AP Biology Vocab and Review Unit 2: Cells

Cells

the basic structural and functional; units of every organism

Prokaryotes

domains Bacteria and Archaea; cells that contain DNA in the nucleoid, are generally smaller in size, and lack membrane bound organelles

Eukaryotes

includes Protists, fungi, animals, and plants; cells that have DNA in the Nucleus and contain membrane bound organelles that compartmentalize cellular functions

Chromosomes

condensed form of DNA that contains proteins

Organelles

membrane bound structures in eukaryotes

Nucleus

organelle that contains genetic material and is surrounded by the nuclear envelope

Nucleolus

dense region of the nucleus where ribosomal RNA (rRNA) is synthesized

Ribosomes

synthesizes proteins and is comprised of ribosomal RNA and protein

Rough ER

contains ribosomes bound to the ER membrane and compartmentalizes protein synthesis

Smooth ER

contains no ribosomes, synthesizes lipids, and detoxifies cell

Cisternae

membranous sacs; make up ER and Golgi

Golgi

contains flattened membranous sacs, has directionality (cis face and trans face). receives transport vesicles from ER then modifies, sorts, add tags to, and packages materials into new vesicles

Lysosomes

membranous sac with hydrolytic enzymes in animal cells; hydrolyzes macromolecules, autophagy, and play a role in apoptosis

Autophagy

lysosomes can recycle their own cells organic materials and organelles that are not functioning properly

Peroxisomes

membrane bound metabolic compartment— catalyzes reactions that produce H2O2, breaks down fatty acid molecules, synthesizes certain phospholipids, and detoxifies compounds

Vacuoles

in animal cells, organelles that are small in size, assist in endocytosis/exocytosis, and store cellular materials

in plant cells, organelle that stores nutrients and water (important for turgor pressure) and can function like lysosomes. plant cells have a central vacuole

Mitochondria

site of cellular respiration and has a double membrane that divides mitochondria into two compartments; the intermembrane and the mitochondrial matrix

Chloroplasts

specialized organelles in plants and photosynthetic algae; site of photosynthesis and contains green pigment chlorophyll

Thylakoids

membranous sacs that can organize into stacks called grana

Grana

a stack of thylakoids; where light dependent reactions occur

Stroma

fluid around thylakoids where Calvin cycle takes place

Endosymbiotic Theory

theory that mitochondria and chloroplasts evolved form once free-living prokaryotes via endosymbiosis (they were engulfed by ancestral eukaryotic cell) — prokaryote become an endosymbiont and cell become one functional organism

Microtubules

thickest filaments in cytoskeleton that serve as structural support for movement of organelles, assist in the movement of chromosomes during cell division, and cell motility

Microfilaments

thin, solid rods made of the protein actin, functions are to maintain cell shape, assist in muscle contraction and cell motility, and division of animal cells (contractile ring of cleavage furrow)

Intermediate Filaments

fibrous proteins made up of varying subunits that are the permanent structural elements of cells. functions are to maintain cell shape, anchor nucleus and organelles, and form nuclear lamina

Actin

protein that makes up microfilaments; work with myosin to cause muscle contraction

what organelles are in animal cells, but not in plant cells?

lysosomes, flagella, and centrosomes

what organelles are in plant cells, but not in animal cells?

cell wall, chloroplasts, plasmodesmata, central vacuole

how do ribosomes help carry out instructions encoded in DNA

ribosomes translate messages found on mRNA into the primary structure of polypeptides

differentiate between the rough and smooth ER

The rough ER has ribosomes and compartmentalizes protein synthesis. The smooth ER has no proteins and its function is to detoxify the cell and synthesize lipids

Main differences between prokaryotic and Eukaryotic cells

Prokaryotic cells domain Bacteria and Archaea, contain DNA in the nucleoid, are generally smaller in size, and lack membrane bound organelles. Eukaryotic cells domain protists, fungi, plants, and animals, contain DNA in the nucleus, and contain membrane bound organelles that compartmentalize functions

describe the Endomembrane System

the Endomembrane System consists of organelles and subcellular components that interact (directly or via vesicles) to modify, package, and transport polysaccharides, proteins, and lipids

Trace the path of a protein, from production to final product

During Transcription in the nucleus, the DNA sequence of a gene is copied into messenger RNA. It then undergoes processing to prepare for translation and exits via nuclear pores. The mRNA is translated by a ribosome (either by one on the RER or by a free ribosome) into a polypeptide chain. Here, the polypeptide is folded into a specific 3D shape. The protein is packaged into a vesicle and sent to the Golgi. The Golgi modifies, sorts, adds molecular tags to, and packages the protein in a new vesicle where it is sent to the plasma membrane for secretion, or to somewhere inside the cell.

