Gene Regulation
Describe the main process through which gene regulation occurs during RNA processing.
Gene regulation occurs through alternative splicing during RNA processing. Introns are spliced and exons are joined together in different combinations to make different protein products.
What is the name for an environmental agent that can induce DNA mutations? What are the two types.
Mutagens. The type types are chemical and physical mutagens.
Name the three steps of cell signaling in order.
Reception, transduction, and response.
What are the two mechanisms through which we can acquire different sets of activator proteins to be active in different cell types?
This is a a special type of paracrine
signaling that comes specifically from neurons.
Synaptic signalling.
What are two components essential to gene transcription that are required for both eukaryotes and prokaryotes?
Promoter sequence and transcription start site (TSS)
Insertions and deletions can completely change the reading frame for a sequence. What is this type of mutation called?
Frameshift mutations disrupt the normal reading frame and the entire gene sequence following the mutation will be incorrectly read.
Describe the process of reception.
The interaction between a receptor protein and its signaling molecule or ligand.
These are cells from very early embryos are capable of becoming every cell type in the adult organism.
Embryonic stem cells.
This category of signaling molecules are used for endocrine signaling. What is the name of the category and how do they travel in the body?
Hormones and they travel to their target cells using the bloodstream/cardiovascular system.
Describe the conditions under which the repressor protein is bound to the operator sequence of the lac operon. What happens as a result of this binding?
The repressor protein is bound to the operator sequence under no lactose conditions. Transcription cannot occur.
What is the difference between missense, nonsense, and silent mutations?
Silent mutations occur when a base substitution results in no change to the protein seq. Missense mutations occur when the amino acid seq. is changed. Nonsense mutations occur when an early stop codon is produced.
Match each phrase to the type of cell signaling it defines. (1) This type of signaling occurs between cells in the same local area. (2) between cells that are in direct contact. (3) between cells throughout the body.
During mitosis, cytoplasmic determinants/activators/ specific TFs which are found in in the zygote get divided up into different cells
At which point in the cell differentiation process does a cell become irreversibly committed to a cell type?
Cell determination
Describe the conditions under which the lac repressor protein is bound by allolactose. Describe what happens as a result of the repressor being bound to allolactose.
The lac repressor is bound to allolactose when lactose is present in the environment (lactose converts to allolactose). Allolactose inactivates the repressor protein and inhibits it from binding to the operator sequence. Transcription can occur.
Name the two types of cell mutations and describe their heritability.
Somatic cell mutations affect the individual only and cannot affect future generations. Germ cell mutations do not affect the individual but DO affect future generations (they are heritable).
changes in gene expression, change in enzyme activity, or remodeling of cytoskeleton
How are cells replaced when they die?
Stem cells! Stem cells are not fully differentiated and are still able to divide so they can replace the lost cells.
Muscle cell differentiation requires activation of this gene. What does this gene determine the precursor cell into?
These are the required elements for gene transcription to occur in eukaryotes.
Distal or proximal control elements (enhancers or silencers) and their specific transcription factors (activators or repressors). Promoter sequence, general transcription factors, and RNA polymerase. Gene itself. Mediator protein. DNA bending protein.
What is the difference between spontaneous and induced mutations?
Spontaneous mutations are mistakes made by DNA pol during replication (random and need no external agent to cause them). Induced mutations occur when environmental agents (like x-rays or asbestos) change the structure of DNA.
What are three ways that a signal can be transduced?
Via Phosphorylation Cascade by kinases
Via production of secondary messengers
Via direct travel to the nucleus (nuclear localization)
Inductive signaling is a process for cell differentiation. Describe this process briefly.
Signaling cells secrete differentiation factors that activate transduction pathways in target cells. This leads to the expression of specific genes.
Integral membrane protein found embedded in cell membrane: binds to signals that cannot cross cell membrane (large, hydrophilic, charged)
Intracellular receptor proteins found inside the cell: binds to signals that CAN cross cell membrane (small, hydrophobic)