Chapter 7 - Inside the Cell

Long, thin protein filaments in the cytoplasm that maintain cell shape and are essential for cell division.

They are tiny, sun-catching sheets inside cells containing enzymes and pigments that convert sunlight into chemical energy.

• They are basically the solar panels for the cell

A tough, fibrous layer that surrounds the plasma membrane, providing shape and protection.

• In bacteria, the cell wall is mostly made of polysaccharide peptidoglycan w/ a glycolipid outer membrane (only some)

Flagella are long filaments that rotate to propel the cell; fimbriae are needlelike projections that help with attachment.

• Allow prokaryotes to interact with their environment (move or attach)

Compartmentalization separates incompatible reactions and increases chemical reaction efficiency

A large, highly organized organelle

• Surrounded by a double-membrane nuclear envelope -- has pores & the nuclear lamina

• Stores DNA and contains the nucleolus for RNA and ribosome subunit synthesis.

• Extensive membrane-enclosed factory

• Rough ER has ribosomes and synthesizes proteins; smooth ER lacks ribosomes and synthesizes lipids and breaks down poisonous lipids & other molecules.

Has distinct polarity -- cis = closest to nucleus, trans = surface oriented toward plasma membrane

• Cis = where proteins from ER are received; trans = where vesicles bud off for shipment of products

Animal cell organelles containing acid hydrolases that digest macromolecules at acidic pH.

• Aka the recycling centers (containing many types of hydrolyzing enzymes-"acid hydrolases")

Storage organelles for water, ions, proteins, pigments, and noxious compounds (protect leaves and stems from being eaten); also involved in digestion.

• Organelles that perform redox reactions and detoxify hydrogen peroxide.

• Originate when empty vesicles from ER are loaded with peroxisome-specific enzymes from cytosol.

  • Essentially, the cells cleanup and detoxify center

Double-membrane organelles that produce ATP & contain their own DNA.

• Two membranes: outer and inner membrane; the inner membrane is folded into a series of sac-like cristae

• Has mitochondrial matrix - solution enclosed within the inner membrane

Proposes that key organelles inside eukaryotic cells—specifically mitochondria and chloroplasts—originated as independent free-living prokaryotic bacteria that were engulfed by a larger host cell and formed a permanent, cooperative relationship.

Actin filaments, intermediate filaments, and microtubules.

Smallest filaments involved in cell shape, movement, and cytokinesis, often interacting with myosin motor proteins.

Fibrous proteins like keratins that provide mechanical support and form the nuclear lamina.

Largest cytoskeletal elements made of tubulin dimers; involved in chromosome separation and vesicle transport.

Convert ATP chemical energy into mechanical work to move vesicles along microtubules

Have a '9 + 2' microtubule axoneme arrangement with nine doublets surrounding two central microtubules.

Tiny channels that connect neighboring plant cells, allowing them to communicate and exchange materials.

Tight junctions prevent leakage, desmosomes anchor cells, and gap junctions allow cytoplasmic communication.

The dense, fibrous protein meshwork lining the inner nuclear membrane, which provides structural support and is involved in cell division and nuclear transport.

Cristae are folds of the inner mitochondrial membrane, while cisternae are flattened, membrane-bound sacs found in the endoplasmic reticulum and Golgi apparatus

Gel-like space inside the inner mitochondrial membrane.

• Metabolic Center: Enzymes for the citric acid cycle, pyruvate oxidation, and fatty acid breakdown produce e⁻ carriers.

• Genetic Hub: Contains circular mtDNA and ribosomes to make some proteins independently of the nucleus.

They both contain their own DNA and manufacture their own ribosomes

• Fungi, algae, and plants

• Provides durable outer layer & gives cell structural support

• The extracellular matrix (ECM)

  • Why? --> Animal cells lack a cell wall

  • It diffuses a mixture of secreted proteins and polysaccharides

Technique used by researchers to isolate cell components and analyze chemical composition

• Information center of eukaryotic cells; decode & process genetic information; produce mRNA

• Site of ribosome assembly

  • Ribosomal RNA binds proteins to form ribosomes

  • Messenger RNA (mRNA) carries information to synthesize proteins

• Tiny, essential cellular machine made of ribosomal RNA (rRNA) and proteins that builds proteins for the cell

• Separates the nucleus from rest of the cell; has openings called nuclear pore complexes; ~ 30 different proteins

• Acts as gate to control access to nuclear envelope

• Nuclear proteins contain 17-amino-acid-long nuclear localization signal (NLS)

  • The "zip code" - marks proteins for transport through nuclear pore complex/allows them to enter

  • Directs nucleoplasmin to nucleus (protein that helps organize DNA)

Each protein must have a specific zip code and delivery system to get to correct location

• Ex: acid hydrolases (break down proteins) must be shipped to lysosomes

• The secretory pathway is the step-by-step route cells use to synthesize proteins in the Rough ER, package them into vesicles, modify and sort them in the Golgi apparatus, and deliver them to the plasma membrane for external release via exocytosis.

• Pulse chase experiment

• Tracked protein movement

• Pulse - label cells by exposing cells to radioactive amino acids

• Chase - wash away modified amino acids & replace with normal version of molecule

  • Showed the path of proteins in the endomembrane system - secretory path exists

Explains how cells target protiens for the endomembrane system

• They all have a molecular zip code which directs the growing polypeptide to RER

• Zip code is 20-amino-acid-long ER signal sequence

• 17-amino-acid-long nuclear localization signal (NLS)

• Zip code is 20-amino-acid-long ER signal sequence