Exam 3 Flashcards
In eukaryotes, where does protein synthesis take place when it comes to transcription
Protein synthesis occurs in the nucleus of the eukaryotes.
Inside the nucleus of eukaryotes, what is being processed inside
RNA processing occurs
Can a single gene code for multiple protein products in eukaryotes?
Yes, a single gene can code for multiple protein products in eukaryotes.
What is the process that allows a single gene to produce multiple protein products in eukaryotes?
alternative splicing
Define alternative splicing.
A process where a single gene can produce different proteins by rearranging its coding sections (exons) in multiple ways during RNA processing.
What is followed after transcription in eukaryotes?
followed by three key steps in RNA processing:
What are the three things being made in RNA processing?
Head
Tail
Introns get cut out (splicing)
Transcription in prokaryotes is happening where?
Cytoplasm
Is there RNA processing in prokaryotes?
No, there is not any RNA processing happening.
Where is translation happening in prokaryotes?
translation happens in the cytoplasm ON the ribosomes
Where is translation happening in eukaryotes
translation happens in the cytoplasm ON the ribosomes
What is transcription?
Transcription is the process where RNA polymerase makes an mRNA (messenger RNA) copy of a gene from DNA.
What is translation?
Translation is the process where ribosomes read the mRNA sequence to build a protein.
What is the role of a ribosome in protein synthesis?
Read the mRNA sequence and assemble amino acids into a protein.
What is the role of tRNA in the process of translation?
tRNA brings amino acids to the ribosome and pairs up with the mRNA code to help build the protein.
What is the role of a codon & what do they code for
Three nucleotide-long sections on the messenger RNA correspond to one amino acid.
What is the start of codon ( 3 letters )
AUG
What is the purpose of the codon
To tell the ribosome to start making protein.
What is the role of the stop codon
A stop codon tells the ribosome that it’s done making the protein, and there are three stop codons: UAA, UAG, and UGA.”
In which types of organisms do we find polyribosomal complexes
Both prokaryotic and eukaryotic organisms.
Define a polyribosomal complex
A polyribosomal complex (polysome) is when multiple ribosomes attach to a single mRNA to make many copies of a protein quickly
What is the enzyme complex that performs splicing?
The spliceosome removes introns and joins exons in pre-mRNA.
What is alternative splicing, and why is it important?
Alternative splicing makes different proteins from one gene, allowing the cell to do more jobs.
How does alternative splicing in (eukaryotes) affect the idea that one gene is responsible for only one protein product?
In eukaryotes, one gene can code for multiple protein products.
How do operons function as on/off switches to regulate protein synthesis in bacterial cells?
How do operons function as on/off switches to regulate protein synthesis in bacterial cells?
The operator is part of gene regulation, what is the role of the operator?
The operator acts as a binding site for repressor proteins. Induces or represses protein synthesis
Does the lac operon function as an inducible or repressible system?
The lac operon is inducible. This means it is normally “ off” but can be “turned on” when lactose is present, allowing the cell to produce enzymes for lactose metabolism only when needed.
What position is the lac operon usually in?
The off position. Lac operon turns to the “on” position when lactose is present in the cell.
Describe the role of the inducer molecule in the regulation of the lac operon. Is the inducer classified as a substrate or a product, and how does it influence gene expression within the operon?”
The inducer molecule in the lac operon is the substrate, lactose.
In an operon, what is the term for the DNA sequence that encodes the proteins, such as enzymes, that are regulated by the operon?”
Structural genes
Identify which types of operons are involved in regulating anabolic reactions and which are involved in regulating catabolic reactions.
Anabolic reactions: Repressible operons, e.g., trp operon (trp operon is a repressible operon in bacteria)
Catabolic reactions: Inducible operons, e.g., lac operon
How can you determine the sequence of an anti-codon based on the codon present in mRNA?
if the codon is AUG, the anti-codon would be UAC.
an anti-codon sequence: Complementary Base Pairing
C pairs with G
G pairs with C
What mechanisms do tRNA molecules use to ensure the correct amino acid is added to the growing polypeptide chain during translation?
through anti-codon-codon pairing
In which direction is DNA or RNA read, and what does the term ‘anti-parallel’ signify in this context?
DNA and RNA are read in the 5’ to 3’ direction. The term “anti-parallel” refers to the opposite orientation of the two strands in a double helix,
What is mRNA role
mRNA (messenger RNA) carries the genetic information from DNA to the ribosome for protein synthesis;
what is tRNA role
tRNA (transfer RNA) brings the appropriate amino acids to the ribosome during translation and contains the anti-codon;
what is the role of rRNA
rRNA (ribosomal RNA) is a structural component of ribosomes, facilitating the translation process. The anti-codon can be found on tRNA.
Bacterial transcription occurs where?
Bacterial transcription occurs in the cytoplasm with a SINGLE RNA polymerase.
