Gatekeepers & VIP Passes
What structure acts as the “bouncer” of the cell, deciding what enters and leaves?
→ The cell (plasma) membrane
This organelle transports substances within and between the cells.
→ vessicles
Water moving through a membrane from low to high solute concentration is called this.
→ Osmosis
The phase where chromosomes line up in the middle of the cell.
→ Metaphase
When normal regulatory signals fail, this type of uncontrolled cell growth can invade nearby tissues and spread to other parts of the body.
→ Malignant cancer (malignancy/metastasis)
This double-membraned structure controls what enters and exits the nucleus.
Nuclear envelope
Proteins that span the membrane and help transport ions or molecules are called this.
Integral proteins
These molecules form the flexible barrier of the membrane with heads that love water and tails that hate it.
→ Phospholipids
These tiny round structures read mRNA to assemble amino acids into proteins.
→ Ribosomes
A red blood cell shrinking in a salty solution demonstrates this type of environment.
→ Hypertonic
This process splits the cytoplasm, creating two identical daughter cells.
→ Cytokinesis
Mutations in these genes remove the “brakes” on the cell cycle, allowing unchecked division.
→ Tumor suppressor genes (e.g., p53, BRCA1)
The dense region inside the nucleus responsible for producing ribosomes.
Nucleolus
These proteins bind to specific molecules outside the cell and trigger internal responses.
Receptor proteins
Moving materials against the gradient—like pushing a boulder uphill—requires this molecule.
→ ATP (active transport)
The “clean-up crew” that digests worn-out organelles and debris.
→ Lysosomes
The Na⁺/K⁺ pump moves ions across the membrane using ATP—this is an example of what?
→ Active transport
The phase when sister chromatids are pulled apart.
→ Anaphase
A mutation that converts a proto-oncogene into this type of gene results in a constant “accelerator” signal for division.
→ Oncogene
Loosely coiled DNA and protein inside the nucleus is called this.
Chromatin
Glucose uses these “doorway” proteins to cross the cell membrane without energy.
→ Carrier proteins (facilitated diffusion)
When molecules move from high to low concentration with no energy required, it’s called this.
→ Diffusion
The “post office” of the cell that modifies, sorts, and packages proteins.
→ Golgi apparatus
“Cell eating” and “cell drinking” describe these two forms of transport.
→ Phagocytosis and pinocytosis
The period of growth and DNA replication between divisions.
→ Interphase
If a cell detects severe DNA damage and cannot repair it, this process of programmed cell death should occur—but often fails in cancer cells.
→ Apoptosis
During cell division, chromatin condenses into these visible structures.
Chromosomes
These membrane proteins anchor the cytoskeleton to the cell membrane, maintaining shape.
Peripheral proteins
These short, hairlike projections move fluid across the cell’s surface.
Cilia
Organelle that protect cells by isolating and breaking down harmful hydrogen peroxide into water and oxygen.
peroxisomes
This process removes cell products like hormones or neurotransmitters.
→ Exocytosis
The stage of mitosis where there is a coiling of chromatin into visible chromosomes, the breakdown of the nuclear envelope, and the formation of the mitotic spindle as centrosomes move to opposite poles of the cell.
→Prophase
Explain how disruption at a checkpoint (such as G₁ or G₂) can increase the likelihood of cancer developing over time.
→ If checkpoints fail, cells with DNA damage can continue dividing without repair. These mutations accumulate, disrupting genes that regulate the cycle and leading to uncontrolled tumor formation.
Explain how gene expression inside the nucleus contributes to cell differentiation.
Different genes are activated or silenced in each cell type, allowing them to produce specific proteins and specialized functions.
This protein plays a vital role in immune system recognition.Cell identification—helping the body recognize “self” vs “non-self”
Glycoproteins