Cell Structure and Function - AP Biology Review

Flashcards covering cell size, SA:V, microscopes, prokaryotic/eukaryotic differences, endomembrane system, plant vs animal cells, organelle functions, and the endosymbiotic theory.

What is the limiting factor for the maximum size of a cell?

Surface area to volume ratio (SA:V); as a cell grows, SA:V decreases, limiting exchange with the environment.

What is the formula for the surface area of a sphere?

SA = 4πr².

What is the formula for the volume of a sphere?

V = (4/3)πr³.

What is Size Solution #1 for increasing surface area in large organisms?

Multicellularity; division of labor among many cells increases total surface area.

What is Size Solution #2 - Cell Shape, and give two examples?

Increase surface area by elongating cells or forming convolutions such as microvilli; examples include neurons and intestinal microvilli.

Why is the surface area-to-volume ratio important for exchange in a cell?

A higher SA:V allows more exchange of materials across the membrane per unit volume, supporting metabolism.

Name the four basic components of prokaryotic cells.

Plasma membrane, cytosol/cytoplasm, genetic material (DNA), and ribosomes.

Two major differences between prokaryotic and eukaryotic cells.

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have a nucleus and membrane-bound organelles.

What is the endomembrane system?

A network of membranes including the nuclear envelope, ER, Golgi, lysosomes/vacuoles, transport vesicles, and the plasma membrane that synthesize, modify, sort, and transport cellular products.

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

RER has bound ribosomes and synthesizes proteins destined for membranes or secretion; proteins enter the cisternal space as they are synthesized.

What is the function of the smooth endoplasmic reticulum (SER)?

Synthesis of lipids, carbohydrate metabolism, and detoxification of drugs/poisons.

What is the Golgi apparatus responsible for?

Modifies, stores, and ships proteins and lipids; cis face receives vesicles and trans face ships them.

What are lysosomes and their role?

Membrane-bound sacs with hydrolytic enzymes that digest macromolecules and can trigger apoptosis.

What are vacuoles and how do plant vacuoles differ from animal vacuoles?

Membrane-bound sacs; plant vacuoles are large and central, store water, maintain turgor; animal vacuoles are smaller and involved in storage/transport.

What is the mitochondrion and its main function?

Site of cellular respiration and ATP production; contains cristae to increase surface area and a matrix with enzymes and mtDNA.

What is the role of the cytoskeleton and its three main components?

Supports the cell, aids in movement, and organizes biochemical activities; microtubules (tubulin), microfilaments (actin), and intermediate filaments.

What are peroxisomes and their function?

Detoxify toxins; contain catalase; generate hydrogen peroxide and convert it to water; also break down fatty acids.

What are gap junctions and tight junctions?

Gap junctions provide channels between adjacent animal cells for ions and molecules; tight junctions seal membranes to prevent leakage.

What are cilia and microvilli, and their functions?

Cilia are short, numerous projections used for movement or moving fluid; microvilli increase surface area to aid digestion/absorption.

What are plasmodesmata?

Cytoplasmic channels through plant cell walls that connect adjacent plant cells.

What is the nucleus and its main components?

Houses DNA; components include the nuclear envelope with pores, chromatin, and the nucleolus.

What are ribosomes and where are they located?

Ribosomes synthesize proteins; free ribosomes float in cytosol, bound ribosomes are attached to rough ER or the nuclear envelope.

What is the endosymbiotic theory?

Mitochondria and chloroplasts were once free-living prokaryotes that were incorporated into larger cells; evidence includes circular DNA, bacterial-like ribosomes, and binary fission.

What are chloroplasts and their function?

Sites of photosynthesis in plants and some algae; contain chloroplast DNA and enable conversion of light energy to chemical energy.

What is the plant cell wall and its composition?

A rigid layer outside the plasma membrane made of cellulose and other polysaccharides that provides support and protection.

How do plant and animal cells differ in organelles unique to plants?

Plant cells have central vacuole, chloroplasts, and cell wall; animal cells lack these features.

What is the plasma membrane and its function?

A phospholipid bilayer that encloses the cell and regulates transport and communication with the environment.

What are plasmids and their significance in prokaryotes?

Small circular DNA molecules that can be transferred between cells and often carry accessory genes (e.g., antibiotic resistance).

What is the difference between chromatin and chromosomes?

Chromatin is the diffuse complex of DNA and proteins; chromosomes condense chromatin into discrete structures during cell division.

What distinguishes eukaryotic cells from prokaryotic cells in terms of nucleus?

Eukaryotic cells have a nucleus; prokaryotic cells lack a true nucleus.

What is the function of mitochondria’s cristae?

Cristae increase the inner membrane surface area to boost ATP production.

Which organelles are involved in protein processing and trafficking?

Rough ER, Golgi apparatus, vesicles; lysosomes also participate in degradation and recycling.

What is the centrosome and its role in cell division?

Centrosome contains a pair of centrioles and organizes microtubules to form the spindle during cell division.