AP Biology: Cell Communication I

heterotrophs

consume preformed organic molecules

autotrophs

synthesize organic food molecules by photosynthesis or chemosynthesis

anaerobic

NOT involve oxygen to produce energy (ex: fermentation)

aerobic

US oxygen to produce energy (ex: respiration)

Heterotrophic Hypothesis Stage 1

primitive conditions

• atmosphere: methane (CH4), ammonia (NH4), hydrogen (H2), water vapor (H2O)

• react to form simple cmpds (amino acids, monosaccharides)

Heterotroph Hypothesis Stage 2

organic compounds

simple organic molecules react to form more complex cmpds (proteins, saccharides, lipids) which become building blocks to larger organic molecular complexes

in oceans (“primitive soup”)

Heterotroph Hypothesis Stage 3

aggregation

complex organic molecules formed functional units that utilized smaller cmpds for energy, repair, and become compartmentalized

anaerobic heterotrophs

• first cell-like

• heterotrophs

• derived energy using ANAEROBIC reactions

fermentation

• first energy process that evolved

• enzyme-controlled anaerobic reactions in which energy stored in chemical bonds of molecules (simple sugars - glucose) is released + utilitized

carbon dioxide

• one of the produces of fermentation

• now released in atmosphere

• sets stage for evolution of photosynthesis

anaerobic autotrophs

food in primitive soup is scarce —> INC competition —> natural selection —> organisms make own food

photosynthesis

process of autotrophic nutrition

oxygen

• product of photosynthesis

• released in atmosphere

• sets the stage for aerobic energy reactions

respiration

• more efficient + energy

• evolved by variation and natural selection w/ newly available oxygen

Hetrotroph Hypothesis Pathway

anaerobic heterotrophs —> fermentation —> carbon dioxide —> photosynthesis —> anaerobic autotrophs —> oxygen —> aerobic heterotrophs +autotrophs —> respiration

eukaryotes

• nucleus

• surrounded by membrane structures

• multiple chromosomes composed of DNA + proteins

• ex: protists, fungi, plants, animals

prokaryotes

• NO nucleus

• NO membrane-bound organelles

• SINGLE chromosomes composed of continuous molecule of DNA

• ex: eubacteria & archaebacteria

nucleus

• “command center” of cell

• presence of DNA (genetic material)

chromatin material

• DNA defused thru nucleoplasm

• become visible as chromosomes during cell division

nucleolus

• rounded bodies formed by cluster of loops of chromatin or DNA segments

• functions as assembly of ribosomal subunits from RNA and proteins which are transported back to cytoplasm for protein synthesis

cytoplasm

in eukaryotic:

• general protoplasm of cell (matrix)

• formed by salts and organic compounds dispersed unevenly through a water-based mixture (colloidal dispersion)

in prokaryotic:

• many SMALL ribosomes (appears granular)

• NOT compartmentalized by mebranes (except cyanobacteria)

plasma membrane

• formed by phospholipid molecular network in which protein + cholesterol is embedded

  • arranged in bilayer

  • inward: hydrophobic tails; outward: hydrophilic heads

• eukaryotic (animals and plants)

• prokaryotic (NO cholesterol)

endoplasmic reticulum

• network of membranous sacs and channels

• communication system

• internal transport of molecules

• export of protein

• eukaryotic (animal + plant)

ribosomes

• locate along the membrane chanenls of rough ER

• synthesis of proteins + enzymes

• eukaryotic (plant + animal)

vacuoles

• storage for water, wastes, food

• in plants: large central vacuole INC size of cell

• some cells have specialized vacuoles like protozoans’ contractile vacuole for water removal

• eukaryotic (animals - small + plants - large)

vesicles

• smaller than vacuoles

• involved w/ transport of materials within, into and out of cell

Golgi complex

stack of membranous sacs surrounded by tubules and vesicles

• sites for carbohydrate synthesis

• packaging center

• production of lysosomes

• processes, packages, and distributes lipids + proteins to form glycoproteins and glycolipids

• finished products into transport vesicles

• eukaryotic (animals + plants)

lysosomes

• contain digestive enzymes

• digestion of food inside the cell (intracellular)

