Chapter 7
What might happen if a stop codon were missing?
Translation would continue indefinitely.
Fill the blank:
During cell differentiation, cells become highly specialized, taking on their final form and function
How do tumors evolve?
a) Through genetic stability and cell differentiation
b) By repeated cycles of mutation, proliferation, and selection
c) By forming protective extracellular matrices
d) Through the activation of tight junctions
b) By repeated cycles of mutation, proliferation, and selection
What nucleotide is found in RNA but not DNA?
Uracil
What is chromatin?
A. RNA that binds to DNA
B. DNA wrapped around histone proteins
C. Proteins that control transcription
D. Ribosomal RNA
B. DNA wrapped around histone proteins
Which process involves removing introns from pre-mRNA?
a) Transcription
b) Translation
c) RNA splicing
d) Polyadenylation
c) RNA splicing
What happens to the lac operon in the absence of lactose?
In the absence of lactose: Lac repressor shuts off the operon .
What are the three specialized contacts that bind adjacent cells and their functions?
tight junction: seals neighboring cells together in an epithelial sheet to prevent leakage.
desmosomes: joins the intermediate filaments in one cell to those in a neighbor.
Gap junction: forms channels that allow small water-soluble molecules, including ions, to pass from cell to cell.
Which cytoskeletal component do desmosomes attach to?
Intermediate Filaments
What is a tissue?
An organized mass of cells with a specific function.
What would happen if the poly-A tail of mRNA were removed?
mRNA stability would decrease.
What type of cell can differentiate into many cell types?
Stem Cells
There are five characteristics of epithelial tissue. Can you name three?
BONUS: name all 5 for double points 😏
What is RNA interference (RNAi)?
A. A process where RNA transcribes DNA
B. A defense mechanism that degrades foreign RNA
C. A process where proteins are synthesized
D. A way to unwind chromatin
B. A defense mechanism that degrades foreign RNA
Which of the following is NOT a type of RNA?
a) tRNA
b) mRNA
c) sRNA
d) rRNA
c) sRNA
Which structure signals the end of transcription?
Terminator
What connects distant activators to transcription factors at the promoter?
Mediator proteins are a large complex of proteins
serves to link the distantly bound transcription regulators (activators) to the transcription factors
What protein links integrins to collagen in the extracellular matrix?
Fibronectin
What is the function of mRNA?
a) To splice out introns
b) To carry genetic information from DNA to the ribosome
c) To link amino acids during protein synthesis
d) To form the structural core of ribosomes
b) To carry genetic information from DNA to the ribosome
Which codon signals the start of translation?
a) UGA
b) AUG
c) UAG
d) UAA
b) AUG
eukaryotic genes are often interrupted by (1)____________, which are removed during RNA splicing to leave behind the coding regions, or (2)____________
eukaryotic genes are often interrupted by introns, which are removed during RNA splicing to leave behind the coding regions or exons
How does chromatin remodeling affect gene expression?
A. It silences all genes
B. It alters DNA sequences
C. It changes the accessibility of DNA to transcription factors
D. It destroys histones
C. It changes the accessibility of DNA to transcription factors
Chromatin structure can be altered by chromatin-remodeling complexes and by enzymes such as histone acetyltransferases that covalently modify the histone proteins that form the core of the nucleosome -> allowing greater accessibility to the underlying DNA. Slide 19
Ground substance is unstructured material that fills the space between cells. What is it made of?
hint: 3 components
Interstitial fluid
Cell adhesion proteins ("glue" for attachment)
Proteoglycans (Protein core + large polysaccharides)
central dogma of molecular biology, which describes the flow of genetic information from (1)______________ to (2)__________ to (3)___________.
the central dogma of molecular biology, which describes the flow of genetic information from RNA to DNA to protein
What are the three elements of connective tissues in animals?
Ground substance, fibers, and cells