Unit 2 APBIO Test Review

Prokaryote

A cell that is basic, not membrane bound, and includes bacteria and archaea.

• flagella - tail like whip

• cilia- hair like structure

• free floating organelles

• unicellular

Eukaryote

A complex cell type that includes animal and plant cells, characterized by membrane-bound organelles.

• has nucleus

• animals, plants, fungi, protists

• uni or multi cellular

Endosymbiotic theory

The theory that chloroplasts and mitochondria were once free-living prokaryotic cells engulfed by a larger cell, forming a symbiotic relationship.

Endosymbiont

A cell that lives within another cell.

Cell wall

The rigid outer layer of plant cells that provides structural support and protection, made of cellulose.

Chloroplasts

Organelles in plant cells and algae where photosynthesis occurs, converting solar energy into chemical energy.

• thylakoids: coin stacks (part of grana)

• stroma: (surrounding fluid)

• chlorophyll: green pigment, captures light energy

Vacuoles

Fluid-filled sacs in cells that store materials including waste, nutrients (water), and food.

• animals have smaller

• plants = large center vacuole

Surface area to volume ratio

A ratio that impacts the efficiency of material exchange in cells

• smaller cells have a higher ratio than larger cells.

  • bigger volume, smaller surface area = less efficiency

  • this is why cells are small

Cytoplasm

The structural support for cells

• the jelly-like fluid that fills cells.

Nucleus and Nucleoli

The storage area for most of the genetic information in a cell.

• has “pores” to let stuff in and out

• nucleoli - where ribosomes are created (protein synthesis) , within the nucleus

Endoplasmic Reticulum (ER)

Thin folded membranes that produce, process, and distribute proteins and lipids.

Rough Endoplasmic Reticulum (rER)

The part of the ER that has ribosomes on its surface and is involved in protein synthesis. (modifies proteins)

Smooth Endoplasmic Reticulum (sER)

The part of the ER that is involved in lipid synthesis and does not have ribosomes.

Golgi Apparatus

Layers of enclosed spaces that process, sort, and deliver proteins.

Mitochondria

The powerhouse of the cell, supplying energy through ATP and the site of cellular respiration.

• double membrane

• cellular respiration

  • C6H12O6 —> 6CO2+6H2O+ATP

Lysosomes

Membrane-bounded organelles that contain enzymes for recycling cellular waste.

• destroys invaders

• breaks down carbs, lipids, + proteins

Centrioles

Cell structures that help divide DNA during cell division.

• have spindle fibers inside microtubules

Extracellular Matrix (ECM)

A network outside the cell that provides structural and biochemical support to surrounding cells.

• function to modify, package, and transport lipids and proteins

Fluid Mosaic Model

A model that describes the structure of the plasma membrane as a mosaic of components, including phospholipids, cholesterol, and proteins.

• semi permeable

  • fatty acid tail (hydrophobic), phosphate head

• bilayer (double layer)

• extracellular = exterior

• intracellular = interior

Carbohydrates

act as ID markers on top of plasma membrane

• usually bonded to lipids and proteins

• glycolipids: lipids + carbs (covalent)

• glycoprotein: proteins + carbs

  • act as signal receptors and with cell adhesion

Cholesterol

• stabilizes membrane and helps with fluidity/rigidness

• high temperatures = restricts movement

  • keeps it from getting too fluid

• low temperatures = spaces out fatty acid tails

  • keeps it from solidifying and becoming rigid

Phospholipids

• AMPHIPATHIC!

• Hydrophilic (polar) heads = extracellular

• hydrophobic (non polar, fatty acid) tail = intracellular

Hydrophilic

Molecules that are water-loving and polar. (phospholipid head)

Hydrophobic

Molecules that are water-fearing and nonpolar. (phospholipid tail)

Integral Proteins

• embedded in membrane with hydrophobic interior + hydrophilic end

• only pokes out of one side of the membrane

• transmembrane !

