AP Biology Chapter 4

Proteoglycan

• def- large molecule made up of a small core protein with many carbohydrate chains attached

• location: found in the extracellular matrix of animal cells

• composition- up to 5% carbohydrate

Extracellular matrix (ECM)

• Def: the meshwork surrounding animal cells

• Components: Made of glycoproteins, polysaccharides, and proteoglycans

• functions: synthesized and secreted by cells

actin

• Definition: A globular protein that links into chains.

• Structure: Two chains twist helically around each other.

• Function: Forms microfilaments (actin filaments) in muscle and other cells.

lysosome

• Definition: A membrane-enclosed sac of hydrolytic enzymes.

• Location: Found in the cytoplasm of animal cells and some protists.

• Function: Helps break down waste materials and cellular debris.

primary cell wall

• Definition: A thin, flexible layer around the plasma membrane.

• Location: Found in plant cells, particularly young cells.

• Function: Provides structure and support as the cell grows.

centriole

• Definition: Structures in the centrosome of animal cells.

• Structure: Composed of a cylinder of microtubule triplets arranged in a "9 + 0" pattern.

• Function: A centrosome has a pair of centrioles, involved in cell division.

vacuole

• Definition: A membrane-bound sac.

• Function: Specialized for different tasks depending on the type of cell.

golgi apparatus

• Definition: An organelle in eukaryotic cells.

• Structure: Made of stacks of flat membranous sacs.

• Function: Modifies, stores, and routes products from the endoplasmic reticulum (ER). Also synthesizes some products, like noncellulose carbohydrates.

central vacuole 

• Definition: A large membranous sac in mature plant cells.

• Functions:

  • Growth: Helps with cell expansion.

  • Storage: Stores water, nutrients, and waste products.

  • Sequestration: Isolates toxic substances.

Organelles

• Definition: Membrane-enclosed structures in eukaryotic cells.

• Location: Suspended in the cytosol.

• Function: Each organelle has a specialized function (e.g., mitochondria, Golgi apparatus, etc.).

Integrin

• Definition: A transmembrane receptor protein in animal cells.

• Structure: Has two subunits.

• Function: Connects the extracellular matrix to the cytoskeleton.

Transmission Electron Microscope (TEM)

• Definition: A microscope that passes an electron beam through thin sections of a sample.

• Function: Used to study the internal structure of cells.

Endomembrane System

• Definition: A collection of membranes inside and surrounding a eukaryotic cell.

• Function: These membranes are connected by direct contact or vesicle transfer.

Microfilament

• Definition: A cable made of actin proteins in the cytoplasm.

• Function: Part of the cytoskeleton, involved in cell contraction.

• Interaction: Works alone or with myosin to cause movement and contraction in cells.

Centrosome

• Definition: A structure in the cytoplasm of animal cells.

• Function: Acts as a microtubule-organizing center, important during cell division.

• Components: Contains two centrioles.

Gap Junction

• Definition: A type of intercellular junction in animal cells.

• Structure: Made of proteins that form a pore.

• Function: Allows the passage of materials between cells.

Desmosome 

• definition: a type of intercellular junction in animal cells

• Function: act as a rivet, fastening cells together

• structure: Composed of proteins that anchor cells to each other

vesicle

• Definition: A small membranous sac in a eukaryotic cell's cytoplasm.

• Function: Carries molecules produced by the cell 

cytoskeleton

def- a network of microtubules, microfilaments, and intermediate filaments in the cytoplasm.

• Function:

  • Provides mechanical support

  • Aids in transport within the cell

  • Involved in signaling functions.

Eukaryotic Cell 

• Definition: A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles.

• Examples of Organisms: Protists, plants, fungi, and animals.

Middle Lamella

• Definition: A thin layer of adhesive extracellular material.

• Composition: Primarily made of pectins.

• Location: Found between the primary walls of adjacent young plant cells.

secondary cell wall

• Definition: A strong and durable matrix in plant cells.

• Structure: Often deposited in several laminated layers around the plasma membrane.

• Function: Provides protection and support to the cell.

cell wall

Cell Wall

• Definition: A protective layer external to the plasma membrane.

