Cell Signaling
In this type of local signaling, growth factors and cytokines act on nearby cells in the same tissue.
Paracrine signaling
Made of long chains of protein subunits, this cellular framework provides internal structural support and enables movement of substances within the cell.
the cytoskeleton
DNA polymerase can only add nucleotides to this specific end of a growing strand, which is why all new DNA strands are synthesized in the 5′→3′ direction.
the free 3' end
Where are the checkpoints located in the cell cycle
G1, G2, M
This type of point mutation is a single-base substitution that changes one codon so that a different amino acid is incorporated into the protein, as in sickle-cell disease.
missense mutation
In hormonal signaling, hormones may reach almost all body cells, but only these cells recognize and respond to a given hormone.
target cells
These two cytoskeletal polymers are polar, growing more quickly at their plus ends than their minus ends; in animal cells, one of them is anchored with its minus ends at the centrosome and plus ends projecting toward the cell membrane. Name both.
microtubules and microfilaments
At the replication fork, this enzyme relieves the overwinding strain caused by helicase ahead of the fork, preventing the DNA from becoming too tightly coiled.
topoisomerase
what is the order of mitosis?
PMAT!
In this kind of substitution, a codon is changed into a stop codon (UAA, UAG, or UGA), truncating the protein, whereas in this other kind of substitution, the codon changes but still specifies the same amino acid, leaving the protein sequence unchanged.
nonsense and silent mutation
In this stage of signaling, the message is passed along inside the cell via intermediate steps, often amplifying the signal.
Signal transduction
For a carcinoma cell to become metastatic via the bloodstream, it must cross this specialized extracellular matrix layer that underlies blood vessels twice, and it often uses specific integrins to do so.
the basal lamina
At a replication origin, the two parental strands separate to create a structure that contains two active sites where new DNA is being synthesized in opposite directions. Name this overall structure and the specific sites where synthesis is occurring.
a replication bubble with two replication forks
what is the difference between G0 and apoptosis
G0 is a holding phase for premature genes, and apoptosis is regulated cell death
This class of mutation is caused by the insertion or deletion of one or two nucleotides, shifting the reading frame from the point of change onward, usually making all downstream amino acids wrong and often introducing a premature stop—especially severe when it occurs near the 5′ end of the gene.
frameshift mutation
Name two types of cellular responses to a signal (must be biological and not moving your hand off of a stove)
gene expression, growth factors, exocytosis, cell replication, apoptosis
Label the cytoskeletal elements from thinnest to thickest
microfilaments, intermediate filaments, microtubules
why is telomerase a unique enzyme and what is it's function in our body?
it extends DNA ends without requiring a DNA template (it uses its own built-in template)
draw and label every part of the cell cycle
g1, S, g2, prophase, metaphase, anaphase, telophase,
Because the genetic code is read in non-overlapping triplets, inserting or deleting nucleotides near this end of the coding sequence tends to produce the most severe protein defects.
near the 5' end
Draw and label every part of a traditional signal transduction pathway
Name every adherins junction and describe their function
tight junctions: connect cells to cell in a tight seal (no liquid passes through)
gap junctions: form pores from cell to cell to allow small molecules to flow across
desmosomes: connect cell to cell using intermediate filaments
hemidesmosomes: connect cell to matrix using intermediate filaments
Draw and label a DNA strand unwinding and being replicated (including Okazaki fragments and leading strand)
bonus points if you discussed enzymes involved!
Describe the function of each step of the cell cycle
G₁ phase (Gap 1): The cell grows, makes proteins and organelles, and checks whether conditions are good enough to start DNA replication.
S phase (Synthesis): The cell accurately replicates its DNA so each chromosome becomes two identical sister chromatids.
G₂ phase (Gap 2): The cell continues to grow, produces proteins needed for mitosis, and checks that all DNA has been correctly replicated and repaired.
M phase (Mitosis + Cytokinesis): The duplicated chromosomes are separated into two nuclei and the cell splits into two genetically identical daughter cells.
G₀ phase (Resting state): The cell exits the cycle and remains metabolically active but does not actively divide.
decribe each type of mutation we dicussed in lecture
Point mutation: Any small-scale mutation that changes one or a few nucleotides in the DNA sequence.
Substitution mutation: A point mutation where one nucleotide base is replaced by another.
Missense mutation: A substitution that changes a codon so a different amino acid is incorporated into the protein.
Nonsense mutation: A substitution that converts a codon into a stop codon (UAA, UGA, or UAG), causing premature termination of the protein.
Silent mutation: A substitution that changes a nucleotide but does not change the amino acid sequence of the protein.
Frameshift mutation: An insertion or deletion of 1 or 2 bases that shifts the reading frame, usually scrambling all amino acids downstream and often introducing a premature stop.
Deletion mutation: A mutation where nucleotides are removed; deleting 1–2 bases causes a frameshift, while deleting sets of 3 bases removes one or more amino acids without shifting the reading frame.