Transmembrane proteins

• span entire lipid bilayer with parts exposed to cytoplasm and extracellular side

• hydrophilic ends and hydrophobic interior

Peripheral Proteins

• hang to extra or intracellular region of cell membrane

• held by cytoskeleton or ECM

Aquaporins

• channel, transmembrane, facilitated diffusion, passive transport

• helps move water across membrane

  • (too big and polar)

• example of a channel and transmembrane protein

• hydrophilic

  • water passes through nonpolar hydrophilic intracellular region

Selective permeability

The property of the cell membrane that allows some substances to pass through while preventing others.

small nonpolar molecules

can pass through membrane w/ simple diffusion

large polar molecules

can pass through membrane w/ facilitated diffusion (protein transports)

Passive transport

Movement of molecules across the membrane

• without needing energy

• following the concentration gradient.

• HIGH TO LOW

• facilitated diffusion, diffusion, osmosis, passive transport = NO ATP!

Active transport

Movement of molecules against their concentration gradient

• requiring energy (ATP).

• LOW TO HIGH

• active transport, endocytosis, exocytosis

Endocytosis

• enters the cell (formation of vesicles to take molecules to surface of membrane)

phagocytosis

• type of endocytosis

• engulfs FOOD

• “FATgocytosis”

pinocytosis

• type of endocytosis

  • engulfs WATER

  • “PEEnocytosis”

Receptor-Meditated Endocytosis

• receptors on surface of membrane bond to certain molecules to form a vesicle

• takes it into the membrane

Exocytosis

• EXITS the cell

• fusion of vesicles to membrane to release molecules

Osmosis

• movement of WATER from HIGH to LOW

• low water = high solute

• high water = low solute

Simple diffusion

• no NRG

• small nonpolar molecules cross membrane by themselves

Facilitated diffusion

• no NRG

• large polar molecules cant cross membrane W/O help of proteins

• interior of bilayer = hydrophobic

  • fatty acid chains

Channel Protein

• embedded into bilayer

• lets specific molecules through tunnel

Carrier protein

• molecules goes through change in shape when moving through

• ex. sodium potassium pump

Ion Channels

• specific ions can diffuse across membrane

• often gated channels that open/close based on stimulus

Tonicity

The ability of a solution to affect the shape of cells by altering their internal water volume.

Hypertonic solution

A solution with a higher concentration of solutes compared to another, causing water to flow out of cells.

Isotonic solution

A solution with equal concentrations of solutes inside + outside of a cell

• no net movement of water.

  • water is constantly flowing in and out but in = amounts

Flaccid

• equal amounts of water going in and out of a plant

  • not wilted

  • low pressure

  • cells are soft

Hypertonic

• “hyper child” = skinny

• solution has more solute than cell, water moves out of the cell

Plasmolyzed

• cell membrane pulls away from cell wall

• looks like cheese?

• water leaves plant cell

Hypotonic solution

A solution with a lower concentration of solutes compared to another, causing water to flow into cells.

Turgid

• more water flows into cell

• creates PRESSURE

• preferred environment for plant cells

• TURGOR PRESSURE

Water potential

The potential energy of water in a system, affecting the direction of water movement.

• water moves from high to low (toward NEGATIVE water potential)

• water potential = solute potential + pressure potential

pressure of pure water + plant cells

water: 0

plant: 1

Solute potential

• adding solute = more negative

  • DECREASING water potential

• solute moves from low solute to high solute

• solute potential = ionization constant* R* (kelvin + temp)

  • S=iRT

Ionization constant and pressure constant (R)

sucrose =-1

NaCl = -2

• pressure constant = .0831

temperature

• always convert to kelvin 273 + Celsius)

Transport Proteins

• diffuse substances in and out of cell (channel + carrier)

  • aquaporins

  • glucose transporter

  • gated channel proteins

Sodium-Potassium Pump

• active transport mechanism

• 3 sodium ions out + 2 potassium ions in

• against concentration gradients

• NA 3 go in —> atp opens to extracellular side —> NA go out —> protein change shape (phosphorylation) —> open on extracellular —> 2 K+ go in (likes new shape) —> goes into cell

electrochemical gradient

difference in ± charge

Chemical gradient

• concentration of ions and their difference

Co-Transport

A method of active transport where the movement of one molecule helps to move another molecule against its gradient.

Proton Pump

A transport protein in the plasma membrane that uses energy to move protons (H+) across the membrane, creating a proton gradient used in processes such as ATP synthesis.