Ap Bio Midterm Review

Amphipathic

Contains polar (hydrophilic) and non polar (hydrophobic) regions. ex: phospholipids

Phospholipid bilayer

Consists of two layers of phospholipids with the hydrophobic tails on the inside. Allow non-polar particles to enter, but often bounces out polar particles.

Structure of Membrane

Contains phospholipids, channel/transport proteins, steroids (carbs), and proteins

Factors affecting membrane fluidity

Unsaturated lipids prevent packing and keep it fluid. Saturated lipids allow it to pack together, making it viscous. Cholesterol buffers fluidity and prevents it from being too fluid/viscous

Peripheral proteins

Proteins bound to membrane surface

Integral proteins

Hydrophobic core of the membrane

Transmembrane proteins

Span the whole membrane

Functions of membrane proteins

Transport, enzymatic activity, signal transduction, cell-cell recognition, intracellular joining, attatching to ECM and cytoskeleton

Glycolipid

Carb bounded to lipid

Glycoprotein

Carb bounded to protein

Selective permeability

Some substances can cross more easily than others. exhibited by membrane. depends on both the lipid bilayer and the specific
transport proteins it contains

Transport proteins

Allow different substances to cross the membrane (embedded in membrane) involved in facilitated diffusion and active transport.

Channel proteins

Embedded in membrane and has a hydrophilic channel that certain molecules/ions can use to move through

Aquaporins

Special types of channel protein that helps water move through

Ion channel

Special types of channel protein that helps ions move through

Diffusion

Diffusion is the movement of particles of any
substance so that they spread out evenly into the
available space (dynamic equalibrium). move from high to low conc. (down a conc. grad) through a membrane

concentration gradient

the region along which the density of a
chemical substance increases or decreases

osmosis

specific type of diffusion involving free water (water not clustered around another molecule)

Passive transport

transport of a substance across a cell membrane by diffusion (facilitated or not)

expenditure of energy is not ==required==

tonicity

is the ability of a surrounding solution to
cause a cell to gain or lose water (depends on conc. of water and other solutes that can move through membrane)

Isotonic

solution conc. is same for both, water diffuses at same rate back and forth, no net movement.
normal for animal cells. makes plant cells flaccid

hypotonic

less solute and more water. water moves/diffuses away from this area,.
causes animal cells to lyse. makes plant cells turgid (ideal condition, means firm)

hypertonic

more solute and less water. water moves/diffuses towards this area.
causes animal cells to shrivel and plant cells to plasmolyse (membrane shrivels away from walls)

osmoregulation

control of solute concentration and water balance
ex: freshwater protists using contractile vacuole to pump out excess water

facilitated diffusion

transport proteins assist in moving molecules down a conc. gradient (high to low)

gated channels

special type of ion channel that opens/closes in response to a stimulus

active transport

transport of a substance across a cell membrane against the concentration gradient by hydrolyzing ATP into ADP for energy. all proteins involved are carrier proteins enables cells to maintain solute
concentrations that differ from the environment

sodium pottasium pump

uses a phosphate from ATP to energize the transport of
K+ into the cell and Na+ out of the cell. allows our neurons to refire

membrane potential

Voltage across a membrane, created by differences in the distribution of positive and negative ions inside is neg and attracts cations inside, outside is pos and wants anions outside

electrochemical gradient

a chemical force (the ion’s concentration gradient) and an electrical force (the effect of the membrane potential on the ion’s movement) combined to drive ion diffusion across a membrane

electrogenic pump

a transport protein that generates voltage across a membrane, storing energy that can be used for cellular work (USES ATP IN THIS PROCESS)

proton pump

transports H+ ions out of the cell. assists in cotransport of sucrose back into the cell

cotransport

passive transport helps provide energy to drive the active transport of another solute

exocytosis

transport vesicles migrate to the
membrane, fuse with it, and release their contents
outside the cell

endocytosis

In endocytosis, macromolecules are taken into the
cell in vesicles & the membrane surrounds the
material for transport into a vesicle.
3 types: phago, pino, and receptor mediated