Plants have a cell wall, therefore, they do not have a cell membrane. true or false?

false, plants have both a cell wall and a cell memebrane

How is the Golgi similar to a warehouse/mail facility?

Like a warehouse/mail facility, the Golgi modifies, sorts, add tags to, and packages the materials it receives.

describe how the SA:V ratio should be in order for cells to optimize exchange of materials through the plasma membrane

the SA:V ratio must be high

Propose problems that would occur if a single cell were to keep getting larger and larger over time

It would be extremely difficult for the cell to regulate what comes in a =nd goes out of the plasma membrane. The cells would lose efficiency exchanging materials, have a high cellular demand for resources, and a very low rate of heat exchange;

Amphipathic

having both a hydrophilic and hydrophobic region 

Hydrophillic

Polar, orients TOWARD aqueous environments

Hydrophobic

Nonpolar, orient AWAY from aqueous environments

Fluid mosaic model

fluid: membrane is held together by weak hydrophobic interactions and can therefore move and shift

mosaic: comprised of many macromolecules

Intergral Proteins

Proteins that are embedded into the lipid bilayer that can be hydrophilic, hydrophobic, or both

Peripheral Proteins

Proteins that are not fully embedded into the lipid bilayer; loosely bonded to the surface

Glycolipids

Carbohydrates bonded to a lipid

Glycoproteins

carbohydrates bonded to a protein (most abundant)

what is the purpose of a plasma membrane?

the purpose of the plasma membrane is to separate the internal cell environment from the external cell environment

What is the difference between saturated and unsaturated tails of the phospholipids

Saturated fatty acids have no double bonds, have more hydrogen, and are more solid at room temp. Unsaturated fatty acids have one or more double bonds, have kinks (bends), and are more liquid at room temperature

what molecule embeds itself within the membrane and affects fluidity? How does it affect fluidity?

Cholesterol embeds itself within the membrane and affects fluidity by preventing tight packing of phospholipids in low temperature and reducing movement in high temperatures

Differentiate between integral and peripheral proteins

Integral proteins are embedded into the lipid bilayer while peripheral proteins not fully embedded into the bilayer and are loosely bonded to the surface.

How are human cells able to maintain membrane fluidity when they are in cold temperatures

The presence of cholesterol and unsaturated fatty acids prevent tight packing of phospholipids and help maintain fluidity.

Selective Permeability

the ability of a membrane to regulate the substances that enter and exit– due to hydrophobic interior: nonpolar hydrophobic tails

polar

having an uneven distribution of charge across a molecule

nonpolar

having an even distribution of charge across a molecule

charged

having a net positive or negative charge due to the gain or loss of electrons

what qualities of the plasma membrane make it selectively permeable

The nonpolar hydrophobic tails on the interior of the plasma membrane are what makes it selectively permeable

are nonpolar molecules hydrophillic or hydrophobic? what does this mean for their passage across the membrane

nonpolar molecules are hydrophobic, meaning they have easy, unassisted passage across the membrane

are polar molecules hydrophillic or hydrophobic? what does this mean for their passage across the membrane

polar molecules are hydrophillic, meaning that they have difficult passage or protein assisted passage across the membrane

If plants have a cell wall, then they cannot exchange material through their plasma membrane. True or False? Why?

False, plant cells exchange material through their plasma membrane via plasmodesmata (hole-like structures filled eith cytosol) in their cell wall

what are cell walls composed of

cellulose

What kind of cells have a cell wall? What is the purpose of a cell wall?

