Biology Exam 2

Kinetic energy

the energy of motion. A hydroelectric dam converts the----of flowing water to electrical energy 

Heat (thermal energy)

kinetic energy associated with random movement of atoms or molecules  

Potential energy

the energy that matter possesses due to its location or structure 

Chemical energy

a form of potential energy stored in a molecule, due to the particular arrangement of its atoms 

First law of thermodynamics

the energy of the universe is constant, energy can be transferred and/or transformed, but it cannot be created or destroyed

Second law of thermodynamics

every energy transfer or transformation increases the entropy (disorder) of the universe, during energy transfer or transformation, some energy is lost as heat 

Anabolism

require input of energy to build complex molecules from simpler molecules

Example of anabolism

Synthesis of proteins from amino acids 

Catabolism

release energy by breaking down complex molecules to simpler molecules

Example of catabolism

Cellular respiration, the breakdown of glucose to carbon dioxide and water 

Metabolism

is all of the chemical reactions that occur in a cell to assemble, disassemble, or modify the cell’s molecules, the totality of an organism’s chemical reactions  

Three types of Endocytosis 

* Phagocytosis (“cellular eating”) 
* Pinocytosis (“cellular drinking”)  
* Receptor- mediated endocytosis 

Phagocytosis

cellular eating

Pinocytosis

cellular drinking

receptor

mediated endocytosis

endocytosis, exocytosis

the cell takes in macromolecules from outside to inside. ----- is a reversal of ------, involving different proteins. 

exocytosis

cells secrete/excrete certain molecules from inside to outside

Sodium-potassium pump and how it functions-1

Cytoplasmic Na+ bonds to the sodium-potassium pump 

Sodium-potassium pump and how it functions-2

Na+ binding stimulates phosphorylation by ATP 

Sodium-potassium pump and how it functions-3

Phosphorylation causes the protein to change its conformation, expelling Na+ to the outside 

Sodium-potassium pump and how it functions-4

Extracellular K+ binds to the protein, triggering release of phosphate group 

Sodium-potassium pump and how it functions-5

Loss of the phosphate restores the protein’s original conformation 

Sodium-potassium pump and how it functions-6

K+ released and Na+ sites are receptive again; the cycle repeats  

Passive Transport

is a naturally occurring phenomenon and does not require the cell to expend energy to accomplish the movement. 

in Passive transport

substances move from an area of higher concentration to an area of lower concentration in a process called diffusion. 

Active Transport

uses energy to move solutes against their gradients 

Active transport functions

* Moves substances against their concentration gradient 
* Allows cells to maintain concentration gradients that differ from their surroundings 
* Requires energy usually in the form of ATP  
* Performed by specific proteins embedded in the membranes Ex. Sodium-potassium pump 

Hypertonic Solution 

* Animal cell: Shriveled  
* Plant cell: Plasmolyzed  

Isotonic Solution 

* Animal cell: Normal state 
* Plant cell: Flaccid (limp) 

Hypotonic Solution 

* Animal cell: Lysed 
* Plant Cell: Turgid (firm) normal state 

What happens when you place plant cell into hypertonic solution? 

plant cells lose water; eventually, the membrane pulls away from the wall, a usually lethal effect called plasmolysis  

Diffusion (the spreading of something more widely)

water diffuses across a semipermeable membrane from region of lower solute concentration to region of higher solute concentration until the solute concentration is equal on both sides 

Osmosis

the movement of water across a semipermeable membrane 

Hypotonic-

solute concentration is less than that inside the cell; cell gains water 

Hypertonic

solute concentration is greater than that inside the cell; cell loses water 

Isotonic

solute concentration is the same as that inside the cell; no net water movement across the plasma membrane 

Tonicity

the ability of a surrounding solution to cause a cell to gain or lose water 

Attachment to cytoskeleton and extracellular matrix (ECM)

Microfilaments or other elements of the cytoskeleton may be bonded to membrane proteins, a function that helps maintain cell shape and stabilizes the location of certain membrane proteins

Intercellular joining-

Membrane proteins of adjacent cells may hook together in various kinds of junctions, such as gap or tight junctions 

Cell-cell recognition

Some glycol-proteins serve as identification tags that are specifically recognized by other cells 

 Signal Transduction

A membrane protein may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. The external messenger (signal) may cause a conformational change in the protein (receptors) that relays the message to the inside of the cell.  

Enzymatic Activity

A protein built into the membrane may be an enzyme with its active site exposed to substances in the adjacent solution. In some cases, several enzymes are organized as a team that carries out sequential steps of a metabolic pathway.  

Transport-

A protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute. Other transport proteins shuttle a substance from one side to the other by changing a shape. Some of these proteins hydrolyze ATP as an energy source to actively pump substances across the membrane. 

6 major functions of membrane proteins.

