Principles of Biology Exam Quizzes Latest 2026
With Answers
DNA
genetic material of life; able to store info that pertains to development, structure, and activities of
the cell
structure of DNA
chain of nucleotides, each with three subunits (phosphate, deoxyribose, and nitrogen base);
polynucleotide backbone made of alternating phosphate and sugar molecules; two strands that
form a double helix by hydrogen bonds
purines
adenine and guanine; always bonds to pyrimidine
pyrimidines
thymine and cytosine; always bonds to purine
DNA replication - What? When? How?
process of copying one DNA double helix into two identical; during the s phase of interphase
during mitosis; semiconservative because new helix strand conserved one old and one new
steps of DNA replication
1. helicase unwinds and unzips the double stranded DNA by breaking hydrogen bonds 2.
polymerase positions and joins complementary DNA nucleotides to first strand 3. lagging
strand's okazaki fragments are connected and sealed by ligase
,outcome of DNA replication
two new double helix molecules are identical to each other and the original DNA molecule
Leading vs. lagging strand
DNA synthesis is in opposite directions; leading strand follows helicase enzyme and is faster;
lagging strand has fragments
gene expression
process of using the information within a gene to synthesize a protein
RNA molecules used in gene expression
messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA)
two processes of gene expression
transcription and translation
transcription - Where? What? Which RNA are involved?
In eukaryotes' nucleus; DNA is template for mRNA formation; messenger RNA
messenger RNA in transcription
carries genetic info from DNA to the ribosomes for protein synthesis
how is mRNA formed
in transcription; enzyme RNA polymerase binds to the region of DNA with nucleotides, enzyme
opens up DNA helix so complementary base pairing can occur, then RNA polymerase inserts
RNA nucleotides
, translation - Where? What? Which RNA are involved?
In eukaryotes' cytoplasm (at the ribosome); mRNA determines sequence of amino acids in
polypeptide; transfer RNA messenger RNA and ribosomal RNA
stop codons
UAA, UAG, and UGA
transfer RNA in translation
bring amino acids to ribosomes
ribosomal RNA in translation
several rRNAs make up ribosomes; rRNA is produced in the nucleolus, joins proteins from
cytoplasm to form ribosomal subunits, then leave nucleus, join together to form ribosome
three steps of translation
initiation, elongation, and termination
initiation
small ribosomal subunit attaches to mRNA, large and small subunits join
elongation
polypeptide increases in length of amino acids in four steps 1. a tRNA with an amino acid binds
to the A site of the ribosome 2. anticodons pair to the codons 3. original tRNA with peptide chain
passes it to the tRNA with the new amino acid 4. "empty" tRNA that donated peptide chain exits
and other tRNA moves forward so next amino acid can arrive
With Answers
DNA
genetic material of life; able to store info that pertains to development, structure, and activities of
the cell
structure of DNA
chain of nucleotides, each with three subunits (phosphate, deoxyribose, and nitrogen base);
polynucleotide backbone made of alternating phosphate and sugar molecules; two strands that
form a double helix by hydrogen bonds
purines
adenine and guanine; always bonds to pyrimidine
pyrimidines
thymine and cytosine; always bonds to purine
DNA replication - What? When? How?
process of copying one DNA double helix into two identical; during the s phase of interphase
during mitosis; semiconservative because new helix strand conserved one old and one new
steps of DNA replication
1. helicase unwinds and unzips the double stranded DNA by breaking hydrogen bonds 2.
polymerase positions and joins complementary DNA nucleotides to first strand 3. lagging
strand's okazaki fragments are connected and sealed by ligase
,outcome of DNA replication
two new double helix molecules are identical to each other and the original DNA molecule
Leading vs. lagging strand
DNA synthesis is in opposite directions; leading strand follows helicase enzyme and is faster;
lagging strand has fragments
gene expression
process of using the information within a gene to synthesize a protein
RNA molecules used in gene expression
messenger RNA (mRNA), transfer RNA (tRNA), ribosomal RNA (rRNA)
two processes of gene expression
transcription and translation
transcription - Where? What? Which RNA are involved?
In eukaryotes' nucleus; DNA is template for mRNA formation; messenger RNA
messenger RNA in transcription
carries genetic info from DNA to the ribosomes for protein synthesis
how is mRNA formed
in transcription; enzyme RNA polymerase binds to the region of DNA with nucleotides, enzyme
opens up DNA helix so complementary base pairing can occur, then RNA polymerase inserts
RNA nucleotides
, translation - Where? What? Which RNA are involved?
In eukaryotes' cytoplasm (at the ribosome); mRNA determines sequence of amino acids in
polypeptide; transfer RNA messenger RNA and ribosomal RNA
stop codons
UAA, UAG, and UGA
transfer RNA in translation
bring amino acids to ribosomes
ribosomal RNA in translation
several rRNAs make up ribosomes; rRNA is produced in the nucleolus, joins proteins from
cytoplasm to form ribosomal subunits, then leave nucleus, join together to form ribosome
three steps of translation
initiation, elongation, and termination
initiation
small ribosomal subunit attaches to mRNA, large and small subunits join
elongation
polypeptide increases in length of amino acids in four steps 1. a tRNA with an amino acid binds
to the A site of the ribosome 2. anticodons pair to the codons 3. original tRNA with peptide chain
passes it to the tRNA with the new amino acid 4. "empty" tRNA that donated peptide chain exits
and other tRNA moves forward so next amino acid can arrive