• Found in: Plant cells, prokaryotes, fungi, and some protists.

• Key Components:

  • Cellulose (in plants and some protists)

  • Chitin (in fungi)

  • Peptidoglycan (in bacteria)

• Function: Provides structural support and protection.

glycoprotein

• Definition: A protein with one or more covalently attached carbohydrates.

• Function: Often involved in cell recognition, signaling, and structural roles.

Intermediate Filaments

• Definition: A component of the cytoskeleton.

• Size: Intermediate in size between microtubules and microfilaments.

• Function: Provide structural support and help maintain the cell's shape.

cilia

• Definition: A short appendage containing microtubules in eukaryotic cells.

• Function:

  • Motile: Specialized for movement or moving fluid past the cell.

    • Structure: "9 + 2" arrangement (nine outer doublet microtubules and two inner single microtubules).

  • Primary : Nonmotile, plays a sensory and signaling role.

    • Structure: "9 + 0" arrangement (lacks the two inner microtubules).

tight junction

• Definition: A type of intercellular junction between animal cells.

• Function: Prevents leakage of material through the space between cells.

• Structure: Formed by proteins that seal adjacent cells together.

stroma

• Definition: The dense fluid within the chloroplast.

• Location: Surrounds the thylakoid membrane.

• Components: Contains ribosomes and DNA.

• Function: Involved in the synthesis of organic molecules from carbon dioxide and water (e.g., during the Calvin cycle).

nuclear lamina

• Definition: A netlike array of protein filaments.

• Location: Lines the inner surface of the nuclear envelope.

• Function: Helps maintain the shape of the nucleus.

nucleolus

• Definition: A specialized structure in the nucleus.

• Composition: Contains chromosomal regions with ribosomal RNA (rRNA) genes and ribosomal proteins from the cytoplasm.

• Function: Site of RNA synthesis and ribosomal subunit assembly.

food vacuole

• Definition: A membranous sac formed by phagocytosis.

• Function: Encapsulates microorganisms or particles to be used as food by the cell.

• Formation: Created when the cell engulfs material by phagocytosis.

Chromosome 

• Definition: A cellular structure made up of one DNA molecule and associated proteins.

• In Eukaryotes: Multiple, linear chromosomes located in the nucleus.

• In Prokaryotes: A single, circular chromosome located in the nucleoid (no membrane).

Rough Endoplasmic Reticulum (Rough ER)

• Definition: The portion of the endoplasmic reticulum with ribosomes attached.

• Function: Involved in protein synthesis and modification.

Flagella

• Definition: A long cellular appendage specialized for locomotion.

• Eukaryotic Flagella:

  • Structure: "9 + 2" arrangement (nine outer doublet microtubules and two inner single microtubules).

  • Function: Helps in cell movement, enclosed by plasma membrane.

Fibronectin 

• Definition: An extracellular glycoprotein secreted by animal cells.

• Function: Helps cells attach to the extracellular matrix (ECM).

• Role: Important for cell signaling and maintaining cell structure.

Basal Body

• Definition: A eukaryotic cell structure with a "9 + 0" arrangement of microtubule triplets.

• Function: Organizes the microtubule assembly of a cilium or flagellum.

Peroxisome

• Definition: An organelle containing enzymes that transfer hydrogen atoms to oxygen (O₂), producing hydrogen peroxide (H₂O₂).

• Function: Degrades hydrogen peroxide into water and oxygen to prevent damage to the cell.

• Role: Involved in various metabolic processes, like lipid metabolism and detoxification.

Prokaryotic Cell 

• Definition: A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles.

• Examples of Organisms: Bacteria and archaea.

Phagocytosis

• Definition: A type of endocytosis in which large particulate substances or small organisms are engulfed by a cell.

• Carried Out By: Some protists and certain immune cells in animals (e.g., macrophages, neutrophils, and dendritic cells in mammals).

• Function: Helps with the ingestion of harmful particles, pathogens, or dead cells.

Contractile Vacuole

• Definition: A membranous sac that helps remove excess water from certain freshwater protists.