phagocytosis

a cell engulfs a particle by extending pseudopodia around it and packing it in a membranous sac called a food vacuole, and then fuses with a lysosome to digest the particle

pinocytosis

molecules are taken up when extracellular fluid is “gulped” into tiny vesicles. takes in any and all substances, nonspecific

receptor mediated endocytosis

Receptor proteins bound to specific solutes from the extracellular fluid are clustered in coated pits that form coated vesicles
Emptied receptors are recycled to the plasma
membrane by the same vesicl

cytosol

the aqueous part of the cytoplasm within which various particles and organelles are suspended.
found in all cells
located in cytoplasm

cytoplasm

where cytosol is located
found in all cells
region between plasma membrane and nucelus

nucleus

holds DNA, genetic instructions, and ribosomes. contains genes
found in eukaryotic cells
located in middle of the cell, surrounded by nuclear envelope and membrane

cell/plasma membrane

selective barrier that allows oxygen, nutrient, and waste passage to service the cell
found in all cells
located at the very outside (inside cell wall for plants)

cell wall

protects cell (prevents physical damage) and gives cell shape and structure. made of cellulose, other polysaccharides, and proteins
found in plants, fungi, protists, and prokaryotic cells.
(eubacteria made of peptidoglycan, archae dont)
located at the very outside

mitochondrion

uses oxygen to turn glucose into ATP (cellular respiration) and generates chem energy for the cell
found in eukaryotic cells
located in cytosol

chloroplast

converts light energy into chemical energy stored in sugar through photosynthesis
found in plant cells
located near cell wall in cytosol

ribosome

creates proteins by reading mRNA and translating it into amino acid string
found in all cells
bound ribosomes located outside of ER or nuclear envelope, free ribosomes located in cytosol

endoplasmic reticulum

smooth produces lipids, carbs (metabolism). rough produces ribosomes
found in eukaryotic cells
located on top of the nuclear envelope

golgi apparatus/body

processes proteins from ER (cis side), transports them to a new location (trans side), modifies and packages proteins in vesicles
found in eukaryotic cells
located near the nucleus

lysosome

cells digestive system that can also recycle old materials through hydrolysis. some come from golgi trans face. destroy worn out parts (autolysis) and programmed cell death (autopsis) can fuse w fuel vesicle and digest contents
found in animal cells
located in cytoplasm

central vacuole

a resivoir/waste dump, storage for water and waste, maintains water pressure, and keeps the cell in shape
found in eukaryotic cells (big in plants small in animals)
located in center of cytosol

centrosome

region where cells microtubules are initiated provides structure. centriole pairs help in cell division
found in animal cell
located near nuclear envelope

nucleoid

area of DNA with no nuclear envelope
found in prokarytic cell
located in the center

flagellum

motility structure composed of some microtubules (plasma membrane extension) that helps it move
found in bacterial, animal, and protist cells
located at the pole of the cell

peroxisome

specialized metabolic functions, takes hydrogen peroxide and converts it to water and oxygen. area for oxidation reactions, lipid biosynthesis, and cholesterol synthesis
found in eukaryotic cells
loocated in the cytoplasm

nucleolus

site of ribosome production. 1+ in a nucleus
found in eykaryotic cells
located in center of nucleus

chromatin

coil and condense to form chromosomes, which make DNA replication, etc possible. visible in a dividing cell
found in all cells
located in nucleus

plasmodesmata

cytoplasmic channels through cell walls to connect cytoplasm of adjactent cell, enables transport
found in plant cells
located in cell wall

contractile vacuole

a vacuole that discharges fluid and water from cells
found in freshwater protist cells
located in center of cell

cilia

hairlike fringe on a cell that helps it move through water
found in animal and protist cells
located on cell surface

tight junctions

establish a barrier between outer cell layers that prevents leakege of fluid, regulates solute movement
found in animal cells
located at the border between apical and lateral membranes

gap junctions

consist of membrane proteins. has pores to allow small molecules to pass through, enable cell comunication.found in animal cells
located between plasma membranes

desmosomes

ashesion zone to fasten cells together like rivets, made of sturdy keratin proteins (in muscles to prevent tears)
found in animal cells
located along lateral membrane

cytoskeleton

protein microtubules, intermediate filaments & microfilaments to provide strength and shape to cell and anchor cell in place
found in eukarytic cells
located in cytoplasm

