and ligase
◉ 3 main process of DNA replication. Answer: - initiation
- elongation
- termination
◉ Central Dogma. Answer: DNA -> RNA -> Protein
The process by which DNA is used to encode proteins
◉ what some of the characteristics of transcription/RNA. Answer: -
Only specific regions are copies
- RNA strands are produced, which do not bind with the DNA (exist as
single strands)
- No proofreading
, ◉ what are the 5 steps in transcription. Answer: Step 1: RNA
polymerase binds to the promoter (a regulatory region directly upstream
of the gene) and initiates DNA unraveling
Step 2 : RNA polymerase facilitates the assembly of free ribonucleotides
into chains of RNA, using the DNA as a template
Step 3: The RNA polymerase continues along the gene adding to the
RNA chain, which does not permanently pair with the DNA, but exists
as a single strand
Step 4: RNA synthesis continues until the RNA polymerase encounters a
specific region of DNA known as a terminator
Step 5: Once the terminator is reached, the RNA polymerase stalls and a
rho termination protein facilitates the RNA polymerase and RNA strand
to disassociate from the DNA
The DNA is re-wound and the RNA is free to go on to the next step
◉ name for groups of 3 base pairs of the mRNA. Answer: codons
◉ how many codons are non-coding or stop codons?. Answer: 3 are
non-coding or stop codons
only 61 of the 64 encode amino acids
