LIFESCI 7A Exam Questions with Correct Answers Latest Update 2025-2026
Anabolism - Answers Metabolic pathways that construct molecules, requiring energy.
Catabolism - Answers Metabolic pathways that break down molecules, releasing energy.
1st law of thermodynamics - Answers Energy cannot be created or destroyed
2nd law of thermodynamics - Answers Every energy transfer or transformation increases the
entropy of the universe.
Entropy - Answers A measure of disorder or randomness.
Change in G - Answers G products - G reactants
Exergonic - Answers negative delta G, spontaneous, release energy
Endergonic - Answers Positive delta G, requires energy, not spontaneous
C-G - Answers 3 hydrogen bonds
A-T - Answers 2 Hydrogen Bonds
A and G - Answers Purines
C,T and U - Answers pyrimidines
Spliceosome - Answers complex of enzymes that serves to splice out the introns of a pre-mRNA
transcript
poly-A tail - Answers Modified end of the 3' end of an mRNA molecule consisting of the addition
of some 50 to 250 adenine nucleotides. Provides stability
Enhancer - Answers A DNA segment containing multiple control elements that can recognize
certain transcription factors that stimulate the transcription of nearby genes.
Promoter - Answers specific region of a gene where RNA polymerase can bind and begin
transcription
Terminator - Answers A special sequence of nucleotides in DNA that marks the end of a gene. It
signals RNA polymerase to release the newly made RNA molecule, which then departs from the
gene
Alternative splicing - Answers Splicing of introns in a pre-mRNA that occurs in different ways,
leading to different mRNAs that code for different proteins or protein isoforms. Increases the
diversity of proteins.
operator - Answers Region of DNA that controls RNA polymerase's access to a set of genes
, with related functions.
CAP site - Answers regulatory sequence recognized by an activator protein
Lactose in Lac operon - Answers - No lactose: repressor prevents transcription
- Lactose present: some converted to inducer allolactose
Binds to repressor
Repressor releases
operator
RNA polymerase
transcribes operon
- Only occurs when
glucose unavailable
Repressor - Answers A protein that suppresses the transcription of a gene.
Lac Y, Lac Z and Lac A - Answers STRUCTURAL genes found on coding region of lac operon
glucose and lac operon - Answers Prevents lactose operon activation.
inhibits cAMP and CAP
silent mutation - Answers A mutation that changes a single nucleotide, but does not change the
amino acid created.
missense mutation - Answers A base-pair substitution that results in a codon that codes for a
different amino acid.
nonsense mutation - Answers A mutation that changes an amino acid codon to one of the three
stop codons, resulting in a shorter and usually nonfunctional protein.
frameshift mutation - Answers mutation that shifts the "reading" frame of the genetic message
by inserting or deleting a nucleotide
SRP receptor - Answers embedded in the ER membrane, recognizes the SRP
SRP - Answers signal recognition particle
Smooth ER - Answers Makes lipids
Rough ER - Answers Packages proteins in vesicles
Anabolism - Answers Metabolic pathways that construct molecules, requiring energy.
Catabolism - Answers Metabolic pathways that break down molecules, releasing energy.
1st law of thermodynamics - Answers Energy cannot be created or destroyed
2nd law of thermodynamics - Answers Every energy transfer or transformation increases the
entropy of the universe.
Entropy - Answers A measure of disorder or randomness.
Change in G - Answers G products - G reactants
Exergonic - Answers negative delta G, spontaneous, release energy
Endergonic - Answers Positive delta G, requires energy, not spontaneous
C-G - Answers 3 hydrogen bonds
A-T - Answers 2 Hydrogen Bonds
A and G - Answers Purines
C,T and U - Answers pyrimidines
Spliceosome - Answers complex of enzymes that serves to splice out the introns of a pre-mRNA
transcript
poly-A tail - Answers Modified end of the 3' end of an mRNA molecule consisting of the addition
of some 50 to 250 adenine nucleotides. Provides stability
Enhancer - Answers A DNA segment containing multiple control elements that can recognize
certain transcription factors that stimulate the transcription of nearby genes.
Promoter - Answers specific region of a gene where RNA polymerase can bind and begin
transcription
Terminator - Answers A special sequence of nucleotides in DNA that marks the end of a gene. It
signals RNA polymerase to release the newly made RNA molecule, which then departs from the
gene
Alternative splicing - Answers Splicing of introns in a pre-mRNA that occurs in different ways,
leading to different mRNAs that code for different proteins or protein isoforms. Increases the
diversity of proteins.
operator - Answers Region of DNA that controls RNA polymerase's access to a set of genes
, with related functions.
CAP site - Answers regulatory sequence recognized by an activator protein
Lactose in Lac operon - Answers - No lactose: repressor prevents transcription
- Lactose present: some converted to inducer allolactose
Binds to repressor
Repressor releases
operator
RNA polymerase
transcribes operon
- Only occurs when
glucose unavailable
Repressor - Answers A protein that suppresses the transcription of a gene.
Lac Y, Lac Z and Lac A - Answers STRUCTURAL genes found on coding region of lac operon
glucose and lac operon - Answers Prevents lactose operon activation.
inhibits cAMP and CAP
silent mutation - Answers A mutation that changes a single nucleotide, but does not change the
amino acid created.
missense mutation - Answers A base-pair substitution that results in a codon that codes for a
different amino acid.
nonsense mutation - Answers A mutation that changes an amino acid codon to one of the three
stop codons, resulting in a shorter and usually nonfunctional protein.
frameshift mutation - Answers mutation that shifts the "reading" frame of the genetic message
by inserting or deleting a nucleotide
SRP receptor - Answers embedded in the ER membrane, recognizes the SRP
SRP - Answers signal recognition particle
Smooth ER - Answers Makes lipids
Rough ER - Answers Packages proteins in vesicles
