Cells
Cells
- Every living thing is made of cells — the smallest unit that can carry out life processes.
- We compare plant, animal and bacterial cells.
- Each structure has a job.
Which structures are where
- Both plant and animal cells have: cell membrane, cytoplasm, ribosomes, nucleus, mitochondria.
- A plant cell also has three extras: a cell wall, a large vacuole, and chloroplasts (in green parts).
Practice
Which three structures does a plant cell have that an animal cell does not?
Plant cells add a cell wall, a large vacuole and (in green parts) chloroplasts.
What each does
- cell membrane — controls what enters/leaves.
- cytoplasm — where reactions happen.
- nucleus — controls the cell; holds the genetic material.
- ribosomes — make proteins; mitochondria — respiration (energy).
- cell wall (cellulose) — strength; chloroplasts (chlorophyll) — photosynthesis; vacuole — keeps the cell firm.
Practice
Where does respiration release energy in a cell?
Mitochondria are the site of respiration; ribosomes make proteins; the nucleus controls the cell.
Practice
The cell membrane:
The membrane is a selective barrier controlling entry and exit.
Bacterial cells
- A bacterium is a prokaryote — it has no nucleus.
- Its DNA is a single loop, plus small rings called plasmids; no mitochondria or chloroplasts.
Practice
A bacterial cell:
Bacteria are prokaryotes: a loop of DNA and plasmids, no nucleus, no mitochondria or chloroplasts.
You've got it
Key idea
- both plant & animal cells: membrane, cytoplasm, ribosomes, nucleus, mitochondria
- plant extras: cell wall, large vacuole, chloroplasts
- mitochondria = respiration; ribosomes = proteins; chloroplasts = photosynthesis
- bacteria: no nucleus (a DNA loop + plasmids), no mitochondria/chloroplasts