Biology 160 - Chapter 11 Study questions

How does a ribosome know where to start translating mRNA?

A ribosome knows where to start translating mRNA by recognizing a specific sequence called the start codon. (AUG - Methionine)

How does a ribosome know where to stop translating mRNA?

A ribosome knows where to stop translating mRNA by recognizing specific stop codons, also known as termination codons or nonsense codons. Stop codons (UAA, UAG, and UGA)

What does a signal sequence do?

A signal sequence is a short amino acid sequence found at the beginning of certain proteins, typically those destined to be targeted to specific cellular compartments or for secretion outside the cell.

What is a transcription bubble?

A transcription bubble is a region of unwound DNA during transcription where the RNA polymerase enzyme synthesizes an RNA molecule using one of the DNA strands as a template.

Be able to translate an mRNA sequence. Remember to look for the start codon.

AUG- START UAA, UAG, UGA - STOP

Once translation has occurred, what happens to the mRNA?

After translation, the mRNA molecule is typically degraded or recycled by cellular mechanisms.

Describe the processing that mRNA undergoes before leaving the nucleus.

Before leaving the nucleus, mRNA undergoes processing that includes the removal of introns (non-coding regions) and the addition of a protective cap at one end and a poly-A tail at the other end.

In which direction does translation occur (both in terms of the mRNA strand, and the protein it builds)?

Both the mRNA strand and the growing protein are synthesized in a directionality that proceeds from one end to the other, allowing for the sequential assembly of amino acids into a functional protein.

What do chaperone proteins do?

Chaperone proteins, also known as molecular chaperones, are responsible for aiding in the proper folding, assembly, and stabilization of other proteins.

Describe the differences between DNA replication, transcription, and translation, including where they occur and results of the processes

DNA replication - occurs in the nucleus and results in the creation of an identical copy of the DNA molecule. Transcription - takes place in the nucleus and produces an RNA molecule from a DNA template Translation - occurs in the cytoplasm and synthesizes a protein using the information encoded in the mRNA molecule.

Mutations can involve large sections of chromosomes, too. How do each of the following change the chromosome? deletions, duplication, inversion, and translocation

Deletion: A section of the chromosome is lost, resulting in the loss of specific genes or genetic material. Duplication: A section of the chromosome is duplicated, leading to the presence of extra copies of certain genes or genetic material. Inversion: A segment of the chromosome is reversed in orientation, which can disrupt gene function if it affects coding regions or regulatory elements. Translocation: A segment of one chromosome breaks off and attaches to a different chromosome, leading to the rearrangement of genetic material between non-homologous chromosomes.

Make sure you can give the transcribed sequence of mRNA if given the template or non-template DNA strands.

Dna: 3' ACC AAA CCG 5' Template 5' TGG TTT GGC 3' Non-Template mRNA: 5' UGG UUU CCG 3'

Describe the process of translation. Be detailed. Include large and small ribosomes, tRNA , peptidyl transfer, mRNA, amino acids, release factor, and A, E, and P sites and more.

During translation, the mRNA sequence is used as a template to synthesize a protein. It involves the binding of tRNA molecules carrying specific amino acids to the ribosome, the formation of peptide bonds between amino acids, and the movement of the ribosome along the mRNA to read the codons and assemble the protein. The process consists of initiation, elongation, and termination stages.

How is transcription and translation different in prokaryotes and eukaryotes?

In prokaryotes, transcription and translation occur simultaneously in the cytoplasm, whereas in eukaryotes, transcription occurs in the nucleus, and the mRNA is processed and transported to the cytoplasm for translation.

What are the main types of RNA, and what are each of their functions?

Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes for protein synthesis. Transfer RNA (tRNA): Carries amino acids to ribosomes during translation. Ribosomal RNA (rRNA): Forms a structural and functional component of ribosomes.

Describe the four types of DNA point mutations, and the effects they would have on a protein.

Missense mutation: A single nucleotide change results in the substitution of one amino acid in the protein sequence, which may alter its structure and function. Nonsense mutation: A single nucleotide change introduces a premature stop codon, leading to the production of a truncated and likely non-functional protein. Silent mutation: A single nucleotide change does not result in an amino acid change, so the protein sequence remains unaffected. Frameshift mutation: Insertion or deletion of a nucleotide shifts the reading frame, causing a disruption in the protein's entire amino acid sequence, often leading to a non-functional protein.

Does all the RNA on the primary transcript code for protein? If not, explain what remaining RNA is called.

No, not all the RNA on the primary transcript codes for protein. The remaining RNA, which does not encode proteins, is called non-coding RNA (ncRNA).

How does RNA polymerase know where to transcribe?

RNA polymerase knows where to transcribe DNA because it recognizes specific DNA sequences called promoters, which are located near the beginning of genes.

The Moderna and Pfiser vaccines for Covid-19 contain which of the following nucleic acids: DNA, mRNA, rRNA, tRNA, or other?

The Moderna and Pfizer vaccines for COVID-19 contain mRNA (messenger RNA).

What enzyme transcribes DNA?

The enzyme that transcribes DNA into RNA is called RNA polymerase.

What is the central dogma of biology?

a theory stating that genetic information flows only in one direction, from DNA, to RNA, to protein, or RNA directly to protein (Transcription, RNA processing, Translation)

Why is transcription necessary?

the process by which genetic information encoded in DNA is transcribed into RNA molecules. These RNA molecules, particularly messenger RNA (mRNA), serve as templates for protein synthesis during translation.