Cell Structure & Cytoskeleton
Organelle that modifies and packages proteins.
Golgi apparatus
Where does translation occur?
Ribosomes
Main structural component of cell membrane.
Phospholipid bilayer
Junction that prevents leakage between cells. like between your skin and bladder cells.
Tight junction
Phase where DNA replicates.
S phase
Which cytoskeleton element is used for muscle contraction, and in cytokinesis cleavage furrow?
Microfilaments (actin)
Proteins destined for secretion are synthesized where?
Rough ER
Na⁺/K⁺ pump moves what? and what is the net charge across the cell membrane?
3 Na⁺ out, 2 K⁺ in. Positive outside, negative inside.
Junction that anchors cells together using intermediate filaments.
Desmosome
What are the three types of sexual life cycles?
Diploid-dominant
Haploid-dominant
Alternation of generations
Which cytoskeleton element forms the mitotic spindle?
Microtubules
A protein is inside a transport vesicle. When the vesicle fuses with the plasma membrane, will that protein face the cytosol or the extracellular environment?
Extracellular environment.
Is the Na⁺/glucose transporter primary or secondary active transport?
Secondary
Junction that allows direct ion flow between animal cells. has protein channels made of connexon proteins (donut like)
Gap junction
If chromosomes are lined up individually at the center, is this mitosis or meiosis II?
Either — they look similar
Structure that organizes microtubules in animal cells.
Centrosome (centrioles)
Correct pathway for secreted protein.
ER → Golgi → vesicle → membrane
What provides the energy for the Na⁺/glucose transporter?
Na⁺ gradient created by Na⁺/K⁺ pump
Plant cell equivalent of gap junction. what is unique about it?
Plasmodesmata. They are cytoplasmic channels that connect adjacent cells and allow direct transport of materials and communication between them.
Name two sources of genetic variation in meiosis.
Crossing over + independent assortment
If microtubules fail to function, what process stops?
Chromosome separation in mitosis/meiosis
How does a cell recognize and destroy misfolded or unwanted proteins in the cytosol?
They are tagged with ubiquitin and degraded by the proteasome.
What are the three types of passive transport, and what makes them “passive”?
Simple diffusion
Facilitated diffusion
Osmosis
They move substances down their concentration gradient and do not require ATP.
If tight junctions fail in the intestine, what happens?
Leakage between cells.
How do cyclins and CDKs work together to control progression through cell cycle checkpoints?
CDKs (cyclin-dependent kinases) are enzymes that are always present but inactive.
Cyclins are regulatory proteins whose levels rise and fall during the cell cycle.
When a cyclin binds to a CDK, it activates the CDK.
The activated CDK phosphorylates target proteins.
This pushes the cell past checkpoints (G1, G2, or M).