\-Transport

\-cell-cell recognition

\-enzymatic activity

\-signal transduction

\-intercellular joining

\-Attachment to cytoskeleton and extracellular matrix (ECM)

Cholesterol

* reduces membrane fluidity at moderate temperature by reducing phospholipid movement,


* at low temperature it hinders solidification by disrupting packing of phospholipid 

Phospholipids

* when in the plasma membrane they can move within the bilayer
* The type of hydrocarbon tails in---- affects the fluidity of the plasma membrane

Common features between prokaryotic and eukaryotic

* Enclosure by a semi-permeable plasma membrane, which is composed of amphipathic lipid molecules 
* At least 1 DNA chromosome, that contains the genes  
* Molecular machineries for replicating the chromosomes and dividing the cell into “daughter” cells  
* Molecular machinery for producing RNA, using genes as templates that govern the RNA sequence 
* Ribosomes and RNA, which are molecular “interpreters” that read mRNA sequence and assemble amino acids into proteins 
* Aqueous cytoplasm 

Prokaryotes

* all contents of the cell, including the DNA, reside in the cytoplasm 
* if something lies physically within the boundary of the plasma membrane, it is in the cytoplasm  

Eukaryotes

\-there are many membrane-bound compartments submerged in the cytoplasm, their aqueous contents are not cytoplasm  

\-cells are typically 10-100 micrometers in diameter 

\-cell’s cytoplasm surrounds a variety of membrane-bound organelles that are highly specialized in form and function 

prokaryotes

The cytoplasm of a ----- cell is water that contains many water-soluble molecules. There are no organelles 

The endoplasmic reticulum (ER)

accounts for approximately half the total membrane mass in a eukaryotic cell, comprised of an enormous number of sac and tumbles

ER membrane

a phospholipid bilayer in the same basic design as the plasma membrane

major difference between the plasma and ER membrane

cholesterol content

smooth ER is the site of

\-lipid synthesis

\-detoxification of many compounds

rough ER is the site of

synthesis for proteins that must be shipped to certain organelles, the cell surface, or fully out of the cell

rough ER

its appearance to microscopists, they found out it is coated with ribosomes on its cytoplasmic surface

ribosomes

“machines“ that perform protein synthesis, in the cytoplasm, using mRNA as a template

what subunits is the ribosome made of

large subunit and small subunit

True

Of proteins synthesized in the ER lumen, most, (NOT ALL) are shipped onward to the golgi apparatus

vesticular transport

protein movement that requires vesicles to “pinch off” from an organelle, travel across the cytoplasm to another organelle and fuse with it

the role of golgi apparatus in cells

* a central “distribution warehouse”for proteins imported from the ER
* site of most carbohydrate synthesis in the cell
* site of extensive oligosaccharide addition to certain proteins

Lysosomes

* are compartments of hydrolytic enzymes
* has a single phospholipid bilayer that separates the lysosome lumen from cytoplasm

hydrolytic enzymes

digest proteins, lipids, carbohydrates, nucleic acids, etc.

nucleus

* contains most of the cell’s genes

nuclear envelope

encloses the nucleus, separating it from the cytoplasm

nuclear membrane

a double membrane; each membrane consists of lipid bilayer

pores

regulate the entry and exit of molecules from the nucleus

nuclear lumina

maintains the shape of the nucleus which is composed of protein

chromatin

in the nucleus, DNA and proteins form genetic material called….

condenses to form discrete chromosomes

chromatin

nucleolus

located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis

lysosomal enzymes; phagocytosis

can hydrolyze proteins, fats, polysaccharides and nucleic acids

* some types of cell can engulf another cell by…..; this forms a food vacuole
* fuses with the food vacuole and digests the molecules

true

lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules a process called autophagy

true

lysosomal storage diseases demonstrate the critical role of individual proteins

tay-sachs disease

lysosome

causes neurological problems and blindness by age 2 and typically fatal by age 3

mitochondria

* have a smooth outer membrane and an inner membrane folded into cristae
* the inner membrane creates two compartments: intermembrane space and mitochondrial matrix

false

metabolic steps of cellular respiration ARE NOT catalyzed in the mitochondrial matrix

cristae

present a large surface area for enzymes that synthesize ATP

true

a plant cell or fungal cell may have one or several vacuoles

food vacuoles

formed by phagocytosis

contractile vacuoles

found in many freshwater protists, pump excess water out of cells

central vacuoles

found in many mature plant cells, hold organic compounds and water

chloroplasts

* contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis
* found in leaves and other green organs of plants and in algae

Thylakoids

* chloroplast structure
* membranous sacs
* stacked to form a granum
* stroma, internal fluid

peroxisomes

* specialized metabolic compartments that produce hydrogen peroxide and convert it to water
* oxygen is used to break down different types of molecules

Refsum’s disease

storage disease of peroxisomes

roles of cytoskeleton

motility, regulation and support

true

other peroxisomes detoxify alcohols and other compounds

glyoxysomes

specialized peroxisomes, convert fatty acids in seeds to sugars

cytoskeleton

* a network of fibers extending throughout the cytoplasm
* organizes the cell’s structures and activities, anchoring many organelles

what are the 3 types of molecular structures in the cytoskeleton

* microtubles
* microfilaments
* intermediate filaments

centrosome

* a “microtubule-organizing center”
* in animal cells, it has a pair of centrioles, each with 9 triplets of microtubules arranged in a ring

microtubules

control the beating of cilia and flagella, locomotor appendages of some cells

false

cilia and flagella share similar in their beating patterns

how are cell boundaries made possible?

by water’s polarity and a special type of amphipathic molecule: phospholipid

phospholipids-

similar to fat molecules except that 1 of the 3 fatty acids has been replaced by a hydrophilic, phosphate containing group

Hydrophobic molecules/non charged ions

are lipid soluble and can pass through the membrane rapidly

Polar molecules such as water

do not cross the membrane rapidly. Water has a special carrier protein for transport, called ‘aquaporin’.

Charged ions/molecules

can not get in/outside without a carrier.

The free-energy change (∆*G*)

* Biologists measure changes in free energy to understand the chemical reactions of life.
* \