What extra steps occur during transcription in eukaryotes?
Head
tail
introns are splicing
Where does Eukaryotic transcription occur?
Eukaryotic transcription occurs in the nucleus with MULTIPLE RNA polymerases
Define Exon
Is a coding segment of a gene that is RETAINED in the final mRNA after splicing and translated into protein.
Define Intron
An intron is a non-coding segment of a gene that is REMOVED from the pre-mRNA during splicing and is not translated into protein.
Define Splicesome
A spliceosome is a complex of proteins and RNA that removes introns from pre-mRNA and joins exons together during the splicing process.
What is a GENOME
A genome is all the DNA in an organism, including its genes.
What is a Chromosome
A chromosome is a long thread of DNA that contains many genes.
what is a Gene
A gene is a small segment of DNA that gives instructions for making a specific protein.
What are the three parts that make up a general structure?
The three parts are a sugar, a phosphate group, and a nitrogenous base.
The bond that binds two strands together is called?
Hydrogen bond
What are the two strands that make up a single molecule of DNA
Double Helix
What the two-step processes are part of protein synthesis?
Transcription & translation
During the second step of translation, the genetic code is translated into the language of proteins called what?
Amino Acids
What is the name of the enzyme that carries out transcription?
RNA polymerase
How do RNA strands differ from DNA strands?
RNA stand is a single strand
DNA strand has two strands
What is being converted during the translation step, and what type of chain is formed as a result?
What is being converted is amnio acids, and the chain type is a polypeptide.
Initiation during translation
The codon AUG serves as the start codon during initiation in translation, signaling the beginning of protein synthesis.
Elongation during translation
During elongation in translation, the A, P, and E sites on the ribosome are involved, and enzymes within the ribosome facilitate the formation of peptide bonds between amino acids.
termination during translation
Termination during translation occurs when a stop codon is reached, signaling the end of protein synthesis.
What is the regulator’s role
A regulator’s role involves controlling or influencing the activity of a process, system, or organism.
What is the role of the repressor protein
To stop gene expression and block the transcription of target genes
What is the role of the control locus
To regulate the expression of nearby genes, often binding regulatory proteins.
What does the promoter play in
Starting transcription by giving a binding site for RNA polymerase to start the process of gene expression.
What role of the structural locus involved in
Coding proteins, transcribing DNA sequences into mRNA, and then translating mRNA into proteins to determine the traits and functions of an organism.
what do structural genes do
Code for proteins that determine an organism’s traits and functions.
In the regulation of protein synthesis, where does the repressor protein attach, and which enzyme does it block from carrying out transcription?
The repressor protein attaches to the operator, blocking RNA polymerase from transcribing.
Does the regulator region need to be adjacent to the operator region of a DNA strand?
No
What does it mean for regulator proteins to be allosteric, and why is this characteristic important for their role in regulating protein synthesis?
Because the protein can change its shape and function when a molecule binds to it at a site other than the active site.
Under what conditions is the synthesis of enzymes responsible for breaking down lactose activated?
When the lactose is present in the environment and glucose levels are low.
In eukaryotic organisms, what factors are used to regulate protein synthesis in the absence of operons?
Transcription Factors
What regulatory roles do small interfering RNA (siRNA) and microRNA play in the process of protein synthesis?
siRNA and microRNA regulate protein synthesis by silencing specific mRNAs, preventing their translation into proteins.
describe mutation
Changes in the DNA sequence of a gene can affect how that gene functions.
For mutations to impact a population and natural selection, should they occur in somatic cells (body cells) or sex cells (gametes)?
Mutations need to occur in sex (gamete) cells to affect a population and natural selection.
Define missense
A change in the DNA sequence that results in the substitution of one amino acid for another in a protein.
The two main causes of mutations are:
Spontaneous: change in DNA during replication. Occurs naturally.
2. Induced: occurs in the presence of mutagens. Results from the environmental factors.
What type of mutation will not cause any bad or harm? and why?
Silent mutation because they do not change the amino acid sequence of the protein.
What two types of mutations are deadly and why?
Frameshift, because they shift the reading frame, altering every amino acid after the mutation.
Nonsense, because they introduce a pre-mature stop codon leading to an incomplete protein.
What is genetic recombination & why is it important?
Recombination is when DNA from one bacterium is transferred to another, creating a new combination of genes in the recipient bacterium. It’s important because it gives bacteria new traits, like antibiotic resistance, helping them survive and adapt to different environments.
What is natural selection
When organisms with helpful traits survive and have more offspring, allowing them to pass those traits off.
At what specific time does genetic recombination happen in eukaryotic organisms
During meiosis, the process that creates sex cells.
Does recombination in prokaryotes, like bacteria, involve transferring DNA from plasmids and chromosome fragments?
Yes, recombination in prokaryotes involves transferring DNA from plasmids and chromosome fragments.
