Cell theory and types
What are the three parts of the Cell Theory?
All living things are made of cells
cells are the basic unit of life
All cells come from preexisting cells
What organelle controls the activities of the cell?
Nucleus
What is the main function of the cell membrane?
Controls what enters and leaves the cell.
Define homeostasis.
Maintaining a stable internal environment.
What is the longest phase of the cell cycle?
Interphase
What is the main difference between prokaryotic and eukaryotic cells?
Eukaryotes have a nucleus; prokaryotes do not.
Which organelle is responsible for producing energy?
Mitochondria
What does “selectively permeable” mean?
Only certain substances can pass through.
What specific type of diffusion uses channel proteins?
Facilitated diffusion
What happens during the S phase?
DNA replication
Give one example each of a prokaryote and a eukaryote.
Prokaryote → bacteria
Eukaryote → plants, animals, fungi, protists
What structure packages and modifies proteins?
Golgi apparatus
Diffusion moves particles from ______ to ______ concentration.
High to low concentration.
What happens to a cell placed in a hypertonic solution?
Water leaves the cell → cell shrinks
During which phase do sister chromatids separate?
Anaphase
Name two structures found in both prokaryotes and eukaryotes.
Cell membrane, cytoplasm, ribosomes and DNA
A cell cannot break down old organelles. Which organelle is likely malfunctioning?
Lysosome
Why can’t large molecules pass directly through the phospholipid bilayer?
They are too large or polar to slip through the hydrophobic center.
What type of transport requires energy?
Active transport
Explain the purpose of checkpoints in the cell cycle.
They ensure DNA replication occurs correctly and proper cell growth before division
Why does cell division support the Cell Theory?
It shows new cells come from existing cells.
What is the difference between rough ER and smooth ER?
Rough ER → has ribosomes, makes proteins
Smooth ER → no ribosomes, makes lipids
Describe osmosis.
Diffusion of water across a selectively permeable membrane.
Why does loss of selective permeability quickly harm a cell?
It can no longer control internal conditions.
During which phase does the nuclear membrane disappear, when does it reappear?
Prophase, telophase