• breakdown of old organelles

• “suicide sac”

• eukaryotic (ANIMAL ONLY)

peroxisomes

• assembled by proteins that are synthesized

• substrates broken down by oxidative reactinons including uric acid, amino acids, fatty acids

• in plants: breakdown of toxic hydrogen peroxide

• eukaryotic (animal + plant)

mitochondrion

• double-membraned

• site for cellular resporation

• formation of ATP molecules

cytoskeleton

• maintain cell shape

• allow cell movement, anchor organelles, flow of cytoplasmic streaming

actin filaments (microfilaments)

• type of cytoskeleton

• thread-like protein fibrils through cytoplasm

• each filament has many globular actin molecules

• function to facilitate intracellular movement to include cyclosis (streaming)

microtubules

• type of cytoskeleton

• tube-like protein bundles in the cytoplasm

• formed from globular tubulin proteins

• functions as part of internal skeleton

• structural basis for centrioles, cilia, flagella

cilia and flagella

• formed by nine pairs of fused microtubules surrounding central pair of non-fused microtubules

• transport of materials along the cell surface

• lines trachea + oviduct

• flagella for locomotion and feeding in protists such as euglena

• eukaryotic (ANIMAL ONLY - made of microtubules in a “9+2” arrangement)

• prokaryotic (flagella made of flagellin - not enclosed in membrane)

basal body

• underlies cilia and flagella and anchors them

• nine triplets of microtubules around periphery (no central microtubule)

• transmit ATP nutrients to cilia and flagella

centrioles

• bundles of microtubules

• identical in arrangement to those of basal body

• form spindle fibers

• two centrioles arranged at a right angle to each other

eukaryotic (ANIMAL ONLY)

chloroplast (plastid)

• rounded/oval shaped containing photo pigment chlorophyll arranged in membrane stacks

• Chromoplasts: contain red, yellow, orange

• leucoplasts: NO photopigments, storage sites

• site for photosynthesis

• ekaryotic (PLANT only)

cell wall

• outside the plasma membrane

• middle lamella composed of pectins and other polysaccharides

• primary cell wall composed of cellulose

• protection, rigidity, shape

• eukaryotic (PLANT only - cellulose)

• prokaryotic (peptidoglycan)

plasmodesmata

pores that cross through the cell walls and lamella to connect the cytoplasm of adjacent plant cells

nucleoid

nuclear region or cell that contains genetic material described as a single continuous molecule of DNA

endosymbiotic theory

• explains origin of eukaryotic cells

• endosymbiosis: one organism lives inside cell of another organism w/ mutual benefits

• aerobic and photosynthetic bacteria were engulfed by cells

evidence:

1. presence of DNA in mitochondria + chloroplasts

2. ability of these organelles to reproduce themselves

3. make own proteins

3 Stages of Signal Transduction Pathway

1. reception

2. transduction

3. response

reception

• proteins on cell membrane recognize and bind to signal molecules

• signal molecule: causes a confugulration or shape change to initiate transduction - activates receptor (ligand)

transduction

• conversion of a signal to a form that can bring about a specific cellular response

• activate other proteins and so on until the final cellular response

• involves relay protein molecules

• shape changes associated with phosphorylation (transfer of phosphate group)

protein kinase

kinase in transduction…

transfer phosphate groups from ATP to protein/substrate

protein phosphate

in transduction…

• reverse the effects of protein kinase

• remove phosphate groups from proteins

response

activation of cellular responses

• catalysis by an enzyme

• gene activation in the nucleus

The G-Protein is attached to which side of the membrane?

cytoplasmic

When GDP is attached to G Protein, the G Protein is…
When GTP is attached to G Protein, the G Protein is….

GDP - inactive

GTP - active, changing shape, displaces GDP by GTP

GTPase enzyme

• hydrolyzes its bound GTP to GDP to inactivate and cause the prtoein to leave enzyme

• allows pathway to shutdown when signal molecule is no longer present

second messengers

• carry signals FROM cell surface TO targets inside the cell

• cuz ligand cannot enter the cell, so secondary messengers continue the signal inside the cell