AP bio quiz - unit 2

What are cells?

The basic structural and functional units of every organism.

What four components are found in all cells?

Plasma membrane, cytosol, chromosomes, and ribosomes.

What are the two major cell types?

Prokaryotic and eukaryotic cells.

Which domains contain prokaryotes?

Bacteria and Archaea.

Where is prokaryotic DNA found?

In the nucleoid region.

How do prokaryotes compare in size to eukaryotes?

Prokaryotes are generally smaller.

What internal structures do prokaryotes lack?

Internal membrane-bound organelles.

Which organisms are eukaryotes?

Protists, fungi, animals, and plants.

Where is eukaryotic DNA found?

In the nucleus.

What distinguishes eukaryotic cell organization?

Membrane-bound organelles compartmentalize cellular functions.

Can prokaryotes have localized specialized functions?

Yes; proteins for motility or cell division can be concentrated in particular regions.

What are organelles as defined in these notes?

Membrane-bound structures in eukaryotes.

What two broad organelle classifications do the notes use?

Endomembrane system and energy organelles.

What does the endomembrane system do?

Interacting structures modify, package, and transport polysaccharides, proteins, and lipids.

Which structures belong to the endomembrane system?

Nuclear envelope, ER, Golgi complex, lysosomes, vesicles/vacuoles, plasma membrane.

Which organelles convert energy into forms usable for cellular work?

Mitochondria and chloroplasts.

What is compartmentalization?

Separating metabolic processes and enzyme reactions into different cellular locations.

What are two benefits of compartmentalization?

It increases reaction surface area and prevents interfering reactions from sharing a location.

Why are membrane-bound organelles advantageous?

They organize distinct reactions and help keep interfering processes separate.

Which plant cell components are highlighted as distinctive?

Chloroplasts, central vacuole, cell wall, and plasmodesmata.

Which animal cell components are highlighted in the notes?

Lysosomes, centrosomes, and flagella.

How do plant and animal cell components differ in these notes?

Plants: chloroplasts, central vacuole, wall, plasmodesmata; animals: lysosomes, centrosomes, flagella.

What does the nucleus contain?

Genetic material.

What surrounds the nucleus?

The double-membraned nuclear envelope.

What is the purpose of nuclear pores?

Regulate movement of materials into and out of the nucleus.

How is the nuclear envelope linked to the endomembrane system?

Its membrane is continuous with the ER membrane.

What is the nucleolus?

A dense nuclear region where ribosomal RNA (rRNA) is synthesized.

How are ribosomal subunits assembled?

rRNA combines with proteins to form large and small ribosomal subunits.

How do ribosomal subunits leave the nucleus?

Through nuclear pores; they assemble into ribosomes afterward.

What do ribosomes do with mRNA?

Translate its message into a polypeptide amino acid sequence.

What is the general flow of genetic information?

DNA → RNA → protein (transcription followed by translation).

What enzyme transcribes DNA to mRNA?

RNA polymerase.

What happens to mRNA before it leaves the nucleus?

The mRNA transcript is modified.

Where does translation occur?

At ribosomes in the cytoplasm.

Does DNA itself normally need to leave the nucleus to make protein?

No; DNA is transcribed into mRNA, which travels to cytoplasmic ribosomes.

What are ribosomes made of?

Ribosomal RNA and proteins.

What is the primary function of ribosomes?

Protein synthesis.

Where are free ribosomes found?

In the cytosol.

What proteins do free ribosomes usually make?

Proteins functioning in the cytosol, such as enzymes.

Where are bound ribosomes located?

Attached to the ER or nuclear envelope.

What proteins can bound ribosomes produce?

Proteins that may be secreted from the cell.

How may secreted proteins leave the cell?

They are carried through the endomembrane system in transport vesicles.

How do free and bound ribosomes differ?

Free: mostly cytosolic proteins; bound: proteins that can be secreted.

What is the endoplasmic reticulum (ER)?

A network of membrane sacs (cisternae) and tubules.

What two general functions does the ER have?

Mechanical support/cell shape and intracellular transport.

What are the two kinds of ER?

Rough ER and smooth ER.

Why is rough ER called rough?

Ribosomes are bound to its membrane.

What is a main function of rough ER?

Compartmentalizing protein synthesis.

What distinguishes smooth ER?

It lacks ribosomes.

What does smooth ER do?

Synthesizes lipids and detoxifies the cell.

What happens to protein production if ER-bound ribosomes are disrupted?