• Function: Pumps excess water out of the cell to maintain osmotic balance and prevent the cell from bursting.

cytoplasm

• Definition: The contents of the cell enclosed by the plasma membrane.

• In Eukaryotes: Includes everything except the nucleus.

• Function: Site of most cellular processes, including metabolism and organelle functions.

Ribosome

• Definition: A complex of RNA and protein molecules that functions as the site of protein synthesis in the cytoplasm.

• Structure: Consists of a large subunit and a small subunit.

• In Eukaryotes: Each subunit is assembled in the nucleolus.

Mitochondrion

• Definition: An organelle in eukaryotic cells that is the site of cellular respiration.

• Function: Uses oxygen to break down organic molecules and synthesize ATP (energy).

Microfilament

• Definition: A cable made of actin proteins in the cytoplasm of eukaryotic cells.

• Function: Part of the cytoskeleton, involved in cell contraction.

• Interaction: Works alone or with myosin to cause cell movement and contraction.

Mitochondrial Matrix

• Definition: The compartment of the mitochondrion enclosed by the inner membrane.

• Contents:

• Enzymes and substrates for the citric acid cycle (Krebs cycle).

• Ribosomes and DNA.

• Function: Site of important metabolic reactions, including the citric acid cycle, for
  ATP production.

Collagen 

• definition: a glycoprotein in the extracellular matrix of animal cells

• function: forms strong fibers, providing structural suppport.

• location: found extensively in connective tissue and bone

cell fractionation

def- the disruption of a cell and separation of its parts by centrifugation at successively higher speeds

• purpose: Allows the isolation of different cellular components for study 

• process: components are speparated based on size and density 

myosin

def: a type of motor protein that associate into filaments

function: interacts with actin filaments to cause cell contraction

role: important in muscle contraction and many cell movements processes

Peroxisome

Definition: An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (02), producing hydrogen peroxide (H202).

• Function: Degrades hydrogen peroxide into water and oxygen to protect the cell.

• Role: Involved in detoxification and lipid metabolism.

light microscope

Microtubule

• def: a hollow rod composed of tubulin proteins

• function: Part of the cytoskeleton in all eukaryoptic cells

dynein

• def: A large motor protein in cilia and flagella

• function: Extends from one microtubule doublet to the adjacent doublet, driving movement

Plastid

• def: A family of closely related organelles

• Types: chloroplast, chromoplasts, and amyloplasts

• Function: involved in photosynthesis, pigment synthesis, and storage

scanning electron microscope (SEM)

• def: a microscope that uses an electron beam to scan the surface of a sample

• function: studies details of the sample’s topography 

Thylakoid

• def: a flattened, membranous sac inside a chloroplast

• structure: often exists in stacks called grana, which are interconnected

• function: The membranes contain molecular machinery for converting light energy into chemical energy

Endoplasmic Reticulum (ER)

• def: An extensive membranous network in eukaryotic cells

• structure: continuous with the outer nuclear membrane

vesicle

• def: a small membranous sac in a eukaryotic cell’s cytoplasm

• function: carries molecules produced by the cell

• role: involved in transporting substances within and outside the cell

chromatin

• def: the complex of DNA and proteins that makes up eukaryotic chromosomes

• structure: when the cell is not dividing, it is in a dispersed form as long, thin fibers

smooth endoplasmic reticulum (Smooth ER)

• def: the portion of the endoplasmic reticulum that is free of ribosome

• function: involved in lipid synthesis, detoxification, and calcium ion storage

Plasma Membrane

• def: the membrane at the boundary of every cell

• function: acts as a selective barrier, regulating the cell’s chemical composition

plasmodesma

• def: an open channel through the cell wall that connects the cytoplasm of adjacent plant cells

• function: allows water, small solutes, and some larger molecules to pass between cells

nucleus

• def: atomic: the central core of an atom, containing protons and neutrons

• cellular: the organelle in eukaryotic cells that contains genetic material in the form of chromosomes, made up of chromatin

• neutral: a cluster of neurons, typically in the brain or spinal cord