Bacteria, Archaea, Fungi, and Plants have cell walls. Cells walls provide a structural boundary, a permeability barrier for some substances, and protection from osmosis lysis.

passive transport

transport of molecule that does not require energy from the cell because a solute is moving with it concentration or electrochemical gradient

diffusion

spontaneous process resulting from the constant motion of molecules, substances move from high to low concentration

osmosis

the diffusion of water across a semi permeable membrane

facilitated diffusion

diffusion of molecules through the membrane via channel or carrier protein

channel proteins

form an open pore/channel in the membrane and moves charged ions; Most have high selective and have“gates’ that can open and close in response to stimuli

carrier proteins

Alternate between two conformations and move large polar molecules like glucose/ sugars, amino acids, nucleosides

aquaporins

specialized channel proteins for water

Active Transport

transport of a molecule that requires energy because it moves a solute against its concentration gradient

Exocytosis

the secretion of molecules via vesicles that fuse to the plasma membrane

• Vesicles can fuse to the membrane by forming a bilayer

• Once fused, the contents of the vesicle are released to the extracellular fluid

Endocytosis

the uptake of molecules from vesicles fused from the plasma membrane (opposite of exocytosis)

• The cell membrane fold inward → this forms a vesicle→ vesicle pinches off and moves into cell

Phagocytosis

when a cell engulfs particles to be later digested by lysosomes

• Cell surround particle with pseudopodia → packages particle into food vacuole → food vacuole fuses with a lysosome to be digested

Pinocytosis

nonspecific uptake of extracellular fluid containing dissolved molecules

receptor mediated endocytosis

specific uptake of molecules via solute binding to receptors on plasma membrane

• Allows cell to take up large quantities of a specific substance

• When solutes bind to receptors, the cluster in a coated vesicle to be taken up into the cell 

How are molecules able to go through diffusion? (what about them allows for this process)

the spontaneous movement of molecules allows them to go through diffusion

Sodium potassium pump

 animal cells will regulate their relative concentrations of Na+ and K+— 3 Na+ get pumped out of the cell, and 2 K+ get pumped into the cell; resulting in a +1 net charge to the extracellular fluid

cotransport

 the coupling of a favorable movement of one substance with an unfavorable movement of another substance. Uses energy stored in electrochemical gradients

sucrose-H+ cotransporter- Sucrose can travel up into a plant cell against its concentration gradient ONLY if it is coupled with H+ that is diffusing down its concentration gradient

proton pumps

integral membrane protein that build up a proton gradient across the membrane; Pumps H+ out of the cell and is used by plants, fungi, and bacteria

ATP

Adenosine triphosphate (ATP): energy source used by cells; can transfer the terminal phosphate group to the transport protein, which changes the shape of the transport protein to better move a substance (conformational change)

is facilitated diffusion a type of active ro passive transport? Why?

no, because it does not require energy and still moves substances down their concentration gradient

what are two ways that water can pass though cell membranes

either osmosis or aquaporins

difference between concentration gradient and chemical gradient

Concentration gradient: can refer to the difference in concentration of anything

chemical gradient: specifically refers to the concentration gradient of a cell membrane

Tonicity

the ability of an extracellular solution to cause a cell to gain or lose water (Depends on the concentration of unpenetrating solutes)

Osmoregulation

cells must be able to regulate their solute concentrations and maintain water balance

Isotonic Solutions

• NO net movement of water

  • The concentration of nonpenetrating solutes inside the cell is equal to that outside the cell

  • Water diffuses into the cell at the same rate water moves out of the cell

Hypertonic (more solute) solutions

• Cells immersed in a hypertonic solution lose water to their extracellular surroundings

  • The concentration of nonpentrating solutes is higher outside the cell

  • Water will move to extracellular fluid

    • Plasmolysis: vacuole shrinks and plasma membrane pulls away from cell wall

• Solution is HYPERTONIC, cell is HYPOTONIC

Hypotonic (less solute) solutions

• Cells immersed in a hypotonic solution gain water

  • The concentration of nonpenetrating solutes is lower outside the cell 

  • The cell will gain water

    • Animal cells swell and lyse (burst)

    • Plants work optimally and maintain turgor pressure

• Solution is HYPOTONIC, Cell is HYPERTONIC

Water Potential

a physical property that predicts the direction water will flow

• Includes the effects of solute concentration and physical pressure

Water will flow from areas of

• High WATER POTENTIAL to area to low water potential

• LOW SOLUTE to areas of high solute concentration

• HIGH pressure to LOW pressure