8 Cellular Regulation Free Online FlashCards

At which stages can cells regulate gene expression?

Gene expression can be regulated during transcription, RNA processing and stability, and translation.

How do transcription factors affect gene expression?

Transcription factors bind regulatory DNA sequences and can increase or decrease transcription.

Why can cell types express different genes despite having the same DNA?

Different cell types use different combinations of regulatory proteins, so they can express distinct genes despite generally containing the same DNA.

How can an external signal alter gene expression?

External signals can activate signaling pathways that change transcription-factor activity, connecting outside conditions to gene expression.

How can small molecules rapidly regulate protein activity?

A small molecule can bind a regulatory site and change a protein’s shape or activity, allowing rapid regulation without making a new protein.

How do kinases and phosphatases regulate proteins?

Kinases add phosphate groups and phosphatases remove them. Phosphorylation may activate or inhibit a protein, depending on the protein and context.

What can ubiquitin marking signal for a protein?

Ubiquitin can mark a protein for breakdown by proteasomes, regulating how long that protein persists.

How do protein-activity changes differ from gene-expression changes in timing?

Changing protein activity can produce a fast response; changing gene expression can have longer-lasting effects by altering how much protein is made.

What is negative feedback, and what does it help accomplish?

In negative feedback, a process or its product reduces the activity that produced it, helping prevent excessive buildup and stabilize conditions.

What effect does positive feedback have on a process?

In positive feedback, an output reinforces the process that generated it, which can strengthen a response or help maintain a cellular state.

Which major events must a cell coordinate before dividing?

Before division, a cell must coordinate growth, DNA replication, and chromosome separation.

How do cyclin–Cdk complexes promote cell-cycle progression?

Cdks become active when bound to particular cyclins. Active cyclin–Cdk complexes modify proteins that promote transitions between cell-cycle stages.