37 Questions
What is the role of H1 in DNA packaging in eukaryotes?
Stabilizing both nucleosome structure and higher-order chromatin architecture
During mitosis, what happens to the chromosomes?
They condense even further
How many H2A-H2B dimers and H3-H4 dimers form the histone octamer?
Two of each
What is the purpose of the 30-nm chromatin fiber in DNA packaging?
Facilitating gene expression
Which protein is not involved in the formation of the histone octamer?
H1
What is the function of linker DNA in DNA packaging?
Link the histone cores with H1 protein
In DNA packaging to produce a chromatid of a chromosome, what process follows tight coiling of the 250-nm wide-fiber?
Compressing and folding the 300-nm fiber
What type of nucleotide substitution occurs in mRNA compared to the coding strand?
Adenine is substituted by Uracil
Which components form the spliceosome involved in splicing pre-mRNA?
Proteins and snRNA
What is the function of the branch point nucleotide in the splicing process?
Attacks the 5’ splice site to cut the mRNA
Where is the acceptor site located in the splicing process?
At the 3’ end of an exon
What happens when ribonucleoprotein complexes (snRNPs) bind to exon-intron junctions?
Cutting at splice donor and splice acceptor sites
Which sequences are recognized by spliceosomes during splicing?
GU and AG sequences at intron ends
What is the role of spliceosomes in mRNA splicing?
Intron removal and exon joining
What is the role of Poly(A) polymerase enzyme in mRNA processing?
Adds a poly(A) tail to the 3’ end of the pre-mRNA
At what position downstream of the polyadenylation signal sequence does the endonuclease enzyme cleave the pre-mRNA strand?
~ 10-35 bp
Which enzyme is responsible for cleaving the pre-mRNA strand?
Endonuclease enzyme
What is the function of the poly(A) tail added to mRNA?
Protects mRNA from degradation
In what manner does Poly(A) polymerase add the poly(A) tail to pre-mRNA?
Template-independent
What is the size limit of the poly(A) tail added to pre-mRNA in mammalian cells?
~ 200 nucleotides
Which process described is crucial for tRNA to bind to the correct sequence of mRNA during translation?
Forming hairpin loops
What is the role of the initiator tRNA in translation?
Carrying the Met amino acid to the A-site
What distinguishes the start codon for polypeptide synthesis?
It differentiates initiating methionyl tRNAs from internal methionine tRNAs
Which of the following is NOT a role of the anticodon loop?
Facilitating peptide bond formation at the P-site
Why are base substitutions sometimes not changing an amino acid?
Because of degeneracy in the genetic code
How is the termination of an amino acid chain signaled in translation?
By one of the three nonsense or termination codons
Where does the uncharged tRNA move after peptide bond formation?
To the E-site
Which site on the ribosome does the empty tRNA move to after being released?
E-site
What is the term used to describe the many non-apoptotic ways for severely damaged or stressed animal cells to die?
Necrosis
Which process ensures that damaged or infected cells are eliminated before they can threaten animal health?
Apoptosis
How are the two original portions of each chromosome rearranged during crossing-over?
Swapped
Which type of cell death is associated with loss of ion gradient and tissue damage across the membrane?
Necrosis
What is the primary cause of cell death through necrosis?
Depletion of energy
Which pathway involves an extracellular signal leading to cell death?
Extrinsic pathway
In which way do damaged or infected cells die to prevent a threat to animal health?
Apoptosis
What type of cell death involves an intracellular signal, often from the mitochondria?
Intrinsic pathway
Which type of cell death is known for being a programmed process?
Apoptosis
Learn about the formation of phosphodiester bonds in DNA and RNA, including the covalent bonding between nucleotides and the directional synthesis from 5' to 3'. Understand the significance of the negatively charged phosphate group in both DNA and RNA.
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