A2.2 Cell Structure and Life Processes (Notes)

Question-and-answer flashcards covering cell theory, prokaryotic/eukaryotic differences, organelles, endosymbiosis, life processes, differentiation, and multicellularity topics from the notes.

What are the three basic principles of cell theory?

All living things are made of cells; cells are the smallest units of life; cells arise from pre-existing cells.

What does endosymbiotic theory propose about the origin of mitochondria and chloroplasts?

Mitochondria originated from aerobic prokaryotes and chloroplasts from photosynthetic prokaryotes, via endosymbiosis.

What evidence supports the endosymbiotic theory for mitochondria and chloroplasts?

Both have 70S ribosomes, naked circular DNA, double membranes, and can divide by binary fission; they are susceptible to some antibiotics.

Name four structures that are common to all cells.

Plasma (cell) membrane, cytoplasm, DNA, ribosomes.

Which four kingdoms are part of the eukaryotic domain?

Protista, Fungi, Plantae, Animalia.

List the seven basic functions of life.

Metabolism, growth, reproduction, homeostasis, excretion, nutrition, response (sensitivity).

What is homeostasis and give an example from unicellular organisms?

Maintenance of a stable internal environment; e.g., Paramecium uses contractile vacuoles to regulate water content.

How do prokaryotic and eukaryotic cells differ regarding the nucleus?

Prokaryotes lack a true nucleus; DNA is in the nucleoid region. Eukaryotes have a nucleus that houses their DNA.

What are the sizes and types of ribosomes in prokaryotes and eukaryotes?

Prokaryotic ribosomes are 70S (50S + 30S); eukaryotic ribosomes are 80S (60S + 40S).

What is the function of the Golgi apparatus?

Modifies, sorts, concentrates, and packs proteins into vesicles for destinations inside or outside the cell.

What is the function of the rough endoplasmic reticulum (RER)?

RER has ribosomes and synthesizes proteins; it also helps process and shuttle them to the Golgi.

What is the function of mitochondria?

Site of aerobic cellular respiration; produces ATP (energy) for the cell.

What is the function of chloroplasts?

Site of photosynthesis; contains chlorophyll and produces sugars (glucose) using light energy.

What are the nucleus and nucleolus, and what do they do?

The nucleus houses the cell’s DNA; the nucleolus is where ribosomes are made.

What differences exist between plant and animal cells regarding chloroplasts, cell walls, and vacuoles?

Plant cells have chloroplasts, cellulose cell walls, and a large central vacuole. Animal cells lack chloroplasts and cell walls and have small or no vacuoles.

What is the function of the cytoskeleton?

Maintains cell shape, organizes cell parts, enables movement and cell division; made of microtubules, actin filaments, and intermediate filaments.

What is the function of lysosomes?

Contain hydrolytic enzymes that digest waste and recycle damaged organelles and macromolecules.

Describe the mitochondrion’s structure and why it matters.

Double membrane with inner membrane folded into cristae; location of aerobic respiration and ATP production.

Where is DNA located in prokaryotes versus eukaryotes?

Prokaryotic DNA is in the nucleoid (no membrane-bound nucleus); eukaryotic DNA is in the nucleus with histones.

What is the structure and function of the Golgi apparatus’s cis and trans faces?

Cis face receives vesicles from the ER; the cisternae process them, and the trans face sorts and dispatches vesicles to destinations.

What are some components of the endomembrane system mentioned in the notes?

RER, SER, Golgi apparatus, vesicles, and the nuclear envelope (involved in protein/lipid synthesis and transport).

What is the function of the plasma membrane?

Controls entry and exit of substances; serves as a boundary and protection for the cell.

What is the plant cell wall composed of and its function?

Cellulose; provides structural support and prevents the cell from bursting when water enters.

What evidence supports the endosymbiotic theory about mitochondria and chloroplasts?

Mitochondria/chloroplasts have double membranes, naked circular DNA, 70S ribosomes, replicate by division, and are antibiotic-sensitive.

What is compartmentalization in eukaryotic cells and its advantages?

Organelles create separate environments, increasing metabolic efficiency and allowing distinct conditions (pH, environment) for different processes.

Give three examples of atypical cells and how they challenge the idea that all living things are made of discrete cells.

Striated muscle cells fuse to form long multinucleated fibers; aseptate fungal hyphae lack septa; giant algae like Acetabularia can be very large single cells.

What is the difference between autotrophs and heterotrophs?

Autotrophs synthesize their own carbon compounds (usually from light via photosynthesis); heterotrophs obtain carbon from other organisms.

What is excretion, and how do different organisms excrete waste?

The removal of metabolic wastes; in humans via lungs and kidneys; in plants via leaves/roots; unicellular organisms often by diffusion across the membrane.

What is the genome?

All the genetic information of an organism; all cells in a multicellular organism share the same genome.

What are euchromatin and heterochromatin?

Euchromatin is loosely packed and transcriptionally active; heterochromatin is tightly packed and generally transcriptionally inactive.

Which kingdom has cell walls made of chitin?

Fungi.

Which kingdom is typically autotrophic with cellulose cell walls?

Plantae.

Which kingdom lacks a cell wall and is primarily heterotrophic?

Animalia.

Who formulated the endosymbiotic theory?

Lynn Margulis.