STEM Readiness: Pre-Calculus Readiness - Vectors/Parametric: Parametric Equations - Graphing, Eliminating the Parameter, Calculus Preview

Must?Know (20–25 detailed bullets)

• Prokaryotic cells range from 0.1–5.0 ?m in diameter; eukaryotic cells range from 10–100 ?m.
• Prokaryotes include bacteria and archaea; eukaryotes include animals, plants, fungi, and protists.
• Prokaryotic DNA is located in the nucleoid, an unenclosed region; eukaryotic DNA is enclosed within a membrane-bound nucleus.
• Prokaryotes lack membrane-bound organelles; eukaryotes have endoplasmic reticulum, Golgi apparatus, mitochondria, and lysosomes.
• Ribosomes in prokaryotes are 70S (composed of 50S and 30S subunits); eukaryotic cytoplasmic ribosomes are 80S (60S and 40S).
• Mitochondria and chloroplasts in eukaryotes have 70S ribosomes, similar to prokaryotes, supporting the endosymbiotic theory.
• Cell walls in most bacteria contain peptidoglycan; archaea lack peptidoglycan but may have pseudopeptidoglycan.
• Plant cells have cell walls made of cellulose; fungal cells have chitin; animal cells lack a cell wall.
• Mycoplasma species are bacteria that lack a cell wall, making them resistant to antibiotics like penicillin.
• Both prokaryotes and eukaryotes have a phospholipid bilayer plasma membrane with embedded proteins.
• Eukaryotic cells contain internal membranes forming organelles; prokaryotes generally lack internal membranes (except in some photosynthetic bacteria with thylakoids).
• The nuclear envelope in eukaryotes is a double membrane with nuclear pores that regulate transport.
• Nucleolus is present within the nucleus of eukaryotes and is the site of ribosomal RNA synthesis; absent in prokaryotes.
• Prokaryotes reproduce by binary fission; eukaryotes undergo mitosis and meiosis.
• Plasmids are small, circular DNA molecules commonly found in prokaryotes; rare in eukaryotes (e.g., 2-micron plasmid in yeast).
• Cytoskeleton components (actin, microtubules, intermediate filaments) are present in eukaryotes; prokaryotes have homologous proteins (e.g., FtsZ, MreB).
• Flagella in prokaryotes are made of flagellin and rotate; eukaryotic flagella are composed of microtubules (9+2 arrangement) and undulate.
• Endosymbiotic theory is supported by mitochondria and chloroplasts having circular DNA, 70S ribosomes, and double membranes.
• Red blood cells in mammals lack a nucleus and most organelles, increasing space for hemoglobin.
• Plant cells contain chloroplasts for photosynthesis; animal cells do not.
• Lysosomes are membrane-bound organelles in animal cells containing hydrolytic enzymes; absent in most plant cells (vacuoles perform similar function).
• Peroxisomes are present in both plant and animal eukaryotic cells and are involved in fatty acid breakdown and detoxification.
• Glycocalyx is present in some prokaryotes (capsule or slime layer) and eukaryotic cells (cell coat), aiding adhesion and protection.
• Archaea have ether-linked lipids in their membranes (vs ester-linked in bacteria and eukaryotes), making them more heat- and acid-resistant.

Difficulty Level

Intermediate – requires understanding of structural and functional differences, including exceptions and evolutionary implications.

Common Traps (3–5 factual traps)

Trap: All cells with cell walls have peptidoglycan – Fact: Only bacteria have peptidoglycan; plants (cellulose), fungi (chitin), and archaea (pseudopeptidoglycan or other) have different compositions.
Trap: Ribosome size correlates with organism complexity – Fact: Mitochondria and chloroplasts in eukaryotes have 70S ribosomes, identical in size to prokaryotes, due to endosymbiotic origin.
Trap: Prokaryotes have no internal structure – Fact: Prokaryotes have nucleoids, ribosomes, and some have protein-based cytoskeletal elements (e.g., FtsZ).
Trap: The nucleus is the only organelle with a double membrane – Fact: Mitochondria and chloroplasts also have double membranes (outer and inner).
Trap: Eukaryotes evolved from prokaryotes directly – Fact: Eukaryotes likely arose from archaeal ancestors, with bacterial contributions via endosymbiosis; not a linear progression.

Practice MCQs (5–7 questions)

Question: Which of the following is a feature shared by both prokaryotic and eukaryotic cells?
A) Membrane-bound nucleus
B) 80S ribosomes
C) Phospholipid bilayer plasma membrane
D) Mitochondria
Answer: C
Explanation: Both cell types have a phospholipid bilayer as the plasma membrane.
Why the top distractor is wrong: D (mitochondria) are only found in eukaryotes.