Production of proteins normally made by bound ribosomes is impaired.

What processes may be affected if smooth ER fails?

Lipid synthesis and detoxification.

What is the Golgi complex made of?

Flattened membranous sacs called cisternae.

What do Golgi cisternae separate?

Their internal compartments from the cytosol.

What is the cis face of the Golgi?

The receiving side; accepts vesicles arriving from the ER.

What is the trans face of the Golgi?

The shipping side; sends vesicles to other destinations or the plasma membrane.

What does the Golgi do to materials arriving from the ER?

Modifies/folds, sorts, tags, and packages them into transport vesicles.

Why does the Golgi add molecular tags?

To help sort materials for their destinations.

What is exocytosis in this context?

Vesicles fuse with the plasma membrane to release their contents.

Trace a protein destined for secretion.

Bound ribosome/rough ER → transport vesicle → Golgi cis face → Golgi trans face → vesicle → plasma membrane.

What is the direction of material flow through the Golgi?

From the cis receiving face to the trans shipping face.

How do rough ER and Golgi functions complement each other?

Rough ER synthesizes proteins; Golgi modifies, sorts, and packages them.

What may happen if Golgi packaging fails?

Proteins or other materials may not be correctly sorted or delivered.

What is a lysosome?

An animal-cell membrane sac containing hydrolytic digestive enzymes.

What do lysosomal enzymes break down?

Macromolecules.

What is autophagy?

Recycling a cell's organic materials and malfunctioning organelles.

How does lysosomal autophagy help the cell?

It allows the cell to renew itself by recycling materials.

What is apoptosis?

Programmed cell death.

What lysosome-related process is described during apoptosis?

Its membrane becomes permeable; enzymes enter the cytoplasm and break down cell components.

How do lysosomes differ from peroxisomes?

Lysosomes digest/recycle with hydrolytic enzymes; peroxisomes carry out metabolic and detox reactions.

Are peroxisomes part of the endomembrane system?

No.

What reactions occur in peroxisomes?

Reactions producing hydrogen peroxide (H2O2).

Why must peroxisomal H2O2 be controlled?

It helps detoxify some compounds but can damage the cell if it escapes.

What does catalase do?

Breaks down hydrogen peroxide into water and oxygen.

What are three functions of peroxisomes?

Break down fatty acids, synthesize certain phospholipids, and detoxify compounds.

What would happen if peroxisomal catalase stopped working?

H2O2 could accumulate and damage the cell.

Where do vacuoles originate?

From the ER and Golgi.

How are animal-cell vacuoles described?

Smaller and more numerous; store materials and aid endocytosis/exocytosis.

How is the plant central vacuole described?

A large vacuole storing nutrients and water, supporting turgor, and sometimes acting like a lysosome.

What is turgor pressure associated with?

Water stored in the plant central vacuole.

What is a major difference between plant and animal vacuoles?

Plants have a large central vacuole; animals usually have multiple smaller ones.

What could happen if a plant central vacuole loses water?

Turgor pressure decreases.

How can vacuoles and lysosomes overlap in function?

The plant central vacuole can perform lysosome-like functions.

What is the main function of mitochondria?

They are the site of cellular respiration.

How is a mitochondrial double membrane organized?

Smooth outer membrane and highly folded inner membrane.

What are cristae?

Folds of the mitochondrial inner membrane that increase surface area.

What is the mitochondrial intermembrane space?

Space between the outer and inner membranes.

What is the mitochondrial matrix?

The compartment enclosed by the inner membrane.

Where does the Krebs cycle occur?

In the mitochondrial matrix.

What does the mitochondrial matrix contain?

Respiration enzymes, mitochondrial DNA, and ribosomes.

How does mitochondrial abundance relate to metabolic activity?

More metabolically active cells generally have more mitochondria.

Which cells are likely to have many mitochondria?

Cells that move or contract, because they have high metabolic activity.

Why do cristae matter to mitochondrial function?

They increase the inner-membrane surface area.

Which cells contain chloroplasts according to the notes?

Plant cells and photosynthetic algae.

What is the primary function of chloroplasts?

Photosynthesis.

What pigment is found in chloroplasts?

Chlorophyll, a green pigment.

What are thylakoids?

Membranous sacs inside chloroplasts.

What are grana?

Stacks of thylakoids.

Where do light-dependent photosynthetic reactions occur?

In the grana (thylakoid membranes).

What is the stroma?

Fluid surrounding thylakoids in a chloroplast.