Chapter 4 Inside the Cell

Flashcards cover key concepts from Chapter 4: Inside the Cell, including organelles, cell types, membranes, and cellular processes.

What is the primary function of the plasma membrane?

To mark the boundary between the cell’s interior and exterior and regulate the entry and exit of substances; it is a phospholipid bilayer with embedded proteins, described by the fluid mosaic model.

Name the main types of membrane proteins and their general roles.

Channel proteins form tunnels for specific molecules; Transport proteins move molecules across the membrane (often using energy); Receptor proteins bind signal molecules to trigger cellular responses; Enzymatic proteins catalyze reactions; Cell recognition proteins help identify self vs. non-self; Junction proteins form connections between cells.

What are the two main types of cells and a key distinguishing feature of each?

Prokaryotic cells lack a membrane-bound nucleus; Eukaryotic cells have a nucleus that houses their DNA.

Where is DNA located in prokaryotic cells and what is this region called?

In the nucleoid, a single circular chromosome located in the cytoplasm (not membrane-bound).

What components comprise the endomembrane system?

Nuclear envelope, endoplasmic reticulum (ER), Golgi apparatus, and numerous vesicles that transport materials between them.

How do Rough ER and Smooth ER differ in structure and function?

Rough ER has ribosomes on its surface and modifies proteins; Smooth ER lacks ribosomes and synthesizes lipids and detoxifies substances.

What is the Golgi apparatus responsible for?

Receiving vesicles from the ER, modifying and sorting their contents, and packaging them for delivery; it also contributes to lysosome formation in some cells.

What are lysosomes?

Vesicles containing digestive enzymes that break down molecules or old cell parts.

What are mitochondria and what crucial process occurs there?

Energy-related organelles where cellular respiration occurs to produce ATP; they have a double membrane, cristae, and a matrix with enzymes, DNA, and ribosomes.

What are chloroplasts and what are their key features?

Organelles that perform photosynthesis in plants and algae; contain thylakoids (granum) and stroma, have their own DNA and ribosomes, and a three-membrane system.

Describe the cytoskeleton and its importance.

A network of protein filaments extending from the nucleus to the plasma membrane that maintains cell shape and provides tracks for movement of organelles and vesicles.

Name the motor proteins and their general roles.

Myosin interacts with actin for muscle contraction and amoeboid movement; Kinesin and Dynein move along microtubules to transport vesicles and organelles.

What are centrioles and where are they located?

Two centrioles made of nine microtubule triplets located at the centrosome; present in animal cells but not in most plant cells.

Describe the structure and difference between cilia and flagella.

Both have a 9+2 arrangement of microtubules; cilia are short and numerous, while flagella are longer and fewer.

What distinguishes plant cell walls and plasmodesmata?

Plant cell walls are made of cellulose (primary) and sometimes lignified secondary walls; plasmodesmata are channels through cell walls that connect adjacent plant cells.

What is the extracellular matrix (ECM) and its main components?

A meshwork of fibrous proteins and polysaccharides outside animal cells; major components include collagen (resists stretching) and elastin (provides resilience).

What are the three main types of cell junctions and their functions?

Adhesion junctions connect cells via cytoskeletal linkages; Tight junctions form impermeable barriers between cells; Gap junctions create channels for intercellular communication.

Why are cells typically small, and what is the role of microvilli?

Small cells have a higher surface-area-to-volume ratio, enhancing exchange with the environment; microvilli increase surface area to aid nutrient absorption.

What are chromatin, chromosomes, nucleolus, and the nuclear envelope?

Chromatin is diffuse DNA-protein in the nucleus; before cell division it condenses into chromosomes; the nucleolus makes rRNA; the nuclear envelope surrounds the nucleus and contains nuclear pores.

Where are ribosomes located and how do they differ in eukaryotes?

Ribosomes are in the cytoplasm and can be free or attached to the rough ER; in eukaryotes, ribosomes are 80S (cytosolic) or attached to ER, while prokaryotes have 70S-type ribosomes (note: this detail is general biology knowledge; the notes indicate ribosomes are in prokaryotes and eukaryotes).

Outline the path for a lysosomal hydrolase from synthesis to lysosome.

Translated on the rough ER, transported to the Golgi for processing and targeting, then delivered to lysosomes via vesicles.

What is plasmodesmata?

Channels through plant cell walls that connect adjacent plant cells and allow transport of water and small solutes.

What is the extracellular matrix and its main function in animals?

A meshwork of fibrous proteins and polysaccharides outside cells that provides structural support and mediates cell signaling; major components include collagen and elastin.

What is the difference between primary and secondary plant cell walls?

Primary walls form during growth; secondary walls form inside the primary wall in some cells (e.g., woody plants) and are thicker with lignin for extra strength.

What is the role of vacuoles?
And how do they differ from vesicles?

Vacuoles are larger membranous sacs involved in storage and water balance (e.g., central vacuole in plants); vesicles are smaller transport packages within the cell.

What is the path diagram of an endomembrane transport vesicle?

Transport vesicles move molecules from one part of the endomembrane system to another (ER → Golgi → other destinations, including lysosomes or plasma membrane).