chapter 4-6 college biology

nuclear envelope

phospholipid bilayer, innermost surface has DNA attachment sites, pores span bilayer

nucleolus

one or more masses of dense material in the nucleus, ribosomes made

chromatin

loose DNA when cell is not actively dividing

Endoplasmic Reticulum

(in animal cells) continuous with nuclear membrane, extends throughout cytoplasm (rough+smooth)

smooth ER

interconnected tubules without ribosomes on the surface / lipid assembly, inactivates waste and drug (such as in the liver)

golgi bodies

put finishing touches on proteins and lipids arriving from the ER / package finished material

vesicles

membranous sacs that can pass through cytoplasm (lysosome+peroxisome)

lysosome

vesicle with digestive enzymes / breakdown cell parts

peroxisome

vesicle that breaks down fatty acids and amino acids / hydrogen peroxide (H2O2)

thylakoid

flattened discs in chloroplasts / photosynthesis+chlorophyll / light reactions in membrane

granum

stack of thylakoids

stroma

dark reaction center

chromoplast

(plastid) store red and brown pigments

amyloplast

(plastid) lack pigments, store starch

endosymbiosis theory

mitochondria and chloroplasts were independent prokaryotic cells that were engulfed by another cell (own DNA, RNA, ribosomes)

Plasmodesmata

channels between plant cells for communication and nutrient exchange

tight junction

type of cellular junction between animal cells that prevents leakage / very tightly packed

adhering junction

cell junction in animal cells... stretchy/present in heart tissue, skin, lungs

gap junctions

the plasmodesmata of animal cells / channels for communication and nutrient exchange

cytoskeleton

present in all eukaryotic cells / basis for cell shape and internal organization / allows movement

microtubule

largest element of the cytoskeleton / composed of protein tubulin / move chromosomes during cell division / involved in shape

microfilament

thinnest element of the cytoskeleton / composed of protein actin / take part in movement, formation, and maintenance of cell shape / cell cortex

intermediate filaments

present in certain animal tissues / most stable of the cytoskeleton / strengthen and maintain cell shape

motor proteins

attach to microtubules and microfilaments (kinesin, dynein, myosin)

centrioles

barrel-shaped structures found near the nucleus / made of microtubules / used during cell division in ANIMAL CELLS, organize microtubles in cilia or flagella

pseudopods

"false feet" (ex: amoeba) / function in locomotion and prey capture

Robert Hooke

coined the term "cell"

Robert Brown

discovered the nucleus

characteristics of life

must have cells, be able to reproduce, react to stimuli, energy, grow, evolve, maintain homeostasis, have DNA

cell

smallest unit with the properties of life

nucleus

membrane-bound organelle that contains a cell's DNA / control center of the cell

cytoplasm

everything between the plasma membrane and the region of DNA

ribosomes

molecular structures on which protein is built

prokaryotic

No nucleus (archae and eubacteria)

eukaryotic

Has a nucleus (plants, animals, protists, fungi)

chromosome

long, tight strand of DNA

rough ER

flattened sacs with ribosomes on the surface / polypeptide chains enter and are modified

mitochondria

ATP-producing powerhouse, double-membrane system / carry out most efficient energy-releasing reactions, reactions require oxygen

cristae

folds in the inner membrane of mitochondria

chloroplast

(plastid) convert sunlight energy to ATP through photosynthesis

central vacuole

stores water, amino acids, sugars, waste / 50-90% of mature plant cell interior

cell wall

structural component that wraps around the plasma membrane / occurs in plants, fungi, and some protists

transport proteins

allow materials to pass through the cell membrane using the interior of the protein; may or may not require energy

integral proteins

the general name for proteins that are physically embedded within the cell membrane

recognition proteins

act as molecular fingerprints to identify tissues or individuals

peripheral proteins

a general group of proteins positioned at the surface of the membrane

receptor proteins

bind extracellular substances that trigger changes in the cell's activity

passive transporters

proteins that allow molecules to move through the plasma membrane without expending energy

ion selective channels

contain molecular gates that move small molecules

bulk flow

mass movement of one or more substances in response to pressure, gravity, or other external force

hydrostatic pressure

the general term for a fluid force exerted against a cell wall and/or membrane enclosing the fluid

turgor pressure

term for hydrostatic pressure in plants

Exocytosis

a cytoplasmic vesicle moves to the cell surface; its own membrane fuses with the plasma membrane while its contents are released to the environment

receptor-mediated endocytosis

chemical recognition and binding of specific substances; coated pits sink into the cytoplasm and close on themselves

membrane cycling

membrane initially used for endocytotic vesicles returns receptor proteins and lipids back to the plasma membrane

Endocytosis

small patch of plasma membrane balloons inward and pinches off inside the cytoplasm

Pinocytosis

"cell drinking" / taking in liquid particles

fluid mosaic model

a composition of phospholipids, proteins, sterols, and gycolipids

phosopholipid

the primary component of the cell membrane; consists of both hydrophilic and hydrophobic regions

adhesion proteins

help cells of the same type stick together

communication proteins

Let signals travel rapidly between two adjoining cells

lipid bilayer

the double layer of phospholipids that forms the cell membrane

ATPases

use the energy of adenosine triphosphate to actively transport molecules across the membrane

osmosis

diffusion of water across a selectively permeable membrane (water concentration gradient between two regions)

Tonicity

refers to the relative solute concentrations of the fluids

hypotonic solution

the fluid one one side of a membrane that contains fewer solutes than the fluid on the other side of the membrane

hypertonic solution

the fluid on one side of a membrane that contains more solutes than the fluid on the other side of the membrane

isotonic solution

have the same solute concentration

osmotic pressure

the amount of force that prevents further increase in a solution's volume

Phagocytosis

"cell eating"...taking in solid particles / a cell engulfs microorganisms, large edible particles, and cellular debris

intermediates

compounds formed between the beginning and end of a metabolic pathway

energy carriers

Mainly ATP; donate energy to reactions

enzymes

proteins (usually) that catalyze reactions

degradative pathway

organic compounds are broken down to release energy (catabolic)

biosynthetic pathway

Complex organic compounds are built from simpler molecules (anabolic)

chemical equilibrium

the rate of the forward reaction is equal to the rate of the reverse reaction

metabolic pathway

an orderly series of reactions catalyzed by enzymes

cyclic pathway

a pathway in which the last step regenerates a reactant molecule used in the first step

entropy

a measure of the disorder of a system / measure of the amount of concentrated energy that has been dispersed in a system

Metabolism

includes all of the activities by which a cell acquires energy and materials and uses them to build, break apart, store, and release substances in controlled processes that are typical for that cell

kilocalorie

the measure of energy that can heat 1,000 grams of water from 14.5C to 15.5C at a standard pressure

chemical energy

the potential energy stored in the attractive forces (bonds) that cause atoms to group together into molecules

heat

also called thermal energy, resulting from collisions among molecules and their surroundings is a kind of kinetic energy

cofactors

small molecules and metal ions that assist enzymes or serve as carriers

transport proteins

membrane-bound substances that adjust concentration gradients in ways that influence the direction of metabolic reactions

reactants (substrates)

substances able to enter into a reaction