Question: A cell is observed to have a nucleus, mitochondria, and a cell wall made of cellulose. This cell is most likely from a:
A) Fungus
B) Bacterium
C) Plant
D) Animal
Answer: C
Explanation: Cellulose cell walls are characteristic of plant cells.
Why the top distractor is wrong: A (fungi) have chitin, not cellulose, in their cell walls.

Question: Which structure is evidence supporting the endosymbiotic theory?
A) Presence of a nucleolus
B) 70S ribosomes in mitochondria
C) 80S ribosomes in the cytoplasm
D) Nuclear envelope with pores
Answer: B
Explanation: Mitochondria having 70S ribosomes, like prokaryotes, supports their bacterial origin.
Why the top distractor is wrong: C (80S ribosomes) are typical of eukaryotic cytoplasm and not evidence of endosymbiosis.

Question: Which organism lacks a cell wall and a nucleus?
A) Escherichia coli
B) Saccharomyces cerevisiae
C) Mycoplasma pneumoniae
D) Human red blood cell
Answer: D
Explanation: Mature human red blood cells lack both a nucleus and a cell wall.
Why the top distractor is wrong: C (Mycoplasma) lacks a cell wall but is a prokaryote with a nucleoid (has DNA, though not enclosed).

Question: What is the primary component of the cell wall in fungi?
A) Peptidoglycan
B) Cellulose
C) Chitin
D) Lipopolysaccharide
Answer: C
Explanation: Fungal cell walls are primarily composed of chitin.
Why the top distractor is wrong: A (peptidoglycan) is found in bacterial cell walls, not fungi.

Question: Which of the following is found in eukaryotic cells but NOT in prokaryotic cells?
A) Ribosomes
B) Circular DNA
C) Endoplasmic reticulum
D) Plasma membrane
Answer: C
Explanation: The endoplasmic reticulum is a membrane-bound organelle unique to eukaryotes.
Why the top distractor is wrong: B (circular DNA) is present in prokaryotes (chromosome and plasmids) and also in mitochondria/chloroplasts.

Question: Which statement best describes the nucleoid?
A) A membrane-bound organelle containing linear DNA
B) A region in prokaryotes where circular DNA is concentrated
C) The site of ribosome assembly in eukaryotes
D) A structure found only in archaea
Answer: B
Explanation: The nucleoid is an unenclosed region in prokaryotes housing the circular chromosome.
Why the top distractor is wrong: A describes the eukaryotic nucleus, not the nucleoid.

Last?Minute Revision (20–25 one?liners)

• Prokaryotic cell size: 0.1–5.0 ?m; eukaryotic: 10–100 ?m.
• Prokaryotes: DNA in nucleoid; eukaryotes: DNA in nucleus.
• Prokaryotic ribosome = 70S; eukaryotic cytoplasmic ribosome = 80S.
• Mitochondria and chloroplasts have 70S ribosomes and circular DNA – evidence of endosymbiosis.
• Bacteria: peptidoglycan cell wall; archaea: no peptidoglycan; plants: cellulose; fungi: chitin; animals: no wall.
• Mycoplasma lacks a cell wall – resistant to penicillin.
• Both prokaryotes and eukaryotes have phospholipid bilayer membranes.
• Eukaryotes have internal membranes (ER, Golgi, etc.); prokaryotes generally do not.
• Nuclear envelope has double membrane and nuclear pores.
• Nucleolus synthesizes rRNA – present in eukaryotes, absent in prokaryotes.
• Binary fission in prokaryotes; mitosis/meiosis in eukaryotes.
• Plasmids common in bacteria; rare in eukaryotes.
• FtsZ protein in prokaryotes is homologous to eukaryotic tubulin.
• Prokaryotic flagellum: flagellin, rotates; eukaryotic: microtubules (9+2), bends.
• Red blood cells lack nucleus and organelles.
• Chloroplasts only in plant and algal cells.
• Lysosomes in animal cells; plant vacuoles perform degradation.
• Peroxisomes: contain catalase, break down fatty acids and H?O?.
• Glycocalyx: capsule (organized) or slime layer (unorganized) in prokaryotes; cell coat in eukaryotes.
• Archaeal membranes have ether-linked lipids; bacteria and eukaryotes have ester-linked.
• Endosymbiotic theory: mitochondria from alpha-proteobacteria; chloroplasts from cyanobacteria.
• Mitochondria have own DNA and replicate independently of the cell.
• Nuclear pores regulate transport between nucleus and cytoplasm.
• Cytoskeleton: actin, microtubules, intermediate filaments – in eukaryotes only.
• Verify from standard textbook: exact lipid composition in archaea varies by species.