ECM

made up of glycoproteins such as
collagen, proteoglycans, and fibronecti

Sulfhydryl

-SH, polar. 2 SH can react, forming a cross link

Hydroxyl

-OH, polar. Found in alcohols, tend to make substances dissolve in water.

Carbonyl

C\=O, polar

Ketone

C\=O in the middle

Aldehyde

C\=O at the end

Carboxyl

COOH, polar. Acts like an acid (donates H+ ions and lowers PH)

Amino

NH2, acts like a base (picks up H+ ions and increases PH)

Phosphate

-OPO3^-2, Polar in 2 places, often involved in energy reactions (ATP)

Methyl

-CH3, nonpolar

Polymer

A long molecule consisting of many similar or identical monomers linked together.

Monomer

A simple compound whose molecules can join together to form polymers

dehydration synthesis

A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule.

Hydrolysis

Breaking down complex molecules by the chemical addition of water

Enzyme

A type of special macromolecule that speeds up a chemical reaction (making and breaking polymers)

Carbohydrates

Sugars and polymers of sugars

Monosaccharides

Simple sugars. Usually have multiples of CH20. serve as a major fuel for cells and as raw material for building molecules

Glucose

Most common monosaccharide. C6H12O6

Disaccharide

A double sugar, consisting of two monosaccharides joined by dehydration synthesis.

glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction.

Polysaccharides

Carbohydrates that are made up of more than two monosaccharides. Have storage and structural roles. Structure and function are determined by its sugar monomers and position of glycosidic linkages.

Starch

A storage polysaccharide in plants consisting entirely of glucose. Simplest form is amylose. helical structure.

Glycogen

An extensively branched glucose storage polysaccharide found in the liver and muscle of animals

the animal equivalent of starch. Hydrolysis of glycogen releases glucose when needed

Cellulose

polysaccharide consisting of glucose monomers that reinforces plant-cell walls. straight and unbranched structure

alpha and beta ring structures

Hydroxyl group attached in different position
(in alpha the hydroxyl group is attached to number 1 carbon below the plane of the ring, in beta the hydroxyl group is attached to number 1 carbon above the plane of the ring)

Chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.

Lipids

one class of large biological molecules that does not include true polymers. Unifying trait is that they all mix poorly with water. consist mainly of hydrocarbons

Fats

constructed from two types of smaller molecules: glycerol and fatty acids

glycerol

a three-carbon alcohol with a hydroxyl group attached to each carbon

fatty acid

carboxyl group attached to a long carbon skeleton

triaclyglycerol/triglyceride (fat)

3 fatty acids and 1 glycerol molecule
ester linkage between glycerol and each fatty acid chain (dehydration synthesis)
hydrophobic molecule

ester linkage

The linkage formed between the glycerol molecule and the fatty acids in a fat is the ester linkage. This bond is formed through dehydration synthesis.

saturated fatty acid

A fatty acid in which all carbons in the hydrocarbon tail are connected by single bonds. solid at room temp. found in animals

unsaturated fatty acid

A fatty acid possessing one or more double bonds between the carbons in the hydrocarbon tail. liquid at room temp. found in plants and fish

Hydrogenation

The process of converting unsaturated fats to saturated fats by adding hydrogen (trans fats)

Phospholipids

a lipid consisting of a glycerol bound to two fatty acids and a phosphate group. phosphate group and attatchments form a hydrophilic head, but fatty acid chains are hydrophobic.

phospholipid bilayer

A double layer of phospholipids that makes up plasma and organelle membranes. boundary between cell and external environment